doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com need help with British Proof markings

I was curious to see if someone could help interpret these markings, I know it's 2 1/2 inch chambers and choked. I'm not familiar with British shells but I have a ton of Holland and Holland light loads at 67mm would these be suitable for this gun based on the proof marks?

By the proofmarks, that gun was made between 1925-54. If you look at those H&H shotshell boxes--and I happen to have a box of 67mm 16's from H&H--it will likely tell you that they're OK if the gun is proofed for loads of at least 1 oz and the chambers are at least 2 1/2" in length. Your gun is good to go in both those areas.

Thanks Larry! I thought I would ask, do appreciate the reply!

Can confirm. Cartridges marked in metric 65mm., 67mm., or 67.5mm. will be o.k. if gun is in proof with 2 1/2" chambers. Lagopus.....

Excellent! Thank you guys! So I take it the 1 1/8 oz is what it was proofed with, so anything under that should be fine.

Well, yes and no. Check the European metric length as above on the box. There are suitable cartridges for 2 1/2" chambered guns that are loaded with 1 3/16th. ounce(Eley 'Maximum')and even some that have 1 1/4 ounce (the old Eley 'Alphamax') in them that are o.k. for your gun but there are a lot of 1 ounce loads loaded into cases that state 70mm. on the box. Light loads but high pressure for use in semi autos. All rather confusing so always go by what is printed on the box.

Those H&H cartridges in 67mm. cases with have been specifically made for 2 1/2" chamber guns. Enjoy shooting them. Lagopus.....

Would just like to add a note of caution about British cartridges.
In the photograph are two cartridge cases from boxes of cartridges sold for guns with chamber lengths of 2 1/2 inch one is 67mm and the other is 65mm, you can see from the shredded top that the 67mm has entered the forcing cone causing an increase in the guns recoil. So some guns with 2 1/2 inch chambers are very sensitive to the cartridge length used.

Usually, the problem with 67MM shells in 2 1/2" guns comes with older guns which have very short and sharply-angled forcing cones. More like a step than a taper. Even though those British shotshell boxes will tell you that those 67MM loads are fine in 2 1/2" guns, that's not always true. If you get blown ends and increased recoil . . . stop! You need to stick to true 2 1/2"/65MM loads.

I had a Stevens 20ga in 2 1/2 that couldn't use 67mm shells. I'll try this one and see what it does.

The problem with one of those "Stepped" chambers is the end of the shell does not just enter the forcing cone, but actually goes into the bore proper. This both gives an extreme reduction in size for the load to pass through but also slows the opening of the crimp, both conditions conducive to "High Pressures". On an older gun always examine the forcing, if it is very short & abrupt "Do Not" use shells longer than the actual chamber length (After Firing length)
.

Using the longer hulls is based on a forcing cone with a minimum length of around 3/8" & most are around 7/16" to �" long.