Pull Through Type Finishing Reamers

[Stats Shooter]

I have a G98 Large Ring Mauser project I am working on at the moment. My first one. I have the action, and I have had the bolt bent already. I was thinking about using one of those pull-through type finishing reamers to headspace it once I get the new barrel.

I plan to chamber it in .30-06 (it is going to be a hunting rifle setup). I was thinking about putting on a pre-cut and contoured Shilen barrel that is short chambered where all that needs done is a finishing reamer used to headspace it. I have never done this and I was wondering if any of yall do it or have tried it? Does it leave the chamber smooth or do you need to polish it afterward?

From what I am told it isn't a difficult task, and I can rent them locally as well as the gauges. But it really is the closest thing to a drop-in barrel you can get without a barrel nut and still get proper headspace.

Thanks

 

[HiBC]

First,good luck on your project!!

Not long ago,I used a pull-through on an M-1 Carbine that was a touch tight on a replacement barrel.It worked fine,BUT!! They cost more to rent,and really are not necessary on a Mauser.
Semi-Auto guns like a Garand,M-14,the Carbine,do not allow access to ream the final headspace from the breech.Your Mauser does.

I can't give you a full lesson on chambering here.Besides,folks disagree on everything!!
First.make sure,after your bolt was bent,that nothing,including the safety lug,prevents the bolt locking lugs from resting in battery.You can't get headspace set if the bolt handle root holds the bolt forward.
A few points.Original,military Mauser barrels do not have a shoulder to bear on the face of the receiver ring.They bear on the diaphragm at the bottom of the threads.
IMO,its a very good idea to put the receiver on a mandrel (see Brownells) and face the receiver ring square and true.That IS the foundation the barrel rests on.
I depth mic receiver face to diaphragm.I also depth mic receiver face to bolt face. Both are important numbers.

I face the larger shoulder on the barrel,or the face with the chamber mouth,so that I get about .0005,or less than .001,crush on the chamber end of the barrel to the diaphragm when the larger shoulder torques up to the face of the receiver ring.(Others may disagree)

I use the depth mic measureents to determine how far the headspace gage should protrude from the chamber .I'm familiar and confident enough to ream within about .003 to .005 from the final "Go" depth.Make a drawing,plug in the numbers,study till you are sure.

If you let the pilot do its job,and apply no side loads as you turn the reamer with a large tapwrench, a good job CAN be done with the .025 or so extra they leave you when they short chamber,without a lathe.
But facing the receiver and establishing the shoulder and barrel face are lathe jobs.

I do that final .003 to.005 with the barrel torqued in the receiver,through the receiver with an appropriate extension. Just a socket is not good,as you need a setscrew or two to retain the reamer as you with draw it out,rotating in the "cut" clockwise direction,always!.Never go backwards,and driving it out with a cleaning rod will leave marks.It may hurt the reamer.

You must backout and clear chips BEFORE the gullets get packed with chips.

Its the chips that will screw you up.

Each and every time you withdraw the reamer,meticulously wash the reamer in solvent with a brush,blow it off,and set it on a towel.
Blowall chips out of the chamber and bore,and run a patch through.

YOU ARE DOOMED if a tiny little sliver of steel gets over the top of a reamer cutting edge.It will cut a ring in your chamber,and may flake the cutter.

Use a good cutting oil. A number of tapping fluids work well.That black nasty,stinky old sulphur cutting oil plumbers use to thread pipe with will work,if it must.Its not my first choice!It work,its just a mess.Like molasses.

If you use the mics to get to .003or .005,check with the stripped bolt and headspace gage every two or three (at most) turns of the reamer,by hand.

If the reamer is sharp,and you use it right,no polishing should be necessary.

The first requirement of a good polish is a good tool finish.

Within the dimensional bounds required for a chamber,you can't polish out a bad tool finish.
Do carefully put a small radius on the sharp corner of the chamber mouth and polish it so the brass does not scrape on chambering.

Once again,good luck!

 

[ligonierbill]

Mississippi, I was successful in my first run at rebarreling a '98 Mauser, but I used a standard reamer. Just go slow, check the 'Go' gauge often, and keep it oiled and cleaned out. I did a 6.5x55. You probably know this already, but at SAAMI max COL, the '06 won't fit a Mauser magazine. I had to reduce mine to 3.27 loading for an older commercial Mauser conversion. Not a problem with most bullets, but I had to seat 165 Sierra GameKings deeper than I wanted. Good luck.

 

[Stats Shooter]

You probably know this already, but at SAAMI max COL, the '06 won't fit a Mauser magazine.

Yup, I'm going to be using different bottom metal and a deldrop box magazine.

As for HIBC, that's a crap ton of information. I will read and re read that

 

[kraigwy]

I've done a ton of finish reaming with the pull through reamers.

Its not that big of a deal if one takes his time and uses care.

The way its taught at the CMP Advanced Maint. Course on M1 (and similar) barrels is:

Get the reamer in the barrel, push bolt against the reamer, and hold down the bolt lug with your finger, with slight downward pressure. Turn the reamer until the lug drops in place and your done. Check with a go then no go gage.

On a bolt gun I ream until the bolt handle is about 1/4 inch from locking up on the Go Headspace gage. Then I take a couple turns with the reamer, check again, a couple more turns and check, repeat until the bolt barely closes on the headspace gage. Then check the No Go to make sure it doesn't close on it.

Go slow, clean and oil the chamber each time you go for another cut. DO NOT use a lot of pressure when pulling and turning the reamer. Make the reamer do the work with light pressure. It takes longer but you don't screw up.

I have done several bolt guns just using math and measuring on a lathe and have done ok but its scary. I'd rather take the last couple thousands by feel.

If is serious about learning to chamber I recommend contacting a gun smith and purchase some old barrels he has taken off, cut the shank a bit and use them for practice.

The main thing is go slow, keep the chamber clean and oiled (with cutting fluid). Take your time. Measure often. Remember the time you think you are wasting going slow, cost a lot less then another barrel.

 

[Reloadron]

I have used them in 30-06 Springfield and .308 Winchester on M1 Garand, M1A, and a few Remington 700 guns, all with the short cut chambers. Keep things clean and use quality tap oil and things should go fine. Kraigwy and the others have outlined the procedure which requires little effort, patience and cleanliness. Actually a pull through reamer and a Go Gauge is about all you need. I would true the action before fitting the new barrel.

Ron

 

[Stats Shooter]

So it sounds like it isn't too daunting of a task, if I just take my time and be patient with it. I really want to do this myself because I want to "build" my own hunting rifle. And while I don't have the lathe to turn my own barrel or chamber it....This is as close as I can get to building it.

But someday, hopefully soon, I will in fact have a lathe!