Magazine tube thread size for 12 gauge?

Hello everyone,
Would anyone know the thread size of the magazine tube side that fit into the receiver. Would it be metric?
Thank for your help

Hi Biz. I just looked at the MGW website, and through the Field Service Manual with no luck. I’m sure if you call them or Art’s they can give you the information.

What’s the problem, by the way?

I called Art’s Gun Shop and the gentleman that answered, said that he didn’t know. I would like to acquire a tap and die kit to rectify slightly damaged threads.

Thank you Ranger. I checked with my gauge thread and my electronic caliper and indeed, it is 1 inch x 32 tpi. I was convinced, since it was made in Europe, that it was metric size.

Sorry for the late follow up, I was geese hunting. I found the tap and die on EBay here: https://www.ebay.ca/str/northbaycuttingtools?_trksid=p2047675.l2563
I confirm that the early model has the same thread, furthermore, my 1904 with the suicide safety has the same thread on both side of the magazine tube. Imagine screwing the magazine cap on fine thread! No wonder the FN went to corse thread the following year, somewhere around 1904/05. Here on the pic, the top tube shows the side that screws into the receiver while the bottom tube shows the side on which the end cap screws.

Totally surprised it is not metric as well coming from Europe. I thought at first it may have been a non standard machine shop special to keep it all in house and be a “get off F N thing” in its day.
Nice to find sanity prevailed and an off the shelf size and pitch.

Yes, taking the cap off of my 1903 takes forever. How did you remove the tube without twisting the receiver?

I mounted the receiver in a vice, making sure to snuggly insert a piece of wood inside it and protecting the outside with a thick piece of rubber. Then, I clamped the magazine tube with a 2"x 2" piece of walnut (obviously could be any hardwood) in which I had drilled a 1 inch hole and then sliced the piece of wood in half. The longer the piece of wood, the more leverage you have.

Good jig setup. I also machined up a precision steel mandrel to fit inside mag tube to give it that bit extra support internally where it was pinch clamped and keep it all straight. Far out the one l did was super tight and was worried about distorting the tube and receiver.

The threaded style action spring tube can be equally as tight , awkward and challenging to get out without damaging anything if fitted by a heavy handed ape.

Good for you, Biz. Did you learn that from Art’s video?

It was largely inspired from a post made on a French forum by a retired gunsmith from the FN. Can you share the link of Art’s video. May be the retired gunsmith got is idea from Art or vice versa.
BTW, what do you think PM stand for on the serial number of my receiver picture?

I’ll look for Art’s video. And PM is code for 1980.

http://www.nramuseum.org/media/940941/serialization-date of manufacture.pdf

By the way, there’s a typo there. M = 0, not 10.

The magazine removal starts about 24 minutes in.

Thank Rudolph for serial number info and I really enjoyed Art’s pipe job. Better not to mess with him in a bar. I also checked the magazine tread of my pre-first war Remington Autoloading Shotgun and it is exactly the same however the magazine cap is not interchangeable.