Question on steel breeches

gdm620 · January 06, 2012, 09:59:54 PM

I going to make steel breaches for my 1377 and 2240. On the Crosman site the breech is the same for both guns except the bolt. One is for a .22 and the other is for .177. The tubes they bolt to is different dia. on the two different guns. So what does the custom makers like Don Cothtran and other do? Do they make one radius for the two different tubes or the right radius for each tube size and have that breech just for that type of gun? I'm just curious what the after market breeches are like. I might make a couple extra and sell them if they turn out good. Thank You.

arkmaker † · January 06, 2012, 10:44:33 PM

Quote from: gdm620 on January 06, 2012, 09:59:54 PM
I going to make steel breaches for my 1377 and 2240. On the Crosman site the breech is the same for both guns except the bolt. One is for a .22 and the other is for .177. The tubes they bolt to is different dia. on the two different guns. So what does the custom makers like Don Cothtran and other do? Do they make one radius for the two different tubes or the right radius for each tube size and have that breech just for that type of gun? I'm just curious what the after market breeches are like. I might make a couple extra and sell them if they turn out good. Thank You.

Hmmm, not sure what others do, but I used a 3/4" diameter ballnose to cut mine. I did not have a 7/8" for the 2240 tube, but the rise in height is minimal and the fit is good because you are locating your breech against the tube on two edges the entire length of the breech, so stability remains intact for such low recoiled shooters. That is versus the reverse where is I used a 7/8" on a 1377 3/4" tube, I would be prone to rocking side to side as the breech would only locate in the middle of the 7/8" diameter groove.

gdm620 · January 07, 2012, 03:25:51 AM

Quote from: arkmaker on January 06, 2012, 10:44:33 PM
rise in height is minimal and the fit is good because you are locating your breech against the tube on two edges the entire length of the breech, so stability remains intact for such low recoiled shooters. That is versus the reverse where is I used a 7/8" on a 1377 3/4" tube, I would be prone to rocking side to side as the breech would only locate in the middle of the 7/8" diameter groove.

Good point. In this case smaller is better

I am still curious as to what radius others use. Is the steel breech from Crosman 3/4" or 7/8"? I'm guessing 3/4" because of your point you made about the outside edges would touch the tube at 3/4" on both tube sizes.

JEBert · January 07, 2012, 05:30:17 AM

QuoteIs the steel breech from Crosman 3/4" or 7/8"? I'm guessing 3/4" because of your point you made about the outside edges would touch the tube at 3/4" on both tube sizes.

I am pretty sure that Crosman cuts them to match the 22XX tube. My 2300KT has a nice tight fit while my 1377's each have a slight gap on each side of the steel breech. Seems like it would be a better fit the other way around.
Oh, and one of my 1377's has a .177 kit and the other has a .22 kit. They both have the same radius cut with the same slight gap next to the air tube. Doesn't seem to have any wobble in them that I can tell. maybe they do it that way because of the transfer port fit.
Cheers,
Jerry

arkmaker † · January 07, 2012, 01:49:47 PM

They cut the radius for the 3/4" 13xx tube. Smaller is better in this case.

0351_Vet · January 10, 2012, 06:48:56 PM

Quote from: arkmaker on January 07, 2012, 01:49:47 PM
They cut the radius for the 3/4" 13xx tube. Smaller is better in this case.

x2 I totally agree.

arkmaker † · January 10, 2012, 07:12:11 PM

Quote from: gdm620 on January 07, 2012, 03:25:51 AM
Good point. In this case smaller is better I am still curious as to what radius others use. Is the steel breech from Crosman 3/4" or 7/8"? I'm guessing 3/4" because of your point you made about the outside edges would touch the tube at 3/4" on both tube sizes.

Does anyone have a Crosman steel breech and a radius gage? I did this once before, but the search isn't turning up anything for me. I believe it was 3/4". For what it is worth, I just checked the plastic breech measures and it measures with a 7/16" radius gage. which means 7/8" diameter tube.

So I stand corrected as it looks like they are using a radius to fit the 22xx tubes. Makes no sense to me, but hey, they are the ones with a successful business, not me!!

arkmaker † · January 10, 2012, 07:16:30 PM

Here is the post, but it looks like there was still no definitive answer on the steel breech radius.
http://www.crosman-air-pistol-owners-forum.com/board/index.php?topic=2516.msg21709#msg21709

gdm620 · January 11, 2012, 01:33:05 AM

Quote from: arkmaker on January 10, 2012, 07:12:11 PM
So I stand corrected as it looks like they are using a radius to fit the 22xx tubes. Makes no sense to me, but hey, they are the ones with a successful business, not me!!

I agree it don't make since. I have a 2240 and a 1377 and both plastic breeches measurer for a 7/8" dia. tube but the 1377 is a 3/4" dia. tube. It works that way but I guess Crosman didn't want to spend more money on a mold to make the correct radius for each gun tube size. I guess I'm wondering what the steel crosman breech radius is and what don cothran does with his breeches......the mystery continues.

NorthStaR · January 11, 2012, 12:04:34 PM

I have a steel breech on my 13XX and on my 22XX's. I don't recall a gap!?
I mean technically there would/must be but we're talking tiny? I'm gonna have to inspect my setup tonight!

If they are made for the 22XX it would make sense. It would then fit both easily and it would keep production costs down compared
to making one for each gun. More chance of getting the wrong parts sent too. I'd rather get the wrong caliber but still be able to use
it than get a part that won't ever fit.

Probably more important is..... being able to see your breech design!

Will it be a direct copy or a new unique style?

Great if you do make a few extras. A few people have made some fantastic one-offs but they are just that....one-offs.

arkmaker † · January 11, 2012, 01:00:37 PM

I thought about this and think I have an answer as to why Crosman would use the larger radius rather than the smaller one. Even though the smaller radius would make the breech more secure buy locating on two edges rather than just the center, it would also raise the barrel a tad and thus leave that same gap for your transfer port tube.

So, it is all about assuring that the TP stays sealed. By using the radius for the 22xx tubes, they assured that the TP will seal exactly the same on the 13xx guns. What else could it be? When you think about it this way (duhh) it makes sense if you are going to only mfg one breech for two different guns.

I'm thinking that they should have not cut corners and made radii to suit for each gun. That's one reason to make your own or purchase and after market.