Attainable velocity and loads for ar10 308

[chuckbuster243]

Looking for good loads and what safe velocity I could get from a 20" 308 criterion lr308 pattern rifle. I am looking to shoot 175's and 190's and maybe a 168 or 185 berger in the mix. I have lc brass, cci primers, imr 4064 and varget. Just looking for what to expect in the velocity and accuracy dept. Thanks, Matt

 

[chuckbuster243]

Anybody shoot and load one?

 

[spencerhenry]

i run 42gr of imr4895 with 168gr sierra's. i do not remember my velocity, but it shoots one ragged hole in both my armalite ar10t 24" and in my 700pss.

 

[jonbearman]

First off since it is a semi auto you shouldn't be trying any hot loads in these types of rifles in my opinion. I use mild loads compared to a bolt action. I would be using the section used for the m1a meaning service rifle loads. Do you have a hornady manual?

 

[bsumoba]

You're going to be mag length limited so anything over 175gr is going to be tough.

Out of a 20" barrel, expect about max 2650fps. I'm at 2600fps with 175gr pills and Varget. This is enough to get to 1k supersonic under most conditions.

I have a JP supermatch barrel and my accuracy is easy 3/4" 5-shot groups

 

[chuckbuster243]

You're going to be mag length limited so anything over 175gr is going to be tough.

Out of a 20" barrel, expect about max 2650fps. I'm at 2600fps with 175gr pills and Varget. This is enough to get to 1k supersonic under most conditions.

I have a JP supermatch barrel and my accuracy is easy 3/4" 5-shot groups

I would be very happy to get to that. If I can get 2600 I would be happy. But as Jon said earlier this aint my 30"boltgun. Thanks guys, Matt

 

[XTR]

bsumoba hit on my first thought when reading your post. Why use heavy for class bullets in a short barreled gas gun.

You should be able to get 150s in the 2700FPS range with no problems. I've shot the hollow point 150SGKs (which are way cheaper than target bullets) in a bolt gun that consistently produced .75MOA at 200 yards.

The other option would be to work up a load that mimicked the FGGM 168SMK load so you could shoot your loads of factory loads to the same POA. (<- probably what I'd do if I had a gas gun) I've seen some guys write that the 150SGK shoots the same POA as the 168SMK out to some pretty reasonable distances.

 

[benchracer]

With the limitations of a gas gun vs a bolt gun, I believe the lighter bullets are a more sensible option. The 155 grain Sierra Palma bullets can easily be driven to 2700 or so with good accuracy. Sierra is getting ready to release a new line of plastic tipped Matchkings that will boost bc's by quite a bit. I think the 155 TMK's may be just the ticket in a gas gun. If the bc's of the new bullets are accurate, the 155 TMK should outperform the old 175 SMK's. Less recoil, more velocity, mag length... Sounds like the perfect combo to me.

 

[chuckbuster243]

Thanks, XTR and Benchracer you two have peaked my interest on that. I may try the 168 match bullet as well as a 168 nosler ballistic tip. I may even try to find some 155's to test. I am wondering what the real world price for the tipped matchkings will be? If its close to the msrp they posted I will stick with Bergers for that money. Thanks for the replies everyone your making me think outside the box. Matt

 

[bsumoba]

Thanks, XTR and Benchracer you two have peaked my interest on that. I may try the 168 match bullet as well as a 168 nosler ballistic tip. I may even try to find some 155's to test. I am wondering what the real world price for the tipped matchkings will be? If its close to the msrp they posted I will stick with Bergers for that money. Thanks for the replies everyone your making me think outside the box. Matt

Just be careful with the 168gr bullets. Although you will get the velocities you are looking for, assuming you are trying to pick up velocity to shoot longer distance, the 168gr bullets may not get there as they have a tendency to act funny around 800-900+ yards and accuracy tends to degrade around that distance.

If your distances are shorter than that, then you will be fine. If you are going to try to shoot out to 1K, stick with the 175gr.

 

[Turbulent Turtle]

First off since it is a semi auto you shouldn't be trying any hot loads in these types of rifles in my opinion. I use mild loads compared to a bolt action. I would be using the section used for the m1a meaning service rifle loads. Do you have a hornady manual?

My AR-10 is jet-propelled so I'm not worried about bending the non-existent op-rod. I do not have any compunction about using hot loads in my Armalite, and I use a CWS to tame the action and not beat up my brass too much.

I use the Nosler CC 175gr with 4064 in Winchester brass. I have not had a chance to chrono yet, but the testing I've done on the target shows right around an inch with 5 shot groups. Still a work in progress.

 

[XTR]

I assumed you were talking about shooting a gas gun at waht I would consider "reasonable" distances (like inside 600 yards) If in fact you want to shoot beyond that, and you are not trying to compete as a service rifle, then get a bolt gun, or rebarrel your upper into a 6 or a 6.5 (243/260) of some flavor. As noted above, 168SMKs are not designed for long range shooting. They can and do get wonky when they go transonic.

If you want to shoot a 308 gas gun to 1000 yards, then get an adjustable gas port, and single load really long 175s or 185s. (and by all means talk to some guys who do it and know what works best, I'm not one of them)

 

[chuckbuster243]

I assumed you were talking about shooting a gas gun at waht I would consider "reasonable" distances (like inside 600 yards) If in fact you want to shoot beyond that, and you are not trying to compete as a service rifle, then get a bolt gun, or rebarrel your upper into a 6 or a 6.5 (243/260) of some flavor. As noted above, 168SMKs are not designed for long range shooting. They can and do get wonky when they go transonic.

If you want to shoot a 308 gas gun to 1000 yards, then get an adjustable gas port, and single load really long 175s or 185s. (and by all means talk to some guys who do it and know what works best, I'm not one of them)

I follow... I understand about 168"s those jokers go stupid around 750... I will keep them inside that. 175's for on out. If I could only find a few more of the "old" 180smk's I have that have the old boat tail angle. Those shoot very well at long range. Then sierra changed it...

 

[chuckbuster243]

I have a boltgun for 1k. This gas gun is for 600 and to "play" at longer ranges.

 

[Finney]

LR308, 24" heavy barrel
165SGK
Win. brass
CCI primer
44gr Varget
2716fps

 

[mic2377]

I don't have any chrono data for my loads, but have always had good luck with IMR 4064 in my 18" Mega barrel and 20" Criterion. If I were you, I would look at bullets like the 168/175 Berger, 178 Amax, and 175 SMK if trying to reach out. You could also try other propellants - I just starting experimenting with 2000-MR with good results, and it has the potential to really boost velocity due to increased load density.

LR 308's/AR-10's are a different beast than M1A's and can tolerate hot loads much better. My 308 AR has a heavier buffer and adjustable gas and brass comes out looking it was fired from a bolt gun, minus some nicks/dings.

I have not done much long-range experimentation with 308 AR's since I now have a 24" 6.5 Creedmoor McGowen barreled AR in progress. That is the TRUE solution...