Bolt head rubbing on barrel face?

[Screwyou1977]

Hi I'm new here and just converted my 111 30-06 to 308. Have a problem someone might be able to help me with.Problem is bolt is slightly rubbing barrel face.Bolt depth .135 and case protrusion .145 so I should have 10 clearance correct. Using Manson hs gauges closed on go without any resistance just like nothing in chamber. Wouldn't come close to closing on no go.So what's the problem? Parts shilen prefit , sss lug, stock bolt. Thanks!

[Hotolds442]

The way I read your post, you've got .145 (protrusion) sticking out of the chamber and .135 (bolt depth) to accommodate it. Your pictures reveal that you don't have the .010" you think you do.
.145" is a little long for my preferences.

[DanSavage]

Back the barrel out just enough for the bolt head not to rub,, then check with the no gauge.,, I bet it still won't close on the no gauge.

[adammiddagh]

The cartridge, or headspace gauge should stick .125-.130" out of the barrel, unless something odd like 338 Lapua. A std caliber bolt head should not be that deep.

http://www.savageshooters.com/content.php?322-Barrel-Chamber-Depth-Verification

I would recheck your chamber depth and your bolt head depth. If your barrel is right, and your bolt head is .135 deep, It will rub if the headspace is set on the tight end.

Used my caliper to measure the head thickness on a 308 Win Lapua case. At the center, it was .160" thick, given that it would be slightly thicker at the walls. So, the .130 spec would leave about .030" of overlap to take~50-60000psi. Change that to .160-.145 = .015" to hold the same pressure, may cause reduced case life at the very least. Others may now better.

I also just had this thought, if the above measurements check out.
If dry fired, with no spring tension(firing pin retainer) against the action/sear, and no cartridge in the chamber, the bolt can be pushed forward against the rear baffle or bolt head(which ever touches first). If this is the case, it is probably no problem. The first 2 actions I built on had so little primary extraction, I am sure they would have rubbed the barrel in this situation.

To test.
You could take a marker and darken the shinny spot on your bolt head. Open and close the action several times and see if any wore off.
Then dryfire and recock it several times(make point to hold bolt forward), and recheck.

Hope that helps, curious what you find.
Adam.

[Screwyou1977]

So I did what dansavage said backed off barrel and retested. Closed on go and did not close on no go . No more rubbing. Did file very lightly on barrel face to knock down engraving marks and the bolt face.So would it be safe to say it's safe to shoot? I read that article about chamber depth before posting today and how it should be .125 - .135" but even my factory barrel has .150 of stick out so I
I did open close with nothing in chamber and was ok.But when dried fired and racked action with nothing in chamber it did rub some.But with snap cap no rub.Left spring in bolt.
So again if bolt doesn't close on no go gauge it should be ok to shoot?
Thanks again for all your inputs

[sharpshooter]

First thing to do is throw those "toy" calipers in the trash and use a REAL measuring devise.

[DanSavage]

I like to use new brass to head space with, I then put tape on the back of the brass and make sure there is resistance closing the bolt.

[Scott Evans]

Prefits- Chamber is usually cut too deep, and with a worn out, chipped, totally dull reamer.

May want to have .010" or so clearance between bolt head and barrel for gas to escape in case of a case head failure or pierced primer.

Your best solution for that is to remove barrel and lathe cut .010" off the breech end, it doesn't need to be set up to .00000001" of bore axis or anything fancy just cut reasonably perpendicular and then put a very slight polish radius on the chamber entry.

[FW Conch]

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