Threading/shoulders and having enough meat

[Deavis]

Threading for a Harvester .30, thin barrel hesitancy
I have a Harvester .30 pending x-fer.

I just assumed all my intended hosts would be able to take 5/8 (.625) x 24 with plenty of shoulder meat. Wrong.

Guns are as follows:

Rem 700 .308 22" .760 - no problem

Rem 7 .308 20" .555 - 5/8 and shoulder problem?

Howa 1500 300 win mag 24" .605 5/8 and shoulder-problem?

Marlin 336 30/30 20" .655 -shoulder problem?

The middle two I hunt with most.

1/2 x 28 is available for the thread mount but I'm a tetch leery of .10 wall with the middle two, in particular with the 300 win. Should the lack of shoulder also be a concern with not much to snug up to?

I don't want to reduce much of the 300 barrel for more meat and the .308 m7 won't matter because it is still thin.

Options?

[johndoe3]

http://www.store.silencerco.com/collect ... read-mount

They have a 9/16x24 in between the 5/8 and 1/2 mounts.

[yondering]

Use 9/16-24 for most sporter barrel bolt actions. You can also tighten against the muzzle, instead of a shoulder on the barrel, if your muzzle device is set up for that.

[rimshaker]

For rifle calibers, always index/tighten on the shoulder.

Indexing off the muzzle should be recommended just for pistol calibers; the metric threads.

[RJT]

All of my sporter barrels are 9/16×24 with my Harvester.

[Deavis]

All of my sporter barrels are 9/16×24 with my Harvester.

9/16 is .5625 right? My m7 is smaller than that.

1/2 x 28 with limited shoulder scares me a bit with the 20" 308 and 24" 300 win mag.

I'm getting a 1/2 x 28 thread with adapter to 5/8 x 24 feeling for these two.

[RJT]

.5605 for the Major. I had mine cut based on this chart(supplied by Silencerco employee). You're most likely going to have to lose a couple of inches, mine did.
https://thunderbeastarms.com/tech/thread-specifications

[yondering]

For rifle calibers, always index/tighten on the shoulder.

Indexing off the muzzle should be recommended just for pistol calibers; the metric threads.

Why?

[Bendersquint]

For rifle calibers, always index/tighten on the shoulder.

Indexing off the muzzle should be recommended just for pistol calibers; the metric threads.

Why?

Yeah, why?

[rimshaker]

For rifle calibers, always index/tighten on the shoulder.

Indexing off the muzzle should be recommended just for pistol calibers; the metric threads.

Why?

Yeah, why?

Because the muzzle crown is more "fragile" than the barrel shoulder, especially under heavy torque when tightening down mounts.

Too much stress at the muzzle will start affecting POI at some point. Some FH's and thread adapters index off the muzzle.

Ok nevermind. Sounds like the OP was talking about direct threading a Harvester... guess it doesn't matter since the can isn't being torqued down.

[yondering]

Because the muzzle crown is more "fragile" than the barrel shoulder, especially under heavy torque when tightening down mounts.

Too much stress at the muzzle will start affecting POI at some point. Some FH's and thread adapters index off the muzzle.

Ok nevermind. Sounds like the OP was talking about direct threading a Harvester... guess it doesn't matter since the can isn't being torqued down.

On a really thin muzzle, sure. But the recommendation was to register on the muzzle and use a larger thread, which is a better result than a thinner muzzle with a smaller thread. Torquing against a shoulder has it's issues too, and using a smaller thread to accomplish it only makes things worse. More steel around the muzzle is almost always better.

[Conqueror]

As noted above, you could also shorten your barrel a couple inches prior to threading if the length would remain legal.

[Deavis]

As noted above, you could also shorten your barrel a couple inches prior to threading if the length would remain legal.

The m7 is 0.555 all the way to the stock.

Is 1/2 x 28 just not acceptable for 300 win mag/308?

[RJT]

There will be a very thin wall at the root of the threads on a .30cal threaded 1/2 x 28, and it would be pretty "fragile".

ETA: Looks like a re-barrel is what it is going to take to suppress the M7.

[Deavis]

So..... Which is more important here a) sufficient shoulder. Vs. b)?barrel wall thickness at muzzle?

Think of the 300 : 1/2 x 28 would give more shoulder with weak walls. 9/16 gives more wall less shoulder.

[Deavis]

On the 300 with a 9/16 x 24 (.5625) on the .605 barrel gives me a shoulder ring of .0425... Or .02125 step between the thread and can.

Confirming that is sufficient?

[RJT]

Both are equally important.


Per the TB chart, for 9/16x24.

Major(thread diameter) .5605, Min barrel O.D .6620, .050 would be the minimum recommended shoulder.

Lose some length, thread it 9/16, and get an adapter to 5/8.

[Deavis]

Here is what the manufactuer replied with:



Thank you for contacting us. We recommend that the diameter of the barrel be .100" larger than the threads. For the barrels you mentioned the recommended thread length would be

Rem 700: 5/8x24

Rem 7: 7/16x28

Howa 1500: 1/2x28

Marlin 336: 1/2x28

You shouldn't have any problems using 1/2x28 threads on your 300 Win mag. The concern is the Rem 7 as the 7/16x28 is going to give you a very thin wall. If your barrel has any sort of taper to it your best option would be to cut back to where the barrel has .600" diameter an. Please let me know if there is anything else we can help you with.

Have a great day,