True barrel length question for those in “the know”!!!

[albritt]

Well sorta, I recently ordered a Criterion match .308 barrel for a compact Remage build that I wanted 18" + of lands and grooves so I ordered a 20" barrel. But yes I understand where your coming from, just originally wondered if that was the norm of thinking.

20" AOL ATF measure standard

 

[albritt]

Might not be a real "technical" way to order but I just wanted 18"s of twist LOL

 

[albritt]

The 5 shot 100yd groups were respectable.

 

[Tony243]

What about revolver vs pistol? Chamber not included in revolver measurement, but is in pistol measurement, correct?

 

[BHP9]

AFAIK pistols are measured slide forward, dowel in barrel touching the breechface, mark the end of the barrel and measure dowel mark to the end where the breechface was.

Revolvers - open cylinder and use calipers and measure the barrel.

 

[jpndave]

What about revolver vs pistol? Chamber not included in revolver measurement, but is in pistol measurement, correct?

Correct, the chamber of a revolver isn't a permanent part of the barrel.

 

[jpndave]

The ATF measurement doesn't care how much is really rifled barrel. It is the combined overall length of anything permanently attached and would include flash hinders or brakes if "permanent" ie pinned and welded, etc.

 

[albritt]

AFAIK pistols are measured slide forward, dowel in barrel touching the breechface, mark the end of the barrel and measure dowel mark to the end where the breechface was.

Revolvers - open cylinder and use calipers and measure the barrel.

ATF standard

 

[yorke-1]

It seems like you're over thinking this. Just pick the barrel length that feels/looks good to you and go with it.

As far as the idea of getting the optimal powder burn, don't get too hung up on that. Here are the predicted differences in the percentage of powder burned and burn efficiency of a 308 Win using the pretty standard load of 45.5gr of Varget and a 168 SMK in 18", 20", and 45.4" barrels. The images also show the actual bullet travel (based on a SAAMI spec chamber).

You need a 45.4" barrel to get a 100% powder burn. You give up very little, even with an 18" barrel.

 

[albritt]

Kinda like taking calculus in school, useless for 99% of the population overthinking overkill.