velocity loss of an ar-15 vs. bolt rifle?

Mine gets higher velocity. I am getting a 35 gr. berger at 4000fps with 26gr. of BM compared to my dad, who is running about 27gr. out of his cooper and is getting 3900 fps.
 
Dan is right velocity is the same. BUT you can't load AR loads as hot as a bolt gun, RIGHT. So if you are a hot load type of guy this may be the only difference you will find in velocity.
 
I am not sure what will happen to the gun itself with too hot of a load. But it is my impression that the real hot loads won't allow the chamber to properly function and cycle the rounds correctly.
 
The case is the weak link in a rifle of any design. The AR will stand any pressure that would open up the primer pocket, to the point it won't hold a primer.
The gas system on an AR will handle pressure well beyond what would be considered optimal. The AR bolt locking system, as designed for use on the 223 based cartridge is strong as a bolt actioned rifle's.
I've loaded a 204 beyond any reasonable pressure, the only event was blown primer pockets in the brass.
 
I think the military has done test regarding that and found that a gas operated semi-auto lost about 3% vs. a fixed breech gun such as a bolt rifle. Pretty insignificant, but there may be a small difference. Probably less than the difference that can be found between individual barrels and various loads.
 
Sierra Reloading Manual Lists differernt data for bolts and AR's in their Edition V, 2nd printing.

There is definate velocity loss with the same load data according to their specs.

For example using IMR4198 and 55 grain bullets, they show 21.5 gains for 3000 ft/sec in the AR while in the bolt gun it only requires 20.6 grains to get the same velocity.

I understand that it is all relative, but most bolt guns have tighter chambers than most 5.56 AR chambers. Then there is also a 223 chamber or a Wylde chamber for the AR's. If the barrel chambers and lengths were identical I bet the data would be a lot closer.

As always when delevloping load data every gun is different and one load could and does develope differrent velocities in differrent guns, but it is possible that the AR could have a higher velocity than a bolt gun.

Did I make this even more confusing?
 
If the 5.56 Nato round is rated at a higher cup pressure I think it's 58,000 cup, "please correct me if I'm wrong". And the Military is still using Colts made in the 80's with no problems I doubt you going to damage an AR with a hot .223 Remington round. I have seen pictures of AR's broken on AR15.com but I have to wonder weather the operater did not have a portion of the responsibility.
 
Quote:
There is definate velocity loss with the same load data according to their specs.



That's because they used a 20" barrel for the AR and a 24" barrel for the bolt gun.

If they would have used the same length barrels in both, with similar chambers, there would be no meaningful difference.


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First off the AR has a locking breech the same as any bolt action. I think where some of the confusion is comeing from is that Many AR's have a 5.56 Chamber instead of the .223 there is a differance. That has been addressed with the .223 Wylde chamber ect.
As far as Chamber pressure goes consideering the AR is chambered in many chamberings besides the .223/5.56 some with higher average pressures than the .223 family it really is a moot point.
I think most cases of AR's Kbooming is tracable to handload error or some other operator problem.
 


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