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[ARCHIVED THREAD] - Lightweight Barrel Acuracy Thread (Page 1 of 2)
Posted: 2/8/2015 6:29:10 PM EDT
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Lightweight barrels are a common topic here. Lots of requests for recommendations, lots of advice against them because of decreased accuracy, and lots of rumors about the subject. I went out and tested several of my lightweight rifles for accuracy, and I ask that others do the same and post their results. For this discussion, lightweight refers to a barrel that is thinner than a government profile or an M4 barrel, particularly in front of the gas block. I would think 0.625 and 0.750 gas blocks would be fine, as would "pencil" profiles and hybrid styles, and any barrel length. For my evaluation, I will use 10 shot groups from a bench, using a SS 10X mildot scope in an ADM mount as shown below. The lower used for each upper has a fixed stock and an ACT trigger. Ammunition is commercially available Black Hills 52gr HPBT and Federal Gold Medal Match 69 gr. Shots were fired at about a twenty second interval. Each barrel got considerably warm.  Why ten shots and not three or five? Please read this: click Groups will be evaluated using the On Target software available for free online and both Extreme Spread (CTC, center to center) and Mean Radius (ATC, average to center) will be provided. For some reading on these ideas go here: click The most important measure of the center is the mean radius. It tells how all of the shots in the group compare to each other. Extreme spread only gives the distance between the two farthest shots; it does not tell anything about the other shots in the group. For example, a mean radius of 1" means that half of the shots fell within a circle with a 2" diameter. Ammunition and a rifle that produces a mean radius of a little under 0.3" is considered match quality. ________________________________ 1. First rifle is built up using a factory assembled BCM BHF hammer forged 16 inch 1/7 5.56 midlength pencil chrome lined barrel. I have previously tested this barrel as can be seen here: click   The first six rounds of the GMM went into that little cluster with one thrown right. Then the range officer called "one minute" and I lost it in rushing the last four. Note that the top group has a SMALLER extreme spread (labeled MAX, the straight line distance shown) than the bottom group, but a LARGER mean radius (labeled ATC, shown as the circle). Think about what that means. ________________________________ 2. the second rifle is a home assembled RRA 16 inch midlength 1/9 5.56 barrel with chrome lining and a 1/9 twist. This barrel is a bit thicker than a pencil barrel, measuring about 0.65 in front and behind the 0.75 gasblock. I have previously tested this barrel here: click   First group went really well. But the GMM was a fight. I couldn't seem to get the rifle settled and was dealing with some glare off the front sight ears. It is what it is. _____________________________ 3. The third rifle is a home assembled Daniel Defense 14.5 inch midlength 1/7 5.56 barrel with chrome lining and a pinned C2 Phantom flash hider.   On the top group, I forgot that I had a FMJ hand-charged round first out of the mag and I put it on the target instead of the dirt. It was not included in the group. I was surprised at how low the 69 grain shot compared to the 52 grain. On the two 16" rifles, the heavier load was about an inch and a half low. The 14.5" barrel shot them 3 inches low, almost off the paper. I did not expect to lose that much velocity with 1.5" of barrel. ____________________________ Conclusions: All rifles have standard hand guards, are not free floated, and all rifles shot well within my personal defensive standard for accuracy: A Mean Radius of 0.8" or less and an Extreme Spread of 2.5" or less. This standard implies that at 500 yards, half of the shots will fall within a 8-inch diameter circle, with none exceeding 13 inches. The width of my torso is 13" and I've got a medium athletic build. I cannot imagine a scenario short of TEOTWAWKI that would require me to make a rifle shot at a distance greater than 100 yards. A lightweight barrel of good quality with standard hand guards is just fine for a defensive long gun. and as a homage, here's Molon's test of a Colt LW barrel click |
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Good thread, MRW. I will try to post some pics of what I have so far and hope to go to the range this weekend to shoot more 10 round groups.
Rifle: Colt LWT 6720 upper with a DD Omega rail on a Stag lower with SSA trigger. Rifle had a Leupold VX-III 4.5-14x40mm scope in a LaRue SPR-E 
Groups XM193, 10 shots, 100 yards 
69gr BH blue box, 10 shots, 100 yards 
And here is a 5-shot group for MOLON, because we all know he loves 5 shot groups, lol: 69 gr Black Hills blue box 
I need to stabilize the rear of my carbine better. I think this will help shrink the groups some. |
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Went to the range today to test my SR15 Mod1 after it reached 11,700 round mark. (probably 11500~12000rds)
Best Group was with CBC 5.56 77gr 
I shot at 100yards range Not the best shooting condition, no support for my right arm and elbow (Shooting Range website pic) 
Testing Rifle/Setup (I used Primary Arms fixed 6x scope) 
Disappearing lands in the barrel... This is what happens when 90% of my shooting were rapid fire and about 3000rds of 11700rds were steel case Bear or Wolf 
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Quoted: Went to the range today to test my SR15 Mod1 after it reached 11700 round mark. (probably 11500~12000rds) Best Group was with CBC 5.56 77gr https://farm8.staticflickr.com/7285/16475234351_808723eb62_o.jpg Not the best shooting condition (Shooting Range website pic) https://farm9.staticflickr.com/8624/16289545410_a4c89e9a25_o.jpg Testing Rifle/Setup (I used Primary Arms fixed 6x scope) https://farm9.staticflickr.com/8663/16240804427_dca41b06ba_o.jpg Disappearing lands in the barrel... This is what happens when 90% of my shooting were rapid fire and about 3000rds were steel case Bear or Wolf https://farm9.staticflickr.com/8642/16477743215_bb36894494_o.jpg |
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Quoted:
How far did you shoot? That looks like a really short range. Quoted:
Quoted:
Went to the range today to test my SR15 Mod1 after it reached 11700 round mark. (probably 11500~12000rds) Best Group was with CBC 5.56 77gr https://farm8.staticflickr.com/7285/16475234351_808723eb62_o.jpg Not the best shooting condition (Shooting Range website pic) https://farm9.staticflickr.com/8624/16289545410_a4c89e9a25_o.jpg Testing Rifle/Setup (I used Primary Arms fixed 6x scope) https://farm9.staticflickr.com/8663/16240804427_dca41b06ba_o.jpg Disappearing lands in the barrel... This is what happens when 90% of my shooting were rapid fire and about 3000rds were steel case Bear or Wolf
https://farm9.staticflickr.com/8642/16477743215_bb36894494_o.jpg The range I shot at is 100yards, I just found another pic showing their 100yards range. I just edited my previous post... forgot to mention was 100yards haha 
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Here's some results from an M16A1 1/12" barreled upper I shot a while back Test bed, not free floated:  Hornady 52gr HPBT, Extreme Spread of 1.543" , Mean Radius of 0.472"  And on another day, 70 Degrees and very breezy- wind gusts up to 20 MPH, each group has a few stray rounds. Ammunition from top to bottom, all handloads 52 Sierra HPBT 52 Sierra HPBT 55 Hornady FMJBT  |
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I just got all of the parts in for a build using the following pencil barrel from Faxon. I'll be building the rifle today with a freefloated tube. I'll test it out this week and report back with my results.
• Barrel Material: 4150 CMV Steel • Barrel Type: Button Rifled • Barrel Caliber: 5.56 • Barrel Twist: 1:8 • Barrel Length: 16” • Barrel Profile: Pencil • Barrel Gas System: Mid • Inside Finish: QPQ Nitride • Outside Finish: QPQ Nitride • Muzzle Thread: 1/2-28 TPI (Threads Per Inch) • Gas Block Diameter: .625" • Gas Port Diameter: .078 • Barrel Extension: M4 • Weight: 1.19 lbs Magnetic Particle Inspected 
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Quoted: Pics now up in my post. excellent! thanks! Is the omega rail a free float? I'm going to take my 16" 1/9 bushmaster superlight out for a run this weekend and see how it compares to your Colt. and not to bust your chops, but I only count nine shots in your first group. |
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Quoted:
excellent! thanks! Is the omega rail a free float? I'm going to take my 16" 1/9 bushmaster superlight out for a run this weekend and see how it compares to your Colt. and not to bust your chops, but I only count nine shots in your first group. Quoted:
Quoted:
Pics now up in my post. excellent! thanks! Is the omega rail a free float? I'm going to take my 16" 1/9 bushmaster superlight out for a run this weekend and see how it compares to your Colt. and not to bust your chops, but I only count nine shots in your first group. Ooops, you're right. My bad. And, yes, the Omega Rail is an FF rail. What's funny is that your non-FF rifle shot better than my FF rifle. I know that I need to bag the rear of my rifle better in order to take me out of the equation more, as I know that I'm not the best "precision" shooter. I have some CBC 77 gr and 62 gr Fusion and some more 75 grain Privi I wanna shoot this weekend. I hope I'm able to make it out there, as I'm curious to see how the CBC and Fusion shoots outta my Colt. However, a big bummer for this next range session is that I do not have the 4.5-14x40mm Leupold scope. It was my buddy's scope and he needed it back. I only have a 1.5-5x Leupy at this time, but I'll see if I can use his again. It's a lot more work when you're shooting 10 round groups. I don't know how MOLON did it, but it sure gets tiring after awhile. So, kudos to Molon for all the work and effort he put into all of his posts! |
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I would think the stock on your rifle makes it difficult. The telestock probably does not settle into a rear bag very well. I do all of my testing with a fixed A1/A2 stock and a rear bag with ears. PS, the way your scope sits right behind your front sight base makes me chuckle. Mine does the same if you notice. It sure looks silly, but it works. |
Yeah, I agree with you about the stock being more difficult to get planted, but I'm gonna buy something better from the gun store, as I was using the shitty range bags. I also need to buy something to better stabilize the front end as I was using sand bags on top of my shooting bag.   Lol.
As for the scope thing, yeah, it looks all retarded, but it does work. 
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New Results Today: I took my home-assembled old-Maine Bushmaster Superlight 16" and shot the same ammo as previously, Black Hills 52 gr HPBT and Federal Gold Medal Match 69 gr HPBT. This upper has a pencil profile, carbine gas, standard handguards, 556 chamber and a 1/9 twist. I used my fixed stock lower with the ACT Trigger and SS 10x mildot in an ADM mount. Upper:   I shanked a round low in the 52 group, but the 69 load really surprised me. I've never used this upper for anything other than blasting. The barrel was quite hot by the time to got to the end of the 69 string. ____________________ I also shot my BCM 16" Midlength with some Federal Fusion MSR 62 grain SP and some Wolf Gold 55 FMJ. Upper also has a pencil profile, midlength, 556, and 1/7 twist. upper:  Again, I pulled a shot low in the top group, and the Wolf Gold surprised me. I expected at least a 3 inch extreme spread. |
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I will try to post the eight 10-shot groups that I obtained over this past weekend sometime tonight, after running the pics of the groups through the On-Target program I have. I shot the following ammunition: CBC 77 gr, Privi 75 gr, Fusion 62 gr and some more XM193.
Off the bat, I will tell you guys that my 16" Colt LWT upper did NOT like CBC 77 gr ammo for nothing. However, it continued to shoot XM193 pretty good, as well as the Fusion load. Prive fell between CBC and XM193/Fusion loads. |
| Thanks, Molon! I do gotta say that MRW is a better shot than me, as his non-FF groups are better than my FF groups!! I tried to find an adjustable rest for the front of the rifle, but was not able to find one locally. I'm not too happy with the results, but I did the best I could with what I had. Although, I do like how XM193 and Fusion group with my Colt upper. |
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I'm gonna be placing an order for an el-cheapo Caldwell Rock Jr. rifle front shooting rest, that way I only have to worry about stabilizing the rear. I'm gonna be taking out my 16" Noveske N4 light upper next when I get the rest. I wanna see how that upper does with the CBC stuff and Privi. I also have a nitrided Rock Creek barrelled upper that I'm itching to see how it does with CBC ammo, as well. All in all, after thinking about it further, I'm cool with how the Colt shot with XM193 and Fusion, as I have a lot of XM193 and a decent stash of Fusion. In addition, I wasn't expecting the Colt upper to shoot like an SPR/DMR/SAM rifle, so the results, for a GP rifle, are more than acceptable. If it was a Krieger or Lilja barrelled upper, then I'd be a bit disappointed. ETA: Just ordered the rifle rest from Amazon and should be in my grubby hands by the 17th of this month. Now I know what I'll be doing on the 21st: Shooting for more groups! |
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On the CBC 77grn ammo, which powder was it? the PB or WC 748?
Also what year on the brass, 2013? I have had excellent results with the PB marked powder charge. I just got some with the WC powder and will test it out next week. Barrel is VooDoo Arms 14.5" ultra light with over 3,500 rnds through it. |
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Quoted:
Good show on the Fusion. I've got a bunch of those to load up and hope they shoot that well Quoted:
Quoted:
Good show on the Fusion. I've got a bunch of those to load up and hope they shoot that well Indeed, this thread has become very relevant to my interests. I've got a bunch of those 62gr Fusions and two Bushmaster LW barrels, a 1/7 and a 1/9. |
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Quoted:
On the CBC 77grn ammo, which powder was it? the PB or WC 748? Also what year on the brass, 2013? I have had excellent results with the PB marked powder charge. I just got some with the WC powder and will test it out next week. Barrel is VooDoo Arms 14.5" ultra light with over 3,500 rnds through it. Ok, so the CBC 77 grn. with Winchester powder proved to be really accurate out of this barrel too. I also tried Privi 69 grn. match and it shot 3/4" group at 75 meters. Couldn't go further as we were losing daylight. The CBC 77 grn. was consistent, printing respectable 5 shot groups at 75 meters of 1". 10-15 shot groups opened to 1.5-2.0". Not ammo problem, it was me getting too fast on the trigger. I think if I used a scope the groups would shrink and be consistent. Daniel Defense fixed sights at 50 meters and Primary Arms micro red dot at 75 meters. More testing in June. With a scope and hopefully at 200-300 meters. All in all, really happy with the CBC ammo. |
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Quoted:
Shot the M16A1 barreled upper again yesterday http://i1011.photobucket.com/albums/af236/onehalfmvsquared/hobby/IMG_1472_zps11ifszyv.jpg Testing this 50 grain tipped ammo with the Green Mountain 1/6 twist barrel. I used a 10x optic, not the carry handle iron sights <a href="http://i1011.photobucket.com/albums/af236/onehalfmvsquared/hobby/GM%201-6%20Twist%20Barrel%20test/IMG_1487_zpsuppkcmn5.jpg" target="_blank">http://i1011.photobucket.com/albums/af236/onehalfmvsquared/hobby/GM%201-6%20Twist%20Barrel%20test/IMG_1487_zpsuppkcmn5.jpg</a> Lightweight M16A1 barrel results on top <a href="http://i1011.photobucket.com/albums/af236/onehalfmvsquared/hobby/GM%201-6%20Twist%20Barrel%20test/62024201520A1A420and20GM201820Fed205020varmint_zps7z2tfg32.jpg" target="_blank">http://i1011.photobucket.com/albums/af236/onehalfmvsquared/hobby/GM%201-6%20Twist%20Barrel%20test/62024201520A1A420and20GM201820Fed205020varmint_zps7z2tfg32.jpg</a> Looking good, MRW. |
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I shot my BCM 16" Lightweight Middy again. 100 yards, 10 shots, 10X optic (Not the ACOG) Black Hills 69 and 77grain  Was doing well with the 69, first seven shots went into a nice group. then a fly bit me on the heel of the hand when I was shooting the 7th shot and after the battle the last three were down low. And the 77 was fine but the last shot went way wide. I dunno.  |
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Those are pretty good groups considering the rifle isn't even sporting an FF rail. You're a pretty good shot, MRW.
I just completed a 604 clone and hope to shoot for groups soon, but I won't be using an optic, as I don't have anyway to mount the scope I have. I also want to go back out with my LWT Colt, as I now have a proper front shooting rest. ETA: As for that one 77gr round that went way left, you must have pulled that shot, because thats just weird how only one shot that way. I'd shoot another 10 rds to see if it did that again. |
[ARCHIVED THREAD] - Lightweight Barrel Acuracy Thread (Page 1 of 2)
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