doublegunshop.com - home Forums Thread Like Summary - Boswell won’t close with Win AA hulls

Hey guys, I just received a Charles Boswell box lock I had brought in. Gun was made in 1905.

I am going over the gun and everything is as advertised. The peculiar thing is the gun won’t close all the way with a Winchester AA HS hull. No problem with an RST (Cheddite) hull. Upon closer examination, the O.D. of the Winchester brass rim is .002” larger than the RST. The rim diameter is just large enough that it won’t fit into the rim cut in the chambers of the barrels to allow the gun to close. I filed down the rim on the Winchester .002” and then it fits properly to allow the gun to close. Does anyone know if it is an easy fix for a gunsmith to open up the I.D. of the chamber rim cut .002”, as to allow the use of Winchester hulls? Has anyone else run into this?

Would you rather modify it than just use appropriate loads in it that will seat properly? I'd think over that decision very carefully if it were mine.

Seems a shame to mess with something that`s been ok for almost 120 years !!!! Personally I`d be using approprate cartridges .

Some photos for those interested

My first thought; Is this a once fired AA hull you're using? If that's the case it may be fire-formed to the chambers & rims of the gun the hull was fired from.

I have a model-21 Winchester that I had a similar problem with. The once-fired AA hull was tight in the chamber & it wouldn't let the gun close. I then tried a new AA shell and it dropped right in & the gun closed without an issue. My conclusion was the once fired hull had expanded to the chambers of the gun it had been fired in previously.

Just a thought.

It's a no brainer to buy a collet to resize the case head or buy ammo that works

I’ve seen shotgun hulls with no metal head, so I doubt the plated steel has any structural function.

If AA cases are a must, I would go the extra mile on resizing.
If not, just use a brand of cases that work.

Modifying the gun would be my last choice, just because there’s always the chance of something going wrong, even a UPS screw-up.

Lovely gun, OP.

Just use a small oval file on the rim cut. Takes about 15 minutes per barrel. I have had to do this on about 5 of my doubles. You can buy a cheap 8 file set at Home Depot or other hardware store. Just go slow and the result are fantastic.