Gunsmithing 1/2x24 Barrel Threading Ruin Accuracy?

[clyancey]

Hi all, need some assistance deciding what to do about threading for a suppressor:

A reputable gunsmith told me he is leery of 1/2x28 threading when it comes to accuracy because: 1) common sense says that having 0.138” (.5-.224)/2 =.138) of metal at the muzzle to hold/direct/stabilize the bullet isn’t much 2) he has personally seen how threading a barrel to 1/2x28 and simply adjusting how hard a thread protector was torque on (by hand) varied groups from over 2” to around 1” and 3) several customers have bought his uppers after growing accustomed to their accuracy (.5 moa or even better) being disappointed when they threaded the barrels for suppressors and lost accuracy.
The gunsmith said he will not do 1/2x28, would do 5/8x24 but wouldn’t guarantee accuracy and preferred/recommends/uses ¾ threads for his guns. But, as far as I know, there is only one suppressor on the market that is offered at 3/4x20 or 3/4x24 (Thunderbeast Arms) and it’s for 30 cal and I’m looking for a 22 cal.

Questions:

1) Do you think 5/8x24 will work (tons of other folks have used this….but then again tons of other folks are excited with 1 moa accuracy, so what do they know)?

2) Do you know of any other 3/4x24 threading suppressors? Or do you know of a Thread Over the Muzzle Break (TOMB) or Quick Detach system where the break/flash hider threads to 3/4x24?

3) A bit of a tangent but still a parallel thought: if the muzzle is so critical to accuracy, and is machined so thin while under pressure, and is so susceptible to how a can is torque on, wouldn’t a TOMB or quick attach system be the best for consistency (because the flash hider/break is permanent)? I know this goes against the current group think of threaded suppressors for accuracy rigs; but I don’t care about group think, I care about facts….so help me sort it out!

Thanks guys

 

[2156SMK]

Re: 1/2x24 Barrel Threading Ruin Accuracy?

Are you looking at this on a centerfire 22 or a rimfire 22?

Rimfire barrels are softer than barrels for centerfire.
I have not seen accuracy problems due to muzzle device torque (assuming they are not over-torqued!) on 22 centerfire barrels.
However, 22 rimfire barrels are sometimes much softer.
For example, I won't use a crush washer to index a muzzle device on a 22 rimfire barrel with 1/2-28 threads.
I will index either with a peel washer or via machining the shoulder on the barrel.
Both of these methods will allow me to keep to a lower torque requirement.

The worst offender in these regards is the 1/2-36 threads on 9mm barrels.
You are talking about barrel wall thickness down around 0.05"!
I prefer 9/16-24 threads on 9mm barrels.
Any 1/2-36 muzzle device can be opened up to 9/16-24 without much issue.

 

[jasonixo]

Re: 1/2x24 Barrel Threading Ruin Accuracy?

I've never had a barrel lose accuracy after I've threaded it. Personally, I'm not a fan of how small barrel tenons are for a given caliber, but the dimensions are proven and do work fine. There are a lot of things that can be accidentally done to a barrel to cause problems. Typically, these problems are caused by cutting the threads, not the mere presence of the threads themselves. If machine work is taking place around the bore, it should be done in a specific manner to avoid distortion.

My shop has built many rifles and they all perform well-under our accuracy guarantee. A vast majority of them are threaded at the muzzle. I'd recommend sticking with the industry-standard thread dimensions. You're more like to see poor accuracy with an off-brand non-standard threaded muzzle accessory than you are with the mainstream equipment.

 

[ddavis]

Re: 1/2x24 Barrel Threading Ruin Accuracy?

I have a 30 caliber barrel that is threaded 1/2x28. It is pretty thin at the muzzle, but still manages to shoot 1.25" groups. That is pretty good considering it is a 10" AR barrel. If I had a choice I'd go 5/8x24, which is thick enough. I think 1/2x28 is more than adequate for .22 caliber. There are lots of AR's out there that shoot great with the industry standard 1/2x28.

 

[LRI]

Re: 1/2x24 Barrel Threading Ruin Accuracy?

I started in this trade building smallbore guns used in international 3P.

Olympic stuff.

I've put every marquee barrel there is on an anschutz receiver.

The steel has the same heat treatment as any other barrel.
28-32 rockwell. Cut barrels are usually a pinch harder than buttoned bores.

Think of steel as a ball of rubber bands stretched tight over one another. If I get a pair of clippers and snip away at the bands do I create stress or do I relieve it?

You relieve it.

If I run that ball of rubber bands through a heat process and take out the majority of the tension do I create stress by doing so or do I make some of it go away?

I make it go away.

Steel is no different.

The point of this is that a guy should have reasonable confidence when machining on a blank that he's not screwing it up by putting a tool to it.

Orders of operations comes into play. Its far more practical to thread then chamber. If the bore did get goofy, who cares? You ream it out anyway.

I used to stress over this stuff. To the point of simulating the tensile load of the tennon once assembled.

"Torque ring chambering" is what I called it. Just like torque plate honing a cylinder in an engine. Distort/load the part before you chamber. The idea being it'll be "perfect" in the assembled state when it really matters.

Sounds cool right? Its a pain in the ass and doesn't accomplish a thing besides burning up the minute hand on the clock.





A good rule of thumb I use is to put as much distance between the root of a thread and the land on a barrel. You can never have too much. What I'm saying is use the largest thread that will still get the job done.

I modify almost every muzzle brake that comes into our shop for this reason.

 

[furburner]

Re: 1/2x24 Barrel Threading Ruin Accuracy?

I have a threaded remy 700 with YHM phantom flash hider and I shoot 1/2" consistent. I was worried, but shoots same before and after.

 

[LRI]

Re: 1/2x24 Barrel Threading Ruin Accuracy?

What caliber is it in?

 

[furburner]

Re: 1/2x24 Barrel Threading Ruin Accuracy?

I have it on a couple a 223 and 308

 

[furburner]

Re: 1/2x24 Barrel Threading Ruin Accuracy?

I have it on a couple a 223 and 308

 

[furburner]

Re: 1/2x24 Barrel Threading Ruin Accuracy?

Sorry for double tap guys, also mine are varmint barrels don't know if this helps u out.

 

[Goin'Hot]

Re: 1/2x24 Barrel Threading Ruin Accuracy?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: furburner</div><div class="ubbcode-body">Sorry for double tap guys </div></div>

If nobody quotes your post, you can hit edit and then delete the post.