Gun screws

I was given a lovely old Dublin made side by side sidelock shotgun a few years back. Being busy i never did much with it, but now want to shoot it. One of the things i noticed however was the pin (screw) that holds the rear of the lockplates together, had stripped. Luckily the threads in the lock are ok.

Measuring the screw i get 0.1695 inches thread diameter and what i think is 36 tpi. I naturally assumed it would be a BA screw thread, but it seems not to be. The closest i can find is No.8 UNF.

Anyone happen to know what thread forms were used by gunmakers in the late victorian/early edwardian period ? Was it a case of using whatever taps and dies you could find, or coming up with your own thread cutting tools ?

Hi Ronan, I think you will find that the gun screws are of no known type and thread, I have been there and decided to make my own for an old Atkins d/b gun with Damascus barrels The hinge pin was badly worn and I replaced it with a piece of stubbs steel and reamed a clean hole through.

BA I doubt is a normal gun screw and in fact while fitting scopes etc the threads were quite coarse threads for the mounts but as you have found on the shotgun they are fine at 36 tpi.

Trying all the types of screw I did not find a matching thread so started making my own. Every gunsmith had their own system it would seem. Further to this it would have been a Black Powder gun and the type of cartridge now would be Eley Grand Pri to be safe.Try and check your proof marks if any!

Ronan If it's only black powder proof. You either need black powder cartridges ( if you can still get them ) or the gun wants reproofing. Do NOT use smokeless

Roy

Thanks Clive and Roy. Its a laminated steel barreled gun, hammerless. Thats whats stamped on the barrel bottoms. There is a proof mark on the barrel flats, but cursed if i can make them out, Ireland was part of the uk when this gun was built, so proof would have been compulsory, unless there was a special clause otherwise. Someone told me to use M4.5, as its so close it will make no odds, we'll see. Its odd that the gun trade never standardised threads as the cycle industry did for instance.

Ronan, photograph the proof marks and message me, happy to advise. Remember just because it has proof makes does not mean it is safe now ! There is more to proof than the arm bearing marks !

Screw threads are generally BA -- BUT ! and herein is the problem, I was told by an old Birmingham gunmaker that what happened was as an apprentice they would buy or even inherit a die plate - the type you often see on auction sites - these were used to make taps so the parts always fitted but over many years they became worn so they were no longer "standard" but no matter the parts still fitted. Today we have a problem !

What you usually find its they are close to and oversize BA but some barrel actions were imported for very cheap guns and many of these were metric.

John

PS the gun may not have been made in Ireland but made in Brum then branded, either way it would have proof marks; 

Edited By JohnF on 08/07/2018 15:17:59

Spot on John BA is a common thread still used to this day in traditional lock making and other areas. The other is UNF.

Bridles 2 off 6BA and one 7BA

BA and UNF is still used by a well known Scottish gunmaker producing the round action.

Lock in question was very likeley made very very locally by Stanton, ex workers setup in Whitmore Reans Wolverhampton then two of them set up in Bilbrook 74 ish carrying on the traditional methods to 2010 as the only tradition lock makers to the trade.

.1695" they usually wear on the peaks of the threads so will measure under!
No 8 UNF 36 TPI effective dia .1697"
2BA near on 35 TPI
Since Stanton was producing large quantities they wouldnt have put a gun thread in, taps would have been purchased and repeatable for the actioners to make the said screw. There again this may have been the change over period to standardise

Have a look inside the lock there will be a makers stamping unless it was going to a big name house like H&H etc stamping on each lock.

Even better post a piccy up, should be able to tell who has done any work.

Edited By Jon on 08/07/2018 23:21:51