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Military Firearm Restoration Corner

How Hard Is It To Ream A Short-chamber?


rustvyper

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By hand it is relatively simple if you don't have to ream much.

 

I try to do all my chamberiing in the lathe only. I hate short chambered barrels becuase of setup. I'd rather chamber a blank.

 

Maybe some of the guys that have more experience hand reaming will add to this.

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You would be surprised at how fast a reamer turned by hand can cut. Just take it a turn or two at a time so you don't over-cut.

 

I have used the Brownells Shilen barrels threaded for Mausers, and I have one of the $69 specials in the shop right now, but I have not fitted it to anything yet. The barrel looks OK.

 

Clemson

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Like Clemson said go pnly a turn or two btween measuring.

It really depressing to discover you've gone too far, and 'wishing you hadn't done that' don't put the metal back.

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Here's a page from my "electronic diary" cobbled together from old posts I made during my first project. Hope the perspective helps:

 

I've seen two techniques espoused for this procedure, and was wondering if there were any pros or cons to either or whether it was simply a matter of personal preference.

 

method 1: Install barrel on action and use an extension to ream chamber, checking depth frequently with headspace gauge in bolt.

 

method 2: Measure distance from bolt face to front of receiver ring, subtract the distance from shoulder to barrel shank, then ream unmounted barrel until gauge protrudes by this amount. (final test is obviously to try to chamber appropriate gauges...)

 

 

 

Well, still haven't started to make any chips yet, but I got everything out and started setting up. (I have to whittle away at projects like this in small chunks of available time!) I measured everything carefully, drew a sketch, then checked and rechecked my math. I also hand tightened the barrel and tried to chamber a go gauge to measure on the bolt how far I needed to ream as a final common sense check of my work before I start removing metal. (I've made enought mistakes in my time that I've learned it's worth the extra effort...)

 

After all that I've determined that without a good micrometer I don't trust myself to get it reamed to the proper depth before screwing the barrel on. I tried multiple measurments with a good dial caliper and as careful as I was I still got variations plus or minus >.002. Not close enough to allow for a crush fit.

 

So, I think I will start reaming with the barrel off for the best control, and once it is within approx .01 or so, mount the barrel and finish it off using the headspace gauge for final depth measurement.

 

 

 

Well, I finally got 'er done this afternoon and reamed my first chamber. (In between periodic breaks to watch my Seahawks achieve a spectacular last second victory!)

 

Anyhow, it went pretty well for the most part. Lesson learned: The reamer can cut either very slowly, or very quickly. It depends on how much pressure you put on it.

 

As stated above, I started with the receiver off, and would drop in a Go gauge every time I cleaned the reamer off to measure progress with the depth end of my dial calipers. To clean the chamber I used a can of WD-40 with the little straw to essentially flood and rinse all the chips out, with everything dripping on a towel I'd laid on the floor.

 

Things were going slowly at first, and each time I measured there wasn't much apparent change. I had about .4xx to go so I started increasing the force a bit. The next time I took the reamer out and checked, the Go gauge suddenly dropped WAY in. I had calculated that the gauge needed to protrude by .118, and held my breath as I measured it at .17.

 

So far so good, time to mount the barrel. I cinched it down good and snug and stamped an index mark on the underside just in case it should ever need to come back off. I then got out the extensions and bolt, and continued.

 

Once again things were progressing somewhat slowly, so I increased the force a little. I was going slowly and checking frequently, hoping to achieve a nice tight chamber, yet suddenly on the next check the go gauge was just swallowed up!

 

Oh oh...

 

Once again I crossed my fingers and hoped for the best as I got out the "No Go" gauge. Thankfully it would not chamber, although it is closer than I had hoped. The bolt will stop about 10-20 degress of arc short of closing.

 

Not exactly match quality, but I have to assume that it is at least safe.

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I can't answer the first part with any degree of credibility, but I just used a finish reamer on mine. It shoots a little over MOA with factory ammo. I haven't shot it since bedding however, and don't currently reload. I'm sure I can do a bit better.

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Buy a finish reamer with a floating pilot. The difference between a floating pilot and a solid pilot is that the solid pilot is attached to the reamer while a floating pilot is detachable. A floating pilot is more desirable in case you need to swap it out with another to get a good fit to your barrel to keep the reamer from wobbling. Floating pilot reamers cost more, but if you end up with a barrel that's got a tight bore and your solid pilot doesn't fit, you'll wish you'd spent the extra $40. Also, since you need to cut a precision hole, I'd stay away from eBay and buy a new reamer from Pacific Tool & Gauge or Dave Manson. Unless I had a calibrated micrometer and the exact specs in front of me, I am not sure I'd trust a used reamer whose origin I wasn't sure of. You can always sell your reamer on eBay when you're done with it (might even turn a profit too!).

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I use a throat reamer to hollow out the casing space

 

No....

 

You'll only need a finish reamer and headspace guages with a short chambered barrel (throat reamers are for specialized applications - don't worry about throating right now - unless you're trying to make a benchrest rifle and then start working on finding a good gunsmith). Assuming you'll be happy with a hunting rifle, read on:

 

With a blank you'll only have the bore drilled, and then you'll need to "hollow out" a chamber before finishing it. But you will only want to chamber a blank if you have and know how to use a lathe.

 

You can ream a short chambered and threaded (the "hollowing-out has been done at the factory") barrel by hand with: 1) a finishing reamer; 1) your hand and the reamer in a good tap handle; 2) patience and attention; 3) a willingness to try, try, try again; 4) an ability to measure your progress.

 

Monte captured the process beautifully above.

 

Keep chewing on the idea and asking questions until it all makes sense. Then buy the finish reamer and barrel!

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