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Posted: 11/28/2006 11:53:14 AM EDT
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Actually more like a "Caliche Pit Report" Colt LE6921 M4 14.5" barrel EOtech 553 Remington 55 GR. 10 shot group 100 Yds 15-20 mph cross wind (left to right) Needless to say, I was pleased with the results. I had concerns about the accuracy of a 14.5" barrel. Not any more http://www.geocities.com/inlinestroker/Range032a.jpg |
why would a longer/heavyer bullet have any effect on the throat? Lower velocity? |
| That's essentially sub-MOA shooting. Not saying you didn't shoot that good, but most "master" class competitors can't shoot that good with small apeture open sights on a custom built competition rifle using hand-loaded ammo at 100 yards much less the far less accurate EO-tech with a much larger than MOA dot. Scoped at a bench rest I can believe. EO-tech no. |
Lighter gr bullet = slightly shorter = more area to jump into barrel via throat. Knew someone would catch that and Im sure it could become a bigger argument. Ive read alot.....about it, and talked to alot of people about buying 55gr because in BH Reman its cheaper. Their arugment started with what about the throat, this is with Colt 1/7 twist barrels because they are chambered for 62 and the 77 SMK. Im surprised we see no keyholes...or BS just kicked in (just kidding). 
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The EOTech's dot is only 1 MOA, not a "much larger than MOA dot". It is much smaller than either a standard or NM front sight post. |
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I had read about some people having problems using 55gr's in their AR's but I personally didn't have any problems. I shot a couple of boxes at around 170 yds (that was pretty much the limit of that particular caliche pit) and don't recall any keyholes. I'm going to try some other weights and see how they perform. For the record, the above was shot in a kneeling position using a makeshift rest (a Black and Decker workmate bench with sand bags). Trey |
I was joking, but lighter bullets have been known to spin apart and tumble to the target. M193 55gr will shoot fine in 1/7 but is better in 1/9. 1/7 should be using 62gr and above for best results. |
Hmmm. I don't agree with you there. There's no way a 55 grain M193 bullet is going to come apart when leaving a 1/7" twist barrel (40 grain Blitzes, yes!). There may be accuracy differences between barrels of 1/7" and 1/9" twists when firing M193 or M855, but the personal proclivities of any given barrel shouldn't be confused with any inherent difference in accuracy between twists. In other words, I haven't ever seen any solid statistical data to infer that 1/7" does better with M855 vs. M193, or the inverse. Old wife's tales do persist, however. Not that it's statistically significant, but 2 of my 1/7" Colt barrels shoot better with 55 grian ammo than they do with 62 grain and above. The "likes" and "dislikes" of any given barrel, bullet construction and consistency, and ammunition quality have alot more to do with accuracy than twist, assuming the twist is adequate for stabilizing the bullet used. I'll be swayed from my opinion by hard evidence to the contrary, but until then I'll continue to shoot teeny little groups out of my 1/7" twist barrels with 55 grain ammo Brewer |
Actually it is something like 1/3 MOA but the human eye can't see smaller than 1MOA so it's effectively that size. If you use a 3x magnifier with an EOtech the center dot will still be 1 MOA |
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