I noticed that you guys never specify your rifle's barrel twist, it would help a lot in making a choice.

My Colt AR 15 SP1 Sporter is 1/12, holds a washing machine @ 100 yards
My Colt AR 15 A2 HB is 1/7, 2 MOA @ 500 yards
My Colt AR 15 A3 Carbine is 1/9, 1 MOA @ 300 yards.

All of the above with factory ammo, Black Hills Match for the A2 and the A3.

For 77 grain Match Kings I like 1:7. Sniper accurate.

For 68 grain Hdy Match I like 1:8. Sniper accurate.

For 55 grain Ballistic Tips I like 1:9. 1 moa.

Hope this is useful info.

I have two AR's

A CMMG 20" 1/7 govt profile barreled gun that really likes Hornady 75gr BTHP's

A 16" carbine with a 1/9 DTI barrel that does 55gr Hornady BT FMJ bullets well and 69gr SMK even better.

ZM

I have a five-digit numbered SP 1 that won't shoot anything but 55 gr. The 62 gr. stuff keyholes at fifty yards.

quote:

A CMMG 20" 1/7 govt profile barreled gun that really likes Hornady 75gr BTHP's

Did you custom work the throating? Do you load magazine length only? I would like to know the overall length of your ammo with this projectile, I have some that I would like to load.

All three of mine are 1/9 twist and all I shoot out of them are 50 and 55 grain bullets.

I'm getting a White Oak match barrel (just for the heck of it) and it is twisted 1:8" for 26" so I hope to be able to shoot 77 grainers out of it.

quote:

Originally posted by Edmond:

quote:

A CMMG 20" 1/7 govt profile barreled gun that really likes Hornady 75gr BTHP's

Did you custom work the throating? Do you load magazine length only? I would like to know the overall length of your ammo with this projectile, I have some that I would like to load.

No fancy throating or 'smithing. Regular 5.56MM chamber and chrome lined chamber and barrel.
I'm loading to just under mag length. About 2.272" That's approximate. I use a comparator to seat, then test each round in a 20 round NHMTG mag. The OAL is as long as I dare to go. Feeds fine and hits better.
24gr of RL15 gets about 2700 fps with the 75gr Hornady BTHP

In a pinch it'll shoot 55 grain Hornady BT-FMJ too


CMMG upper and govt profile barrel
Clark Custom carbon fiber FF handguard
LMT BCG
CavAid MkII lower
Larue Tactical SPR 1.5 mount
Bushnell Elite 3200 10x scope

XTP

There must be somthing wrong with your SP1 or the ammo you are shooting in it.

Back in the day when the SP1 was the only AR around I have shot many of them.

And I have shot a Carbine [16" barrel with the 1-12 twist] quite a bit.

With good 55gr ammo the SP 1 should shoot @ 2 to 2.5 inches at 100 yards. This is prone, with iron sights.

I used a SP 1 as a work gun [it was an original full auto AR-15, and so marked], and it would hit a man sized target every time at 300 yards, and most of the time at 425 yards, iron sights.

It would make head shots all day at 100 yards.

Something must be wrong with your rifle.

If that SP 1 has been shot a lot it may need a new barrel.

With the Colt Carbine [1-12 twist] I have killed peccary at 225 and 300 yards, with 55gr remington SP factory ammo.

I did have an original Colt 3X scope with the ballistic cam, on the rifle.

My wife had killled several turkeys with it as well.

DPMS-16 inch stainless HB is 1:9 very accurate with 50 and 55 grains Armalite m-15 with 16inch 1:9 also 1moa. Both rifles shoot Black Hills 52grain match bullets the best

quote:

There must be somthing wrong with your SP1 or the ammo you are shooting in it.

As mentioned above, mine won't shoot anything but 55 grainers, but it certainly does a heck of a lot better than a washing machine at 100. Shoots about 3 MOA with S&B FMJ's and Federals, also some old surplus, but it's had about 15,000 rounds through it. Back when one could buy a 3000 round case of 55 gr. surplus for $189.00, I used to burn up a lot of ammo, so I would imagine that the old girl is showing some signs of wear. In a defensive situation ,though, I wouldn't hesitate to take on an adversary at 150 or so.

my first AR 15 was a Colt SP1 in .222 Rem Magnum followed by a second one in .222 due to french regulations then two in .223 (16" and 20" barrels). I liked them but in terms of accuracy not one of them was close to the other rifles I had: Valmet, Beretta 70, FA MAS, Galil. Only the Mini Ruger did worse especially the first batch model 180.
Then I installed belgian Match quality barrels and I had accurate AR 15s. The newest version of the Colt was a pleasure to shoot with its 1/7 twist and Sierra 69 grains or SS 109. Finally the Delta Heavy Barrel I purchased in 1989 was par with my SIG 90.