Is a Mauser barrel supposed to seat against the reciever face with the small shoulder forward of the barrel threads, or is it supposed to seat at the end of the barrel inside of the reciever? Or both? Is there supposed to be a slight gap on one or the other?

The instructions I have indicate that measurments are taken to make it seat at the end of the barrel, yet other sources suggest truing the "face" of the reciever for a square fit. What gives?

Wstrnhuntr, It should be hard against the abutment and touching the action face.

I cut my shank length around .0005"to .001" longer than the measurememt from the rec. ring to the C "breech" ring. They will be both touching when you tighten the barrel.
gunmaker

should lock on c or H ring (mauser or FN) and butt up to the action face... the rear most is the most important. Got a great deal of info on this one...


jeffe

quote:

Originally posted by gunmaker:
I cut my shank length around .0005"to .001" longer than the measurememt from the rec. ring to the C "breech" ring. They will be both touching when you tighten the barrel.
gunmaker

Me too....except I cut the barrel +/-.0005 of the action length.

Personally I believe it's OK to butt the barrel on the front of the receiver ring and have a .001 gap on the inner "C" or "H" ring..... I was told to try to match the action step with the barrel

I've seen barrels cut with a .010 gap at the end of the receiver ring.....this isn't for me.

Thanks guys. Very helpfull and informative as usual.

Okay, I think I just heard both that the inner shoulder contact is most important and that it's unimportant (the outer shoulder contact is enough). Which is true?

My pre-threaded barrel shank is .005 shorter than the receiver shoulder to C-Ring distance. What is the technically sound thing to do?

Thanks,
Steve

I asked a similar question on the old forum about a year ago.

I remember someone replying that it is virtually impossible to get equally close contact between the barrel and the receiver on two spots. I think this is true. Since the bearing surface on the inner C-ring is larger than on the shoulder, I just slightly lapped the shoulder, so there is no gap, but just no contact with the shoulder of the barrel.

I also remember someone else explaining that crushfitting a barrel to the action destroys most of the effort taken in trueing the c-ring and the barrel threading. So I used a locking compound and tightened the barrel just slightly.
After about 200 bullets gone through, headspace has not changed.

Accuracy in this rifle is < 0,6 MOA @ 3 shots.

SKL1,

Technically speaking, you should set back the barrel "shoulder" .01 to make the thread shank .005 longer than the receiver. You'll need a lathe to do that.

Or, you could machine .01 off the face of the receiver to achieve the same results.

Practically speaking, you're probably ok to do nothing, as long as you properly torque the barrel.

My advice would be to square the receiver face at least .005 to ensure good breech contact with the primary torque shoulder (the C ring)

Regards,

Dan

Thanks, guys. I'll leave threading and shoulders as they are. I believe Springfield and other military barrels were installed from pre-threaded and short-chambered blanks.

It's always struck me as contradictory that some folks claim that both shoulders engaging keeps everything tight, consistent, and therefore accurate.

Yet the SMLE is always referenced as the most accurizable milsurp weapon, and it's always stated that's because the action flexes.

Wish I was smarter.

Steve

quote:

Originally posted by DanM:
SKL1,

My advice would be to square the receiver face at least .005 to ensure good breech contact with the primary torque shoulder (the C ring)

Regards,

Dan

I think that is sound advice, seems to me that truing the face is essential just to get accurate measurments. The BRNO action Im presently working with varys from the face to the "C" ring as much as .006".

I kind of like Vapodogs idea of truing the face and leaving the shank .001" short too, but I wouldnt do it unless the specific barrel had a pretty substantial shoulder, unlike the millsurp bbls.

I have heard that Paul Mauser intended that the shank be .0015" longer than the reciever, so that the shank gave the stiffness and the large ring gave the damping.

But I am getting great results making them the same length, so it is hard to stop