Go with 6.8 SPC for SBR and get your barrel from AR Performance.
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That time period would put it in the early years when it was being pushed as a military replacement.Originally posted by SC-Texas View Post
Since then the entire cartridge was re-specced for SAAMI because it was causing massive pressure spikes that were deemed dangerous. This was resulting in broken bolts and many other issues.
Main part of the difference was the longer throat and less twist in the rifling.
In the SBR which is being talked about here the SPC will work slightly better on paper.
But we are literally talking about how a car traveling 32 MPH will cause more damage than a car traveling at 31 MPH. While technically correct, for all intents and purposes it is not relevant. Especially when the advantage decreases with distance from muzzle.Comment
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Actually. I was there. I was at Wild River Ranch when hi tech Rancher and constructor Harrison Bean, the owner of a r performance barrels and three or four other people came down and did the initial pressure testing that compared the SPC to Chambers, rifling twist and the number of grooves in the barrel to the effect on pressure.
We also identified that some Barrel manufacturers had constrictions in the barrels which affected Peak pressure.
I had an ER Shaw barrel that was improperly chromed
Kotonics I think, went out of business because he had a whole Run of barrels that were improperly chromed and could not warrant them all
Yep. I was there for the original 68 65 wars and arguments.
As far as the barrel length, for some reason the 12.5 number stuck in my mind and that's what dr. Roberts was talking about when we had our conversation.
That was ages ago
Sent from my SM-N920V using TapatalkLast edited by SC-Texas; 03-01-2018, 08:52 AM.Comment
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Found it. Wow! 2008. This is where the development of the SPCII chamber was developed
We shot my Er Shaw barrel and my then new at performance barrel.
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Just read your report and it was well done, wish the pics were still there and it pretty much is inline with my summary.Originally posted by SC-Texas View PostFound it. Wow! 2008. This is where the development of the SPCII chamber was developed
We shot my Er Shaw barrel and my then new at performance barrel.
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That was the start of spcii chamberOriginally posted by Outbreaker View Post
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Docgkr posted. "The original AMU loaded 115 gr OTM ammo we began testing in 2002 was running up to 2700-2750 fps out of our 16" test weapons without pressure problems; however, these were Mike Rock 5R 1/10 barrels using the original "Murray" chamber, not a SAAMI chamber"
Maybe those were 16" afterall
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So the 6.5 pushes 123's <100 fps slower out of a 12.5" than the 6.8 with 115's and within 100 fpe at the muzzle, exceeds velocity, fpe, drop and drift <250 and it is an inferior sbr round?Comment
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'terminally' I was more or as impressed with the 300 <100 yards. I saw no difference between the 6.5/6.8 with sst's other than the obvious on paper advantage the g' takes at extended range. The 5.56 was a fourth place finisher. That was 16-18" bbls vs a 9" blackoutComment
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The reason for this is that the .300 BO was specifically made for CQB and subsonic usage. It is really a toad once you get past about 50 yards especially subsonic.Originally posted by TexMax View PostComment
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Sure. I never shot them. Being a 'toad' with subs is not exclusive to the 300. My point was really that even though the 6.8 may be superior inside 'x' range the 6.5 is also adequate and in fact very close to it within that same range and moves easily beyond it outside of that making it a more effective round overall. Though not as effective as the 300 in shorter than 12" barrels, <150 yards, or in a subsonic capacity really leaving a narrow place for the 6.8 to live between the two. And even that is more perceived than realityOriginally posted by Outbreaker View PostComment
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I agree. Like I said......Getting hit by a car going 32mph vs 31mph......and saying the 32mph car hits harder.Originally posted by TexMax View Post
.300 was specifically made for the SBR. But is basically a 9mm pistol round......even with supersonics ballistically.Comment
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Originally posted by Outbreaker View Post
(Supersonic 300 BLK is a lot like a 7.62x39; similar in energy to a 5.56 at 100yds. Like *four times* a 9mm)
I like the range of bullet options and powders for the 6.5 better than the 6.8; something that hadn't been mentioned.Last edited by Balcones_Walker; 03-01-2018, 03:42 PM.Comment
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Ah. Didn't read that farOriginally posted by Outbreaker View Post
Yeah even subs in a 300 is way beyond a 9mm. One of the reasons I don't really get 9 mil ar's or any of the other little carbines other than fun little plinkersOriginally posted by Balcones_Walker View Post
(Supersonic 300 BLK is a lot like a 7.62x39; similar in energy to a 5.56 at 100yds. Like *four times* a 9mm)
I like the range of bullet options and powders for the 6.5 better than the 6.8; something that hadn't been mentioned.Comment
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Little short barrel 6.5 Grendel test done by a Firearms and Ammo Manufacture and posted on another site
7.5 Bartlien at 100 Yards. Groups averaged 1.5 Inches 2000 FPS 123 Match King
8.5 Bartlien at 100 Yards. Groups Averaged 1.4 Inches 2100 FPS 123 Match King
10.5 Bartlien at 100 Yards. Groups averaged .9 Inches 2200 FPS 123 Match King
12.5 Lilja Blank Chambered by PF at 100 Yards. Groups .75 2300 FPS 123 Match King
14.5 Lilja Blank Chambered by PF at 100 Yards. Groups .5 2350 FPS 123 Match King
14.5 Krieger at 100 Yards. Groups averaged .38 2375 FPS 123 MatchKingComment
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