Hand reaming a short chambered barrel

[montea6b]

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...)

 

Thoughts anyone?

[riceone]

For someone real good with measuring tools the second way would be alright. But the simplest and most fool proof way is to install the barrel and do it that way. Less chance for error. riceone.

[z1r]

Method 2 with these changes. Subtract .0015" to .002" from your original reading dependingon how tight you like things to allow for crush. Simply put, the chamber should indicate that it is a bit deep so that when you cinch things up your account for the crush. An extension allows for too much side play IMHO.

[Clemson]

I use method 1 unless I have an awful lot of metal to cut out. I don't own a floating reamer holder, so I avoid cutting with the lathe unless I have to. I have had to lathe-ream a stainless steel barrel when I used a rental reamer that was not quite as sharp as it should have been, but I usually don't need to.

 

Actually, a hand-cut chamber, particularly in a barrel with a short-chamber already cut (as most of the barrels I buy have), will run very true if you take care to hold the barrel vertically while reaming. A reamer naturally centers itself in a hole.

 

As Z1r points out, you must allow .002" of crush in your fitting. I just cinch the barrel up, cut until the bolt closes with light pressure on a "Go" gauge, then remove the barrel and use a deburring tool to cut a 1/64" chamfer on the inside rim of the chamber. I reinstall the barrel, check with the "Go" gauge, and I am good to go. Beware of chips when checking the headspace. Also, know that a sharp reamer will cut a thousandth or so per turn and can cut a chamber too deep in a heartbeat. Go slow, check often, use lots of Rapid Tap, and clean the tapping fluid off your reamer after you use it. Oil it up with RemOil for storage.

 

Clemson

[Guest MorgansBoss]

Sage advise is found above. All I might add is to be particularly cautious when reaming for smaller calibers. Lots of oil and frequent cleaning (every few turns) is suggested, but this is particularly critical with very small tools where there is precious little supporting metal after the flutes are ground.

[montea6b]

Thanks to all, good advice. I'll let you know how it goes.

[montea6b]

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.

 

Maybe tonight?

 

(kids have Scottish Highland dance lessons...)

[z1r]

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.

 

Maybe tonight? 

 

(kids have Scottish Highland dance lessons...) 

5077[/snapback]

 

That sounds like a sound plan of attack. I'm sure you won't have any problems. Just go slow, and clean & oil often. Oh yeah, measure a lot too!

 

[Guest MorgansBoss]

I have a device for aiding in this operation, which is no more than a pipe that fits into a socket screwed to the ceiling over my vise and a threaded extension on the other end with a pointed tip.

 

In operation the barrels are set vertically in the vise. The pipe is set into the ceiling socket and the pointed tip is set on the butt of the reamer. The threaded portion is then adjusted to keep tension on the reamer - just enough to cut, not too much! In this way you are free to concentrate on the "feel" of the reamer cutting and can better control the operation.

 

This is an over-simplified description but hopefully you get the idea. Its certainly better to do single barrels in the lathe but unless you have a monster machine it's not an option for doubles!

[montea6b]

I remember that now! Seems to me you even posted a photo of the contraption once. You should repost the technique with a photo on the tech tips page.

 

Thanks for the idea again, but I think I'll skip for now as that will delay the process for at least another month or two while I construct it!

[montea6b]

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. (?!)

 

Now for the feeding problem...

 

I then assembled the rifle to check for function. Since I don't have a way to load dummy cartridges, I decided to remove the firing pin assembly and very carefully attempted to chamber a few live rounds... with very dissapointing results.

 

I can't get it to feed. At all. It's not just a little rough around the edges, it sucks! I'm pissed! The cartridges go forward about 1.5 inches and just jam. I tried to feed from both sides of the magazine with the same results. It is hanging up where the bullet enters the chamber. It's catching on the shoulder of the chamber just back of the tip a ways. Now I'm starting to see the wisdom of Winchester's "Coned Breech".

 

I didn't mention it this post, but it's a .30-06 and these particular rounds were factory standard 150 gr spitzers. Nothing in the bullet length or seating depth that should cause problems.

 

With careful fiddling, I could occasionally milk one in past the bullet ogive, only to apparently have the lip on the neck of the case also hang up. Even if I successfully eased one past this point the edge of the chamber would shave brass off. I feel like I need to de-burr or lightly bevel the edge of the chamber.

 

Would this help? Should I open up the feedrails a little to keep the cartridge from trying to enter the chamber from such a sharp angle?

 

I figured that such a standard cartridge would have no problems. Heck, I even tried chambering an 8mm Mauser, (which this action was originally chambered in) just to check and had similar, if not quite as bad results.

 

I'm a little disappointed and frustrated at this point, and I'm not sure what to do next.

 

Help!

 

[z1r]

You do need to cut a chamfer on the chamber mouth. Do you have one of those rcbs case deburring tools? Otherwise a counterbore should work. I do all mine I the lathe so I don't have much helpful advice. Remove the barrel and at a minimum hit the edges of the chamber mouth with some 320, then 400 wet/dry.

 

Congrats!

[Doble Troble]

Is it the mouth of the barrel that's shaving brass? Are your cartridges hanging-up in the first part of the chamber? If so, did you bevel the chamber mouth after reaming? If everying's feeding perfectly you may get by without a bevel, but going from an 8 x 57 to the longer -06 chances are its not feeding as designed any more.

 

This may call for some slow, careful dectecive work, but don't worry, many have been in your exact same position and you will figure it out. I'd be checking the mouth of the barrel for a sharp edge.

[roscoedoh]

Monte,

 

One other thing you might check if the rifle is not feeding properly is the magazine follower. If after you've tried everything else you're still having a problem with feeding, try swapping around followers. It may help.

 

Jason

[Clemson]

I do like to cut a little chamfer on the mouth of the chamber. A deburring tool run around the chamber by hand works just fine for this, followed by polishing with 400 grit sandpaper. You don't need to cut more than 1/64 inch. The only way that I have found to do this effectively is to pull the barrel, chamfer, and reinstall. Since you already have the chamber to full depth, make sure you put reference marks on the barrel and action before you pull it.

 

Clemson

[montea6b]

Thanks guys, that confirms what I thought I'd have to do.

 

Jason, thanks for the suggestion about the follower. I hadn't considered this, but had wondered if a stiffer magazine spring might force the cartridges up into alignment quicker. The only aftermarket followers I've seen have been for single shot benchresters if I remember correctly. Is there another type I should look for?

 

I'll try chamfering the rim of the chamber first, then order a new spring if that is unsatisfactory. If that still doesn't do the trick I may try some very careful surgery around the front lip of the feed rails.

 

Or maybe take it to an expert...

[montea6b]

Well, a little light smoothing of the edge was all it took. It's slick and flawless now, thanks for the help!

 

Stand by for an eventual range report...