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Posted: 6/18/2003 3:36:14 PM EDT
I bought a .750 rail-top gas block from Model 1 sales and slipped it onto my Bushy .750 HB 20" postban barrel and guess what - it easily spins around the barrel when it is at it's proper location over the gasport area!!!

Is this normal???

What, if anything, can I do to tighten it up???

Thanks in advance...
Link Posted: 6/18/2003 4:10:40 PM EDT
It don't have to be on there tight. It shouldn't wobble but if it's on nice and smooth you'll be OK. I just mic'ed one in my basement and I get about .005" difference. Does it use set screws or pins?
Link Posted: 6/18/2003 4:13:58 PM EDT
One or both is out of spec,if it's loose it aint gonna work it's going to leak and the action is going to short stroke. Measure the barrel and the block and hope it's the block thats out of spec.If it's both(referred to as tolerance stack) you have a worse problem.Either way you need to do some measuring can't nobody tell you whats wrong until you do.
Link Posted: 6/18/2003 4:31:41 PM EDT
Originally Posted By Halfcocked: It don't have to be on there tight. It shouldn't wobble but if it's on nice and smooth you'll be OK. I just mic'ed one in my basement and I get about .005" difference. Does it use set screws or pins?
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...2 set screws on the bottom which I suppose would tighten the gas ports together...hmmmmmm... I thought I read once that someone had used red loctite to tighten it all up...is this correct?
Link Posted: 6/18/2003 4:36:35 PM EDT
I don't know about the loc-tite. I don't think I would use it. Yes the set screws or pins will help hold it together. Do you have a mic?
Link Posted: 6/18/2003 4:42:29 PM EDT
Originally Posted By bgenlvtex: One or both is out of spec,if it's loose it aint gonna work it's going to leak and the action is going to short stroke. Measure the barrel and the block and hope it's the block thats out of spec.If it's both(referred to as tolerance stack) you have a worse problem.Either way you need to do some measuring can't nobody tell you whats wrong until you do.
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OK - the barrel at the machined gas block mounting shoulder measures .750" (+/- .001") and the inside of the gas block measures .755" (+/- .001"). What now???
Link Posted: 6/18/2003 4:51:58 PM EDT
You're fine. Mount it.
Link Posted: 6/18/2003 5:38:41 PM EDT
I don't think I'd use Loc-Tite either.I don't know what the acceptable tolerance is but .005 is miniscule. I suspect this is to accomodate barrels that are parkerized under the block.Is yours parkerized under the block or no? I would think that with the set screws in the bottom and gas port on top with only .005 clearance there should be no leakage. That being said I would like the fit to be snug.I suspect though that if they manufactured these blocks with an ID of .752 they would get more of them back with a letter that says "no fitty". Go with it.
Link Posted: 6/18/2003 5:43:07 PM EDT
Originally Posted By Halfcocked: You're fine. Mount it.
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Ok guys - you know more than I - I'll get 'er mounted up and report back here after a range session next month... Thanks again to all!
Link Posted: 6/19/2003 12:33:29 PM EDT
Just to clarify and run up the old post count...I wouldn't use loc-tite between the gas block and the barrel. A small spec on the set crews may be in order though. Also the .005" difference is the same as what I have on one I mic'ed.
Link Posted: 6/19/2003 5:06:12 PM EDT
[Last Edit: 6/19/2003 5:07:13 PM EDT by Colt45man]
Originally Posted By Halfcocked: Just to clarify and run up the old post count...I wouldn't use loc-tite between the gas block and the barrel. A small spec on the set crews may be in order though. Also the .005" difference is the same as what I have on one I mic'ed.
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Model 1 Sales seems to agree with you guys. They responded quickly to my email about the specs and said that it is "totally normal - just install it and go shooting". Sooooooooooooo - I guess I will!!! Thanks again guys...
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