doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com .410 SxS's

I know next to nothing about .410 guns so I was struck by the large muzzle separation on these SxS barrels.



Can someone emnlighten me? Is this typical? What is the reasoning for such a large separation (~ 1/2"?)? Is it necessary to get the same POI at a certain distance or, conversely, is it a maunfacturing issue that really doesn't affect POI at all?

This is because few manufacturers can afford making a true .410 action. As it is, most use the same action as they do for 12 or 12 bore guns. The key factor here is the distance between the firing pins. It is, logically, one time the bore dia. at breech add twice the wall thickness at breech. Baikal "big gauge" action, for example, has 27 mm between firing pins. If you try to fit a set of .410 barrels on this action, to have firing pins hit the middle of the primers, the barrels have to be spaced urther apart than what would be in a true .410 action. Then, to have the barrels hit the same POI, they have to be spaced apart at the muzzle as well. And this is what you see. It happens with O/Us too, only it isn't as conspicious.

Mike,
I don't know who made that gun, but many,[especially American], makers put their 410's on a 20ga. frame. In order to make this work, the outside diameter of the barrels was basically that of a 20b. Since the bores are 410 size, this leaves a very thick wall, making the centers fairly far apart. The more distance center to center at the breech, the more required for proper convegence at the muzzle. Based on that picture, I'de say that's a fairly heavy 410. I looked closely to see if there wasn't any rifling in the bores.
Luck,
Jim

Mike,
Many .410 sxs guns are built on larger frames or have firing pin spacing that is further apart than needed to allow the muzzles to come together and still have the requisite convergence to have a correct POI for both barrels.

Of the .410 guns that I have with the muzzles that come together, they all have between .011-013"/inch convergence. I suspect you'll find that the gun pictured has a similar convergence per inch, but that the firing pins are spaced apart such that .011-.013/inch will not bring the muzzles together.

The Winchester M 23 .410's are spaced at the muzzles similar to the picture.

Thanks fellas! I think I understand now.

The Model 23 in .410 is made on baby frame and does not look like the one in the picture.

Don,
My memory was that the muzzles on the 23 are separated similar to the picture. I didn't mean to say that the picture was of a 23. Also, my friend's CSM M21 is separated at the muzzles as well.

This is true of the Winchester made Model 21 because they were made on the 20 gauge frame.

Here are the muzzles on my 1930s Stevens 410. I measure the muzzle wall at .070 and where they meet at .143. So that says a .003 separation.



Here is the breech. Walls at center measure .352; chamber walls horizontally opposed .185 avg. Barrels are 26" and very good regulation.

I have the baby frame Winchester Model 23 Classics in .410-bore and 28-gauge, and the firing pin centers are 15/16 inch on both. The 28-gauge tubes touch at the muzzle and the .410-bore tubes have that horrendous gap. My .410-bore Crescent is on a frame with 15/16 inch firing pin centers and the tubes touch at the muzzle. My Ithaca NID .410-bore has firing pins 29/32 inch center-to-center, the same as my two 28-gauge NIDs. The tubes of both the .410-bore and the 28-gauges touch at the muzzle. The barrels are 26-inch on all six of the above guns.