Min barrel length to thread?

[Trockstroh]

Is there a minimum length needed to thread a barrel for a 1/2x28 thread pattern? I am looking at buying a Marlin lever action that i would like to thread for a suppressor. Any input would be appreciated. Thanks in advance!

[FrankenMauser]

No minimum length (other than staying legal) - just minimum diameter.

Every 'smith will have their own minimum.
"Industry standard" for 1/2-28 seems to be about 0.600" minimum.
Some 'smiths will go smaller if they're installing a custom muzzle brake.
Some 'smiths want more, no mater what will be installed.
I've seen some guys demand as much as 0.700" diameter to thread 1/2-28. (For a 0.100" nominal torque shoulder.)

Every 'smith has their own minimum.

My personal minimum for 1/2-28 is 0.610", but I am a hobbyist. ...And I don't even do the work myself.

[Unconventional]

I imagine the OP is interested to know if he has enough barrel in front of the magazine tube to properly cut threads for a suppressor.

Did that really escape you Franken?

[Scorch]

I've got one in the shop right now. No problem threading the barrel, but the magazine tube will have to be shortened about 1/2", and the front sight moved to the rear about 3/8". This will allow about 9/16" of threads to screw the can or adapter to.

[Unconventional]

It also depends on which model of Marlin you have - some have a magazine tube that extends pretty close to the muzzle. The guide gun model has a shorter tube, but might still need the front sight moved.

Scorch, will you lose any capacity with the shorter magazine tube? Will you be -1 round in the magazine?

[FrankenMauser]

Did that really escape you Franken?

No, it did not.

Magazine modification does not affect threading. It is required on some models, if you want to clear a suppressor; but does not impact minimum length or diameter for things like a muzzle brake, unless you're dealing with a Marauder-style rifle with the front barrel band too close to the muzzle to allow threading without moving the barrel band.

Assuming the threading is for a suppressor (as the OP stated):
As you noted, different models have different length magazines. A 336A, 336XLR, or Glenfield Model 30? No magazine modification required. (But moving the sight may be.)
336C, 336W, Glenfield 30A, and many others...? Yea, you're chopping that mag tube. How much depends upon the year of manufacture, and whether or not further work is desirable (or affordable). Barrel lengths have varied slightly over the years, as have magazine tube lengths. Some year/model combinations might only need the mag tube cut far enough to completely remove the old mag tube plug screw hole. Other year/model combinations might require taking as much as 3/4" off, because the mag tube plugs originally extended slightly past the muzzle. And other year/model combinations (such as the Marauders) are going to require chopping enough to appear as a "3/4-length" magazine, in order to remove the barrel band screw slot.

...Unless, of course, the 'smith is going to give you a good deal on TiG welding slots/holes in the existing tube and turning it back to ID and OD to go with the longest length possible. OR, they want to splice magazine tubes and redrill/recut appropriate holes and/or slots.


Who is to say that it's even a Model 336 or Model 30, though? Perhaps the OP is buying a 39A or LeverMatic...

Scorch, will you lose any capacity with the shorter magazine tube? Will you be -1 round in the magazine?

Assuming it's a 336:
Generally, no.
There is usually enough space in the magazine tube, when using a factory spring, mag tube plug, and follower, to cut the mag tube down by as much as an inch without losing capacity or hitting full compression of the spring with the last round fully loaded.


Oh. One last thing:
Guide Guns don't get threaded 1/2-28.

[Clemson]

I like to thread 1/2 inch long for 1/2-28 threads. The harder job is figuring out how to hold the rifle in the lathe. Either the barrel has to come off the receiver, or the receiver has to be swung in the lathe eccentrically to center the bore with the lathe's axis.


Bill Jacobs

[Scorch]

Scorch, will you lose any capacity with the shorter magazine tube? Will you be -1 round in the magazine?

I don't know the answer to that. Shouldn't, but I am not sure.

Assuming it's a 336:

It's an 1894 in 357 Magnum.

[Unconventional]

Originally Posted by FrankenMauser

No, it did not.

Haha, Ok.

Thankfully, Clemson was able to come in with a relevant answer to the OP's question after your ramblings.

[FrankenMauser]

I should have ignored your comment, as it was clear from the beginning that you were just trying to irritate me.
I tried to take the high ground and provide explanation - as much for people that may be reading this thread without participating, as an attempt for you to possibly realize that there's actual knowledge to be shared and gained here. In return, you reverted to your standard of adding absolutely nothing to the discussion, but continuing to attempt to troll.

Your snarky, completely useless cheap shots and irritations have reached a new high for the month.
I believe you're due to return for the next round in... February?
Go shoot some more windshields, so you can avail members in the T&T forum again with your expert knowledge when you get back.

[Unconventional]

Originally Posted by FrankenMauser

In return, you reverted to your standard of adding absolutely nothing to the discussion, but continuing to attempt to troll.

I disagree. I tried to clarify what the OP was ACTUALLY trying to learn.

What did you contribute to the OP's question? I'm not telling you not to post or not to inundate us with your knowledge. But don't tell me not to call you out when it leaves the OP with his question unanswered.

And please, let's not revert to personal attacks.

That is all.