Acceptable clearance in FF tube

[rvb]

Hi all...

Chasing some accuracy problems.... Not happy with the groups I'm getting. While there are good odds its me, not the gun, I was looking things over and noticed the barrel is no longer centered in the FF tube. The tube is a troy/vac rail (the model before the "alpha"). I never really liked how this rail mounted to the nut. It seems with a bit of tension, the tube is moving on the nut, and not staying concentric to the barrel.

How much clearance is enough? I'm wondering if the barrel could be hitting the tube. Groups are in the 3" range @ 100.

I've pulled and re-mounted the tube. If I get better groups, I'll be searching for a new setup...

Acceptable clearance?

-rvb

[3guns]

Call Troy up and send it back to them. They have excellent customer service.

I had a similar problem with my alpha rail. It had something to do with the mounting. I sent it back to Troy and they sent me a new one.

[rvb]

well, after talking with a couple shooters I trust, I have low confidence this is my problem.

However, I did put some "shim stock" (aka pieces of a pepsi can) between the rail and the receiver just above the gas tube. This forced the front of the rail down so the barrel is more centered. It also made the handguards fit MUCH more snug on the nut. Before I could squeeze the barrel and hardguards and get +/- 1/4" of play at the front of the handguard with very very little effort (incl making the barrel touch the HGs). Now it seems the hardguard is much sturdier and there's almost no play at all, even with some force applied.

I hope to get on the range end of the weak to see if it made a difference. I'm not holding my breath, but at least I'll get some trigger time.

running out of decent ammo.

-rvb