doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com 2 3/4 shells in 2 1/2 chamber?

Joe Wood,
I don't have an autoloader, but your remark about them needing High Pressure loads to function seems off.
Surely it is recoil that keeps them cycling...& you can get loads moving smartly enough to cycle , that are not that high in psi if you look for them?
Of course I am talking reloads
Just asking, n no harm meant my friend
Cheers
Franc

Thanks Matt for the kind words. Shes a fun gun to shoot and yep it's a 12b gun. I've used this load in cold weather and never had a blooper or mis-fire. I like it!

Thanks again!

Greg

In SSM July/Aug 2016, on pg 64, a well known ballistics expert says that it is chamber pressure that controls cold weather ignition consistency.
6200 is too low for reliability.

Could be, all I know is the load I use has been thru 2 ND winters with no problems. One thing that someone suggested is to put disposable hand warmers with your shells and rotate shells between them and the ones in your gun. This will keep the shells fairly warm to avoid any problems. Good idea, but to be honest I never used this method, does make sense.

BTW, my loads have been tested by Tom Armburst and do come in around 5900psi.

Best,

Greg

I have a number of black powder era doubles and a few early smokeless with short chambers with forcing cones designed for paper wads. I cut plastic hulls down to 2-1/2" and load black powder or BlackMZ for those that are black powder guns and light loads of Red Dot for smokeless era guns. Shot load is 7/8 or 1 oz. I use plastic wads and roll crimp. As I can reload, I can make the loads work for the gun. I really don't need heavy loads anyway.

Couple of comments here.
1st; Recoil controls the operation of a recoil operated semi-auto such as the old Browning A-5. Most modern day semi-autos are gas operated & recoil has virtually nothing to do with their operation, it's the gas pressure.
2nd; Be certain when you load a longer shell into the chamber that its loaded length does not exceed the chamber length. Its fine if a bit of the unfolding crimp reaches up into the forcing cone. It is "Not Fine" if the crimped end of the shell is actually forced into the cone. This increases the resistance to the crimp opening which can raise pressures excessively. This is most times not a problem but could occur if loading a roll crimped 2 3/4" shell into a "True" 2�" chamber.
Most short chambered American guns had 2 5/8" chambers. Most British ones will be found to measure from 2 916 to 2/58 in spite of the nominal 2�" classification. Most European ones had 65mm or about 2 9/16" chambers.

I'd say two Dakota winters is a pretty good test of your 5900 psi load. I use a bismuth load in that neighborhood too, but it's not nearly as cold here, so obviously the Deep South is not a very good test. I'm not complaining. It seems to me that the complaints I have heard on forums about poor ignition in cold weather came from the use of 4625, which is what I currently use. But, there are faster burning powders that can be loaded to give pressures in the 6000 psi range as well. I'm thinking they are not as subject to "blooping".

A snowy duck hunt here (with those low pressure bismuth loads) is the exception, but it sure was fun ............for me, not the ducks.

Last Saturday of season Jan. 2016



SRH

2-Piper is absolutely correct. As long as the hull mouth opens somewhere in the forcing cone pressure is not a major factor. However, if it is extending into the bore pressures will spike considerably. If the mouth of a fired long hull is torn off or ragged the hull is probably in the bore.

What Joe said. Left - 65mm Eley 28gm 12g; Right - CompX 65mm 21 gm.



And BTW: 20g 2 3/4" shells
Estate (Federal) 2 5/8"; Fiocchi 2 11/16"; Nobel Sport 2 3/4"; Winchester 2 5/8"; Winchester Universal 2 5/8"; Remington Gun Club 2 11/16"



12g 2 3/4" shells
B&P Competition One 7/8 oz. 2 3/4"; Fiocchi 2 11/16"; Fiocchi 2 3/4"; Federal (and Estate) 2 11/16"; Remington Gun Club 2 3/4"; Winchester 2 3/4"; Herter's (Federal) 2 11/16"



All 2 11/16": Nobel Sport Low Recoil, Remington STS Premier, Remington Nitro, Federal Top Gun, Federal Top Gun

Re: load choice for 2 1/2" chambers, assuming adequate wall thickness

Prior to 1924, the Belgian and British Service (using) maximum load for 12g 2 1/2� and 2 5/8� shells was 1 1/4 oz. / 3 1/4 Dram Eq. (1220 fps). The pressure of that load would have been about 8500 psi with BULK smokeless powder; with DENSE smokeless 9,500 - 10,500 psi.
2 1/2� shells were usually loaded with 1 1/8 oz. shot and 3 Dr. Eq. of BULK Smokeless with a pressure of 6500 - 7500 psi; DENSE Smokeless was 9000 - 10,000 psi.

During WWI the standard English 12g load was dropped by law (to conserve the supplies of lead and powder) to 1 oz. and 3 Dr. Eq. Bulk smokeless. After the War, 2 1/2� shells were generally loaded with 1 1/16 oz. shot and 3 Dr. Eq. Bulk or Dense smokeless powder.

In the 1925 British Proof House revisions, the 2 1/2� & 2 5/8� 12g service load was reduced to 3 Drams with 1 1/8 oz. shot with a mean service pressure of 3 1/4 tons = (converted using Burrard's forumula) 9,682 psi.