Bolt nose clearance question vs accuracy

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hawk-i

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If the front of the bolt is touching the back of the barrel on a closed bolt will this have an effect on the accuracy of the rifle...more specifically the bolt isn't contacting the rear of the barrel but the m16 style extractor is to the point of leaving polish marks on the barrel and a more pronounced mark at the location when fired? (M700 style action)

thx
 
Mystic Precision said:
GT, what would be considered normal for bolt nose clearance to back of breech face?

Thanks
Jerry
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No closer than 5 thou, usually no more than 10 thou although 15 thou would not harm anything... in a hunting rifle more is probably better than the minimum for cycling when dirty...

at 5 thou a loose grain of powder or two can prevent bolt closure if it gets in the gap between bolt nose and barrel...
 
The polishing from the extractor may be occurring when the rifle is dry-fired as the bolt bounces ahead. I always try for .005" clearance ahead of the bolt. I used to fit 700 and 40X bolts close and, in fact, I lapped the bolt nose into the counterbore. They shot fine but so did the ones cut with clearance. I think it is best to make sure everything is clear. I have fitted some 700's with .005" radial clearance but with a teflon O-ring to center up the bolt. That barrel shot well so it didn't hurt any but it shot just as well with the o-ring removed so it didn't mean much either way, I guess.
 
Got a reply from the manufacturer and they said it (lack of proper bolt nose clearance) will cause accuracy problems and asked to have it returned to correct the issue...its currently at the warranty depot for repairs.

Hopefully this won't take to long.
 
guntech said:
Grinding 5 thou of the nose of the extended extractor usually takes 10 seconds...
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Yeah, I asked them about that and the answer was if the extractor was to be replaced in the future the same problem will occur. They are going to remove the barrel and cut as necessary to fix it as it should have been to begin with....I can't argue with that logic. :)
 
hawk-i said:
Yeah, I asked them about that and the answer was if the extractor was to be replaced in the future the same problem will occur. They are going to remove the barrel and cut as necessary to fix it as it should have been to begin with....I can't argue with that logic. :)
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Too bad they can't install a 700 extractor... :) ...
 
It's easy to check for clearance , close the bolt pull the trigger and the bolt should move in and out a bit you can tell it's evident any amount of movement will tell you there is clearance.

If the extractor is touching it should be an easy fix by removing a few thous and deburing
 
coyote said:
It's easy to check for clearance , close the bolt pull the trigger and the bolt should move in and out a bit you can tell it's evident any amount of movement will tell you there is clearance.
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The extractor was leaving marks on the back of the barrel through its rotation when closing the bolt.
 
coyote said:
Check it the way I described and if it is touching take a bit off
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Its at the warranty depot now, the manufacture didn't want to just grin off the extractor. If that was going to be the fix which in all honesty I was willing to do I wouldn't have bothered to send it back. It was their call on how they wanted to address the issue.

And yes I did check it that way....no bolt movement detected.
 
hawk-i said:
Its at the warranty depot now, the manufacture didn't want to just grin off the extractor. If that was going to be the fix which in all honesty I was willing to do I wouldn't have bothered to send it back. It was their call on how they wanted to address the issue.

And yes I did check it that way....no bolt movement detected.
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I didn't realize you sent it back I'm sure they will sort it out
 
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