doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com W & C Scott 12 gauge

Looking at your latest proof marks (the 1954 onwards table) BNP denote Birmingham Nitro Proof and NP denotes London Nitro. If you are in the US I would recommend also looking at the chamber length as marked. That defines the case length ( 65mm being 2 1/2" and 70mm being 2 3/4". That means for example a standard game load, these od guns were not built to handle any magnum or hot shells.
I would be surprised if the post 1954 re-proof did not cover Nitro, if it as for B.P. only there would be some mark to indicate that.

Note that 65mm converts to 2.559" while 70mm is 2.756".
2 9/16 " = 2.5625" so 65mm is only .0035" shy while it is .059" longer than 2�". I personally call a 65mmm chamber a 2 9/16" one rather than 2�". I also believe that most British guns, except very early ones, had the chambers cut from 65-67mm (2 9/16"-2 5/8"). This is covered in W W Greeners book "The Gun & its Development".
I have the 9th edition (1910) edition but much of it is carry-over from previous editions so I do not know the exact point in time this took place.
My pre-1900 J P Clabrough has 2 5/8" chambers, but it was made primarily for the American market. I have never checked the chamber length on my ca 1863/65 W&C Scott pinfire. I need to do that.

I cannot find anything which indicated Nitro, unless just NOT being marked specifically for black powder when reproofed post 1954 means it defaults to nitro?? I am still considering the purchase - both greener and Parker SxS are $2000 at this store whereas this is significantly less.

You have any answers regarding my questions?? BTW...all the proof marks in the world don�t mean a thing until you know exactly what the internal dimensions/measurements of the barrels are.

I believe I am correct on this. If nitro proofed at Birmingham it should have a crown over the letters BNP (Birming Nitro Proof). if proofed in London it should have a raised, bent arm holding a Scepter over the letters NP (Nitro Proof). If not Nitro proofed from Birming it should have the crown over BP (Birming Proof) which was black powder proof.

I did not find a separate mark for a London proofed gun so believe it simply goes back to the original London Black Powder mark of a Rampant >Lion over an intertwined GP (Gunmakers Proof), without the Nitro Proof mark. At some point in time, but do not have the dates for this off-hand the words Not for Nitro or Black Powder Only were added.

I'll post this again if it will help......from Diggory Hadoke

Thanks, ARGO;
Note that after 1954 the word Nitro is not included. The London proof has only the arm & scepter over NP, while the Birmingham proof has the crown over BNP. Doesn't show when the Not for Nitro or Black Powder Only were instituted.