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[ARCHIVED THREAD] - 6.8 problems (Page 1 of 3)
Posted: 11/14/2007 8:20:31 PM EDT
| I just recently built a 6.8 with a W.O.A. barrel, I have 6.8 spc ammo from Silver State Armory, sometimes the rounds will load all the way into the barrel, most usually they wont, they get jammed very bad. Any ideas why ??? I have not tried any other kind of rounds yet. |
Are they blunt tips? |
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WTF? Go see a gun smith. Don't shoot that damned thing. Sometimes the blunt tips have a hard time entering the chamber, but if the bullet gets stuck in the bbl and the casing comes out, then there is a serious problem. I wouldn't take any chances trying to shoot it. |
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WOA barrels are SAAMI spec chambers. Try coloring the bullet with a sharpie and pushing it in the chamber by hand, then take it out and see if there are 6 marks around the bullet where the lands are touching. If there are marks you could seat the bullets a little deeper or try other ammo. If you have a mic, check the dia. of the case neck and bullet just to be sure. The SAAMI neck dia is .3085 so if the neck is more thats a problem. A few other things, Are these the combat loads? How many have you shot? Have you cleaned the chamber with a chamber brush? I had a build up of copper shavings in the area between the case neck and the throat once. |
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If you have the extreme FMJ's the shoulder of the bullet tends to obturate in a SAAMI spec chamber. Try seating another type of cartridge without firing. It should load just fine. Constructor's advice is sound, and I would guess you will see the land marks on the bullet. The SSA extremes did not have a cannelure, and if they obturate, could actually unseat from the cartridge when removed or worse, fall down in to the case, upon recoil while still in the magazine. That is why they were pulled from the market. |
I think you have your historical facts wrong: Remington is the one that Screwed the pooch....er...the chamber drawings. When they made their initial powder formula, they told everyone that the SPC would produce 2800 FPS from short barrels. Then, servicemen testing it out, got the ammo into the sandbox, and when it got to temps of around 120 degrees, the pressures went WAY over 55,000. OOPPPs.  That was not SSA's fault! The extreme bullet was an anomaly, causing problems only in the "original" SAAMI spec chambers, which were based upon the REMINGTON design specs. This incompatibility was recognized as such in the early stages of development of the round, which is why it had to be pulled. SSA did the responsible thing, but they are not to blame for the flawed engineering of the original design, which would never have worked as promised.So, whether you used Remington's original powder, say down here in south Texas on an August day (where it often hits 110), or you used the extreme bullet in a SAAMI chamber you would have had the same problem! When it was realized the prototype ammo was producing too much pressure, to equal the performance first promised, Remington basically gave up. They didn't try a longer throat or leade and they didn't try slower twists. I suppose one could understand why in terms of money, eh?? Everybody else then had to scale the round back to 2500 FPS because of the chamber dimensions and the too-fast twist rate, and there was a composite YAWN from the buying public. I suppose it was thought the idea would then just wither on the vine. If it weren't for people like SSA, Ko-Tonics and others, this round probably would never have been a success. Imagine that....small businessmen, and interested individuals, shooters and enthusiasts have managed to do with this platform what a huge company like Remington couldn't |
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SSA pulled out the ammo, so how did SSA do anything wrong? SSA made the ammo to spec just like Remington did. Remington is the one that screwed up the chamber drawings. Either way who cares? Most companies now have or are catching up and getting the correct chambers. |
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When the 6.8 was being developed by the 5th group it was with the Xtreme projectile. The Xtreme was a Barrett design and Remingtons was making the ammo. The Remington ammo was having issues as Hi-Tech mentioned. Barrett than came to us as the project was dead in the water. We produced ammo within weeks using the Xtreme and our ammo passed all military testing requirements. Hi-Tech is right again about SAAMI spec's whereas the spec's did not do the cartridge any justice. SSA was the one leading the charge on a new chamber (now called the Improved Chamber) as well as a 4 groove 1-11 twist which Ko-Tonics is using. When we came out with 6.8 using the Xtreme we got causgt by the SAAMI spec's and pulled all the ammo we could find. We have the widest selection of 6.8 ammo out there. 115 Grain OTM, 110 grain Pro-Hunter, Barnes Triple Shock, Frangible, and AP round. As for the chamber many gun compaines have adopted the new chamber as they have learned it reduces pressures with no loss in accuracy. LWRC marks their new rifles SSA Improved Chamber. We will take back the ammo you have and replace it at no charge, contact us thru our web site. Art - SSA |
If Remington had tested the round further instead of rushing it to market they would have found another 300fps just like the rest of us have. I would say in a few years everyone will produce the 6.8 with the #2 or DMR chamber and 11 twist barrels. And 10 years from now everyone will forget Remington had anything to do with the 6.8. Does Remington make anything in 6.8? Oh yeah, some slow ammo. IMO Remington or someone there has done everything they could to destroy the 6.8. "Survivor" has shown everyone in this country it's OK to lie, cheat or steal to win. Don't ask for an explanation because I can't say, just read between the lines. |
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I disagree that "someone" at Remington tried to destroy the 6.8. I think it was probably Corporate apathy, which is why smaller more nimble companies has pretty much taken the 6.8 away from Remmy. Things may change at Remington since Cerberus bought them. Back to the OP's topic...........kinda, alright let me get all of this straight. There are basically 3 chambers for the 6.8 correct? One is the SAAMI chamber, not sure what number two is, and number three is the current, or "Improved Chamber". Enlighten me what the second one is please, I know what DMR is, just not what sets that chamber apart from the other two. TIA |
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The #2 chamber is the one Ko-tonics uses and Art at SSA had alot to do with. It is the 6.8x43 or SPC with a .040 longer throat than the SAAMI spec, everything else is the same. The DMR chamber is like a 6.8 WYLDE but Wylde didn't design it. We took the average dimensions of the produced brass and sized the chamber from the brass to make it more accurate and not overwork the brass while maintaining enough clearance to be reliable in a gas gun. Then we took most of the available bullets and seated them at 2.295 which is the maximum safe length that should be used in a PRI mag, from there we located the tangent of the ogive of each load. We averaged that number to come up with a throat length that most bullets could be seated .020" off of the lands to give the best accuracy. The throat is .030 longer than SAAMI. It will handle the hottest loads while allowing the bullets to set at a optimal .015-.020 off of the lands. |
I know very little about ballistics but I do know markets and business. The 6.8 SPC isn't going anywhere. IMHO It's here to stay, and it's here to stay in the Improved Chamber/DMR format. |
Tim at Ko-tonics uses the #2 and I do not know who makes his barrels for him. I use the DMR. WOA was using the SAAMI chamber but I'm not sure he still does because Frank White at Compass Lake makes alot of Johns standard barrels now. I have one of Randalls(AR15barrels.com) reamer prints so unless he has changed he uses the SAAMI Model 1 is SAAMI, as for the rest I don't know, you would need to call the smiths that do the chambering to find out. There really aren't that many that chamber AR barrels. Believe it or not, some can't remember what they used without looking at the reamer. There are very few competitors who use the 6.8 but, when it comes to the 6BR or 6PPC almost every shooter designs his own reamer because they think they have an idea that will make it shoot better. I'll check around in a minute and get back to you. EDIT - Ko-Tonics #2, 11 twist - JTAC sells LMT barrels they are SAAMI 10" twist - Rainer sells WOA barrels that are SAAMI 11" twist - Denny's sells WOA, SAAMI 11 twist -Noveske uses Pac-Nor barrels and they are SAAMI 10" twist Adams & bennet and Shaw do not make 11 twist .277 barrels so I'd say thats why most don't offer the better 11 twist. Wilson and all cut rifled makers will build 11 twist barrels so more than likely Ko-tonics uses Wilson chrome-lined moly blanks. -Barrett SAAMI 10 twist - As Art said LWRC #2 chamber DPMS SAAMI 10 twist STAG SAAMI 10 twist MSTN shows a Douglas blank SAAMI chamber and 10 twist AR15barrels- SAAMi 10 twist Most companies are too small to do their own chromelined moly barrels, I'd be willing to bet all of the 10 twist chromelined moly barrels come from 2 barrel makers. EDIT- Tim from Ko-tonics posts up later to say Shaw IS making his barrels and is using the #2 chamber, I He also said Shaw will be providing barrels to other companies so look for Stag and others to start selling barrels with the #2 chamber and 11 twist. |
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I had problems with my 6.8 at the range today, if anyone can help, I'd surely appreciate it. Stag upper and lower, Hornady V-Max and BTHP ammo, PRI mags. The first 4-5 rounds go, then either the round hits the feed ramp too low, denting the shoulder of the casing and lodging the bullet so that the tip is stuck above the chamber, failure to feed. Or, the BCG slams the round to hard into the chamber and actually shoves about 1/8'' of the casing into the barrel. Help would be good  |
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Do your PRI mags have blue followers? Second, does it do this when there are only a few cartridges left in the mag or is it full minus the 4 or 5? Alot of mags don't have the spring pressure to keep the front of the follower up. The new followers help and there are some stronger springs on the market but, I can't tell you exactly where to get them...yet. |
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To address the original poster "prikev". What Constructor has eluded to is most likely your problem. What happens when the extreme round is used in a SAAMI chamber is when the ammo is ignited the bullets base expands. Because of this it is scraping at the ledge and you are getting build up of the copper there Which has the effect of raising pressure drastically and also trouble chambering when there is enough copper build. Before you do anything you need to throughly clean the barrel. Spend some time with a chamber brush making sure you get all the copper out. Then try to chamber a round again see if it goes. No longer use any extreme ammo as it is a no go is SAAMI chambers. There shouldn't be much on the market anyways as SSA pulled it awhile ago. Go pickup any of the other offerings from SSA and try chambering it. If you have a problem chamber other rounds (not extreme) I would be checking your chamber dimensions as they would have to be tight/ short to cause the problems you are stating. Obviously you could try a different manufacturer's loads as well. I just find SSA to be the best and most accurate. I have a WOA 11:1 SAAMI and it will handle all the SSA chamberings they currently offer including there combat load. Take a look around at some of the loads Constructor has loaded and put through his 18" WOA SAAMI barrel without incident. Some of those would be considered wicked hot. Below is strictly my first hand observations and opinions not intended for other to follow: To handle hot loads ie. SSA Combat land reloaded reloads I have found you need one of the following: 11:1 twist or slower, improved chamber SSA/Kontonics or DMR. After that 5R/C or 4 groove standard rifling only makes things better. The ideal barrel specs to me would be 5R, 12:1, DMR, 16 inches. The 5R/5C rifling seem to reduce pressure. The only reason I choose it over the standard 4 groove is the less number of grooves, the more stress it puts on the bullet jackets and when you get up around 3000 FPS you can have thin jacketed bullets frag in flight. Not that we are there or that is happening with the 6.8 its more a personal choice. The DMR chambering has a shorter throat than the Improved but longer than the SAAMI. It allows you to just about reach the rifling which is good for accuracy and still be longer to allow for the hotter loads. The Improved has even more length in the throat which, if done perfect, is ok but it keeps the bullet farther from the lands which can make finding a sweet load accuracy wise harder at times IMO. One last thing a lot of people have made a huge deal about the 6.8 chambering issues as a sign its a defective round, like this has never happened before with other wildly popular rounds. The last time I checked there was a SAAMI .223 , 5.56 NATO, .223 Wylder, .223 Noveske chambering and probably a few more. Isn't there a thread going right now talking about Ar's going kaboom and .223 SAAMI chambers with 5.56 ammo was listed as one of the causes sounds similar doesn't it? The fact is, its a good thing of sorts; the round is evolving and improving as it goes. The whole issue with the SSA extreme round had more to do with bullet construction then it being a hot load and even that was more the increased length of the ammo to get the extra powder in there than the powder charge itself but that wasn't causing the reported problems. Its also hard to believe that Remmy didn't know that the SAAMI specs they were putting forth were going to cause issues. I would hope they could have at least added and subtracted properly. If minimum and maximum specs overlap between ammo and chamber your are going to have problems. They also knew the type of chamber that was being used in the testing. Other than that, the only other real problems were some sets of out of spec barrels from bad chroming, this has, I'm sure, never happened with any other chambering before!?! At this point all barrels will shoot all readily available ammo just like standard .223. If you choose, there are rounds loaded hotter that are available on request and reloads that work in the other chamberings just like NATO/Wylder /Noveske. By the way all the things I have listed up here can be found in many other posts on this site, if you take the time to research. It would be nice if their was a facts page posted that was a list type with links and simple, not more than a page long. Everyone doesn't have the time I have to read the many 40 + page threads and try to glean real information from them through all the sidetracked posts and petty bickering and others trolling. Just a, these are the facts about general, barrels, ammo, other part etc..if you want more info on this topic look at this link etc... Tim Welter |
blue followers, and full - 4 or 5 I'm thinking it's a feed ramp or buffer prob- CAA stock, buffer and spring. 
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What's your thinking here? I agree it ought to stay but I see all the major AR15 manufacturers selling new 6.8SPC models, and while I'm not sure what chamber a couple of them have, none of them have a 1-11 twist. Assuming Constructor's list is accurate it looks like two very small manufacturers are doing a non-SAAMI chamber and everyone else is in spec. My understanding is that SSA is still selling some ammo that will go kaboom in a 1-10/SAAMI. If that's true that's bad. I just can't see any upside to this situation from a non-wildcatter gun owner's POV. |
It could be the ramps if they aren't M4s. Do you like grinding with a dremmel for hours? I hate to tweek the feed lips because after they are screwed up you can't ever get them right again. HVAC contractors have vise grips with wide flat jaws, I use these and try to lift only the front of the lips. One odd thing it could be. If the BCG travels just far enough to catch the groove of the case it will push the round forward while holding the rear down, so you may be right about the buffer. I had a feed problem at a 3 gun shoot last weekend, I had to swap to my lower that had the CAA ARS stock on it to fix the problem. It was a 16" carbine gas with a A2 stock, after I swapped to the carbine tube and buffer it was fine. |
It's an M4 upper from Stag, so I assume M4 feed ramps. I shouldn't have to dremmel the ramps or touch the mag lips, Stag and PRI should have done that already  I think I'll call Stag tomorrow and ask them about the CAA buffer/spring combo. They appear to be the same as my other 5.56 buffers, maybe the 6.8 requires a different setup. I tried the Endine Hydraulic ARestor buffer, and got the same shit. Maybe it's a feedramp issue, this is one of stags earlier 6.8 uppers. Until I figure it out, the rifle remains "unreliable"  |
Arts not selling combat ammo unless you call and request it. There may be shops that have it on the shelves and aren't in the loop so they don't know to swap it out. Art was pulling that stuff 2 years ago, the first time I talked to him. To be fair, For all the people who do not reload the 10 twist SAAMI chamber works fine. It's kind of like a 7 twist NATO or a HEMI running on 7 cylinders. I took many years for people to pick up on the Wylde chamber but, with sites like this the word gets out much faster and if you watch the threads everytime someone ask about the 6.8, Ko-Tonics is brought up because of the chamber and 11 twist. The 6.8 was designed as an assault cartridge, in my opinion it's the best option at the moment. Some of us have found it is much more than an assault cartridge and we're spending a huge amount of time and money to see what this round will do when all the right parts are used. I've been talking to Berger about making better bullets for almost a year and hopefully I'll be able to test those for Berger in a few weeks. We have found a load that gets 3000fps from a 90gr bullet out of an 18" barrel, 2592fps from a 130gr and several sub-sonic loads. That 90gr load shoots 3/4" groups with an Aimpoint and flies flatter than my 18" 308 AR10 with 175gr SMKs out to 500yds. All of this testing was done with a WOA 11 twist and SAAMI chamber. The WOA that I throated to the #2 design would allow me to push faster but I could't get sub-moa groups unless I loaded long and single fed. Accuracy is the number 1 thing with me so I sold that one to a friend that didn't mind 1 1/4" groups. The DMR is accurate, the first one was done on a cheap 12 twist blank to check the reliability and the 12 twist. Now I'll do a 12 twist cut-rifled, maybe a Lilja or Hart if I get impatient. We have a new high strength alloy bolt with a dual spring extractor that can handle the hottest loads. Just as a test, I shot 2 stages of a 3 gun event with loads around 65000 psi, they had heavy swipes. Over 60 rounds of 90gr TNTs going over 3000fps out of a SAAMI spec chamber 11 twist WOA SS barrel. I think the new bolts will work just fine. They are a combination of LWRCs bolts with LMTs dual spring extractor. IMO the 6.8 is just getting started. EDIT- just came back from another 3 gun match where I shot 70 something rounds at near proof pressure (same as above)to test these new bolts. I think they get a thumbs up  |
Sorry, It is easy for me to get side tracked. Did you check any of the stuff we mentioned somewhere above all of that? I hate to see you pay $20 for a box of ammo just to find out something is stuck in the throat. like a big wad of copper. The truth is, if there isn't anything in the chamber ANY ammo should work. However, You said the cases may need to go in another 1/4"? That sounds like the neck of another case is stuck in there. Ok I read it again and see you just built it so no one else could have broke a case off in there. Look in from the muzzle and make sure nothing is in the barrel. Hornady is better than Remington so try to chamber one but do not use the forward assist. If they will not chamber try cleaning the chamber with a chamber brush or 410 shotgun brush, twist it slowly going in and out, try not to change from in to out without twisting the brush. then try it again |
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DuraToTheMax: If you are shooting Hornady ammo or any ammo with a weaker powder such as H4198, you must use the lightest buffer available. You are probably having short stroking issues. If you have a carbine buffer, use the regular carbine buffer and if you want, try the H-buffer and see if it will cycle. If you have a rifle length buffer, you have to lighten up the rifle buffer. To do this you will need 3 rifle buffers. When you open up the buffer you will see 1 spacer and 5 weights. You have to set it up so that there are 3 spacers and 1 weight (this will bring the weight down to the same as a carbine length buffer.). The Enidine or the other heavier buffers will work with most ball powder ammo such as the SSA or handloads with ball powder. |
Yep, just try some Hornady. Art said he would exchange the extreme ammo you have. Take him up on it. SSA makes good ammo, Their brass(small primer) is the best on the market, so try some of their other loads. |
I have a Stag M4 upper and it definitely does NOT have M4 feedramps. Stag told me the ramps were there own design but I can't tell from looking at them that they are any larger than standard 5.56 upper feed ramps. For that reason I never tried the Extreme ammo from SSA. Also, note that I can't seat my reloaded bullets to mag length in my C Products mags as the bullets will engage the rifling. I had a bullet stick in the chamber when test chambering a round. When I extracted the round it stayed in the chamber and the case ejected spilling powder everywhere. I wound up having to back off on my overal loaded length to get reliable chambering. So far I can't seem to get better than about 2moa accuracy out of this rifle either with factory Hornady, Remington or my reloads. I'm seriously considering buying a new upper from Tim or having him rebarrell my existing upper with one of his improved chamber barrels and modify the upper receiver for the M4 feedramps. |
Try 90gr TNTs set to 2.265, Re7 works best for me but 322 should do well also. |
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The Xtreme will haunt me to the day I die. We have not produced the Xtreme for a long time, where are you guy's finding this stuff. To say this has cost us ten's of thousands of dollars would be in understatement. To say anyone currently makes a better 6.8 round then SSA I would have to take them to task. We only sell commercial loads on the open market that will work even in the 9 1/2 twist weapons sold by Model one. We have taken back all the Xtreme rounds without question from anyone that return them to us at our expense, that includes shipping. We replaced them with our higher priced rounds on a one to one bases. We have had zero complaints on our OTM'S, Pro-Hunters or any other 6.8 projectiles we currently produce. I guess Rem has the right approach sell stuff that barely works and has SO-SO accuracy. Art-SSA |
So if I reload, a 10 twist is bad? I'm confused. What does the twist have to do with the pressure. I don't see anybody complaining about LMT barrels, and they are 10 twist. |
They are not bad, but you cannot go too far over the recommended max. With an improved chamber such as the Ko-tonics, you can go over max without having too much to worry about. |
Any idea what the Randalls(AR15barrels.com) barrel's are setup as. I'd assume 1:10 SAAMI but I could be wrong. Mine shoots 1" groups around 2670 fps. Pretty darn good but I'm thinking of building another 6.8 for more accuracy and more speed. Thanks should go out to the early guys like Randall that helped keep the interest in the 6.8 alive by building barrels for those of us demanding them. Remington could of cared less......... "more warp speed, Scotty"......"I'm givvin' all she's got capt'n" |
Just like the stuff above, It will work but you're not getting all of the performance it is capable of. I had a 10 twist that I reloaded for, the maximum velocity I could get with high pressure signs showing was 2460+- for the 110 vmax. I have had 2- 11 twist and a 12 twist since. The closest to a stock barrel would have been the 11 twist SAAMI chambered WOA. I can get 2780 with the Vmax. 320fps difference. I know this is coming so before anyone says something, I am not getting more velocity from the same LOAD. I can use more powder to obtain more velocity because the pressure is lower with the same charge. |
My Randall build barrel has a SAMMI chamber and a 1:10 twist. It's from the first group buy. |
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Well, I also have a 16" 1:11 WOA barrel and have experienced the problems stated by the OP prikev and DuraToTheMax. My solutions were as follows: 1- Send the SSA Extremes back to SSA (that's what I did). Art's good people and will make things right. Shoot any/all of the other SSA loads and you will do just fine. 2- I seated my 115gr SMK's to 2.250 OAL and 110gr. Vmax to 2.260 OAL, decreased the amount of crimp applied, applied more lube to the bolt and shot about 200-300rds. through this rifle. Things wore in and now the rifle eats everything including SSA 115gr SMK combat loads without significant pressure signs. At my last range session, I shot a 1.5" group @ 300 yds with SSA sm. primer brass, 29 grs. H322 and non cannelured 115 gr. SMKs. Don't giving up on WOA barrels. They'll shoot better than most of us can but you have to respect it's limitations. Just my $.02 Jeff |
wow. 2460, that seems rather anemic. I will just stick with my sks. |
Sorry Wayne, nothing personal, but your answer is utter BS and you don't know what you're talking about. If you would like to know why the call the shop and I will discuss it with you one-on-one |
ER Shaw who makes my barrels, has now converted ALL their 6.8 SPC chamber reamers to be identical to mine. Early on, I supplied them with two chamber reamers made by PTG. I no longer supply them with a special chamber reamer, and the barrels I get now are identical to my earlier ones. For companies that buy 6.8 SPC barrels from Shaw, as their old inventory is sold off, customers will be getting the chamber with the deeper throat. By the way, there is NO OTHER DIFFERENCE between mine and anyone elses 6.8 chamber, it is only 0.11" of freebore in the throat from the end of the neck to the beginning of the lands. |
[ARCHIVED THREAD] - 6.8 problems (Page 1 of 3)
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