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Barrel expected degradation due to usage (Page 1 of 2)
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Posted: 1/21/2026 2:17:37 PM EDT
[Last Edit: AR-Zen][Edited]
| I purchased a brand new Sig Sauer M400 Tread-V2 AR-15 rifle about a year ago, and since then, I shot about 2500 rounds with it. The rifle has a standard original stainless steel 16” 5.56 barrel. I perceive about 0.25 to 0.5 MOA loss of precision over this time. Is it expected that the barrel precision drops by that much after 2500 rounds, or not? |
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It's not really a question that can be answered based on the info given. Firing schedule (how fast you fire and how hot the barrel gets) has much more effect of barrel degradation than just the total round count. And then there is the consideration on the type of wear, the effect it has on the bullet you're using, and a whole bunch of other complex internal ballistics considerations. |
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Just because you perceive 0.5moa difference in accuracy doesn’t mean it’s all due to barrel wear Even a different lot of same ammo can affect accuracy.. If you’re talking about 2.5k rounds without cleaning then it’s time to do some maintenance. |
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Originally Posted By Nobody69s: Maybe try some bore paste and copper remover to "reset" the barrel. It's helped on some of mine. This. And as mentioned the firing rate schedule can certainly effect a barrels wear. |
*Hold on to your AR-15s. Their magic must be very powerful, or they wouldn’t want them.*
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How are you shooting, that you perceive a .25/.50 moa change? Competitors shooting service rifle usually ditch their barrels after about 3K rounds, because they start to throw fliers at 600 yards. That being said, how it's used and cleaned can have an impact on how long it will last. I don't think I've ever worn out a barrel, but I have a stack of them that I don't trust any more. |
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Mag dumps damage barrels. Imagine sticking a blow torch in your chamber and introducing 30 62,000 PSI pressure waves back-to-back. Ammo selection? .25 to .50 moa difference using M193/M855 is irrelevant, .25 to .50 using match grade ammo isn't the end of the world. I started reloading in 1984 because I was so disappointed with FMJ ammo at that time. Match grade bullets are amazing in comparison. Already mentioned was thoroughly cleaning the barrel. Kroil and JB Bore Compound, especially in the throat, Wipe-Out for general barrel cleaning. The USAMU swaps competition barrels at 3000 rounds because they want zero chance of a barrel going south during a tournament. Most precision AR barrels will shoot well in competition to 5000+ rounds. 10,000+ rounds for general blasting purposes after that. Has your bench technique changed? Have you tried bags instead of a bipod? For such a small increase in moa, I wouldn't be concerned. |
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If you see noticeable degradation, get a new barrel. The cost of a barrel replacement is trivial compared to the ammo cost to wear it out. How long a barrel lasts depends on how you use it. Run it like you stole it, it won’t last as long as if you baby it. 2000 rounds of mag dumps is not the same as 2000 rounds of slow fire. |
Not fly enough to be halal....
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Originally Posted By AR-Zen: With the same setup, the same location, and the same ammo, my groups at 100 yards are about .25 to .5 MOA larger than they were before. Yeah but from .75 MOA to 1.25 MOA or 2MOA to 2.25 MOA? Did you do any bump firing or rapid fire during the 2500 rounds? When did you last decopper the barrel? By what method? What is your standard cleaning schedule/procedure? Have you fired any 100% copper hunting bullets through your barrel and gone back to jacketed bullets? Is this the same lot of ammo or a different lot of the same brand/weight? Was there an ambient temperature difference between the first groups and the current groups? Summer vs winter? All these questions need to be answered. But yes, it is possible you have that level of barrel wear to open groups up... but it is FAR more likely it is something else. |
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Originally Posted By DevL: Yeah but from .75 MOA to 1.25 MOA or 2MOA to 2.25 MOA? Originally Posted By DevL: Yeah but from .75 MOA to 1.25 MOA or 2MOA to 2.25 MOA? From .75 MOA to 1.25 MOA. Originally Posted By DevL: Did you do any bump firing or rapid fire during the 2500 rounds? My typical rate of fire is about 1 shot every 20 seconds or so. Originally Posted By DevL: When did you last decopper the barrel? By what method? What is your standard cleaning schedule/procedure? I've never decoppered the barrel. For cleaning, I typically used a bore snake soaked in Hoppe's Number 9 to clean the barrel. But I've discovered that after using the bore snake, if I run a cleaning rod with a patch, there is still a large amount of deposits left in the barrel. So, I'll use the cleaning rod with patches from now on. The barrel is clean now, so I am going to retest the same ammo this weekend. |
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If the ammo isthe same lot and temperatures the same... Then I am 100% confident this is copper fouling. You need to strip the copper 100% to bare metal. You will not be able to do this with a bore snake. Get a bore guide and a one piece coated rod. Get a NYLON bore brush and a piercing style jag made of stainless. You will need to use a strong copper solvent/remover. You can use Wipeout for convenience as a first step. You can use Boretech copper remover as a non-abrasive, non-ammonia based solution, but the most powerful will be ammonia based or abrasive copper removers.. and this cleaning will take a LONG time. Set aside a couple hours on a weekend to do it right and not get distracted. For abrasives, use IOSSO or JB bore cleaning pastes. And not the finer grit with red writing, JB bore bright... the regular non embedding blue writing JB. For ammonia based solvent, I prefer Sweets 7.62 but you have to be careful about not letting it sit in your barrel. For example, getting distracted to take care of something else while it is in your bore and forgetting about it until that night or the next day. Clean as per usual then clean with copper removal stuff. You will see a blue green substance if copper still exists. If you use an uncoated brass rod, uncoated brass jag, but especially an uncoated bronze brush on brass twisted wire, you will get unlimited false positives for copper as the copper solvents eat the copper out of your rod, brush, and jag. Eventually, you will run a Sweets 762 soaked brush back and forth through your barrel, run a wet Sweets 762 patch through your bore, let it sit, and run a dry patch through the bore and it will come out NOT blue/green. That is when 100% of the copper is gone. It will take a LONG time and MANY applications. After that, swab with a normal bore cleaner or oil of your choice to ensure all the Sweets is gone. Your first shot will be WAY off when you go shoot again and your accuracy and SD won't settle down for between 3 to 20 rounds, until the bore gets a uniform copper coating again. So don't expect your group size to be back down on your first 5 shot group... it won't be, but you will know the results on group #5 and beyond for certain. You should then be good for another 1000-2500 rounds with just cleaning carbon. Also. know that a big change in copper alloy getting laid down from all copper bullets, like Barnes TSX or Hornady GMX, can screw up accuracy for up to 100 rounds when you swap back to jacketed bullets or until you decopper the barrel again. |
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Originally Posted By DevL: Eventually, you will run a Sweets 762 soaked brush back and forth through your barrel, run a wet Sweets 762 patch through your bore, let it sit, and run a dry patch through the bore and it will come out NOT blue/green. That is when 100% of the copper is gone. It will take a LONG time and MANY applications. I've decided to use Bore Tech CU copper remover instead of Sweets 762, because Bore Tech stuff is not toxic, and it has good reviews. Got through probably 30 patches and about 5 rounds of nylon brush cycles, and spent like 2 hours so far. The patches still come out bright blue. 
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Originally Posted By AR-Zen: I've decided to use Bore Tech CU copper remover instead of Sweets 762, because Bore Tech stuff is not toxic, and it has good reviews. Got through probably 30 patches and about 5 rounds of nylon brush cycles, and spent like 2 hours so far. The patches still come out bright blue. https://i.imgur.com/6asDqjV.png DevL gave you excellent advice. However, the picture shows that you are using brass nylon brush and brass ended cleaning rod. To remove copper from the barrel use these: https://www.boretech.com/proof-positive-bore-stix-jags/ The cleaning rod can be stainless steel, does not have to be coated. |
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Originally Posted By Richard257: DevL gave you excellent advice. However, the picture shows that you are using brass nylon brush and brass ended cleaning rod. To remove copper from the barrel use these: https://www.boretech.com/proof-positive-bore-stix-jags/ The cleaning rod can be stainless steel, does not have to be coated. Yep, I switched to this nylon brush:  However, the tip of my Tipton Deluxe cleaning rod is still brass. |
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| When we went from using GAU-5's to M4's in 1983 in the Air Force they would gauge the barrels every six months and replace as necessary. Some of the GAU-5's with a 1:12 twist would yaw the projectiles ever so slightly. Would damage what it hit. I don't know how many rounds had gone through them, they were viet nam era rifles. I call the replacements m4's, but they had 16" CP barrels, chambers CP, 1:7 twist, fixed carrying handles, collapsible stock. They did not have a three shot burst, just full auto. From what I gathered the Barrels lasted longer that expected. My understanding is that stainless steel wears differently that Chrome moly or Chrome plating. |
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Originally Posted By bfoosh06: This. And as mentioned the firing rate schedule can certainly effect a barrels wear. Originally Posted By bfoosh06: Originally Posted By Nobody69s: Maybe try some bore paste and copper remover to "reset" the barrel. It's helped on some of mine. This. And as mentioned the firing rate schedule can certainly effect a barrels wear. This. I recall as a young man my shooting buddy bought a Remington Varmint rifle in .243 Winchester. After having it about two years the accuracy was a lot less than it was. He was relatively anal about cleaning it with the standard Hoppes everyone used back in the 80’s. He was talking to the older counter guy at the gun shop about maybe a rebarrel job. The man had been around of course and walked him over to the cleaning supplies and grabbed a botttle of Shooter’s Choice copper solvent. Back then it Shooter’s Choice or Sweet’s as options. He told him to plug the muzzle with a couple tight patches and stand the gun up in the corner on its muzzle and fill the bore with the Shooter’s Choice and let it sit over night. He got a shitload of blue green goop out the next day and he repeated it and got some more goop out a couple days later. Of course it went back to sub moa shooting. Copper build up needs attention after a certain point. |
The only hyphenated names I like are cartridge names......30-06, 30-40, 38-55 etc.
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Oh and ditch the pull cord for your regular cleaning. A good rod is not expensive. I have probably a dozen different high quality cleaning rods, after breaking Hoppes rods through the years I went to Dewey coated rods, then un coated rods, then switched to ProShot un coated rods. No ragerts. I have those and the no bronze or brass jags to use with copper solvent. They’re not a 100% necessary but over time if you don’t rinse brass jags after using copper solvent they will get eaten slowly. Rinsing your brushes and jags in a jar of rubbing alcohol is not a bad practice. Cleans them and gets rid of copper solvent that will eat a copper brush. I buy Nylon bristled brushes for copper solvent and Brownells heavy duty copper brushes. The modern Hoppes brushes are cheap junk compared to what they were in the 70’s and 80’s. There’s barely any bristles in them now. Compare one from your grandpa’s old cleaning kit to a current one. The new ones have no bristles to speak of, they’re thinner copper wire and the wound core is cheap aluminum with a cut off sharp tip. The old ones were a brass core with a loop tip that won’t damage anything like a bolt face if you ill advisedly clean toward the chamber. Buy them by the half dozen or ten pack, whatever from Brownells, or directly from ProShot, Iosso, or another good brand Kleenbore. They’re cheaper in bulk than bubble packed Hoppes on the wall at your local gun shop or Walmart. |
The only hyphenated names I like are cartridge names......30-06, 30-40, 38-55 etc.
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Originally Posted By kwb377: You're getting (or were getting) consistent sub-MOA groups out of a Sig M400 Tread? |
Point shooting will give you monkeypox. - John_Wayne777
The Emu War could have been won if the Australians used red dots on their handguns.
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Originally Posted By kwb377: You're getting (or were getting) consistent sub-MOA groups out of a Sig M400 Tread? Originally Posted By kwb377: Originally Posted By AR-Zen: From .75 MOA to 1.25 MOA. You're getting (or were getting) consistent sub-MOA groups out of a Sig M400 Tread? 
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Not fly enough to be halal....
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Barrel life depends a lot on heat which comes from how fast you're shooting and how long you're giving it time to cool down. I wouldn't worry too much though about this idea because just shooting a couple of rounds can quickly heat the barrel up and give the illusion it's "too hot." I would say if you shoot a typical 120-150 rounds per session, and you're shooting maybe like 3-4 rounds at a time and pausing or whatnot, then you're likely fine. If you want to do it per military manual, just count to 12 each time after you shoot and it should operate normally. But as far as accuracy issues, there's a lot of factors that can come into play with that as well. Personally I would get a good bore solvent and just make sure everything is as clean as feasible. Personally my view is that barrels are disposable items on the rifle as much as people don't want it to be. I went through two barrels in my life time. The first one went at about the 10k mark shooting mostly Tulammo, then my second barrel just started to keyhole about 13-15k rounds area. I shot a lot between 22-24 timeframe but after my second barrel, I tried to rebarrel but for some reason it never could work again which sucked. Ultimately it took me over a year and some to get my rifle back to working condition trying to figure out each small area. I would say your barrel should have decent accuracy for about 10-20k. From my view, it doesn't shift that much from when you got it and then it suddenly, and without warning, goes. One day you'll be shooting and it'll be accurate as it was the day you got it, then next round it'll be wild and crazy keyholes and spraying like a shotgun. If you're noticing subtle changes, chances are it's ammo, dirty, or both. Keep in mind I'm a casual shooter though. Someone who wants a sub moa rifle might start noticing their barrel is out sooner even though it might still be perfectly usable. With that said, if you want a sub-moa rifle all the time, then it sounds like getting a SIG rifle is a very bad idea and you should go with a nice SS barrel that can keep sub-moa out to about 8-10k rounds and more. |
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Originally Posted By AR-Zen: I perceive about 0.25 to 0.5 MOA loss of precision over this time. Is it expected that the barrel precision drops by that much after 2500 rounds, or not? How often do you clean it? How do you clean it? Do you have nylon chamber and bore brushes? Have you done a copper scrub? |
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To all: In an effort to help you consider the OP's experience level and evaluate his accuracy claims here's the various threads he's started lately: Heres a bore scope thread and his discovery of a gas port: https://www.ar15.com/forums/AR-15/wtf-is-this-thing-in-my-barrel-/12-792919/ Here's the 77 Berger: https://www.ar15.com/forums/AR-15/Range-Report-Berger-223-77gr-OTM/16-792712/ Here's the 73 Berger: https://www.ar15.com/forums/AR-15/Range-Report-Berger-73gr-BT-Target/16-792763/ Here's the 69 SMK and a discussion about the rifle set up: https://www.ar15.com/forums/AR-15/Range-Report-Federal-Gold-Medal-SMK-BTHP-69-grain/16-792689/ Here's the Remington 77MK: https://www.ar15.com/forums/AR-15/Range-Report-Remington-Premier-Sierra-MatchKing-BTHP-77-Grain/16-792590/ And some 50yd groups: https://www.ar15.com/forums/AR-15/Range-Report-Berger-77-Grain-OTM-Tactical-only-best-group-50-yards-/16-792532/ OP- AR-zen: With all due respect, and I'm nobody to you and you are nobody to me, here's my honest comments: Your groups with the variety of ammo are much larger than 5 shot groups you seem to be "cherry picking." When I look at the aggregates, you're around 2 MOA, which is more the norm for your set up. Part of why I say this is the fact you are shooting at 100yds and 5 shot groups. Me, just my humble opinion only, shooting 5 shot groups and making some accuracy claim is a waste of time. Now you seem to have taken up the advice here and cleaned the crap out of the barrel. Maybe that will help. maybe it wont. Could you shoot some nice 10shot groups, preferable 2? So 20rds? Same aiming point. no 0.1-0.3 MIL elevation shifts nothing. Just settle in and shoot a 10 shot string. And post it. Please? PS: again just my 2% FWIW, 2500rds is nothing for a 100yd test. I've shot quality AR barrels out to 1000yds with that many rds on them. And I couldn't discern a barrel issue affecting accuracy. So I'm VERY skeptical if at 100yds, having that round count on it would matter. |
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Originally Posted By TGH456E: Could you shoot some nice 10shot groups, preferable 2? I don’t understand what you are trying to prove. Would my 10-shot groups have larger extreme spread than my 5-shot groups? Of course they would, it’s just the law of statistics. If a 5-shot group is 1 MOA, the 10-shot group is expected to be 1.24 MOA. To that end, I would not even use the extreme spread as the measure of accuracy for the 10-shot groups. Something like mean radius would be a much better measure. |
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| Try KG-12. You can buy it directly from the company. Read about it. Military uses it to clean artillery pieces. I run a patch of it down the bore and let it set overnight to dissolve the copper. Depending on the bore fouling you may have to do it again. You won't see pretty blue streaks on the patch like shooters choice. Use a one piece carbon graphite rod with brass jags. Don't use aluminum cleaning rods. They oxidize creating aluminum oxide. Same stuff as what's on most sand paper. |
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Originally Posted By AR-Zen: I don’t understand what you are trying to prove. Would my 10-shot groups have larger extreme spread than my 5-shot groups? Of course they would, it’s just the law of statistics. If a 5-shot group is 1 MOA, the 10-shot group is expected to be 1.24 MOA. To that end, I would not even use the extreme spread as the measure of accuracy for the 10-shot groups. Something like mean radius would be a much better measure. I'm not trying to prove anything. -By shooting 10 shot groups, I could then compare them to others who have tested the same ammunition, including me. -Statistically, in regards to shooting, it's about shooting a large as possible number of rounds to evaluate said ammunition. To that end a 5 round group means nothing. -Who said I was interested in the ES of your groups? I didn't. -With 10 shot groups (even better at 200yds) you can start to "see" how the ammunition is working, eg. vertical stringing or multiple groups. -For the reasons above, instead of cobbling your 5 shots groups together, I could just look at them. -A common internet "thing" is to post a 3 or 5 rd groups and declare some accuracy "Fact." And the common response is to say that person is "cherry picking" groups. The easiest way to then avoid the moniker is to shoot 10rd groups. -Lastly, if you can shoot a .5 MOA group with 5 shots, why can't you shoot it with 10? What I mean is, I have no idea where you got this: "...If a 5-shot group is 1 MOA, the 10-shot group is expected to be 1.24 MOA......." Where did you get that from? Please quote your source. |
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Originally Posted By TGH456E: -Lastly, if you can shoot a .5 MOA group with 5 shots, why can't you shoot it with 10? What I mean is, I have no idea where you got this: "...If a 5-shot group is 1 MOA, the 10-shot group is expected to be 1.24 MOA......." Where did you get that from? Please quote your source. If you want a deep dive into the underlying math, here is a good paper: https://link.springer.com/article/10.1186/1471-2288-14-135#Abs1 This is a little lighter on the math: http://ballistipedia.com/index.php?title=Range_Statistics And this is more conversational between the shooters: https://forum.accurateshooter.com/threads/converting-3-shot-group-size-to-5-and-10-shot-group-size.4117551/ |
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An anecdote. Couple decades ago picked up two used Colt 11.5" A1 (1:7") complete uppers from CDNN. No idea re prior use/round counts, but exterior finish was "fair". Planned to use them as MG blasters. One has seen higher use and is now well past 20k rounds, mostly steel-cased black box poly. No beta drums, few D60 dumps, vast majority of use via 20 or 30 rd mag dumps. Maybe 1% semiauto range firing. Our typical firing sequence limited rounds to 100 to 150 rds followed by a cool-down, switch uppers, etc. But at the end of one VT shoot (barrel around 16k) let the work crew run the gun until nobody could hold the fat plastic handguards. Dunno......500 rds? Back home decided to bench test. Had been stable around 5-6 MOA, was now 12 MOA. At least there was no tumbling with M193 or M855. Good. Bore scope revealed lumps.....repeat.....lumps of carbon/metal fouling. Wish I'd taken before pics. What followed was a full week of sequential Kroil/USP paste sessions till it appeared clean. Back at the range....3-4 MOA with M193 or M855. At 2.5k with a softer firing schedule, and assuming the loss of precision is factual, suggest getting serious with abrasives (as others have already suggested). |
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Idk about 223 but my 308 bolt gun that I was using for long range started opening up at 3800-4000 rds. I had to switch from 178eldx to 175gmm to get my groups back to sub moa. Then after 4000 it was very difficult to stay sub moa and at 4200-4300 I sold it to a guy that hunts hogs. He loves it saus it shoots fine. But I watched to go from .5moa to a little over 1moa in that time frame. I'd suspect ar15s are gonna open up fast just because you typically get the barrels hotter. And the rounds are faster. I lost count of the rd count on my primary ar15 its likely about 1k if that. |
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Originally Posted By Samuel_Hoggson: At 2.5k with a softer firing schedule, and assuming the loss of precision is factual, suggest getting serious with abrasives (as others have already suggested). I decided to not use abrasives for now, but I did construct this apparatus (shown below) to speed up the cleaning process. There is a nylon brush at the end, and yes, I did use the bore guide when using this.  The barrel is super clean now. I'll shoot it this weekend to see the effect. I am predicting at least a few of the 0.7" 5-shot groups. |
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Originally Posted By Samuel_Hoggson: Bore scope revealed lumps.....repeat.....lumps of carbon/metal fouling. Wish I'd taken before pics. What followed was a full week of sequential Kroil/USP paste sessions till it appeared clean. Attached File |
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Originally Posted By AR-Zen: I decided to not use abrasives for now, but I did construct this apparatus (shown below) to speed up the cleaning process. There is a nylon brush at the end, and yes, I did use the bore guide when using this. https://i.imgur.com/FxdgMIr.png The barrel is super clean now. I'll shoot it this weekend to see the effect. I am predicting at least a few of the 0.7" 5-shot groups. That’s absolutely an option which exists. |
Point shooting will give you monkeypox. - John_Wayne777
The Emu War could have been won if the Australians used red dots on their handguns.
The Emu War could have been won if the Australians used red dots on their handguns.
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Originally Posted By HighpowerRifleBrony: Like this? https://www.ar15.com/media/mediaFiles/379478/20220413045639_jpg-3712082.JPG Yup, but add some larger carbon goobers dispersed throughout the length. It cleaned up pretty well, still a bit left in the throat. The first 3" or so of rifling were gone, the gas port raggedy. Still groups reasonably - kinda surprised me.   But it took abrasives. Patch-Out and Accelerator weren't sufficient, though they're my go-to for just about everything else centerfire. |
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Originally Posted By AR-Zen: If you want a deep dive into the underlying math, here is a good paper: https://link.springer.com/article/10.1186/1471-2288-14-135#Abs1 This is a little lighter on the math: http://ballistipedia.com/index.php?title=Range_Statistics And this is more conversational between the shooters: https://forum.accurateshooter.com/threads/converting-3-shot-group-size-to-5-and-10-shot-group-size.4117551/ Originally Posted By AR-Zen: Originally Posted By TGH456E: -Lastly, if you can shoot a .5 MOA group with 5 shots, why can't you shoot it with 10? What I mean is, I have no idea where you got this: "...If a 5-shot group is 1 MOA, the 10-shot group is expected to be 1.24 MOA......." Where did you get that from? Please quote your source. If you want a deep dive into the underlying math, here is a good paper: https://link.springer.com/article/10.1186/1471-2288-14-135#Abs1 This is a little lighter on the math: http://ballistipedia.com/index.php?title=Range_Statistics And this is more conversational between the shooters: https://forum.accurateshooter.com/threads/converting-3-shot-group-size-to-5-and-10-shot-group-size.4117551/ Sir: Maybe you dont realize this but your very own sources refute- deny- the usefulness of 5 shot groups. You realize that right? Here's a better read for you, from a very prolific (at one time) poster here. His ammunition tests set the standard for how they should be done. Molon explains the problem with 3 shot groups and very clearly explains, with several notable sources why 10 groups are the best start for any accuracy test: https://www.ar15.com/forums/ar-15/-/118-279218/ Here's Hornady explaining the problem with 5 shot groups: https://blog.hornady.com/for-accurate-data-sample-size-matters-b0c1d70beaba Here's Shooting Sports discussing the same 5 shot problem: https://www.ssusa.org/content/accuracy-testing-shortcomings-of-the-five-shot-group/ In the mean time, I was hoping to get some valid information from you and your posts. You are over stating your abilities and "cherry picking" results without any actual proof. Also trying to use statistics, when it clearly is NOT "on your side" is a distraction unto itself. Hope you get your rifle figured out. Take Care. |
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Originally Posted By AR-Zen: I decided to not use abrasives for now, but I did construct this apparatus (shown below) to speed up the cleaning process. There is a nylon brush at the end, and yes, I did use the bore guide when using this. https://i.imgur.com/FxdgMIr.png The barrel is super clean now. I'll shoot it this weekend to see the effect. I am predicting at least a few of the 0.7" 5-shot groups. >is concerned about barrel degradation >cleans it with power tools |
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Originally Posted By bluedog82: >is concerned about barrel degradation >cleans it with power tools I thought that’s how all the guys who use backwards optics mounts to shoot half moa groups with rack grade rifles did it. |
Point shooting will give you monkeypox. - John_Wayne777
The Emu War could have been won if the Australians used red dots on their handguns.
The Emu War could have been won if the Australians used red dots on their handguns.
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Just when I thought I was done cleaning, I've used a bronze brush, and it removed a lot more of carbon. After a few more hours, I think I've removed all the carbon and copper that I could, although the bore scope still shows dark color near the throat of the barrel. Also, I've installed NamionalMatch shim to eliminate the wobble between the upper and lower receiver. And finally, I adopted what I call a "supernatural point of aim". That's when/where I am so comfortable behind the rifle that I feel I could fall asleep. The results are now closer to what I want to see. The groups below are 0.65", 0.7", 0.85", 1", 1.3". 
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1. I assume you are happy with the improvement? Your whole composite would be super excellent with the exception of just 2 flyers as long as the upper left groups elevation was an anomaly. 2. If there was no wind, your zero needs to come up a click and right a click... unless you changed it during your shooting session. Your one group on the upper left was super low. Was that the first one? Same elevation setting as the rest? 3. I shoot groups at 300 yards for centerfire. 100 is fine to me, if it is what you have. The reason I shoot 300 most of the time is not for "math" for me, but the ranges I have access to have less shooters and better shooting positions at the 300 yard lines. I also laser range all my targets as there is surprising variation on distances across ranges or even across lane positions at many outdoor ranges. 100y has the advantage of less walking and less wind influence. I shoot 100y indoors to refine zero, but the lighting sucks compared to outdoors. 4. I would not have used a power tool on my bore, but I have seen it demonstrated to show it is not possible to harm a barrel with bronze or nylon brushes... If it works for you, more power to you... but speed and abrasives can do some serious things if you are not careful. 5. I am an advocate of 5 shot groups. 3 shot groups are worthless. No, I take that back. I use 3 shot groups to get my initial zero on an optic. Multiple 5 shot groups can be as meaningful as larger strings. People always rely on math for the advantages of 10, 20, or 30 shot strings. Sure, in a perfect world, 10 shot strings are mathmatically better. But in the REAL world, you have people calling the range cold in the middle of a 10 shot string, thin barrels that heat up excessively after 5 rounds, or some jack wagon posting up a 7mm Mag with a brake right next to you at round 5 of a 10 shot string. It is just much harder to get clean, focused, quality groups of high round count. I shoot 10 shot groups for 22lr because it is faster and cheaper than centerfire and the barrel does not heat up as fast... and if it gets screwed up I dont really care. The barrels last longer and the flyers are more common in 22lr, so I want to have two 5 shot groups stacked in a 10shot string to see the effect more easily. Finally, when you get into big, long action, or magnum calibers... they have horrible barrel life. If you shoot only 10-20 shot groups and worked up a good handload and then shot 30 shot composites to refine or trouble shoot it, you would have smoked a gigantic percentage of your barrel life before you ever get into action. Those barrels only last 1500-2500 rounds. 5 shot groups are fine. Just shoot multiple. |
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Originally Posted By D_Man: It's not really a question that can be answered based on the info given. Firing schedule (how fast you fire and how hot the barrel gets) has much more effect of barrel degradation than just the total round count. And then there is the consideration on the type of wear, the effect it has on the bullet you're using, and a whole bunch of other complex internal ballistics considerations. All of this above. I have seen .223 barrels wear out in 3000 rounds and I have seen them go 9000 rounds before 100 yard grouping went to 2 feet. All boiled down to how fast the rounds were fired through the gun and how fast the bullet was traveling. Go talk to some F-Class bench rest shooters; most of them can give a masterclass on how long a barrel will last / stay within accuracy limits. |
Barrel expected degradation due to usage (Page 1 of 2)
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