Khornet
July 24, 2003, 07:06 AM
Finally got to try this out. It's a replacement gas plug which has been drilled through so that there's a bore from the gas cylinder out the front of the plug to vent gas. The hole is threaded for a small bolt and five bolts are provided, each with an aperture to vent gas, 5 different aperture sizes. The idea is to adjust the amount of gas bled off and thus vary the timing of oprod movement.
I was using my most successful load so far for my particular rifle, 46.5 gr 4064, Hornady 150 gr FMJ, fully prepped brass, Federal Match primer. Most of the apertures made no difference (stayed at 4-5 MOA) or actually worsened accuracy. But the next-to-smallest one was different. I was firing a clip for each aperture, 100 yds from sandbags. Suddenly all the shots began to pile up in 2 1/2", 3:00 in the 10 ring. Then shots 7 and 8 would go left a few inches to open the group to 6". But all shots were within a horizontal band about 3/4" high. Really striking.
This rifle hasn't been bedded or anything: I did peen the barrel splines to keep the cylinder in one place and file the bayonet lug so it doesn't touch anything, but that's all. And I can barely see the target at 100 yd.
With the larger apertures the brass would eject fine but the bolt didn't travel rearward enough to strip the next round from the clip. Recoil was noticeably softer too.
So now I'll try fiddling with the load a little and see if I can eliminate the flyers. I bet they'll remain, and I'll have to send the rifle off for accurizing. I also need to try this thing out with service ammo.
I was using my most successful load so far for my particular rifle, 46.5 gr 4064, Hornady 150 gr FMJ, fully prepped brass, Federal Match primer. Most of the apertures made no difference (stayed at 4-5 MOA) or actually worsened accuracy. But the next-to-smallest one was different. I was firing a clip for each aperture, 100 yds from sandbags. Suddenly all the shots began to pile up in 2 1/2", 3:00 in the 10 ring. Then shots 7 and 8 would go left a few inches to open the group to 6". But all shots were within a horizontal band about 3/4" high. Really striking.
This rifle hasn't been bedded or anything: I did peen the barrel splines to keep the cylinder in one place and file the bayonet lug so it doesn't touch anything, but that's all. And I can barely see the target at 100 yd.
With the larger apertures the brass would eject fine but the bolt didn't travel rearward enough to strip the next round from the clip. Recoil was noticeably softer too.
So now I'll try fiddling with the load a little and see if I can eliminate the flyers. I bet they'll remain, and I'll have to send the rifle off for accurizing. I also need to try this thing out with service ammo.