- Location
- Burnaby, BC
How is the accuracy of your AR if you prevent the bolt from cycling? I know some piston guns can close off port completely. Any one ever block off the DI gas ports?
Piston ARs. Accuracy with closed gas port?
- Thread starter triplepete
- Start date
I don't think anyone who builds a piston AR is going for max accuracy. Not sure about pre-made ones.
I built a piston AR, never tried that.
I did once try it with a 16" DI I build I did, only cause the gas tube did not come in yet.
It was easy, just put the gas block on backwards and it blocked the port.
I was in the break in process, so I didn't do any accuracy tests, but I did notice different pressure signs on my brass, compared to the same load with the rifle running semi.
It was a warmer load, and the signs weren't red flags, I could just tell. It was a couple years ago so I forget the details. Seems the gun was a bit over gassed, so early timed and relieved the pressure of that load a bit during cycling. I have been reloading 223 for years before I got my first AR, so I had an "at one with the brass" thing going on.
So, I guess I don't have much info for you, other then I noticed a slight difference in the performance of the ammo I was using.
In theory as I understand it, a correctly timed DI AR should show no difference in the ammo's performance, and no difference in accuracy assuming you've just shut off the gas and have the same mass attached to the barrel.
Changing the gas block, and or removing the gas tube may very well make a difference, but that just barrel harmonics 101 at work in that case.
I built a piston AR, never tried that.
I did once try it with a 16" DI I build I did, only cause the gas tube did not come in yet.
It was easy, just put the gas block on backwards and it blocked the port.
I was in the break in process, so I didn't do any accuracy tests, but I did notice different pressure signs on my brass, compared to the same load with the rifle running semi.
It was a warmer load, and the signs weren't red flags, I could just tell. It was a couple years ago so I forget the details. Seems the gun was a bit over gassed, so early timed and relieved the pressure of that load a bit during cycling. I have been reloading 223 for years before I got my first AR, so I had an "at one with the brass" thing going on.
So, I guess I don't have much info for you, other then I noticed a slight difference in the performance of the ammo I was using.
In theory as I understand it, a correctly timed DI AR should show no difference in the ammo's performance, and no difference in accuracy assuming you've just shut off the gas and have the same mass attached to the barrel.
Changing the gas block, and or removing the gas tube may very well make a difference, but that just barrel harmonics 101 at work in that case.
The bullet will have left the barrel before anything moves. It takes time for the energy in the gas to overcome the weight of the piston and resistance of the spring and friction of the bolt and carrier.
This is also true in a stoner system. The bullet is gone long before unlocking. However the gas tube is not fixed to the upper receiver and allows for barrel movement.
Accuracy as Conte stated will have more to do with barrel whip and harmonics. The barrel is unable to free float with a piston attached. There is often more or different felt recoil as well since the centre of force is no longer aligned with the bore and there is more weight cycling. This would be eliminated with a piston gas cut off, and might affect follow up shots.
This is also true in a stoner system. The bullet is gone long before unlocking. However the gas tube is not fixed to the upper receiver and allows for barrel movement.
Accuracy as Conte stated will have more to do with barrel whip and harmonics. The barrel is unable to free float with a piston attached. There is often more or different felt recoil as well since the centre of force is no longer aligned with the bore and there is more weight cycling. This would be eliminated with a piston gas cut off, and might affect follow up shots.
