AR Comp and 123s

[sierracharlie338]

I have been working on some hand loads for my Larue upper. It shoots the Hornady black very well but plenty of marks on the brass when it comes out measuring at about 2520 ish on the Magnetospeed.

After much reading and consulting with other G owners I settled on 123 grain projectiles and AR Comp powder and started working up loads.

Problem - Speed is very slow compared to what others are posting. At 27.6 grains I am only around 2380 and not even sniffing 2500 at 29 grains. You read that right. . . I loaded carefully up to 29 grains with absolutely NO PRESSURE signs and was only able to hit 2475.

I have identified what I believe to be a couple of flat spots in velocity and loaded six rounds at two different charge weights (all I had left in that same brass) and will shoot it for accuracy and speed.

Any ideas on why its so slow compared to others here? I am using AA brass and CCI 450 primers as a side note.

Thanks in advance

SC

See update below

[Klem]

Is it an 18" barrel? What type of 123 and what's your OAL?

[Kilco]

Looking through my notes, seems I only recorded data for my 16" Grendel..

16" Odin Works ultralite
Hornady brass
CCI#450
123 ELD-M
2.255 COAL

27.4gr: 2364

27.6gr: 2386

27.8gr 2402

28gr: 2421

28.2gr: 2444

Started seeing mild swipes, stopped there.

Not sure what your barrel length is, but remember each barrel is it's own animal. My father's 20.5" Vepr is the fastest Grendel barrel I've seen, 50-70fps faster than my 22" Grendel so far.

[sierracharlie338]

Is it an 18" barrel? What type of 123 and what's your OAL?

Yes 18 inch barrel. 123 ssts. Shoot factory ELDMs fine as I stated

Looking through my notes, seems I only recorded data for my 16" Grendel..

16" Odin Works ultralite
Hornady brass
CCI#450
123 ELD-M
2.255 COAL

27.4gr: 2364

27.6gr: 2386

27.8gr 2402

28gr: 2421

28.2gr: 2444

Started seeing mild swipes, stopped there.

Not sure what your barrel length is, but remember each barrel is it's own animal. My father's 20.5" Vepr is the fastest Grendel barrel I've seen, 50-70fps faster than my 22" Grendel so far.

[Kilco]

Alot of factors can play here.. your numbers are close to what other have seen with 18" barrels.

Try to use comparative loads/rifles only as a starting reference point, and use careful handloading looking for pressure signs and velocities to find your rifles pressure curve with a specific load.

If you are at 29gr under a 123, and truly arnt seeing any pressure signs and the velocity trend is still normal, you very well might have room for more safe pressure, although 29gr of ARCOMP under any 123 is getting mighty compressed.

I've had R700 308s shooting 175s start showing pressure signs at 43 gr of Varget going 2600fps, wile another clone rifle took 44.3gr to reach the same pressure/velocity.

[Klem]

29 grains is 105.5% of the available case space. I wouldn't go any more than that, even if you can. Might have to choose a different powder if you are unhappy with the velocities but they seem normal to me.

[jason miller]

Fwiw, 29 grains behind a 123 is starting to crunch the powder at the 2.335" I'm loading for my bolt rifle. That also gets a little over 2600 fps from my 20" barrel, while factory 123 AMax ammo only did 2420 or so. I find it strange that you're getting such low velocity compared to factory ammo with 29 grains of AR Comp. Are you sure your chrono was reading accurately that day? Different lighting conditions can alter some chronographs. And if you're loading at 2.260" or thereabouts, I'm surprised you didn't notice some crunching when seating the bullets. How sure are you of the charges you threw being accurate?. If it were me, I'd check it again. And as others have said, some barrels just take more powder to hit the same velocity/pressure. I just find it odd that factory ammo was so much faster in your rifle, while being so much slower in mine. Although I was using older ammo and chronographed it in late winter. Maybe newer ammo is a little hotter or Hornady uses really temp sensitive powder and that's why my speeds were slow with it...?

[Sticks]

I got smacked mentally for chasing velocity, though I still want to be close to factory but accept what works with what I have.

Reality - it does no good to have a load that meets or exceeds factory ammo, but shoots 1.5" groups, when the loads 75fps slower were shooting .3" groups.

One of the most accurate loads I tested were plodding along at 2230fps (IIRC) out of my 18" with a 123gr ELD, and were shooting a ragged hole at 100y. Factory Black was running 2476. I may use that if I ever get into a competition that is 500y or less. Right now I am going out to 900, so I really need that 240 FPS if I can get it.

[sierracharlie338]

[grayfox]

I've got an AR Comp load for my howa 20" hb, 28.5 gr, 2520 ft/sec, worked up to and safe in my rifle, 123 sst's. I stopped at 28.7.

[Texkitch]

For comparison, I’m also in Houston area. I have a 16” AA and with ARComp, I get 2487 FPS with 28.7 gns. Hornady brass, CCI450, 123 SSTs. This is comparable to Kilco’s. Maybe your chrono accuracy?

[sierracharlie338]

[1911man]

I have been working on some hand loads for my Larue upper. It shoots the Hornady black very well but plenty of marks on the brass when it comes out measuring at about 2520 ish on the Magnetospeed.

After much reading and consulting with other G owners I settled on 123 grain projectiles and AR Comp powder and started working up loads.

Problem - Speed is very slow compared to what others are posting. At 27.6 grains I am only around 2380 and not even sniffing 2500 at 29 grains. You read that right. . . I loaded carefully up to 29 grains with absolutely NO PRESSURE signs and was only able to hit 2475.

I have identified what I believe to be a couple of flat spots in velocity and loaded six rounds at two different charge weights (all I had left in that same brass) and will shoot it for accuracy and speed.

Any ideas on why its so slow compared to others here? I am using AA brass and CCI 450 primers as a side note.

Thanks in advance

SC

Is there any chance there is something wrong with your Chronograph. All of your numbers look off to me compared to what I have seen in my guns and others guns. For example in my 18" Larue I am averaging 2460 fps with Boxed ELD and I have seen several others in this range. Your number there looks really high. Then I have Chronograph data from 3 guns using AR comp. 2 of them are 18" and the other is a 20". I get 2500 fps average from 28.1 grains in one of the 18" and the other I get 2500 fps with 28.3 grains. In my 20" barrel I get 2515 fps from 28.0 grains. Even when I did my work up in each of these barrels starting at 27.0 grains I didnt have a single charge clock under 2400 fps. All of these loads are using the 123 ELD FYI.

Also, we should start a Houston club since there is already 3 of us in just this thread and I know there are more on these boards. Just sayin.

[sierracharlie338]

[Jakal]

My PF Bartlein 20" runs at 2475 fps with a 123 Lapua Scenar and 27.9 grains of AR-Comp. Lapua brass, CCI 450 @ 2.260 COAL. Not the fastest but low SD/ES and very tight groups.

It sounds like you are on track but 29 grains is..well maybe a little higher than usual. But different barrel, different tolerances.

That same barrel: 123 SST's and CFE wouldn't even group!