Bought myself a bolt-action .22lr platform yesterday, a Savage MK2 with the "Accu-trigger", with a crisp 2.5 lb pull. Everything I saw with this rifle impressed me for the price. There are better bolt-action rimfires out there, but hard to find (in this quality) for $200-$300. It has received great reviews from users in the real world.

From the Savage web site:



I bought a compact Nikon for optics. The next step is threading the barrel.

Question - is anyone interested in a bit of step-by-step on chopping and threading this barrel for 1/2 X 28? If yes, I'll photograph and document it a bit more. If not, I'll simply cut it, thread it, and show the finished product. Death to tree rats!

I have a pair of cans suitable for this rifle, a slim stainless CAC-22, and a form 1 can.

Anyway, even though I have not fired the rifle, it appears to be an excellent deal. If you buy one, go for the non-tapered bull barrel, which is much more suitable for turning and threading.

Yes, please do.

I am currently reading a great book, "The Complete Illustrated Guide to Precision Rifle Barrel Fitting" by John Hinnant. There are many line drawings but there aren't any pictures.

Your pics would be appreciated.

OK, I'll snap some pics. I'll probably go 18" in case the first attempt gets screwed up...

The good part about simple and compact bolt action rifles like these is the fact that the entire barreled action can be chucked. The receiver section need not be separated from the bbl.

One of the most common questions on just about any silencer or NFA forum is "Where can I get my High-powered aircraft-destroying automatic Sniper Rifle threaded?" Assuming you need such a beast, here is one way to do it.

Obviously tools are important, but practice and experience more so. Practice, practice, practice. If your barrel will not fit through the head stock, get a bigger lathe. This job (as depicted) would be impossible on a lathe with less than a 1" headstock.

Work starts with a new Savage MK2 .22 LR with an Accu-Trigger! I've always wanted an Accu-Trigger. The name reminds me of the old Cessna "Land-O-Matic" landing gear from the 1950's. Actually, it really is a kick ass trigger, crisp and clean at 2.5 lb from the factory.



This came with a 21" bull barrel of about 0.80" diameter. If there is a choice, select a weapon with a constant (not tapered) bbl. Tapered bbls are a bitch to work with.

I measured the bbl and left enough length so I could screw up TWICE and still not enter SBR territory. If you're a noob, DO NOT measure to 16.125" and cut with a hacksaw. You WILL be sorry. I went 17.5"



After stripping off everything except the receiver, into the band saw it went. No band saw? Don't be a puss, get a hacksaw. The steel is not that hard.





SAVE the cutoff piece for setup work, practice, and to make a thread protector.

My first step was to take the stub remnant and give it a whirl to see how it cut. This steel is a nice, medium carbon steel that cuts well with both carbide and HSS. Just abut any .22LR bbl will be easy to work.



I faced it of, then checked the body for chuck jaw markings. Note the 6-jaw Buck "Adjust-tru" chuck, ideal for this work. You must use either an adjust-tru style chuck, a 4-jaw, or a collet. A normal 3-jaw is going to have excess runout that makes the job problematic. The lathe is a Hardinge HLV.

Since the chuck jaws did mark the stub up a bit, I decided to wrap the bbl with precision stainless shim stock, 1 layer. This will protect the bluing, and not affect accuracy. Do not use leather, cardboard, toilet paper, used condoms, etc. Use only precision brass or steel shim stock.



The bulk of the bbl was wrapped in plastic to protect it:



and at the ass-end, I wedged in some very stiff cardboard to keep the mass of the receiver from causing any wobble or additional markings. I did not want to have to reblue anything.



The very first step is to cleanly face the bbl end, then lightly deburr the opening. Why? So I can indicate the bore rather than the OD for the thread. Very few bores are truly concentric with the bbl OD, and this was no exception. Rugers are the worst, with up to 0.015" of variation. This bore was concentric with the OD to within 0.003". Still, I wanted to reference the bore, not the OD, so I made use of a tool I made years ago - a precision widget that wrings into the bore and presents an exact 1" diameter to indicate off of.





When the smoke cleared, I adjusted the chuck as it was designed so that TIR of the bore was less than 0.0002".

Roughing was done using a TPG-222 carbide insert. I elected to make the thread 0.562" long to fit both cans. Roughing went to within 0.010" of final OD, in this case, 0.500" for a 1/2" x 28 thread.




The critical part isn't so much the thread as it is the shoulder. The shoulder must be perpendicular to the bore line, and clean. To do this, I made use of a HSS turning and facing tool. It would do both cuts, the thread blank, and the shoulder:



Most guys will turn the blank down to 0.496" or so - I always go to major diameter. It is easy enough to drop it another 0.004" (if needed) later.



The final blank, both shoulder and thread portion turned to a nice finish. HSS (properly ground) will put carbide to shame in a lighter, home lathe. It is a skill worth acquiring. Compare the finish on the cut between the carbide and the HSS. No question about it.

For accuracy, it is important to properly crown. I used a facing tool to recess the muzzle a bit, then a 45 degree boring bar to barely touch the hole rim.





Time to screw-cut. First step - relief at the base. Doing the math for a 1/2" X 28 thread reveals that the depth of the thread is going to be 0.023" using the standard formula

Depth = 0.6495 / turns per inch

The relief was cut with a 0.040" thick Nicole mini-thin tool.



The insert was swapped out and changed to a 60-degree screw-cutting form tool. BOTH ends of the thread blank were cut to 60 degrees:





The black is magic marker so I can see what's going on. The depth of the cut is to the 0.023" relief.

Oh yes, the tape is there to prevent scarring or marring of the bluing.

The thread-cutting passes were started. Watching a tool bit scream towards a heavy shoulder is about as fun as watching your teenager learn to drive. How the tool bit decouples depends entirely upon the mechanics of the lathe. The Hardinge HLV series has a blessedly simple method - once set up, nothing need be done. The tool tip ends up in the relief cut, and simply stops. Those with other lathes might have to open the half nuts like a monkey on crack at exactly the correct moment. Not fun. If you cannot ensure accurate decoupling of carriage to lead screw, make your relief cut wider. If you crash into the shoulder, first change your drawers, then recut the shoulder farther back, and face off the muzzle end.

First test pass:



Additional passes, culminating in the final cut:







When to stop? Test with a gauge. Make one, or use the can you plan on using. It should be slightly stiff, as it will loosen within a few installations to a perfect fit. If you are having trouble getting it to fit, realize that additional depth with the cutting tool can take off too much, very easily, and it is often better to use 320 wet-dry paper on the peaks of the threads, and perhaps even a 60-degree needle file, allowing the file to follow the grooves with the lathe powered and very slow.

My "gauge" - actually a thread protector I made for a Ruger MK2 pistol that I knew represented a good fit.



The acid test, of course, is the can itself:



DO NOT tear down the setup until you KNOW the threading is complete. If you do, you can carefully clean it up and cut a bit with a good (adjustable) 1/2" X 28 die. I consider it a legitimate operation to do 85% of the cutting with a lathe, and then finishing with a die. I consider it piss-poor to attempt to use a die from the beginning. But you do what you gotta do.

The threading of the muzzle is complete.

The cut-off bbl remnant can make a dandy thread protector.



With the remnant centered as carefully as the bbl itself, it is first drilled out to about 0.437, then bored to 0.460 for the tap. A thread protector is not precise, so tap to your heart's content, but the boring portion ensures that when threaded on, it is inline with the bbl and looks nice.

After boring, here is (IMO) the best way to tap in a lathe, assuming the tap has a center-drilled shank. Install a spring-plungered male center in the tailstock, and allow that to apply pressure on the tap. Work the tap with a small wrench, and get it going several turns before dispensing with it.



I should have mentioned, you want to drill and bore the thread protector at least 1.5X as long as the finished device, so you get 100% threads all through it. Calculate the length needed, add at least 0.010 (or more) for clean-up, and part it off.



Flip it, remount, and face the base to length. Bevel the base of the threads, and re-cut with the tap to clean. You should end up with something like this:









You can knurl if you want. I normally do, but in this case, I didn't want to dick with the bluing.

That's threading in a nutshell. There is no substitute for a good lathe book on screw-cutting, and again, gobs of practice. I'd probably do at least 4 to 5 similar threads before I worked on a real barrel. But that's why the bbl length is 17.5" instead of 16"... so if you F--k it up, you get another (or two) chance(s). Or, you can SBR it, but that would suck.

I hope this helps new machinists. If you can make a good can, you can thread a barrel with accuracy. It is not as bad as it looks. Total time from lathe mounting to completion, including thread protector - about 1.5 hours. So don't bitch when someone quotes $60 to $100+ for the job, the hourly rate is not that good!

Perfect, that's exactly what I needed. THANK YOU!! Your time and info is appreciated.

Now all I gotta' do is figure out a way to justify the money for a good Hardinge and the tooling. The guy next to my shop is willing to part with his (it's in excellent condition) but even 20 years old it's still worth more than I want to spend right now. Really nice ones are hard to find and he knows it.

Good walkthrough. That'll help a whole mess of nooblets.


EDIT: On a second read-through, you have me jealous of your six jaw independent chuck. Might I ask how much it cost you?

Seriously nice gear, and seriously nice work. Thank you for the walk-through and congrats. on your silent setup.

Thanks guys. PTK, the 6 jaw is my absolute favorite chuck. It distributes clamping pressure far better than a 3-jaw and is super-handy for this sort of work.

It is a Buck Forquart, and was about $650 in maybe 1996. Bison makes a similar chuck of decent quality at maybe 1/2 the cost. Whatever you get, be sure it is adjust-tru (drift the body laterally on the backplate); most 6-jaws these days are, it seems.

I'll put the rifle back together today or tomorrow. I want to work on the safety a bit. It takes far too much force to switch from SAFE to FIRE. Other than that, the rifle is a beauty and I am very happy with it.

I ought to be able to find one for my 10x22 lathe cheap, then. Thanks!

Baffled,

What brand of lathe is that?

Nice work! Thanks for sharing

Great write-up and photos. Thanks for posting.

AAA wrote:Baffled,

What brand of lathe is that?

An OLD Hardinge HLV. Narrow-bed "B" model. I'd love a clean HLV-H, but budget and all...

Nothing wrong with old lathes! The first one I used to do a LOT of work was a 16x36 LeBlond. Still held proper tolerance, too.

I thought that's what it was.
At my other licensed premises there's an Hardinge HLV-H, super nice machine for fine work, it'll repeatably hold tenths all day long.

Apparently you can still buy the HLV-H new from Hardinge, and last time a mate of mine checked they wanted about $50,000 for them.

$50k? Geeze, that's in the realm of the small(ish) Haas turning center a local place bought.

My buddy has a super nice, very well taken care of example he wants to sell me for $18,000 and it's over 20 years old! Not saying it isn't worth it, but that's still a lot of coin. I'm holding out, his business isn't real good and maybe the price will come down a bit. Although, I can get a brand new import 'knock-off' for less money.

PTK wrote:$50k? Geeze, that's in the realm of the small(ish) Haas turning center a local place bought.

You can definitely buy a very nice used CNC turning center for less than the cost of a new HLV. I remember when a Hardinge salesman actually showed up at my door at home... somehow he got the address from some internet stuff and thought I was a commercial shop. I explained I was simply a hobbyist, and he was very cool about it. He gave me some brochures, and I remember (this was 1997 or so) that the new HLV-H was $48K, and their new, small COBRA CNC machines were about the same.

If I was a hobbyist looking for ONE lathe, it'd absolutely be a manual machine. Then, you might add CNC as a second lathe. To properly understand and run the CNC machine requires a knowledge of turning, tooling, cutters, etc, and this really comes best from working manually for a period of time.

CNC is ideal for production and multiple units. Manual is still faster in many cases for "one-off" work.

Anyway, I love the HLV, and if I had the space and $$ for a clean Monarch 10EE, I'd be all over it... strip the ancient DC drive, put in a new 3P AC motor with a VFD, and it'd be killer for small work.



Oh yeah!


I shot the Savage a couple days ago. SWEET! The CAC-22 altered the impact point but it did not alter the accuracy. I was disappointed that Remington target ammo went supersonic on occasion, but true subsonic ammo was a joy, very quiet. I need to do some ammo experimentation.

Watching a tool bit scream towards a heavy shoulder is about as fun as watching your teenager learn to drive.

any reason you could not cut it running the lathe backwards ,and the tool upside down ??
That way you would run towards free space,

plenty of time /space to stop

I had to do some threading on a old lathe that took VERY long time to stop
So i had to do it like that

wolf wrote:Watching a tool bit scream towards a heavy shoulder is about as fun as watching your teenager learn to drive.

any reason you could not cut it running the lathe backwards ,and the tool upside down ??
That way you would run towards free space,

plenty of time /space to stop

I had to do some threading on a old lathe that took VERY long time to stop
So i had to do it like that

Totally agree, and I should have mentioned that you can go from left to right as well as the traditional right to left. The HLV feels like cheating when screw-cutting, so I was able to do it as pictured.

Another trick that the Brits especially made popular long ago - do the screw cutting powered off. If your lathe doesn't have a convenient hand wheel, you can make a hand crank that fits on the left of the headstock and allows you to hand crank the thing. The cutting goes fine this way... I've done it before, and while super-slow, it gives 100% control. No crashes.