Gunsmithing What tools do you prefer for threading and chambering barrel?

Rlbol

Master Gunnery Sergeant
Full Member
Minuteman
Nov 5, 2010
617
51
FL
Other then a lathe, what other are your preferred tools?

I have been playing around with a lathe for a while now but would like to get more serious and build a few barrels.

I plan on building an out board spider but I have read about zeroing out the barrel via the lands. If anyone is using the process, did you make the bushings? If anyone has more info on a setup please post it.
 
There are several lines of thought when it comes to indicating your barrel.
Some folks like to use the four jaw chuck and an outboard spider, however, this is highly dependent on the distance between your chuck and the outboard end.
Some folks like to use a fixture like the viper fixture, but there are issues here as well.

other folks like to keep it simple and use the four jaw and bushings to support the barrel in the headstock, indicating the last inch or so of the barrel and using a quality floating reamer holder.

If the machine is big enough, turning between centers alleviates most problems.
 
  • Like
Reactions: MarinePMI
Thanks for the replies

I was asking more on the part of tools verses dial indicators. I have lots of them.

I have a bunch of barrels I would like to thread for brakes/ suppressors. My lathe is an 11” Logan. I am going to build a spider for the outboard side of the headstock. With the spider to the front of the 4 jaw chuck is roughly 16”. That is one of the reasons I ended up with this lathe. It has a pretty short headstock and a 1 5/8 bore diameter.

What I had planned was to zero the chuck, zero the spider. Then measure the differences from outside the muzzle end of barrel and lands of the riffling. If it was off by much I would just zero everything between the chuck and spider based on the bore.

However all I have read with regards to zeroing off the bore, there was little discussion on what tool was used in the bore? I am assuming someone either turns a bushing similar to one of the neck sizing bushings for reloading or is someone making a rod and bushing for each caliber?

If your using the lands on the muzzle end as well as the breach end and you measure farther inside the throat, the dimensions would be the same for each caliber?
 
The Edge Technologies toolpost mounted indicator is phenominal for indicating a barrel.
https://cdn2.bigcommerce.com/n-arxs...uck_front__04421.1427685640.1280.1280.png?c=2

I like the Mesa double ended threading holder for all external threads.
https://www.mesatool.com/product-page/5-8-sq-shank-double-ended-threading-tool

For reaming chambers i use PTG removable pilot reamers.

For Win70 and SPR extractor cuts i use the PTG concave side mill.
https://www.google.com/url?sa=t&sou...BMAB6BAgAEAM&usg=AOvVaw1_YScStVJTMSGhDjKSDHYv
 
Some will laugh, but since I have a bit longer lathe(16 x 40), I hold on the muzzle end in my adjust true chuck, turn the threads holding with the tail stock, and switch over to the ball bearing steady rest to chamber while holding the reamer with my fingers using a lathe dog and tail stock. Things have to be indicated in and centers need to be cut along with a light OD turn as well, but I don't have any complaints other than it being a tedious process. I don't do it for a living though.
 
  • Like
Reactions: MarinePMI
Thanks for the replies

I was asking more on the part of tools verses dial indicators. I have lots of them.

I have a bunch of barrels I would like to thread for brakes/ suppressors. My lathe is an 11” Logan. I am going to build a spider for the outboard side of the headstock. With the spider to the front of the 4 jaw chuck is roughly 16”. That is one of the reasons I ended up with this lathe. It has a pretty short headstock and a 1 5/8 bore diameter.

What I had planned was to zero the chuck, zero the spider. Then measure the differences from outside the muzzle end of barrel and lands of the riffling. If it was off by much I would just zero everything between the chuck and spider based on the bore.

However all I have read with regards to zeroing off the bore, there was little discussion on what tool was used in the bore? I am assuming someone either turns a bushing similar to one of the neck sizing bushings for reloading or is someone making a rod and bushing for each caliber?

If your using the lands on the muzzle end as well as the breach end and you measure farther inside the throat, the dimensions would be the same for each caliber?


You’re over thinking it. Yes, you must reference the bore, always. Range rods are common (not a fan). The other two methods are to direct dial off the bore with a long stem indicator so you can dial in a length (not a single point) of bore out in front of the chamber, or use a gritters style rod and bushing with the same goal. It’s detailed very well in Dave’s article above.
 
Last edited:
For many threading applications, I've become a big fan of full profile inserts. No more sharp crests, perfect thread form.
And a micrometer reamer stop will save a lot of frustration for a beginner (and experts as well).
 
Last edited:
As with anything, quality tooling makes the job easier. One thing I've come to lean on over the years is insert choice. My tool package for barrel work is tailored towards inserts intended for "hard turning". Simply to mean the edge prep on the insert is sharper than one that's going to be used for production threading on softer materials.

The reason is I'm not spitting out thousands of parts pert shift. I'm fitting the thread to a receiver or a thread gauge. Trying to do this a .001" at a time when chasing down a pitch diameter is harder to do with the wrong insert. The one's for production work lack a sharp edge. They rely on tool pressure and consistent material. A sharp edge erodes faster where's one with a healthy radius on the cutting surfaces lasts longer. These inserts are designed to heat the material and make it go into a plastic like state. You see this immediately in the chip formation. It'll come off the tool a lot hotter than a "sharp" tool.

-One thing I avoid in barrel work is a full profile insert that dresses the entire thread profile (thread crest). Once the insert gets to depth, that's it. I have no control or say in what my OD is vs the pitch diameter. A partial profile insert doesn't do that.

When you install a variety of barrels made to different heat treat specifications and different lots of steel, the way the tool behaves when cutting will vary. A "sharper" tool designed for hard turning will have an edge that cuts with less tool pressure. This means its less likely to work harden the surface when trying to squeal that last .001" or .002" from the pitch diameter. Its because these types of inserts are intentionally designed to "get in, get it done, then get out". You don't try to finish with these on a .001" pass. You might do a 16 pitch thread in as little as 4 passes. The setup when writing the program here is the ticket. You take into things like tool rigidity, work holding, Surface Footage, Depth of Cut, material type, and the need to get a cycle time down to where the job is profitable.

What your paying for when hanging a barrel is someone's time to stand there and fit the two parts elegantly. That commands a different choice in tooling.

What often happens with production minded tooling when trying to fit something is that it'll work harden a candy shell on the surface of your part. You keep picking at it trying to get that last bit, then it suddenly gets under the "skin" and rips .005" (or whatever, more than you want...) from the material. Now your thread is like hot dog in hallway.

It does this regardless of whether you have an old chunk o matic manual machine or the latest, greatest cnc that's built like a brick shit house. Machine rigidity plays into it considerably, but the tool package has to be right to start. With a clunky old lathe, it's even more relevant. This is why guys who grind their own tooling from HSS often have better results (assuming they can grind a tool properly). The tool pressure goes way down because the edge prep either doesn't have a radius or its very, very small. The issue here is getting it right every time and keeping up with the maintenance. HSS wears a great deal faster than carbide so tooling resharp becomes more relevant.

It's been my experience that for the most predictable outcome, just choose a carbide insert meant for hard turning. You'll change inserts more often, but its a small price to pay for the results.

Make sense?
 
Last edited:
As with anything, quality tooling makes the job easier. One thing I've come to lean on over the years is insert choice. My tool package for barrel work is tailored towards inserts intended for "hard turning". Simply to mean the edge prep on the insert is sharper than one that's going to be used for production threading on softer materials.

The reason is I'm not spitting out thousands of parts pert shift. I'm fitting the thread to a receiver or a thread gauge. Trying to do this a .001" at a time when chasing down a pitch diameter is harder to do with the wrong insert. The one's for production work lack a sharp edge. They rely on tool pressure and consistent material. A sharp edge erodes faster where's one with a healthy radius on the cutting surfaces lasts longer. These inserts are designed to heat the material and make it go into a plastic like state. You see this immediately in the chip formation. It'll come off the tool a lot hotter than a "sharp" tool.

-One thing I avoid in barrel work is a full profile insert that dresses the entire thread profile (thread crest). Once the insert gets to depth, that's it. I have no control or say in what my OD is vs the pitch diameter. A partial profile insert doesn't do that.

When you install a variety of barrels made to different heat treat specifications and different lots of steel, the way the tool behaves when cutting will vary. A "sharper" tool designed for hard turning will have an edge that cuts with less tool pressure. This means its less likely to work harden the surface when trying to squeal that last .001" or .002" from the pitch diameter. Its because these types of inserts are intentionally designed to "get in, get it done, then get out". You don't try to finish with these on a .001" pass. You might do a 16 pitch thread in as little as 4 passes. The setup when writing the program here is the ticket. You take into things like tool rigidity, work holding, Surface Footage, Depth of Cut, material type, and the need to get a cycle time down to where the job is profitable.

What your paying for when hanging a barrel is someone's time to stand there and fit the two parts elegantly. That commands a different choice in tooling.

What often happens with production minded tooling when trying to fit something is that it'll work harden a candy shell on the surface of your part. You keep picking at it trying to get that last bit, then it suddenly gets under the "skin" and rips .005" (or whatever, more than you want...) from the material. Now your thread is like hot dog in hallway.

It does this regardless of whether you have an old chunk o matic manual machine or the latest, greatest cnc that's built like a brick shit house. Machine rigidity plays into it considerably, but the tool package has to be right to start. With a clunky old lathe, it's even more relevant. This is why guys who grind their own tooling from HSS often have better results (assuming they can grind a tool properly). The tool pressure goes way down because the edge prep either doesn't have a radius or its very, very small. The issue here is getting it right every time and keeping up with the maintenance. HSS wears a great deal faster than carbide so tooling resharp becomes more relevant.

It's been my experience that for the most predictable outcome, just choose a carbide insert meant for hard turning. You'll change inserts more often, but its a small price to pay for the results.

Make sense?
Hit that nail on the head. HS threading tools are slick when you're running a little 10-12" lathe. I've gotten barrel in that the threads looked awful because of the tool chatter. 16-18" machine is much more forgiving with insert tooling. Some of the insert designs work way better than others as well. Lay down inserts from Sandvik with the chip breakers hold up very well compared to a cheap insert(Cheap being $15 or so each vs 25 to 30 dollars each for a Sandvik or Kennametal KC5010 grade, one of the most durable I've ever used for threading or turning welds).
 
  • Like
Reactions: jdemp1