Bullet weight for AR10

[JeffreyDeGraff]

I’ve got an Armalite AR-10 .308, 16” barrel with either a 10” or 11.25” twist ( I haven’t decided which yet). I’ve been testing 165gr bullets, with decent results. A couple loads will produce 1-1.5” groups, but most are 2-3” groups. I am tempted to try 150gr and see what happens. What weight bullets do you guys shoot in your AR-10’s?


JTD

[Shootingblanks]

For my DD5V1 I like to shoot either Federal or LC brass, 168gr Sierra MK with IMR 4064.

I will be trying 168gr and 175gr Sierra MKs with LC brass through my new SCAR 20S.

Every rifle is different, you just need to find which one works best in your rifle.

[SAWMAN]

. . . . . and you will be using this gun for what ?? --- SAWMAN

[JeffreyDeGraff]

. . . . . and you will be using this gun for what ?? --- SAWMAN

Deer and hogs. I have a couple 165gr loads that are very adequate for the intended purpose, but am amazed at how most of my groups look like a shotgun pattern instead of a group.


JTD

[Benny]

Share the loads you are unhappy with, it may shed some light.

The load(s) I finally arrived at to use for hunting purposes in my Remington 750 in 308 with an 18" barrel may surprise you.
Everything, including factory ammo would give me a 2 1/2" group.
Of all things, I arrived at a load that gave me 3/4" groups at 100 yards using 150gr Remington PSPCL with 48.0gr of BL-C(2).
One of the most notorious short barrel semi/auto firearms reputed for jamming and poor groups using a so-so bullet with iffy powder is giving acceptable groups and function.
I tried the same powder/volume with 150gr Remington SP round nose and got the same groups but 1 1/4" higher and 1 3/4" left.

The short barrel "may" be a problem with certain powders. Not so much as to velocity loss but to even powder burn. BUT not necessarily needing a "fast burning" powder. Simply backing off of the volume may help dramatically.
My load is well below the max, I even dropped down near the minimum suggested (45.0gr) and still maintained the good groups.

By the way, the Remington 150gr PSPCL is published to have a muzzle velocity of 2820fps (probably in a 24" barrel). In my 18" barrel it averages 2630fps.
The same bullet with 48.0gr of BL-C(2) is averaging 2625fps, 45.0gr is averaging 2465fps.

[SAWMAN]

Just a thought. - - -> Loading for my guns chambered in 308Win,I have gone to a lighter and lighter bullet over the years.
As bullet developement has progressed,with much better bullet design and materials,I find that I can drop down in weight to obtain a better trajectory.
Out of my AR/308's,I now shoot a 130gr Barnes TSX. I also have a bolt gun that likes this same formula.
You really do not need to go heavy for hogs or deer at the reasonable ranges. Bullet makeup/design is the key.
Look low and see what you find. --- SAWMAN

[JeffreyDeGraff]

Share the loads you are unhappy with, it may shed some light.

The load(s) I finally arrived at to use for hunting purposes in my Remington 750 in 308 with an 18" barrel may surprise you.
Everything, including factory ammo would give me a 2 1/2" group.
Of all things, I arrived at a load that gave me 3/4" groups at 100 yards using 150gr Remington PSPCL with 48.0gr of BL-C(2).
One of the most notorious short barrel semi/auto firearms reputed for jamming and poor groups using a so-so bullet with iffy powder is giving acceptable groups and function.
I tried the same powder/volume with 150gr Remington SP round nose and got the same groups but 1 1/4" higher and 1 3/4" left.

The short barrel "may" be a problem with certain powders. Not so much as to velocity loss but to even powder burn. BUT not necessarily needing a "fast burning" powder. Simply backing off of the volume may help dramatically.
My load is well below the max, I even dropped down near the minimum suggested (45.0gr) and still maintained the good groups.

By the way, the Remington 150gr PSPCL is published to have a muzzle velocity of 2820fps (probably in a 24" barrel). In my 18" barrel it averages 2630fps.
The same bullet with 48.0gr of BL-C(2) is averaging 2625fps, 45.0gr is averaging 2465fps.

So far, all my loads have been with 165gr SST. I’m using LC brass and CCI primers. Powders have been W760, IMR4895, H4895, IMR4064, Varget, and RL15. I can’t remember exact charge weights at the moment (at work), but what seems funny, is that, let’s say, 40.5gr of varget will be a 3” group, 41.0gr varget will be a 1” group, 41.5gr will be 2.5”. With RL15 41.0gr 2.75”, 41.5gr 2.25”, and 42.0gr .75”.


JTD

[JeffreyDeGraff]

Just a thought. - - -> Loading for my guns chambered in 308Win,I have gone to a lighter and lighter bullet over the years.
As bullet developement has progressed,with much better bullet design and materials,I find that I can drop down in weight to obtain a better trajectory.
Out of my AR/308's,I now shoot a 130gr Barnes TSX. I also have a bolt gun that likes this same formula.
You really do not need to go heavy for hogs or deer at the reasonable ranges. Bullet makeup/design is the key.
Look low and see what you find. --- SAWMAN

That’s kind of what I was thinking. I don’t want to go with the barnes bullets, but was wondering about going lighter.


JTD

[Benny]

but what seems funny, is that, let’s say, 40.5gr of varget will be a 3” group, 41.0gr varget will be a 1” group, 41.5gr will be 2.5”. With RL15 41.0gr 2.75”, 41.5gr 2.25”, and 42.0gr .75”.

Well, that shoots a lot of my theories in the ass!
This appears to be working on the realm of rpms per bullet length. Which I'm not up on.

[Benny]

Hey, if you want to know how to get a .223, .308 or 300aac to key hole, I got great experience with those!