TC Cut QLA
 

I asked txhunter to share his pictures of his cut QLA.
This is very typical of a QLA that is mis-aligned with the bore. It happens on some TC bores because the boring bit fails to stay straight drilling its way through the bore. More often the error is very slight and appears as a cosmetic issue on the muzzle of the barrel. This misalignment can occur as the bit gets dull and it is unable to stay true in the bore.

If TC would leave the bore at this point, accuracy would not be effected. But, because cosmetically it does not LOOK good TC chooses to fix the error by installing the QLA centered on the barrel but it will mis-align with the bore. For sabots, Power Belts, and cupped conicals like a FPB - they will shoot very well, but a flat based conical will have problems.









It is hard to see but if you look at the pictures and if you could measure with a mic' you can and would see the offset.

Thanks for the pic's txhunter

That got me curious Sabotloader. So I pulled my X7 from the rack and measured the barrel wall thickness between the bottom of the grooves and outside of the barrel, at the top and bottom and right and left sides. Here's what I got after double checking each measurement at least three times.

Top = .152
Bottom = .152
Right = .149
Left = .151

I wasn't sure what that was telling me other than either the bore or the outside of the barrel is not perfectly round. So I measured the outside barred diameter 1/16" back from the muzzle and got .810 top to bottom and .811 side to side.

I don't have a good micrometer, but the gunsmith that removed the QLA told me there was a max difference of 0.007 in my barrel!

My measurements were nearly identical to these. I also measured the cut-off which is the QLA. It measured 0.146" to 0.150" going around.

It sure doesn't seem like the differences are significant. I guess it is good that i don't make barrels. I am quite certain i couldn't do any better than what TC did.

It is obvious to me that the QLA does affect accuracy when shooting conical. With the QLA in place my rifle produced the following target at 47 yard.












The holes were punched by Art' 499g home cast bullet. These bullet appear to be very inaccurate, but after the qla was cut off, they punched the following target at 100 yard. They are good bullet; the qla is what made for inaccurate shooting when using Art' bullet.

Great example! My Omega made groups like that at 25 yards!

And T/C still claims it has nothing to do with QLA! They claim the twist is too fast for conicals. I told them that must be why White rifles won't shoot conicals..........LOL

I even tried to buy a Omega barrel only from the custom shop WITHOUT the QLA cut into the end of the barrel and they would not sell me one.

Mine was 0.145 to 0.150 going around.

My $2 crown job on an Encore .45 barrel. Rifle became a tack-driver after this was done.

How did you do it? I have had two gunsmiths work on my gun and the crown is still off center.

My $0 crown job on an X7. Rifle may have become a tack driver after this was done, but we'll never know, because of whom is trigger puller.

I did it with a power drill and two 99 cent grinders - one a cone and the other a ball. After I got it shaped, I used some lapping compound patches, then JB patches, then dry patches on the grinding ball to finish it up. It was by guess and by golly with the drill but it was pretty much a self-centering thing. And worked out well.

Ron, shuddup. Mine iz purdier 2, also. ;)