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AR-COMP Loading info needed.


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I am getting into loading rifle, (been loading pistol for a couple years now)
Well anyway. The only powder I have been able to get my hand on is the Alliant AR-Comp powder. Since neither one of my reloading manuals have anything on this powder, I went to Alliant website.
Now they list a couple different bullet weight and what charges they used. Ok good starting point.
He is where I run into another problem. Projectiles - The only ones I have been able to put my hands on is the Sierra Varminter 63gr SMP.

I sent Alliant an email stating the issue I was having and if they could shed some light on this.
The email I received back from Alliant. They told me was to take the bullet and powder weight and split it down the middle then reduce by 10% and work up from there if need be.

This scared me a little. My question is. Is this a common practice when using odd weight bullets?
I did this anyway. Here is what I came up with.

What Alliant had listed on there site.
55g HPBT - 25.6gr
68g HPBT - 23.5gr
The split in powder weight is 2.2gr's. Split the 2.2 in half and get 1.1gr's
The split in bullet weight is 13g. So 61g bullet is in the middle.

So with a little math, I came up with
61g bullet with 24.5gr's of AR-Comp.
From there with a little more math I was able to come up with powder weight for each bullet,
from there I reduced by 10%, thus giving me 22.5gr's of AR-Comp to start with.

With the extra math I was able to get powder weight for the 63g bullet I have.
What I came up with for the 63g bullet is 24.2gr's of AR-Comp.
I reduced this by 10%, this gave me a starting load of 21.78. I round down to 21.5 to start.

I did make up a couple round of ammo. I load 10rd's with 21.5gr, next load was 10rd's with 22.0gr, Next was 22.5gr, Next was 10rd's with 23.0gr and 23.5gr.

Am I on the right track here?
Rifle info - Daniel Defense M4 with a 18'' 1n7 twist barrel.
All LC brass. Bullet OAL is 2.260

CCI SRP #400

Has anybody worked any load using this powder? If so what bullet and weight and charge weight?

I sure hope you all can make out what I'm trying to say. If not let me know and I will do what I can to better explain.


Edited by bryanbag
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Your math works pretty close. Using the Alliant manual I came up with Start load of 22.0gr with a Max load of 24.5gr. When I work up rifle loads I usually don't jump more than 0.5 gr at the most (22.0, 22.5, 23.0, 23.5, 24.0) and if I were working this far off a known load I wouldn't load more than 2 or 3 per charge since I'm really just looking for pressure signs and ballpark velocity. Once I knew I could approach a charge range safely I'd narrow the range down and load 3-5 in 0.3 gr increments (for example 22.7,23.0,23.3,23.6). With that I'm likely to start to see a real pattern for OCW and can hone in with just a few at 0.2 gr increments. When I find consecutive loads with a common point of impact I split the difference and I've got a load that will maintain accuracy with slight variations in charge and I did it with very minimal wasted components. Only then would I bother to load up 10 or more of a certain charge to shoot and verify what I think is a good load. Also, if you do chrono them keep in mind that velocity will likely be less than Manual since your shooting the 18" barrel and they're data is based off a 24".

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Thanks for the info guys. I will be adding this to my mental and physical notes.

I really need to get a chrono or find someone that has one that I can borrow. Right now I'm just working general plinking/ semi accurate loads with what I can get my hands on.(shooting within100yds)

I am wanting to get into 2 and 3 gun competition sometime in the near future. Now with the lack of components available, I got to get what I can till things calm down. (whenever that will be)

Thanks Guys


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