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40x cone breech

8K views 35 replies 16 participants last post by  lion 
#1 ·
Anyone out there running a cone breech on thier 40x? If so, could you give me the diamensions?
 
#2 ·


It works just fine in my repeater conversion, no reason it shouldn't work just as well in a single shot.

I turn the end of the tenon to .400 dia. .150 back. Set cross slide to 30 degrees. Cut on back side running in reverse. Leave .005 shoulder on front. Very simple and no extractor slots needed. Wayne

Looks like I should have cleaned it better.
 
#6 ·
Dumb (but serious) question. What is the advantage?

Thanks,

cb:bthumb:
It's much easier than cutting extractor cuts...less tooling and machining. If you are going to index the barrel coneing the breach saves time.
What he said....
After turning and threading the tenon, the barrel can be set up for chambering and setting headspace, and cutting the cone with only having to re-indicate once in the lathe. Whereas traditional extractor slots require the barrel to be engaged with several more milling steps.
I cut a coned breech on the barrel of my 54 Match Anschutz and installed it with Loc-Tite. No threading really made it a simple process.
 
#7 ·
Makes sense. I am no machinist, but I do build pipe-cutting machines for a living. We have a small machine shop at work, and the guy who works in it is an aspiring gunsmith. We work 4 days (10 hour shifts) and he works an additional 2 days at a gunshop doing trigger jobs, bedding actions, etc. Unfortunately, he views lowly 22s as toys, so not much support there.:D I ask as many questions as he will tolerate--always looking to add skills to the ol' toolbox.

Do you guys leave a "shoulder" for the rim to rest upon? In lion's picture, there appears to be the hint of a flat.

This begs the question, why don't manufacturers make their barrels like this? What are the drawbacks? Or POSSIBLE drawbacks?

Thanks for the education, fellas.

cb:bthumb:
 
#13 ·
Get you a new PTG 40X bolt assembly and dry fire it!!


You install a PTG 40X bolt in without trimming the firing pin on it and dry fire it, your chamber will look like a turn plow went up through it!! Had a friend that put one in and dry fired it and oh boy he messed up the chamber and the firing pin!! It will be the same thing if you get a new firing pin from PTG and put it in your bolt to!! Every 40X I've built to date I've used breech cones in all my rifles!! If you set the head space up for Eley Tenex or Match ammo which is .040-.041 and you dry fire it, there will be a mess!! It's kind of hard to index the barrel for testing as every time you want to rotate it 90 degree's you have to machine off less than .0625 on the shoulder and the chamber end!! It's best to index the riflings where you don't have one at 6:00!!
YBRF! Rambo
 
#9 ·
The only down side to a coned breech in my opinion is one must NOT dry fire it. One hit can damage the cone enough to need cleaning up. A coned breech is far easier to keep clean of wax and crud than extractor cuts.

Yes, the back of the case head must be supported. How else would you achieve ignition?

Most of my bench rest rifles have coned breeches. Whenever someone else touches one of these rifles my first words are "please do not dry fire the rifle". I don't ascribe to the "its a problem" theory. bob
 
#14 ·
It sure will put a divot it your chamber! That's why Remington sets the firing pin protrusion between .031 to .036. A PROPERLY set up 40x is safe to dry fire. If you are dry firing and chewing up your chamber, then it's time to find a new gunsmith.
 
#15 ·
I agree with joe40x. I installed over 6 ptg bolts and had to trim the firing pin on every one. Also had to replace the springs with 30 lb Wolf springs after trimming. The strikes were to light to fire reliably. The handles came off 3 of them and had to be replaced. Drilled and tapped and screwed them on. They work fine now. Wayne
 
#34 · (Edited)
I time the groove to 6:00!



Carney,
Sorry for answering so late. But I time the barrel so the groove is at 6:00 with the riflings on each side at 4:00 and 8:00 (That's with a 4 riflings) if possible. Cause I've read on other forums in the past if the rifling is at 6:00 and over time shooting it will erode and cause the rifle to lose accuracy, I don't know if it's a fact but sounds like a good idea. I love messing with these 22's.

Rambo
 
#19 ·
A quick question for those who use these cone breech barrels. Do you prefer these?

I'm still bouncing back and forth on a rebarrel of a rifle, and one option is a cone breech. It's for a BR type rifle, so no problem with someone goobering the chamber by dry firing. I'll be the only person using the rifle.

It would be a cheaper option for me to go this route than having a new blank set up.

thanks

kenny
 
#20 ·
I don't think cone breeches are better or worse. Just a lot easier then cutting extractor slots. Thread to the shoulder until it is indexed where you want it, face the end off till headspaced, cut the cone and you're done. All in the lathe. No mill required. Of course I'm a little on the lazy side. Wayne
 
#21 ·
Thanks. This isn't for a 40x (actually a 2007 Anschutz). Just looking at options should I end up putting a barrel on. Go back and forth on the thing anyway. Shoots great, but still think a new stock and barrel might make it shoot even better. We'll see soon enough I guess.

Kenny
 
#23 ·
Coned breeches have been used quite a bit in .22 BR rifles to make it easier to set/change headspace with threaded barrels. I had a couple of Time Precision rifles with coned breeches that came with a set of spacers, each .001" different in thickness that were placed between the barrel shoulder and the receiver. Have also seen 40X customs that had a Savage type barrel nut to tighten barrel to receiver and had a coned breech, thus allowing easy headspace adjustment.
The downside is as several have mentioned -- dry fire it once and the chamber must be redone. In a factory setup, the breech of the barrel is flat and the bolt is stopped in its forward movement by the barrel. As long as the bolt is counterbored for the cartridge rim and the firing pin does not extend past the front of the bolt when fired, there is no damage to the chamber if dry fired.
With a coned breech, the bolt front is no longer stopped by the barrel and will move forward when fired, denting the edge of the chamber as it protrudes slightly into the bolt counterbore. (If you have your barrel off, insert the bolt and it will be easy to see how much forward motion the bolt can have without the barrel).
Actions having an adjustable slip fit barrel such as the 2000 series Anschutz and Sako, do not benefit from a coned breech unless one desires to rotate the barrel for tuning or for evening out throat wear.
With coned breeched rifles, it is best to remove the bolt when not in use. If you leave it in place cocked, there is the danger of dry firing and if you let the striker down, the chamber may be damaged if the bolt or bolt handle is accidently bumped forward with any force.
 
#24 · (Edited)
"Bolt Jump"

SBS,
What forward motion of the bolt are you referring to? The lugs on all my bolts restrict any forward movement, if the bolt design like a Rem. 40X had a lot of wear, the forward part could move toward the breech when firing pin spring pressure was applied. But this is still limited by the overall travel of the firing pin. If the F.P. can contact the breech, it is way too long. Ideally it should only crush the casing rim to the point of eliminating the primer "gap", no more. The foregoing is Calfee theory, not mine, but I do adhere to it. And I do like coned breech barrels, mainly for the ability to "Index" them.
willy
 
#26 ·
SBS,
What forward motion of the bolt are you referring to? The lugs on all my bolts restrict any forward movement, if the bolt design like a Rem. 40X had a lot of wear, the forward part could move toward the breech when firing pin spring pressure was applied. But this is still limited by the overall travel of the firing pin. If the F.P. can contact the breech, it is way too long. Ideally it should only crush the casing rim to the point of eliminating the primer "gap", no more. The foregoing is Calfee theory, not mine, but I do adhere to it. And I do like coned breech barrels, mainly for the ability to "Index" them.
willy
While I would not dispute your statement that "the lugs on all my bolts restrict any forward movement", I have never found this to be the case and I have several 40X .22's from 2 digit and up to modern times. They vary from having approx. .010" forward clearance to as much as .030" in the ones I checked since reading your post. The lug to lug cutout is not a tight fit both fore and aft. Again, if you remove the barrel and trigger, you will see that the bolt has some fore and aft slop in the lug cutout. This is not noticeable with a factory breeched barrel, as it stops excess forward movement and as long as the firing pin is no longer than the forward end of the bolt, the breech cannot be struck. A fully coned breech does not offer this protection and the bolt can be moved forward, along with the firing pin. The cone actually projects inside the counterbore of the bolt a short ways, enabling a firing pin to strike it if dry fired. The bolt doesn't need to move forward very much; the amounts above being sufficient. Saw a lot of them dinged in BR shooting.
 
#28 ·
Forgot the Bolt

I suppose I could just be fortunate to not have rifles that exhibit this amount of tolerance. Have you ever got to the range only to discover you forgot the bolt on the work bench? It only took once and from then on I never separate the bolt from the rifle. If you are concerned about dry firing mishaps, insert a wall board plastic insert, used to make screws stay in drywall. only my.02
willy
 
#29 ·
I suppose I could just be fortunate to not have rifles that exhibit this amount of tolerance. Have you ever got to the range only to discover you forgot the bolt on the work bench? It only took once and from then on I never separate the bolt from the rifle. If you are concerned about dry firing mishaps, insert a wall board plastic insert, used to make screws stay in drywall. only my.02
willy
Not yet but it may happen one day. My travel case has a space for the rifle and a seperate space for the bolt. I figure it's better to forget the bolt at home than to damage the cone, cheaper anyway.
 
#30 ·
It's not the end of the world! Menck, makes a "Chamber Ironing Tool", it is used to massage the chamber where the wall has been bulged. I've had to use one on a 2013 with Lilja drop in having a cone breech. you can still see the dent in the breech face, but the chamber wall no longer drags on the case. BTW, F.P. had been "modified by the owner" to make more contact with case rim. He went to far and didn't know it till dry firing. So I got to make the F.P. the correct length and shape besides ironing out the chamber!
willy
 
#31 ·
The rifle I refer to is my USBR Custom class rifle, it's a Stiller 2500X action and a Lilja tight bore barrel riding in a McMillan straightline HV stock. I would probably hate myself if I damaged the cone but I too have a chamber iron if the unthinkable were to happen, I try and limit the chances of that ever happening.
 
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