Chamber dimensions

[bikerbeans]

I have been measuring 1x fired hulls from my Marlin 512 and comparing them to new. Now it is time for a chamber cast. I know most are trying to make sure their slugs are tight in the bore, but what about a loaded cartridge being tight (centered) in the chamber? My thinking is a lose cartridge equals slug out of alignment with the bore.

I have several "fixes" to try but will test before posting about them.

BB

[am44mag]

I'm no expert on shotguns, but in a rifle, you can accomplish exactly what you are wanting by neck sizing shells that you have shot in your gun before. With a shotgun, I'm not sure how well that would work. Plastic is pretty elastic. You can buy brass shotgun shells. I'm not exactly sure how you would neck size a straight walled shell, but you might be able to squeeze a little more accuracy out of the gun if you can pull it off. Then again, I'm no expert on shotguns.

[longbow]

I'll go with a "fat" slug. Make the hull bulge to fill the chamber and that's likely the best you will get. I'm also leaning towards a "fat" slug in the bore too for much the same reason. Shotguns have bore diameters all over the place (smoothbores anyway) so to get a consistent fit without going say 0.735" on the slug O.D. I don't quite see how you would do it unless you cast then sized for each gun.

For instance, my single shot runs 0.733"/0.734" which is pretty big. I am finding (slowly) that the extra clearance, even though only a few thou on a 0.730" slug which doesn't slop around in the bore, results in much larger groups than with a slug knurled up over bore diameter then sized to bore.

I've just knurled up some of the Paradox slugs KrakenFan69 sent me for testing. First time out accuracy with as cast was okay but not nearly as good as I would have expected. However, they are 0.727" diameter so a loose fit to my 0.733"+ bore. Knurled up they are a snug fit. I should be testing those shortly so that may answer some questions about slug fit.

And no, I don't have any trouble chambering 0.735" RB's or slugs in either my single shot or in a rifled Remington 870 so chambers are "generous" (at least mine and the borrowed Remington's are) and I think that is likely a universal statement for all shotguns.

The brass hull idea has merits but I think you would need a thick walled cartridge to shoot standard diameter slugs or they'd be sloppy in the cartridge. Otherwise back to a "fat" slug to fill out that brass cartridge and over fill the bore but be able to be swaged down safely.

Possibly paper patching, Teflon or Mylar wrap or other might accomplish the same thing by bulging the hull a bit and being oversize for the bore.

The SAAMI specs should give you "standard" chamber dimensions but even there the spec could have a large tolerance as bores do.

Longbow

[missionary5155]

Greetings
Years back I came across a 41 Colt revolver. Needless to write there is no 41 Colt ammo. So took some cut down 38 Special brass and wrapped it in masking tape. "Squezzed" the lead 357's in the vice to diameter and seated them nose first into the case. Shot very well with 3F Elephant BP.
So why not wrap the outside mouth area of the plastic shot shell case to size. Would center the load. Barring ejection issues of course..
Mike in Peru

[Hogtamer]

nice observation. MY fix is to shoot so much that a certain amount of plastic residue, feathers and blood stuck to hulls from dove vest, petrified WD-40 and powder residue make for a nice tight chamber. A little tobacco juice will lube one up in a bind. Every decade or so you can chuck a stiff bore brush in your drill and get the big stuff out if you need too. This approach may not be desirable for everyone believe ot or not!

[centershot]

LOL! We love you, Hogtamer!!!

[bikerbeans]

The new hulls I measured are a sloppy fit on the base as well. So with a 1x reload for the same shotgun just forget to resize the base. My gun is a bolt action so no worries, autoloader who knows.

LB, I have been shooting slugs in my 512 that are from 0.007 to 0.009" over groove diameter and they still go into the chamber easily. Maybe a wrap of duct tape around the outside of the hull? Just kidding, about the type of tape, not the idea.

HT, what's this barrel cleaning idea you mentioned. I have never heard of such a thing. Is it just for new fangled belted super-duper magnums?

BB

[17nut]

221536

[bikerbeans]

Regarding rifled shotguns, spec chamber dimensions do not equal real world chamber dimensions.

BB

[bikerbeans]

Regarding rifled shotguns, spec chamber dimensions do not equal real world chamber dimensions.

BB

[MostlyLeverGuns]

Wrapping the base of cartridge or shell to center it, using 'scotch' tape, masking tape, or electrical tape is an 'old' method of centering a 'somewhat' small brass case for even expansion when fireforming.
No reason it would not work on shotshells. One or two wraps, NOT like friction tape on an electrical splice. (What's friction tape? ! ?)

[longbow]

Okay then... Hogtamer pointed out a mistake I am making. I always clean my guns after use. Can't help it. Must be a genetic defect.

Now the tape idea I like and I think I may have some friction tape. If the chamber was clean and shiny before it won't be after a few rounds wrapped in friction tape are run through it!

I'm sure shotgun chambers are mucho oversize to allow for some bulging, crappy crimps, much, grass, feathers, tobacco juice and a few other odds and ends.

We're fighting loose chamber dimensions, random bore diameters, forcing cones and a variety of other non-accuracy inducing items.

Why do we do it?

I'm beginning to think the Dixie Tri-Ball load or a double ball load is the way to go... really big buckshot!

[megasupermagnum]

Okay then... Hogtamer pointed out a mistake I am making. I always clean my guns after use. Can't help it. Must be a genetic defect.

Now the tape idea I like and I think I may have some friction tape. If the chamber was clean and shiny before it won't be after a few rounds wrapped in friction tape are run through it!

I'm sure shotgun chambers are mucho oversize to allow for some bulging, crappy crimps, much, grass, feathers, tobacco juice and a few other odds and ends.

We're fighting loose chamber dimensions, random bore diameters, forcing cones and a variety of other non-accuracy inducing items.

Why do we do it?

I'm beginning to think the Dixie Tri-Ball load or a double ball load is the way to go... really big buckshot!

If Minnesota would allow it, I would choose 000 buckshot, and never look back.

[longbow]

Is the Tri-Ball load legal there?

Not really sure what you would call it... is it "buckshot", multi slug load or multi ball load? If they call it buckshot then it has to fit legal buckshot size but if multi slug/ball load does it?

I mean if you loaded one 0.600" RB into a 12 ga. using a sabot or other centering device that should be a legal slug load same as any other round ball load, so 3 of them...?

[megasupermagnum]

Is the Tri-Ball load legal there?

Not really sure what you would call it... is it "buckshot", multi slug load or multi ball load? If they call it buckshot then it has to fit legal buckshot size but if multi slug/ball load does it?

I mean if you loaded one 0.600" RB into a 12 ga. using a sabot or other centering device that should be a legal slug load same as any other round ball load, so 3 of them...?

There you go using logic to an illogical state. Firearms (even muzzleloaders) must be "single projectile". My favorite one is I hunt in the "shotgun zone" (any handgun 22 caliber center fire or larger, shotgun with a single slug, or muzzle loader of .40 cal or larger), no rifles allowed. I know a number of people who shoot magnum rifle caliber TC Encore "handguns" with 14" barrels. Along that same thinking, you could legally deer hunt with a 25 ACP pistol, there are no case length or barrel length requirements, but a shotgun shooting buckshot is not. Politicians, like winning an argument with a wall. I'm sure in a few years we will make the stepping stone to straight wall rifle cartridges like the rest of the country. Hopefully one day they will realize how pointless the rules are, and just let people use the best tool for the job. Firearms season is just for the crowd to get their 2 weeks of shooting in anyway. The real deer hunters go for the archery or muzzle loader seasons.

[bikerbeans]

Ohio allows many straight wall cartridges for deer but if you want to hunt with 460 Weatherby mag you are restricted to small game. Any caliber CF rifle is legal in ohio for small game, go figure?

BB

[RMc]

Not really sure what you would call it... is it "buckshot", multi slug load or multi ball load? If they call it buckshot then it has to fit legal buckshot size but if multi slug/ball load does it?

Legal Buckshot Size?

Here is a link* to a rather interesting discussion on the subject from 2006 started by James Gates .

After All Just What Is Buckshot

Here are a few excerpts:

"After many, many calls talking to different agencies ... I never did get a postive answer! The very best came in as follows-"Any load that had three or more pellets!"
Well with that answer, I knew my Dixie Tri-Ball (3-.600" balls) would be legal......then I asked how big the pellets could be? Well, that question wiped them out!"

" I found it very interesting that the Feds said I should have the word "buckshot" on Dixie's Tri-Ball II for it to be a legal buckshot load..."

* https://www.shootersforum.com/shotguns-shotgunning-shotshell-reloading/28462-after-all-just-what-buckshot.html

[Ballistics in Scotland]

It isn't as important that a smoothbore slug or ball should have its centre of mass precisely located on the bore axis, as it is with a rifle. But it shouldn't be allowed to tilt before engaging with the barrel. It is clear enough that the thin walls of brass cases are likely to permit this, but I think it is true of plastic as well, since it is usually thinner than the paper around which the long-established shotgun bore and chamber dimensions were designed.

So I think it would be a good idea if the rear (or all) of the case fitted the chamber, and the front (or all) of the case was of a diameter to closely hold the slug. Oh, and for them to be in line of course. In fact it doesn't see like a bad idea with birdshot either. I reflect on the one-piece moulded Wanda slugs of the 1960s, which probably died because pump and automatic shotguns were prone to tear through the plastic rim. Being slightly transparent they would even let a game warden check what you propose firing without destroying your property. I think a weak plastic overshot wad simply engaged with a moulded-in turnover.

A thick-walled case could be made the same way, and if you persist in believing that the shotgun wasn't perfected in the 1890s double, the industry has since got used to crimping a metal head over a plastic body. The trouble is, flocks of deer don't pass overhead, and slugs or buckshot are a tiny fraction of the shotshell market.

I'd be wary of an internal sleeve, other than one attached to the wad. If it comes out, it is a bore obstruction. But sizing the shell and thickening it from the outside, to suit your particular dimensions sounds good. Perhaps a heated die would work best with plastic. Tape would surely work, but there is a current thread on making cases for the French Chassepot rifle with heat-shrink tubing. Personally I think it would only work with something rather thicker and more rigid than the thinner heat-shrink tubing I know - but maybe that is what the originator has. I wouldn't be surprised to find it of the right thickness, once shrunk, to do what is needed with a shotshell.

[MostlyLeverGuns]

Friction tape was meant as a joke, thinner and smoother is better.

[country gent]

Could an expander pin be used to swell the plastic body to a size to fit the chamber? This would take some experimenting with size to compensate for spring back in the plastic body of the cases. It might give you what you want then the issue will be finding a wad or slug to seal the bigger case.

[bikerbeans]

Could an expander pin be used to swell the plastic body to a size to fit the chamber? This would take some experimenting with size to compensate for spring back in the plastic body of the cases. It might give you what you want then the issue will be finding a wad or slug to seal the bigger case.

I think it would work but yhe slug might be way over groove diameter. With a heavy barrel probably not an issue, but with a thin wall barrel and a hard alloy could be a problem.

The 1x fired fio hulls show are about 0.004" larger in diameter than when new. I am going to make identical loads half with new hulls and half with 1x fired and see if it makes any difference. Also I am not going to resize the base of the 1x hulls.

BB