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Gunsmithing measuring coned bolt face tenon

gamma

Sergeant
Full Member
Minuteman
Jul 14, 2009
456
2
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Ive got a custom build coming up soon thats got a coned bolt face, just wondering what you guys use to measure tenon length.
Im thinking of making a tube of the same diameter as the action and an insert with the same diameter as the tenon with the same angle as the bolt face. After sliding the insert down to stop against the bolt face, this should give me my tenon length, right!!. What do you guys use and am I on the right track. Thanks!
 
Re: measuring coned bolt face tenon

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: mikki</div><div class="ubbcode-body">Its a Stolle Grizzly II magnum coned bolt face. </div></div>

The Stolle Receivers I've chambered (Panda) have been as follows, not sure how they compare to the Grizzly as I've only chambered one.

Tenon / Headspace Length 1.115"
Threads 1.0625" x 18 TPI
Cone angle 29 Degrees

Cut the tenon to 1.115" and get 1/2 way through the cone cut. Screw the receiver on with bolt closed and measure the gap between the receiver face and barrel shoulder when the bolt bottoms out. Remove that amount plus .005". The major diameter of the cone will be right at 1.0625". I re-measure when I'm about .020" away from the determined measurement.

Your described method of measurement is the way a lot of guys do it but I've always done it the way I described, works like a charm every time.
 
Re: measuring coned bolt face tenon

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: mikki</div><div class="ubbcode-body">Thanks wmroscoe, I hadnt thought of doing it that way. Great idea from you. Thanks again. </div></div>

I set final headspace the same way when chambering.
 
Re: measuring coned bolt face tenon

Measure from the front of the receiver to the BF. make the tenon that length. Chamber till gauges are flush with back of tenon. Cut cone as Roscoe described.
 
Re: measuring coned bolt face tenon

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: PFCSkoug</div><div class="ubbcode-body">Measure from the front of the receiver to the BF. make the tenon that length. Chamber till gauges are flush with back of tenon. Cut cone as Roscoe described. </div></div>

Thats kinda what I said, we're on the same page.
 
Re: measuring coned bolt face tenon

Excellent advice guys. I see exactly what your saying now but Im thinking from what your saying, would I not be better off making the tenon say 1.120 long and then with my tool set at the correct angle, start cutting the the cone until my tenon reaches 1.115 -005. Just a taught.
 
Re: measuring coned bolt face tenon

I do a lot of builds on "Glue ins". Obviously you can't screw the action on the barrel to check the cone fit. I made a set of screw on jigs to check cone fit and headspace. One set for 30 degree cones and one set for 25 degree cones.
 
Re: measuring coned bolt face tenon

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: DocEd</div><div class="ubbcode-body">I do a lot of builds on "Glue ins". Obviously you can't screw the action on the barrel to check the cone fit. I made a set of screw on jigs to check cone fit and headspace. One set for 30 degree cones and one set for 25 degree cones. </div></div>
They sound interesting, can you post some pics please. I wouldnt mind making something like that.
 
Re: measuring coned bolt face tenon

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: DocEd</div><div class="ubbcode-body">I do a lot of builds on "Glue ins". Obviously you can't screw the action on the barrel to check the cone fit.</div></div>

Obviously
wink.gif


Reason #30, Why I dont like glue ins