View Full Version : Chambering a rimfire barrel
Ron of Va
06-23-2009, 11:25 AM
I have never chambered a barrel but I want to try. I bought Gordy Gritters barrel chambering video and found if very informative.
I thought I would start with a 22 since I have about 15 of them. Six of them are 10/22’s; you might have seen my post on “How I made my integral 10/22”. I have a couple of questions about chambering a 22 rimfire.
There are several who offer services that supposedly improve the accuracy of a 10/22 by moving the breech and shoulder back .020 and running a reamer in to cut a partial new chamber. I thought I would start there. I called Pacific Tool and Gauge and spoke to Dave. After our conversation he recommended the PTG Match reamer. He suggested I buy the one with the pilot bushing. Since I am a novice, and I expect I will screw up the first reamer, I decided to go with the less expensive solid pilot reamer, until I get the feel of what I am doing. ($40 vs $105)
Here are the questions:
Will the PTG match reamer do what I want it to do?
Should I have ordered a different reamer?
When chambering rimfire barrels, I assume you stop reaming when you get to the area of the rim where it will begin to cut for the headspace, (if the headspace is determined by the bolt)? If the headspace is not set by the bolt, then continue an additional .043?
Can I just push a 22 reamer into the chamber with something flat in the tailstock, like a ½” gage pin or should I buy, or fabricate some type of reamer pusher? (Gordy Gritters uses an expensive reamer pusher for a centerfire, I didn’t think I need one yet for a rimfire)
I assume that indicating the barrel on a rimfire is not as critical as a centerfire, since a boring bar will not be or can not be used. Say less than .001 using a pin gage in the bore mounted in a 4 jaw. Am I right on this?
I think that is all the questions I have. Thanks
06-23-2009, 01:51 PM
Are you chambering for a bolt gun or an auto loader?
Bolt-gun match chambers are short in the throat so the bullet enraves the rifleing on closure of the bolt. Auto loaders won't handle this, you'll want what's called a Bentz match chamber for an auto loader.
I use a floating holder available from Brownells and have a precision collar that fits over the rimfire reamer shanks as they are smaller than c'fire reamer shanks.
You can also chamber on a milling machine with excellant results. Hang the barrel off the back side of the table and use your mill's head adjustments to tram in a bore dia. pin. I've done this a couple times just to try it and it works very well, just slow to set up.
As for depth, keep a sample of the ammo you are going to be firing, and run the reamer in till the round chambers with just a touch of bottoming the head on the throat for an auto loader. The chamber will be set to that brand and style of ammo, for generic chambering run till the shoulder of the reamer is just short of contact with the barrel shank for guns that headspace in the bolt, or go .042 dp for guns with recessed rim seats.
Ron of Va
06-23-2009, 02:53 PM
Rusty, thanks for responding.
In addition to the rechamber jobs I discussed on the 10/22 barrels, I also have to chamber bolt action rifles, and auto loader pistols. You suggest I also get a Bentz chamber reamer?
This is the only reamer holder I could find at Brownells: ($100 + $20 for the morse Taper) http://www.brownells.com/.aspx/pid=7742/Product/DAVE_MANSON_PRECISION_REAMERS_FLOATING_REAMER_HOLD ER
I checked Pacific Tool and Gauge and they sell Gre-Tan reamer holders for $93.00 which includes the morse taper. ( I think this is what Gordy Gritters uses). http://www.pacifictoolandgauge.com/products/parts/gretan.htm#jigs
I expect I will also do centerfire chambers when I get the hang of it. Between the two, do you have any recommendations on the reamer holder?
06-23-2009, 04:03 PM
I've not used the Gre'Tan product, so I can't comment on it. Here at work we use Parlec floating reamer holders in the VMC's for the chambering pistol barrels.
Yes, if you want to do match grade auto loaders, I suggest a Bentz reamer.
And do yourself a favor and go live pilot. Its worth the extra bucks.
06-25-2009, 08:16 PM
There are probably as many opinions on the "best" method of chambering as there are on knurling or bearings. I recommend doing just what you are doing, following an example you understand, and practicing on a gun that won't cause a financial catastrophe if it doesn't work out just right.
I would suggest getting a set of go/no-go gages to set the headspace. It can be done with a cartridge for a 22, but the practice of getting the headspace correct will serve you well when chambering a centerfire barrel.
I do question if any real gain is had by setting the barrel back on a 10-22, but there are probably many opinions on that as well.
Ron of Va
06-25-2009, 10:00 PM
While researching floating reamer holders I visited “Benchrest.com”. There I found several examples of reamer holders that are easily fabricated and will not cost me much of anything. (Other than some scrap @ .30 cents a pound) Ok, I am fairly frugal.
I did order a set of gauges.
I also questioned the wisdom of re-chambering a 10/22 barrel for increased accuracy. However several individuals over a RimFireCentral.com sing the praises of such a procedure. I contacted an individual who does this procedure to ask for advice. He was not helpful. I think he thought I was going to steal his business. Not the case. But I would like to try some of my barrels for myself.
So, the one of the big questions I had was, “which reamer”? It seems to me that a sloppy chamber of a 10/22 barrel could not be improved unless you cut away the entire chamber and started anew. This would mandate that the cutout for the V block be moved forward by an equal amount. Apparently not. I knew that Connecticut Precision Chambering does the procedure as well, and he enjoys a good reputation. The procedure these folks do, only changes the length between the V block and the receiver by .020 of an inch, which is compensated for with a shim in the V block area. So I am still trying to figure this out.
I have a few of Anschutz and CZ rifles. I wanted my 10/22’s to shoot as well as them. (not likely I know). But any improvement would be welcome. I was spoiled by the bolt actions.
I have 3 integrally suppressed 10/22’s and one integrally suppressed CZ 452. But compared to the accuracy I get from my Anschutz, they all suck. The CZ isn’t too bad, but not as accurate as the Anschutz.
I am still learning, which is something I enjoy doing.
I appreciate the replies. It is still cheaper that buying a Lilja barrel @$360. So this is the direction I have chosen, if I had to replace all my barrels it might get a little pricey.
06-26-2009, 07:17 AM
There are several economical alternates to floating reamer holders that work well, it sounds like you are on track for that.
With the 10-22, even if setting the barrel back somehow tightens up the chamber, it does nothing to improve the rest of the barrel. I am a fan of Ruger products, but the 10-22 was never built as a target rifle, and the barrel is not made with that in mind.
Lilja barrels are excellent, but Green Mountain also makes some very good barrels at more attractive prices. For the 10-22, they have a pre-cut Stinger chamber, but you might be able to call and get an unchambered barrel for a couple of dollars less.
Rimfire is not my game, I do centerfires, but methods are methods and many work for both.
I would agree that just setting back a barrel will only allow you to change the throat area, nothing else (well the headspace too). I would call David Kiff and talk to him regarding a reamer. He has a wealth of info and can stear you in the right direction.
I'm not a fan of the slip fit in the Rugers, and I have a 77/22. When I get a chance, I will set up the receiver and thread it. That is the only way to ensure a tight lock up between the barrel and receiver.
I'm not a fan of floater holders either. I take the pains to ensure my tailstock is aligned properly, indicate the barrel properly, and use a dead center in the tailstock to push the reamer. I also drill then bore the chamber before the reamer ever gets close to it. I've never had an out of round chamber or a chamber that is big. Rigidity is the whole premise of a metal lathe.
The headspace dimension is kind of voo-doo to some. On my 77/22, the bolt has the recess for the rim, which kindof sets the headspace itself. Of course that can be changed, but I didn't. A rimfire go gauge is nothing more than a blank with a rim of a specified thickness. Unlike a centerfire where you have to work to a datum line, the rimmed cartridge can be worked on without one if you know the dimension.
06-26-2009, 08:14 AM
The chamber end of the barrel on a 10/22 is induction hardened. I question anyone that would cut the end off the barrel, "how are you going to rehardend the face so the bolt doesn't batter it"?
I have built two very accurate 10/22 T while retaining the factory barrels.
Both guns will shoot into .375 at 50yrs with Federal 510's (lightning) and during testing they both shoot into the mid .2's (but this is not the norm.)
The biggest changes where full bedding of the reciever with free floated barrels loctited to the recievers and fire lapped barrels.
Ron of Va
06-26-2009, 08:48 AM
I never considered hardening the end of the barrel.
There is a guy at RimfireCentral who sells these re-chambered 10/22 barrels for $140, and claims they will shoot with any of the top brands at a fraction of the cost. The guy, “Nemohunter” designed his own reamer for the job and calls it a Supermatch reamer. I contacted him for some advice, and as I stated before he was not helpful. I can understand why he wouldn’t be if he thought I might intrude upon his business.
Before I build myself a benchrest rifle, I thought I would play with the 10/22 since I have six of them and a half a dozen extra barrels lying around. I also thought that since I can buy a 10/22 takeoff barrel for $30, I could make a couple of extra barrels for my Hi-Standard Sport King (the one with the push button, pop off barrel) from a single blank. That way I could thread it for a suppressor or build another integral, without altering the factory barrel.
Oh, I did call Pacific Tool and Gauge, I believe I talked with Dave Kiff, and he steered me towards the PTG match reamer for what I wanted to do. He did not have any point of reference for the re-chamber of a 10/22 that Connecticut Precision Cambering or NemoHunter does. There is someone else who does this, but I can not remember the name.
So here I am, taking small steps, searching for information and wanting to expand my skills one step at a time. I appreciate all the advice and help given.
06-26-2009, 09:13 AM
I have a 10-22 barrel in my pile of stuff, and the breech face is fileable, so it might not be too hard, and be OK to take a skim cut. I would suspect that the shoulder & barrel face are cut back but the chamber is left alone. That could move the cartridge ahead enough to engage the rifling. I doubt there is a reamer that will tighten up an oversize chamber.
I would think that Rusty Marlin's work is more in line with known accurizing techniques that will yield results than some magic procedure. It would be an interesting project to make the modifications one step at a time to see where the real improvements come into play.
Edited to add, $140 to "accurize" a factory barrel versus the purchase of a Green Mountain barrel seems a false economy. GM offers barrels for under that cost, and many others at only a few dollars more. Lots of choices there;
I have no connection with GM, but they are a highly regarded barrel maker.
06-26-2009, 12:00 PM
According to some of the guys at RFC removing .070" from the rear of the barrel and using your PTG Match reamer can do the trick without using a shim for the dovetail. If you want the max out of the stock barrel without machining a new dovetail then you can go .200" and make a shim for the dovetail and still have a hybrid chamber. Nemo doesn't just tell all of his secrets but he did point me in the right direction. As far as the "hardening" goes, lots of people have Nemo barrels and have yet to report a problem. I don't think it will be much softer then TacSol aluminum barrels. Even if there were an issue its only a 30$ Ruger barrel. ...I am in the same boat and about to rechamber my first stock Ruger barrels and I purchased an un-chambered 28" barrel from GreenMountain and will be using the PTG match reamer on that also, so it will have the full "Match" specs. Also someone mentioned "headspace" - on a Ruger 10/22 the headspace is set on the bolt face.
Let me state again up front that I do centerfire rifles only. But I have never heard of anyone hardening a barrel after it has been chambered. Any top shelf barrel will be stress relieved prior to being turned to final contour. It is then chambered and installed. I'm not a metal hardening expert by any means, but I have dealt with problems with dies after they have been hardened after reaming. There can be distortion, and that is not good for a reamed chamber end of a barrel.
Now maybe with the slamming of a semi auto it needs something extra. I don't know. Semi autos aren't benchrest guns, and aren't expected to deliver the accuracy of a bench gun. So if a little hardening is needed in this application, it's warranted.
Ron of Va
06-26-2009, 07:52 PM
I realize my factory 10/22 barrel will never shoot as well as a benchrest rifle or a good bolt action for that matter. But since I have a lathe (Grizzly G4003G), time, and motivation, I thought I could squeeze more accuracy out of the 10/22’s. I am trying to avoid something that sometimes happens to me, “learning the hard way”.
I like to approach my projects with a plan, knowing where I am going and how I am going to get there. Nothing beats experience, so that is why I have been asking for advice from people who know more than I do. I really appreciate all the comments and advice.
My next investigation will center on how to “hand lap” one of these barrels to improve the bore. I believe these barrels will benefit from a better chamber, a hand lapped bore, and a new barrel crown. These procedures should show some accuracy improvement. However I am VERY skeptical that these barrels or Nemohunter’s barrels will ever shoot with the name brands. Just some noticeable improvement would be welcome.
I recently tried to read a bunch of stuff written by Bill Calfee trying to learn something about how to squeeze accuracy out of a rimfire. Unfortunately I didn’t learn anything. Calfee seemed to dance around specifics, with a convoluted method of writing that tries to keep your attention without revealing anything meaningful. He seems to want you to know that he “knows” but doesn’t want to tell you what it is. Yea, I got frustrated trying to sift through it, sorry. I guess this is for another discussion.
06-27-2009, 01:49 AM
have you read these two posts ?
Ron of Va
06-27-2009, 06:11 AM
have you read these two posts ?
Thanks for the links. No I had not seen the first link, excellent. Probably all I needed to know.
06-27-2009, 04:53 PM
well I went ahead and took the plunge and chambered my first barrel today :)
it was pretty easy after all of the hard work was done :rolleyes: I have the Grizzly 9036 lathe so I had to drill and tap the rear of the spindle for the spider bolts. I don't have a "range rod" yet so I just stuffed a .217" gauge pin in chamber end and proceeded to dial it in (boy was that fun). the barrel was a new GreenMountain 28" ss with no chamber. And I used the PTG Match reamer. It turned out pretty well.
Ron of Va
06-27-2009, 05:24 PM
Congratulations, I hope you are happy with the accuracy and functionality.
By the way, nice lathe!
06-28-2009, 04:32 AM
Thanks, I really wanted the 4003G but I couldn't wait till August or whenever they would arrive??? Next, like you I will be researching the barrel lapping procedures. Let me know what you find out. So far testing shows promise with cci standard velocity.