Barrel timing misadventures

[scout762]

I put an StG58 barrel on an Entreprise type 03 receiver today. When I timed the barrel so the rods across the receiver flat and through the gas block lined up, the gas piston would bind and not drop through so I had to back off a bit and peened the barrel shoulder some so I arrived at a compromise with the rods very slightly off yet the gas piston drops smoothly without binding. BTW, I checked the rods on my L1A1 which was professionally barreled by Springfield Armory. (They did that 10 years ago)and the rods showed the barrel was over-tight considerably yet the gas piston moved freely. Probably why that rifle has always had to have the rear sight adjusted to it's limit to get it sighted in but it functions fine.

I also double checked my gas piston and used the piston out of the L1A1 on my StG and sure enough the StG piston is slightly bent. I will be ordering a new gas piston soon it seems. I figure I made a compromise between function and accuracy. I just hope the windage adjustment on the rear sight will cover the difference. The cross rods are just very slightly off. I understand that being off center can grossly affect windage especially as the distance increases.

I don't know if this makes any sense to anyone or not.

[W.E.G.]

Each degree of rotation of the barrel will change point of impact 5 inches at 100 yards.

You gotta index it so that the piston can function. Othewise you just have a well-indexed single-shot rifle.

[Slugger]

My STG kit has some of this going on. It groups well at 100yds however the windage is pretty much all taken up. I don't trust it past 100 - 150yds.

I had a "smith" mount the bbl and headspace it for me. I watched while he did the deed in all of 15-20 min. When he was "timing" the bbl, he took a grinder to the bbl shoulder. Whaam baam thank you maam.

On the next few builds that I am doing 100%, I am buying the tools and I'm considering removing the bbl off the STG kit and trying to fix it. I assume I'll need to find someone with a lathe and it will require a breeching washer etc.

Doesn't peening the bbl shoulder cause the same "out of true" condition?

[W.E.G.]

Slugger, when your sight is at mechanical zero, does your rifle shoot to the left or the right?

[Slugger]

It's been a while but I believe it was to the left about 6-7" at 100yds. That sound like a little over time?