In your opinion what is the minimum number of threads required on a large ring 98?

Picked up a couple of actions from a 'Dead Gunsmith' auction.
I purchased them for parts and had planned to sell or give away the bare actions.

The front ring has been cut back notably.
I believe these were Turk GEW actions.
Ring was (probably) undercut during Turk conversion to attach the handguard.
When that undercut was removed by the 'smith it left the front ring short.

If they are past safe minimum, I'll just cut them up to get them off my books.

Thanks!

How long are they? Thread is .625; I don't know the minimum thread length but realistically, about 3 threads would hold the barrel.
They are bare actions;; actions contain the bolt etc. Or are they bare receivers.

I have seen some pretty scary looking ones. The least I have seen was approximately 3 threads on the barrel. It had been set back by some farmer who simply doubled the relief cut, cut 1/10th of an inch off the shank and screwed it back on. He shot the thing for years with his farmer hand loads which I could have used for commercial proving with no ill affects. The commercial, small ring, FN Browning Mauser's in the short, pencil barrel had about four threads on them. The shanks were very short. So, whatever was on the barrel shank can be mirrored to the action.

I suppose one of the math gurus here could dig into the Machineries Handbook and figure out what the exact theoretical minimum would be. But I'm not one of those math hounds.

OK

I dug into my notes (I think this came from Kreckler, Rudy Van Owen or old Gus Crites 35 years ago.

The minimum number of threads for a barrel steel, low pressure vessel (45,000 PSI) is .250 ÷ by the pitch of the thread in inches.

The minimum number of threads for a barrel steel, high pressure vessel (55,000 PSI) is .300 ÷ by the pitch of the thread in inches.

So, for cartridges like the 7x57 etc.
.250 ÷ .083 (pitch of 12 TPI) = 3.012 threads total.

For belted magnums.
.300 ÷ .083 (pitch of 12 TPI) = 3.61 threads total.

Common sense also sort of tells me that those numbers would be the ABSOLUTE MINIMUM ! SO, govern yourself accordingly.

quote:

Originally posted by speerchucker30x378:

So, for cartridges like the 7x57 etc.
.250 ÷ .083 (pitch of 12 TPI) = 3.012 threads total.

For belted magnums.
.300 ÷ .083 (pitch of 12 TPI) = 3.61 threads total.

Common sense also sort of tells me that those numbers would be the ABSOLUTE MINIMUM ! SO, govern yourself accordingly.

speerchucker,

Thank you.
This is exactly the information I was looking for.
I wonder if the 'smith read the same source?
Four and half full threads the two I checked.

No worries about belted mags.
If I use, sell or gift them I'll pass on this information.

quote:

Originally posted by dpcd:
How long are they? Thread is .625; I don't know the minimum thread length but realistically, about 3 threads would hold the barrel.
They are bare actions;; actions contain the bolt etc. Or are they bare receivers.

Action - Receiver
220 - 221

Bought them for the bolts, bottom metal and bolt stops.

quote:

Originally posted by Utah Shotgunner:

I wonder if the 'smith read the same source?
Four and half full threads the two I checked.

I would imagine that if the guy had a machinist background or went to CST or PST they probably simply referred to the Machineries Handbook and did the math.

Math and I get along to the point where I am simply FORCED to do it. There was a time when I did know and use long hand math. But that went the way of the Dodo when the computer came around. There was a day when I had all the math for gear formulas, dividing head plates, thread pitches and depths, rotary tables, tapers and much more all in long form in Basica and ran them off one of those little Texas Instruments super calculators. Later, those same 10 page algorithms were transferred to Lotus 123 and run on a Tandy 1000. Today, I think I have a bigger chip in my watch than I did in those old putors.

Now I simply have charts on the wall for dividing head plates and rotary table divisions. And I have apps on my cell phone and tablet that figure out stuff that are not on the wall charts and other things like tapers and thread pitches and depths. But even the threading apps are pretty much never used now that I have gone to full form carbide. Simply cut and measure the OD until you're done.

Young minds, fresh ideas.

Back to CST days ? We was huntin' dinosaurs back then !
I still have a tap drill size chart from those days. So we have to have info on the % of thread .We want a rigid joint so the shorter the thread the higher percentage we need. Off hand the Steyr SSG has a 2" long thread developed for their sniper and target rifles -yes , rigid. Of course you could redesign the whole thing to have a one piece receiver/barrel.
My CST special was one of those cut and try to get minimum dimensions. The metallurgists way !!

quote:

Reply

I was at CST when Crites, Kreckle, Wentworth ,Cross, Bone, Dowtin, graduted with Novak, J.Mitchell, etc.Grad. 1976

The lr large thread Turks were ww1 vz or German , turkey in 1938 made all inventory similar in appearance so they restocked , rebarrel led when necessary and used thes a lot . There ammo is not on the lite side , in fact most of there 8mm 147-150 gr ammo chronos at around 3000 fps . If the lugs aren't set back and you do not cut or drill into the receiver locking lugs , you should be good to go . I've rebarrel led dozens in 243 ,7-08ackley, 308,30-06 , and 358 . Two of my personal guns are in 6.5 Rem mag , one 6.5 Rem mag is on its 3rd barrel .