Saw a video online by a guy that used a coned breech instead of an extractor cut for a 54r wildcat he'd developed.
Not a rimfire guy and never done one...but seems that wispy bearing surface wouldn't hold up to thousands of rounds before giving up a few thousandths.

Am I wrong?

like a model 70 or 1903?

Look at all the Savage 340 seires rifles ever made. They have a round reverse angle lathe cut on the breech so they did not have to mill a extractor slot. Yes all of the 22 Hornets, 222, and 223's, and a passel full of 30-30 rifles

That way they simply put the bolt in, install a headspace gauge, snug up the barrel, and tighten the barrel nut for ease of production.
And that design goes back to the late 30's. long before the model 110 came out.

Reverse cone breech; you lose at least two or 3 threads when you do that on a receiver not designed for it. Now, on a Mosin, there are plenty of threads so losing three is nothing. But as for headspace, if it grew, then he perhaps made the chamber entry sharper than it needed to be.

It's actually a pretty common thing to do. Today and yesterday. It really does not compromise the system in any way, as far as strength goes. The fact that the bullets being used are lead, means there is no risk of damage during feeding. One would instantly think that feeding itself would be an issue but you have to remember that most 22 barrels are faced off at 90 degrees anyway and because 22 rim fires are practically all straight line ram fed, they feed with no problems no matter what the breech face looks like.

The big plus to it is that it is a cheap and simple way to deal with the problem of an extractor cut which would otherwise have to be witnessed and cut in the mill. A totally separate operation from the rest of the work which is done in the lathe.

The down side is that it looks like a tacky shortcut, done in the same operation as the extension and chamber in order to save a few bucks !

OOPS! I thought you were talking about a 22RF. It's been done to death in center fires too.

It's poor form at best and should not be done on a Model 70 or 03 Springfield.

quote:

Originally posted by dpcd:
It's poor form at best and should not be done on a Model 70 or 03 Springfield.

Unless of course the cone goes the other way and is used in conjunction with an extractor cut. Then it is a cone feed breech and it feeds better. Which, it really doesn't. Or it is a safety breech, which makes it stronger and safer. Which of course it isn't and doesn't.

But it looks and sounds REALLY FAWKING COOL. And it does do-dat !

NOT MY PIC


Other than the 10s of millions of springfields done this way -- but, sure, some folks may not like it...


then again, some people think it's okay to tighten a mauser off the front of the action vs the torque flange (C or H ring) --- Herr Mauser designed it to be off the flange, it's what it's there for --- though i do get a chuckle when people state that they do it off both ---


Just goes to show, there's more than one way to do many things, and many of them work

Coned breech , I've been doing it for 25-28 yrs on both center and rim fire . Usually on my own rifles used for testing . After considerable use I started offering it to customers ( before I retired ) it eliminated the timed extractor cut . On some rifles it saved time $ , I've seen no draw backs on the rimmed cartridges I used it on . 444 margin , 45/70 , 7.62-54 Russian , 303 , 30-30 , 30-40 and the 22 lr .not to mention the pistol cartridge I use in rifles , 38 sp , 357 , 45 lc etc .
Gary

My cones go the other way !

Just so everyone is clear. I'm pretty sure this is what the OP is talking about. I think. Maybe.

reverse cone breech by Rod Henrickson, on Flickr

Yes, sir ^^^, that's the idea (though, I wasn't thinking about making it nearly that deep, slight radius maintaining most of the full chamber diameter. Just enough to face off with adequate depth for the extractor, eliminating the cut. Have a test "project" in mind, where this would be key- if there's no concern of the thin bearing surface of the rim changing dimensionally over time/round count.

Consensus seems to be that it'll work- so I'm going to move forward with cutting one and testing it out. Thanks, gentlemen.

Yes, Speers picture is it; on a Mosin, as I said, there is plenty of threads left; still have 11 full threads left. Do not make the chamber mouth sharp; no need as there is a .040 flat on factory barrels; the extractor still will work.
I just looked at an 03 and M70; I was wrong; no reason for a reverse cone on those; just make them flat if you want to cheat. That area is thread-relieved anyway.
Jeff; nice picture. But definitely not tens of millions of Springfields; they made 1.5 million of them and Remington made 340000. And RIA made 346K. . And 380K of 03A3s total. .

Dpcd,

You raised a good point about rounding off the chamber entry. I use piece of sandcloth on a dowel now, but perhaps I should grind a small HSS tool to for rounding that to get it perfectly concentric given there's not much to work with and I want to still maintain a tiny "flat" for the rim to seat against?

No, I meant not to create a sharp edge; just leave a .040 o4 even .050 flat and lightly chamfer the chamber mouth, as you do with the paper in the stick method. Your chamber shape down there is irrelevant as that is where the case head is solid. So, Perfectly Concentric, will take care of itself. Tiny flat; I was thinking of more than tiny. .040 or so, again, lightly rounded on the ID so the brass doesn't grab.

quote:

Originally posted by Big Gorilla Gunworks:
Dpcd,

You raised a good point about rounding off the chamber entry. I use piece of sandcloth on a dowel now, but perhaps I should grind a small HSS tool to for rounding that to get it perfectly concentric given there's not much to work with and I want to still maintain a tiny "flat" for the rim to seat against?

Having a funnel at the face of the chamber is not needed. All you need is a 1/64th 45 degree on the chamber entrance so the case does not (smiley). Then burnish the edges with #600 wet & dry and kerosene to make it look purdy. After I've cut the chamber. I remove the reamer and put a common 45 degree cutter in the ER32 and just make the lightest 1/64th 45. Doing it that way makes it concentric and it looks professionally done. Then I just burnish it as outlined above. If you get some, sharp shouldered bitch like a 284 Win you can increase it to a 1/32 45 degree cut. Cuts that tiny will leave plenty of area for a rim to seat on.

Hey, that is how I do it.....

Yeah and if you would quit typing fast, while I'm typing slow we wouldn't have those double entry posts Tom. Damned, speed typin kids what spends all day lookin at the inter-webber for porn and cake recipes ! You're gonna end up being a blind diabetic if you keeps lookin at all them porn and cake recipes !

You have to realize that I actually took typing class in high school; all the other students in that class were girls. Don't tell anyone, but I already knew how to type.

I took typing too.
In high school.
For the same reason.
Eyes left.
Elbows out.
Chest out.
Begin.

I never learned a thing in typing class.

quote:

Originally posted by dpcd:
You have to realize that I actually took typing class in high school; all the other students in that class were girls. Don't tell anyone, but I already knew how to type.

ditto

I took shop and home-ec , maybe I should have taken another spelling class.

quote:

Originally posted by Gary MacDonald:
I took shop and home-ec , maybe I should have taken another spelling class.

Knowing how to spell, when your audience can barely read should not be a high priority. LOL

quote:

Originally posted by speerchucker30x378:


I took typing too.
In high school.
For the same reason.
Eyes left.
Elbows out.
Chest out.
Begin.

I never learned a thing in typing class.

This girl used to sit next to me. I think her name was Chauncie or something like that. Big Auburn hair, shortest skirts in the world, and she always messed with her pantyhose. I failed that class miserably, I had to take it again as a senior.

I just found her on facebook, she doesn't look like she did in high school. She became a PRCA barrel racer, and has had a rough 25 years.

Then again, I weight 80 pounds more and have no hair, so maybe I aged worse.

quote:

Originally posted by Big Wonderful Wyoming:
I just found her on facebook, she doesn't look like she did in high school. She became a PRCA barrel racer, and has had a rough 25 years.

Then again, I weight 80 pounds more and have no hair, so maybe I aged worse.

But you didn't waste yer life away chasing cans in the Ro-day-O !

Well, seeing as the banter has died down and all....

Took some measurements to start playing on a takeoff barrel stub. Thing is, the depth of the cartridge rim is only around .035 or so.
Essentially, I need to find the tradeoff between the width of the flat "seat" for the rim and leaving enough hanging over for reliable extraction.

I'm wondering if .010 of rim showing is enough for the extractor to reliably grab it. Barring anything causing hard extraction, I think that might be enough; once it's free it'll slip fully underneath. Maybe just .020 of breech flat would be better, and .015 hanging over for the extractor?

What say ye?

.020 extractor purchase. That will leave you about .017 inch per side wall thickness at the start of the taper. Measure your extractor protrusion and angle to get the depth of cut and angle of cut. The extractor should just tough the cone, but not ride into it hard.

Why not just do it the right way and mill an extractor groove. After all, the cone thing is a poor shortcut to the correct breech.

quote:

Originally posted by dpcd:
Why not just do it the right way and mill an extractor groove. After all, the cone thing is a poor shortcut to the correct breech.

Barrel nut "experiment". Blank has been turned down to .980, hopefully have time to thread it tonight after the "paying jobs" are done. Then, on to the nut...

quote:

.020 extractor purchase. That will leave you about .017 inch per side wall thickness at the start of the taper. Measure your extractor protrusion and angle to get the depth of cut and angle of cut. The extractor should just tough the cone, but not ride into it hard.

10-4. I'll go with the .020 as you suggest. I'm not going to carry the main cut the full diameter of the breech, going to do it as sort of a recessed target crown; that'll provide a bit of protection against banging that skinny flat when handling.

Thanks for the input.