Gunsmithing #3B contour length and 5/8-24 threads

[BoilerUP]

I see on LRI's website that they recommend cutting a #3 contour barrel no shorter than 18" in order to have at least .725" for 5/8-24 muzzle threads and a .050" shoulder.

Can anybody with experience tell me if a #3B would have .725" @ 20 inches?

 

[Wyfox]

LRI built a 243 for me with a 20" Bartlein 3B and they put 5/8-24 threads on it with no issue.

 

[Supersubes]

Do you mean no longer than 18” for a #3? Go to the contour page and get the taper per inch for that portion the barrel(takes a bit of easy math) . Then subtract from the finish length that amount for every inch you shorten the barrel. 5/8-24 threads are .625 in major diameter.

 

[BoilerUP]

Yes, no longer than 18" is what I meant...that's what a lack of sleep gets you LOL

 

[Edds]

I see on LRI's website that they recommend cutting a #3 contour barrel no shorter than 18" in order to have at least .725" for 5/8-24 muzzle threads and a .050" shoulder.

Can anybody with experience tell me if a #3B would have .725" @ 20 inches?

A Bartlein 3B contour will have a muzzle diameter of .725" at a length of 23.5". The diameter at 20" will be .760".

They are .700" at 26 inches and get .010" bigger for each inch shorter.

 

[bohem]

3B is appx 0.0125" per inch of length.

Measuring the one I just cut yesterday:

26" 0.701
24" 0.725
22" 0.749
20" 0.777

 

[xdeano]

i've got a 3B at 24" no problems with the 5/8x24. works well.
Deano

 

[Sonic Crack]

X diameter at X” inchs also depends on blank length. You could always order a barrel and have them bell out the OD at the finish length you want to run