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?

https://pacifictoolandgauge.com/gauge-rim-cutters-no-pix-/743-12-gauge-rim-cutter.html

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.

Are you handloading the AAs? Will RGL's fit? If you aren't a high volume shooter, rather than remove metal in the gun you can't put back, consider chucking an AA into a drill and make a few passes on a stone. In order to hold the shell, find a short dowel that will snugly fit the inside of the AA. Drill a center hole axially through the dowel and run a 1/4" bolt down the center with enough out of the drill end to be able to be chucked. You may have to tape or hose clamp the hull to prevent the dowel from spinning inside the hull. Or swap the AAs for Cheddies or RGLs if they fit. Gil

I have a William Evans from 1901. Chambers still 2 1/2". Remingtons (Gun Clubs and STS) drop right in. So do Herters (Cheddite), Federal Top Guns, and Winchester Super Targets. I don't have any AA's on hand to try. But with a lot of options that work well in my gun which is the same vintage as yours, I think I'd try other hulls before modifying the chamber. I do get a very tight fit on once fired Fed Gold Medal hulls. That's the only "problem child" I could find.

It is an easy fix. It is not an uncommon problem in older guns. Winchester rim diameters have generally been larger than average since I first measured them in the 1970s. Opening up the rim diameter a few thou will be undetectable.

Hi guys, I appreciate all the advice. I am very leery to have the gun modified and just wanted to see other opinions. I am hand loading the AA’s for my other 2 1/2” guns by trimming them short and using a Hartin crimp. I am not a high volume shooter, so I was thinking about buying a small jewelry bench grinder and just turning the hull by hand to grind the rim down smaller to fit the gun. Eventually, if this ammo shortage let’s up, I will buy some Cheddite hulls and RST ammo (I am down to 250 rounds of RST) and just reload those.

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

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.

Some photos for those interested

My 21 VR Trap gun has the same problem with shells fired in other guns. I have solved the problem by using my son-in-laws MEC Super Sizer on my reloads.

https://www.mecoutdoors.com/super-sizer

If using a mec 600, I would try pushing the sizing collar down a little. Not enough to change the headspace but enough to possibly pull the diameter in. If its only .002, it might work. Not sure but worth a try.

I use my Super Sizer on all my reloads. I have collets in three gauges for it. I was wondering if it wouldn't reduce the rim diameter by a couple thousandths.

My SS also does double duty as a shell holder for turning roll crimps on my drill press. No need for any other type of shell holder to do that.

The ring type sizers have the habit of pushing the brass head down toward the rim, where it effectively mushrooms the head, i.e. increases rim diameter.

If you have a steady hand, a stone in a Dremel can be lightly run around the inside of the rim cut to gain you those few thousandths that you need. That said, as others have suggested, the MEC super sizer would be my first attempt to solve the problem

I did try adjusting the sizing collar down on my MEC 600 and it not did make a difference. I just need to ultimately switch over to the Cheddite hulls and for the time being figure out a way to remove the .002” on the AA’s.

If you start filing the rims on those cases, do you not run the risk of compromising the case and blowing a hole? That's folded steel or brass, and if the former, you will also encourage corrosion.

It's a no brainer to hone the rim recess. It just isn't worth the trouble or risk of rupturing a case. But they are your eyeballs (hopefully safely behind glasses).





2201221208

I am not sure how removing .002” from the O.D. of the shell rim would compromise the integrity of the hull to cause it to rupture. Just curious as to your thought process, because if I am missing something, I sure would like to know.

I just cut apart a cheddite that, at various points was as thin as 0.006".

I question the feasibility of removing precisely 16.5% of that thickness and not more on a few hundred, used shotshells. Are they even that perfectly concentric and round to do this safely, and expediently to hundreds of shells? And who is to say that 0.05", if perfectly maintained, is enough. Afte rall, they aren't made that thin to begin with - possibly for a reason. After repeated reloading and possibly sketchy conditions that could add corrosion, maybe they won't stay safe, even if they began safe.

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

Turning down rim diameters on AA hulls just to be able to use them in one gun is too much sugar for a dime when there are other options, IMHO.

My goodness! Just open the rim by .002–isn’t going to hurt a single thing. Believe me, Boswell wouldn’t have hesitated a split second to do it. Zero affect on originality. It may be that the chamber reamer originally used was smaller than normal. People act as though components are available on every street corner. Not!

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.

So have I. I have a bunch in fact. They are not comparable for a lot of reasons. Your eyes. Not mine.

I had this problem a few years ago with an English 20 ga side-by-side. Got my smith to open the rim. Worked perfectly and could use any ammo that I wanted.

A quick look at the SAAMI drawing for the 12 gauge shell indicates the maximum rim diameter to be .886", with a remarkable amount of tolerance on the low side (.021").

This is of course the dimension one would expect AA shells to be at or under. The chamber specification is .887".

AA shells seem to measure .882 to .883 here, fired or sized in a Grabber. STS shells here measure .875 to .877. Both meet SAAMI spec.

If you want the gun to chamber ANY SAAMI spec shell, the rim cut will need to be .887".

Only you can decide if this is a acceptable. The gun predates any SAAMI or CIP standards.

Personally, I'd leave the rim cut alone and just use STS cases for my reloading. They are not particularly scarce. Yet.

Grinding on the rim of a AA is not the brightest thing you can do. The rim is not solid. The brass case head is formed from sheet stock in a die. The rim is therefore hollow.

While the rim is not part of the pressure vessel per se, making it thinner invites a partial case head separation which at minimum would be inconvenient.

Shotgunjones, I appreciate all the information.

You have confirmed that my AA’s measure the same as yours,.882”. At .880, they fit into the gun no problem.

Also, thank you for the Remington STS measurement. It gives me another hull to look for. The Cheddite/RST measures .875”, so that’s on my list as well.

I have decided to not open up the rim cut and just try and scrounge up some STS’s or Cheddite’s.

I really appreciate everyone who has contributed to the thread. Thanks to you all!

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.