Headspacing the M48 bbl w/o lathe

[ilcop22]

'Evening,

I bought a few M48 bbls recently, and was considering mounting one to my shot out M48 project. I did some research, and nearly every forum post I found on the web about hand head spacing invariably devolved to a discussion about why the OP needs to just "buy a lathe" or "take it to a GS". By definition, I'm a poor armorer who does minor gunsmithing, so neither of those two suggestions are neither helpful or possible. My question is, is it practical to finish headspace one of these bbls (chamber is already cut and the bbl threaded) by hand?

In the future I will invest in a lathe to expand my part time FFL business, but for now, I'm only interested in doing it by hand. Thanks.

[B R Shooter]

If you have a short chambered barrel that is threaded, and you have a reamer that is the same as the one used in the short chamber, then it is "possible". But it ain just the headspace. The tenon length has to be appropriate too.

Assuming you screw the barrel on and the tenon length is OK, then you could feasibly hand ream the chamber deeper. Your reamer will follow what is there fairly well, and if you don't exert side pressure while turning the reamer, it should be OK.

Unscrew the new barrel a few turns, insert the go gauge in the chamber, and with the bolt closed and locked, screw the barrel back in until the go gauge bottoms out. You can measure the gap between the barrel shoulder and receiver face to know how much you need to ream.

This isn't the proper way, but as long as you take your time and not go too deep, it's doable.

[MBTcustom]

You've got to make sure that the barrel screws into that action far enough. If not, you will get bulged and possibly ruptured brass, and have safety issues. If the barrel threads (tenon) are long enough then you can probably get it done with hand tools. Mainly, you need the reamer and an extention that will allow you to drive the reamer through the action. You will also need headspace gauges (you can rent them for $5 so do your fellow man a favor and forget all that cr@p about scotch tape, OK?)
Oh, and yes, a lathe is a wonderfull addition to a gunsmithing operation as well as a mill.

[Mk42gunner]

By definition, I'm a poor armorer who does minor gunsmithing, so neither of those two suggestions are neither helpful or possible.

It is very feasable. I rebarrelled several Mausers using short chambered barrels (and one long chambered one), without a lathe.

I was very hesitant to do the first one, until I read an article by Max Clymer about chambering a barrel by hand. I think the article was in the first volume of Brownell's "Gunsmith Kinks" but I'm not real sure; I have all four volumes. The Gunsithing Projects book from Wolfe Publishing has some good info too.

Be sure you understand what measurements need to be taken, and think about how to use your measuring device.

Don't be surprised when the front face of your Mauser isn't square.

Robert

[phaessler]

My concern would be , not to cast a dark shadow, as I have looked at doing my own too, but unlike a "typical" Mod98 (VZ24,K98,GEW), the M48 (intermediatesM48/47/52's) have a little different set-up as to the location of the extractor relief on the face of the chamber tenon.

Thus when mounting a barrel, one must set headspace first, then provide the relief for the extractor. I have seen guys file it by hand, dremel it, and mill it.

Just another note to offer you on this before proceeding.

NOTE: here is the best picture I could find of the extractor groove which is present on the M48 intermediates. Swapping barrels doesnt guarantee it will line-up where it needs to be.



Pete

[Casting Timmy]

If you have enough extra barrels, I would just try them all out on the action and see if one of them lines up right. Or at a minimum try and determine which one is the closest.

Accurazing the Factory Rifle he talks about improving the mating surfaces of the barrel, receiver, and bolt using lapping compound. Lapping the front of the receiver into the barrel will decrease head space and lapping the locking lugs into the receiver will increase headspace. Neither of these methods should be used to an extreme however, but can be used to take something that had 20% contact up closer towards 100% contact. Use your own judgement and try and leave melt there.

I also think Nonte's Pistolsmithing book talks about using files to set a pistol barrel back one turn. He would file the shoulder back and then the end of the barrel as needed when installed to get the correct barrel/ cylinder gap.

Although I wouldn't do it, I have also read in old books of the suggestion of shimming the barrel out a little to increase headspace. I don;t know what I would think about a barrel that was shimmed to get correct headspace, but it seems like some of the other time people did that.

My personal suggestion is if you have time.....use it. Vickery's Advanced Gunsmithing book is available free over the internet, and so are some others if you search around. Take some time to read everything you can and also start contacting friends and people here on the forum to see if there's a lathe you can use within driving distance. You might be able to trade something for some lathe work even, just try and see what's out there so you can make the best decision for yourself.

[leadman]

At one time long ago there were commercial barrels sold with shims to set the headspace.
An old gunsmith told me that most of the military barrels screw into most of the actions like Mausers pretty close.
I have done a couple of short chambered barrels and a couple of take off commercial barrels on military Mauser actions. I guess I have been lucky since none had excessive headspace and only had to cut .010' to .015" approximately out of the commercal take offs.
Reamer Rentals has been getting some of my money for reamers and headspace gauges lately. Good company to deal with with quick shipping.