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Gunsmithing my solution to one set-up bolt truing

300sniper

Gunny Sergeant
Full Member
Minuteman
Jan 17, 2005
3,438
23
Greenwood, Ca
i saw a discussion here the other day about bolt truing and hating to use the steady rest. i came up with a simple solution that allows all operations to be done in one setup, and no steady rest. it was so obvious, once i thought of it, it was one of those "why didn't i think of that before" moments.

i already had my action truing jig that i made a while back. a bolt wouldn't fit in it because of the handle. i machined a slot in the jig to allow the bolt handle to fit though. i thread my 1/2-13 mandrel that i had been using for bolt work into the rear of the bolt. this is where the rear adjusting screws ride on. the front adjusting screws are against the bolt body. i give it enough stickout to be able to indicate in a couple spots and have enough room to get a tool on the rear of the lugs.

this is not a set up for heavy machining or high rpm but it worked great for this purpose. once the bolt was done i could go straight to truing the receiver in the same jig.


actiontruingjig-1.jpg


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Re: my solution to one set-up bolt truing

when i have time, i plan on making a new one of these jigs but built directly on a d1-4 backing plate. i think i can loose over 3" of length and i'd feel a lot safer not holding all that way off a 4 jaw. my current jig uses 1/2-13 adjusting screws. the new one will have 1/2-20. i think this jig will also work good for precision threading short barrels such as a 12" 10/22 barrel.
 
Re: my solution to one set-up bolt truing

Nice....I got to thinking about it after I mentioned it and came to the same conclusion. My real job has been taking too much of my time lately. Just finished a gun I did for my neighbor and was goig to get started modifying mine.
 
Re: my solution to one set-up bolt truing

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: AZPrecision</div><div class="ubbcode-body">Very nice.
Hell you could sell those


And what lathe are you running? </div></div>

this one may be for sale when i finish my direct spindle mount one. i am collecting parts for it now.

i am using a kent kls1340a.
 
Re: my solution to one set-up bolt truing

300Sniper, nice set up! I'll confess, I'm gonna copy it.

A guy had a simular jig at Lassen GS's summer program in 07. I don't remember his name, I need to dig it out and credit him. He loaned me the jig and the bolt came out great for my needs/ability. The distance between indicators for zeroing the runout is a little short and probably results in a little less precision. With my measuring tools and ablility I had less than half of 0.001 on the lugs and face (with the bolt in a fixture that measured on the full length). This was as good or better than bolts others had done an a LaBounty bolt fixture.

Thanks A LOT for sharing. DC

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Re: my solution to one set-up bolt truing

i like that one. if i were to make a separate jig just for truing the bolt, i'd probably copy that one. the smaller diameter should make it a bit easier to see what you are doing on the rear of the lugs.