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Posted: 3/28/2006 5:52:13 PM EDT
If my barrel times out to 10:00 can I wrench it into place from there? Someone told me that Imbel doesn't care about where they hand time and that they just twist them on till they're at 12.
Link Posted: 3/28/2006 6:22:04 PM EDT
Link Posted: 3/28/2006 8:16:50 PM EDT
60 degrees (from 10:00) is a little far to go...

Personally, I like about 20 degrees of crush on the barrel shoulder. Anything under 30 degrees (11:00) will work pretty well...

Remember that each 0.001" turned off the barrel shoulder will give you just under 6 degrees... Also, when first hand-tightening the barrel to see where it ends up (for example, 10:00 in your example), make sure that the end of the barrel isn't hitting the inside of the bullet guide in the receiver (bottoming out) instead of tightening against the barrel shoulder...

Forrest

Link Posted: 3/28/2006 8:41:31 PM EDT

Originally Posted By ftierson:
60 degrees (from 10:00) is a little far to go...

Personally, I like about 20 degrees of crush on the barrel shoulder. Anything under 30 degrees (11:00) will work pretty well...

Remember that each 0.001" turned off the barrel shoulder will give you just under 6 degrees... Also, when first hand-tightening the barrel to see where it ends up (for example, 10:00 in your example), make sure that the end of the barrel isn't hitting the inside of the bullet guide in the receiver (bottoming out) instead of tightening against the barrel shoulder...

Forrest




What if it does? Then what do you do?

My barrel hand tightens to about 10:30ish, maybe more but the barrel is really, really close to the inside of the receiver. (can't find my feeler guage) It looks like it will bottom out before I get it fully tightened/timed.
Link Posted: 3/28/2006 10:17:25 PM EDT
The usual approach with a non-chromed barrel is to take a few thousandths off of the face of the barrel...

You can also take it off the inside of the feed lips, but that's much trickier to get at (since it's inside the front receiver "ring."

Generally speaking, if you have to remove material, you work with the cheapest part. That usually means the barrel, especially with receivers somewhat hard, and expensive, to get right now...

If your barrel is not quite bottomed out when hand tightened to 10:30, you can probably get by without worrying too much about it bottoming out... After all, with the appropriate crush, we're only talking about the barrel being about 0.007" farther into the receiver...

Even when exactly right, the barrel will be so close to touching (bottomed out) that you probably won't notice the gap with the naked eye... If you have some of the Prussian blue to coat the surface of the barrel face, you'll be able to tell when it touches the back of the feed lip surface. For example, my current build (using an Argentine chrome-lined open eared gas block barrel and an Imbel receiver) hand tightened to about 10:00. I had 0.005" milled off the barrel shoulder, so that it now hand tightens to within 15-20 degrees of TDC (if I was doing it again, I would have had only 0.004" taken off...). Now, the back side of the feed ramp is just barely marking the Prussian blue. I'm not worried about that, because another 0.002" or so into the receiver will not cause problems...

Anyway, that's what I think...

Good luck with your build. I doubt that you'll have to worry about the feed ramp.

Forrest


Link Posted: 3/29/2006 8:13:54 PM EDT
Blue,

Have you had a chance to ask your bottoming out question over on the falfiles yet?

I'll look for it...



Forrest

Link Posted: 3/29/2006 8:15:02 PM EDT
[Last Edit: 3/29/2006 8:16:16 PM EDT by ftierson]
Deleted because I'm stupid and duped the last post...

Forrest

Link Posted: 3/29/2006 9:59:33 PM EDT
[Last Edit: 3/29/2006 10:14:26 PM EDT by operatorerror]

Originally Posted By ftierson:
The usual approach with a non-chromed barrel is to take a few thousandths off of the face of the barrel...

You can also take it off the inside of the feed lips, but that's much trickier to get at (since it's inside the front receiver "ring."

Generally speaking, if you have to remove material, you work with the cheapest part. That usually means the barrel, especially with receivers somewhat hard, and expensive, to get right now...

If your barrel is not quite bottomed out when hand tightened to 10:30, you can probably get by without worrying too much about it bottoming out... After all, with the appropriate crush, we're only talking about the barrel being about 0.007" farther into the receiver...

Even when exactly right, the barrel will be so close to touching (bottomed out) that you probably won't notice the gap with the naked eye... If you have some of the Prussian blue to coat the surface of the barrel face, you'll be able to tell when it touches the back of the feed lip surface. For example, my current build (using an Argentine chrome-lined open eared gas block barrel and an Imbel receiver) hand tightened to about 10:00. I had 0.005" milled off the barrel shoulder, so that it now hand tightens to within 15-20 degrees of TDC (if I was doing it again, I would have had only 0.004" taken off...). Now, the back side of the feed ramp is just barely marking the Prussian blue. I'm not worried about that, because another 0.002" or so into the receiver will not cause problems...

Anyway, that's what I think...

Good luck with your build. I doubt that you'll have to worry about the feed ramp.

Forrest





I relieved the barrel shoulder using the WECSOG sanding disc method, the barrel now times perfectly to 11:00. I found my feeler gauge and I have .004" clearance between the barrel and the receiver. By my guesstimate I figure that I will have approx. -.001" of clearance after bringing it into alignment.

I gotta' do some remeasuring. Think crush.
Link Posted: 3/29/2006 11:43:28 PM EDT

Originally Posted By operatorerror:
I relieved the barrel shoulder using the WECSOG sanding disc method, the barrel now times perfectly to 11:00. I found my feeler gauge and I have .004" clearance between the barrel and the receiver. By my guesstimate I figure that I will have approx. -.001" of clearance after bringing it into alignment.

I gotta' do some remeasuring. Think crush.



It's sounding good...

Forrest

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