Gunsmithing bolt face diameter question?

[300sniper]

i was in the process of helping a friend out with his 7wsm chamber today. the barrel dialed in, threads cut, counterbore done and chamber nearly complete and then we realized he received a standard bolt face when he ordered a magnum (or at least he swears he ordered a magnum bolt face). my bad for not checking or noticing this before hand. sometimes you just assume you got what you ordered. i guess i won't make that mistake again

.

either way, i am not going to take the barrel out of the lathe at this point to open up the bolt face. we weren't able to get ahold of the manufacture today to see how fast a replacement bolt can be had. if i don't hear from them by tomorrow morning i am going to have to open up the bolt face on my cnc mill. i am not really looking forward to the set up on the mill but i need to get it done to free up my lathe.

so that is the back story. now my question is how much over the .532" rim diameter does the bolt face need to be? i have searched but i can't find this information. is .010" over, .542" good?

 

[wnroscoe]

Re: bolt face diameter question?

RH or LH rifle. I may have an extra mag bolt.

Mine measures .546" / .547" with calipers

If you open your friends bolt up, you then have the issue of extraction. Sako comes to mind.

 

[300sniper]

Re: bolt face diameter question?

it is an aftermarket action and uses a sako style extractor. i am having a hard time measuring a remington magnum bolt face with the extractor groove but it looks like it is about .540". the bolt i am working with measures .480" with callipers for a .473" cartridge. maybe i'll shoot for .539"-.540" for this one. i don't know how critical this dimension is but after looking at a remingotn bolt, i am guessing it is not as critical as i originally imagined.

this bolt also has a nice finish on it that i would really like to avoid messing up. hopefully the manufacture can get a replacement out quickly. if not, i guess i have to do what i have to do.

 

[wnroscoe]

Re: bolt face diameter question?

6PPC bolt faces in Stolle Receivers are opened up all the time for the 6BR cartridges. Look at any push feed claw extract, no rim on the OD of the bolt face. The rim on the 700 clones are part of that three rings of steel deal, or was it three rings of pineapple with whip cream

As long as the extractor catches the case rim it's GTG. Just allow a little wiggle room for feeding and you'll probably be OK.

 

[300sniper]

Re: bolt face diameter question?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: wnroscoe</div><div class="ubbcode-body"> or was it three rings of pineapple with whip cream

</div></div>

 

[eddybo]

Re: bolt face diameter question?

If you are using a floating reamer holder and piloted reamer,I would think that if you have reamed it to within .100 or so that you would be safe to pull the barrel and wait on a replacement. I do not take them out as a rule, but it seems that the reamer would just follow the nearly completed chamber after you indicated it back in.

 

[Clark]

Re: bolt face diameter question?

Funny you should ask that

Right now in my lathe, I am opening up a 1908 Brazilian Mauser [made in Oberndorf] from an 1889 7.65x53mm case head [.473"] to a 1925 300 H&H case head [.532"].
Actually I am converting from 7x57mmMauser [1893] to 7mmRemMag [1962], but those are the parent cartridges.

The SAAMI drawings for the chamber bolt face is .4777" reference to a .535 + .012".
That means I want to be somewhere between .535" and .547" when I am done, if I care about SAAMI drawing tolerances.

The 7mm WSM [2001] has a .535" case head, and I expect the SAAMI drawing for the chamber bolt face to be the same as the 7mmRemMag [Probably one of the reasons that Winchester rebated the case head.]:

What did I learn?
With a surface hardened Mauser bolt face, do not try to cut it with high speed steel. Start out with Carbide, even in the interrupted cut.

 

[WRM]

Re: bolt face diameter question?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: wnroscoe</div><div class="ubbcode-body">6PPC bolt faces in Stolle Receivers are opened up all the time for the 6BR cartridges.</div></div>

And there is enough travel on the extractor that the Stolle 308 BF will still work with a 6PPC! Most of my "Stolle" barrels are .473 rim, but I do have a 6 PPC barrel that works just fine with my 308 BF Kodiak.

Cheers,

Bill

 

[300sniper]

Re: bolt face diameter question?

he got ahold of the action manufacture today and is going to swap it out. that is fine with me as i am doing this as a favor and don't need to do more work than is necessary. when i see the new bolt i will measure it for future reference.

 

[wnroscoe]

Re: bolt face diameter question?

Whose receiver are you using?

 

[300sniper]

Re: bolt face diameter question?

stiller tac30