AR Comp 77SMK HPBT

[DieselWSM]

Just wanted to throw my 2 cents in on some load data.

With all the "hype" and "scare" surrounding firearms and reloading components these days I have been a little hesitant to load any more .223 with Varget since that is my primary .308 match powder with limited supply and I have plenty of .223 on the shelf.

I went to our local supply store the other day, and low and behold there was 2# of AR Comp on the shelf. Having never used this powder I decided to load up some 77gr SMK HPBT with Alliant recommendation of 22.1gr.

I am shooting a Noveske 18" 1:7 with a Vortex 1-4 PST. This isnt the best rifle to test loads on since it is a little more difficult to get a refined aiming point on 4x, as opposed to say my 42x NF benchrest on my .308. Never the less, I tested the loads and I must say that a 1" group with that setup was good enough for me.

Again, I loaded 22.1gr AR Comp, and OAL book length. Just wanted to give some feedback on the powder. It meters very consistently, most throws within .1 grains. Overall, I am impressed with the little work I put into it. I did not have a chance to chrony the load unfortunately, that is for the next outing.

 

[Tx_Flyboy]

Diesel,

I shoot highpower, and have settled on this powder for both 223/308 loads, moving away from varget. AR-comp is a Cheaper powder, has better availability, better metering through a powder measure, lot-to consistency, twice as temp insensitive as varget (per tests conducted by a hide user, Kumbyotch).

My 223/556 laods are as follows:

Both loads through a 20" 1x8 twist RRA NM upper

200 & 300 yard load:
77gr SMK
23.5gr AR-comp
LC brass (2011)
Win SRP
2.26 OAL

600yard load:
80gr SMK
24gr AR-comp
Win SRP
LC brass (2011)

None of the loads above show any pressure signs through my rifle, and i'm on my third firing of the brass already.

 

[Niles Coyote]

When and if you crono your loads guys, I’d love to hear what you are getting… I tried this in my 18” AR FNH barrel and was not to impressed with the speed, it did shoot good groups though.

 

[DieselWSM]

What kinds of groups are you getting with your 77s and 80s? I have not loaded my 80gr Amax bullets yet but intend to shortly. I will chrony both when I do.

I typically build my loads for groups but if the speed is super slow (i.e. 2400 fps for .223) I will build it a little hotter.

 

[knifenix]

With the loads you have listed you must be getting powder compression. Are you getting the ring on the bullet from your seater die and if so have you found a way to elimanate it? I also shoot highpower and load Sierra 69 gr.HPBTM with 22.8 gr. of AR Comp. I am getting a pretty good seating ring on the bullet with my competition redding seat die.Thanks!

 

[lazyengineer]

Diesel,

I shoot highpower, and have settled on this powder for both 223/308 loads, moving away from varget. AR-comp is a Cheaper powder, has better availability, better metering through a powder measure, lot-to consistency, twice as temp insensitive as varget (per tests conducted by a hide user, Kumbyotch).

My 223/556 laods are as follows:

Both loads through a 20" 1x8 twist RRA NM upper

200 & 300 yard load:
77gr SMK
23.5gr AR-comp
LC brass (2011)
Win SRP
2.26 OAL

600yard load:
80gr SMK
24gr AR-comp
Win SRP
LC brass (2011)

None of the loads above show any pressure signs through my rifle, and i'm on my third firing of the brass already.

Thread resurrection!

I picked up some ARComp at Camp Perry this year, and have to say I must have gotten a different lot. I tested my loads in the 99 degree Texas heat. (in the shade). I got very different results than reported above. Here is what I got:

Brass: LC, 0.244 bushing Redding sized
Primer: CCI 41
Charge: 22.7gr ARComp (slightly compressed)
Bullet: 77 gr Nosler Match
COAL: 2.265" (magazine depth)

Rifle: RRA NM 1/8 Wylde chamber - 400 rounds on this Barrel. A4 rifle, with 16X scope mounted and fired from sandbags.

Results:
MV: 2793FPS +/- 6.7 FPS stnd dev
5 shot group: 1.32" extreme spread, 0.5"average to center
Brass: The CCI 41 primers were completely flattened, indicating high pressure.

The muzzle velocity also indicates this was a high pressure load. That's a considerably milder charge that Tx_Flyboy was using, and gave a higher pressure result. Just goes to show different lots can give very different results! I suppose the Texas heat could be a factor, but then, isn't temperature insensitivity it's selling point? Accuracy results are decent'ish, but nothing to be particularly please about. I am going to reduce the charge a bit and slow it down to about 2750 FPS, and see if that helps tighten things up.

I had some other rounds loaded up to 23.5 gr, but just pulled them rather than fire them. (On a different load, I once took it too far on a ladder loading process and watched brass extrude 1/16" into the ejector and primers go flying - not doing that again!)

 

[woojos]

I have some of this powder and have been too busy loading for other guns to try it.

I'll load some with 77 smks and see what happens.

 

[Tx_Flyboy]

Lazy,

I have since gone onto different lot of powder from when i tested the above.

I shot three different AR-15s w different chambers & noticed the following with load info below:

77smk
22.5gr AR-comp
LC brass
Tula SRP

RRA A4 with wylde chamber (different barrel from the one above which is shot out): 2,661 ft/s avg
RRA A2 with Kriger Minimum Spec CHamber: 2,800ft/s avg
BCM A4 upper with 5.56 Nato Chamber: 2,750ft/s

When i re-barreled the upper above, i noticed that me previous loads was popping primers and causing stoppages (trigger lock due to spent primers in trigger well). Had to back all the way back to 22gr and come up in order to find accuracy and same velocity. To be fair, the universal highpower load of 24.5gr Varget + 77s was also popping primers in my minimum spec krieger...for the first 300-400 rounds.

I will test up to 23gr & 23.5gr loads in the Wylde & NATO chambered ARs to see when pressure arises. Hope to do so in next couple of weeks.

 

[ArmyJerry]

Jumping in here, I cant get my RRA 20inch ar to shoot sub 3/4

 

[nbkky71]

I'm running the following out of my NRA/CMP AR15 service rifle with a 20" 1-7.7 CBI barrel.

Sierra 77gr MK
22.4gr AR-COMP
CCI450 primer
LC brass
2.26" OAL
~2680 fps across the chrono

Berger 82gr MT
23.3gr AR-COMP
CCI450 primer
LC brass
2.50" OAL
~2700 fps across the chrono.

Warning: the 82gr load is a bit warm in my gun and I shoot that using a carrier weight to take the edge off. That load hammers for me though and I shot a personal best with it: 197-12X

 

[lazyengineer]

Which would you pick:

ARComp 22.1 Sierra 80 LC (.245) CCI Mil 2.393"OAL 2698.6FPS 0.81MOA 0.34ATC RRA A4 Mild pressure sign
ARComp 22.3 Sierra 80 LC (.245) CCI Mil 2.393 2726 1.625 0.48ATC RRA A4 Some pressure sign, but can take more
ARComp 22.6 Sierra 80 LC (.245) CCI Mil 2.393 2760.6 1.875 RRA A4 Some pressure sign, but can take more
ARComp 22.9 Sierra 80 LC (.245) CCI Mil 2.393 2789.6 0.5 0.25ATC RRA A4 Flattened primers

So the first load is 22.1 gr of ARComp pushing a Sierra 80 out of LC brass that was bushing sized to 0.245". A CCI military (41) primer lite it off. It ran at 2698.6 (effectively 2700) FPS. It hit the paper and grouped 0.81 MOA. The average to center statistics on the 5 shot group is 0.34 MOA average to center (ATC). It was launched out of a RRA A4 rifle (with a scope for this test). There was some mild pressure sign on the brass, but nothing of note. The barrel is relatively new, so very little throat erosion. Was seeing rifling scratches on a Sharpee marked bullet not much past 2.393" OAL, so that's why I picked that one.

Of those 4, the 22.1gr ARComp delivered 2700 FPS, with a group of 0.34 MOA average to center (0.81" extreme spread)

The 22.9 gr load delivered almost 2800FPS, which is just screaming along. And delivered an incredible 0.25 MOA average to center, or 0.5 MOA extreme spread (5 shots). The problem there is the primers were flattened, and there was some mild ejector smearing.

For some reason, the loads in between those two gave terrible groups. Not sure if me, scope parallax, or what, but was going to focus on the top and bottom loads.

It's a tough one for me, the windage chart for this bullet in the common AR15 score book is at 2700 FPS, and they aren't shy about pushing loads. Is that good enough, or should I think serious about pushing it up to close to 2800 for 600 yards?

Of these loads, which one would you pick for your next 600 yard match?

 

[Tx_Flyboy]

Lazy,

It's tough to say. I don't believe your loads are unsafe, despite the "pressure signs". Some gas guns tend to give false pressure signs even at low charge weights.

My experience with this powder is that the hot loads is where the accuracy is, and your results seem to match that.

If you shot this powder in the heat, close to match conditions, and your primer pockets aren't loose, I'd roll with the 22.9gr load for 600yards, and the 22.1gr load for your rapid strings.

On that note how are your primer pockets?

Despite my loads flattening the occasional primer, i can get over 7 reloads (I toss them after 7) out of each case before i notice loose primers pockets.