Threading and chopping a barrel?

[mtmuley]

Peer pressure? He asked for opinions....

Mellow out. Guess I should used a smiley face. mtmuley

 

[Fire_9]

Mellow out. Guess I should used a smiley face. mtmuley

Ok, mellowing out....

 

[Blue Steel]

Maybe everyone could be right:

Barrel Length vs. Velocity - Guns and Ammo

I'm destroying a perfectly good barrel in the name of science. And not just a perfectly good barrel — an expensive one."How much velocity do I lose if I shorten the barrel on my AR?"The answer ranges from

www.gunsandammo.com

>>>>So, how many fps do you lose shortening a barrel? It depends on where you started. Going from 26 inches down to 20 inches actually picked up speed, not lost it. In the regular zone, between 20 and 16, the velocity loss could be anything from 12 to 50 fps. When we started down into the SBR zone, we sometimes saw velocity losses of more than 100 fps just from a 1-inch change in length. The short answer to the question of how much velocity do you lose per inch? It depends.<<<<

Does Barrel Length Really Matter? Understanding Velocity, Accuracy, and Performance

Does barrel length really matter? Learn how it impacts velocity, accuracy, and handling—and how to choose the right setup for your shooting style and performance goals.

www.remington.com

>>>... traditional rifle cartridges like .30-06 Springfield or .270 Winchester were originally designed around longer barrel lengths, often 22 to 24 inches. Shortening those barrels can reduce velocity noticeably.

But modern cartridge development has changed the game. Many newer cartridges and loads are designed to perform efficiently in shorter barrels, using optimized powders that burn faster and more completely. This allows hunters and shooters to maintain impressive ballistic performance without carrying excessively long rifles.<<<

 

[Wind Gypsy]

How short do people think a barrel really needs to get to go from 3000 FPS to 2100 FPS (30% reduction)? It isn't anything that doesn't require an ATF tax stamp. Have to get to sub 10"?

Also, lot of people worried about velocity that shoot factory ammo that can easily vary over 100 FPS between lots and they'd never know.

 

[Dakotakid]

Gun is 300wsm r700 with sporter barrel. Took it to smith to thread barrel for a can. Will need a shoulder/collar according to the gun smith. Question is for those that have chopped a barrel what are pros and cons. Can length is 6”.

Can you mic your barrel at where you plan to chop? I can give you diameter of mine at the suppressor.

 

[golfer]

Can you mic your barrel at where you plan to chop? I can give you diameter of mine at the suppressor.

I don’t have those tools. I told the smith to chop it and thread it At 20”

 

[Ajax2744]

I’ve personally threaded hundreds of barrels, specifically for suppressor use. And while 1/2x28 threads can technically be used on a .30 cal, the minor diameter of the threads will cut to ~.450”. That leaves about .070” wall thickness between the bottom of the threads and the bore. When you throw a 6”+ can on the end there can be enough leverage to actually bend/snap the barrel at the threads if the can hits something or the gun is dropped/stepped on. I’ve also seen 1/2x28 threads swell from higher pressure of .30 mag cartridges. For .30 cal 9/16 threads or even better 5/8x24 threads are preferred if the barrel OD is big enough.

Your smith is correct and for suppressor use a shoulder for the suppressor or mounting attachment to seat against is highly recommended for a handful or reasons.

As for velocity drop it is not always so cut and dry. I just shot Sunday and my 6.5creed with a 20” barrel and a 5” suppressor was shooting ~75fps under factory rating. My .270win w/ a 20” barrel and 7” suppressor averaged 2fps faster than factory rating of the ammo out of a 24” barrel. And my 6.5prc with a 18.5” barrel and 5” suppressor lost ~about 100fps. So depending on the load, caliber, and firearms they lost anywhere from 0-18fps per inch of barrel lost. I have seen greater velocity lost just depending on specific loads but this was just my most recent testing.