Best Bullet for Match Shooting (Not a 30-40 Question)

Ammunition, reloading, shooting, etc
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psteinmayer
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Best Bullet for Match Shooting (Not a 30-40 Question)

Post by psteinmayer »

Perhaps this belongs in the Other Rifles/Firearms department... but it's an ammo related question, so I figured WTH...

I acquired my first AR last year on Venders Row because I want to shoot Modern Military along with all of the other stuff I shoot at Perry. I have it initially sighted in with a 55 gr FMJ bullet, but I have a box of match ammo (Creedmore) that I won in a raffle several years ago, and that is 77 grain. So here's my question: When shooting the AR in 5.56mm in a CMP style Modern Military Match, what is the preferred bullet weight? I'm hitting the range on Sunday to practice and I will re-sight the rifle if 77 grain would be better. Otherwise, I'll stick with 55 grain. I have plenty of ammo for both, so it's really just a question of which would be more accurate at 200 yards!

Thanks very much in advance.

If this question belongs elsewhere... please let me know and I'll move it!

Paul

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butlersrangers
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Re: Best Bullet for Match Shooting (Not a 30-40 Question)

Post by butlersrangers »

Paul - What rifling twist does your AR-15 barrel have? (I think that could be a factor in selecting the optimum projectile weight).

Possibly, at 200 yards, the 55 grain and 77 grain projectiles will group about the same.
I believe the advantage of the heavier projectiles is for distances beyond 300 yards?

Shoot both loads on Sunday and see what your rifle prefers.

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King carp
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Re: Best Bullet for Match Shooting (Not a 30-40 Question)

Post by King carp »

I think the length of the bullet has a lot to do with stabilizing and accuracy. My friend uses 75 gr. Amax bullets with a 1 in 7 twist rate. He says the 1 in 9 twist rate was not as accurate. The 1 in 9 twist did work for other 70 gr. Bullets. Try both out and see which works best. Usually a heavier bullet will work better than a light one in the wind. Good luck with the new project!

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Cat Man
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Re: Best Bullet for Match Shooting (Not a 30-40 Question)

Post by Cat Man »

OK I will confess that I do shoot an AR in competition. Of course I must say I like the sight radius of a M1898 Krag rifle more better.

But since you asked. We generally used to shoot 69 Gr BTHP bullets at 200 and 300 yards and switch to 80 grain at 600 yards. We have learned with reloading (in quantity) for our junior rifle teams we can load everything with 77 Grain bullets and they shoot that at all ranges. Keeps things simple for ammo issue. And the kids win matches!.

I do have a can or two of Lake City GI 55 Grain ball that I will shoot at 200 yard reduced matches. Good enough for me. Position, Trigger Control and Sight Picture will make more difference than 55 or 77 grain bullets. Save the match ammo for a long range match.

Glad to hear you are stepping up.

Jeff the Caterpillar Man
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Parashooter
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Re: Best Bullet for Match Shooting (Not a 30-40 Question)

Post by Parashooter »

From a ballistic perspective, if both bullets show you equal grouping ability in calm conditions, the advantage of the 77-grain lies strictly in its better ability to resist a crosswind.

To quantify this, a 55gr FMJBT at 3000 fps will drift about 5.2" at 200 yards in a 10mph crosswind while 77gr Sierra MK at 2800fps drifts about 3.6" in the same condition. In practical terms, this means when you miss a wind change (or get a gust) that adds or subtracts 10mph of crosswind value, a shot that would have gone dead center before the change will be a solid 9 on the 7" SR 10-ring with the 55gr. but has a good chance at a "nipper" 10 with the 77gr.

Of course it's a big target, short range, and there's never much wind at Perry. :roll:

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psteinmayer
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Re: Best Bullet for Match Shooting (Not a 30-40 Question)

Post by psteinmayer »

Well, shot it today at 100 yards with both the 55 and 77 grain bullets. Although it shot well with both, it did group a little better with the 77 grain, so I think that's what I'll be using at Perry!

Thanks everyone for the great help and advice!

madsenshooter
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Re: Best Bullet for Match Shooting (Not a 30-40 Question)

Post by madsenshooter »

Barrel twist rate is a big factor to consider when deciding what bullet weight. Too fast a twist and some bullets start coming apart before they get to the target. Too slow a twist and the bullets don't stabilize, nothing like hitting the target next to the one you're shooting at, w/o it being a crossfire. I have a 1-9 twist barrel. I usually shoot 62gr FMJ or 68gr HPBT. 62gr at 200, 68 at 300 at a club that has both ranges. I generally use a caseful of 4064 or H380 behind the bullets, CCI#41 primers. I have a load for the 62gr bullets using 19.5gr of a powder than burns 4198 speed. That load shoots tiny cloverleafs @100yds.

oney
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Re: Best Bullet for Match Shooting (Not a 30-40 Question)

Post by oney »

69gr and 80gr bullets were the go to bullets when I started shooting the A2 across the course. The 69's were used at 200/300 loaded to magazine length, and the 80's at 600 loaded to fit the rifle, and not at magazine length. The 77gr bullet was a compromise that allowed the competitor to use the same bullet at 200, 300, and 600 yards, and load it to magazine length. If only shooting out to 200 yards I would give the 69gr bullets a hard look. They always seemed to put up good groups and shot tighter than the 77's in my experience. Usual powders work well... AA2520, RL15, and Varget. If you stick with the 77's, I would not overlook 8208XBR.

Capt. Frank
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Re: Best Bullet for Match Shooting (Not a 30-40 Question)

Post by Capt. Frank »

With 1 in 9 twist, 55 to 62 grain bullets will be most accurate. With 1 in 8, 69 to 80 grains are best. My match AR has a 24 inch Krieger bull barrel with 1 in 8 twist. It likes 75-77 grain bullets best. The Sierra match king 77 gr have shot 2 1\2 inch groups at 600 yards. The Hornady ELD match 75 gr, have shot 1\4 inch groups at 100 and 300. I have not tried them at 600 yet. With the Sierra and Hornady's, I use 23.5 grains of Varget powder, trim the cases to specs, and seat at Sierra and Hornady recommended over all length.

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