I was wondering if there is any difference in the MV of a piston based AR versus a non-piston based AR with the same length barrel.  I kind of suspect that a piston based system might need more gas and would therefore result in a bit lower MV but I'm not sure and would appreciate any feedback on this.  If there is a difference how much is it?


Thanks,

Brian

Put that under your list of things that shouldn't be worried about.  There's a difference between shells and between two identical guns.  Not enough to worry about.  

No measureable difference.  Not sure what physics you think would result in a difference.  Both use gas to drive the operating mechanism.  Both take the gas from a similar location on the barrel.  In each case the bullet has left the barrel at the point the gas is diverted to operate the bolt.

Yeah, I wasn't sure hence the reason I asked...

The reason I suspected pistons versions might have a bit lower MV was based on the suspicion that the volume would be greater.  OTH, pistons might well be more efficient in that they could have less blow by.  The standard AR with gasses blowing the bolt open and carrier back isn't really sealed tightly so there's going to be a good bit of wasted gas at the key.

In either case I didn't expect much of a difference...


Brian