touch hole liner threads ?

[skwerl-eater 1]

I am finishing up a 45 cal 13/16 green mountain barrel with a 1/4 - 28 touch hole liner. It appears that with the liner filed flush it is threaded about 3 1/2 threads in the barrel wall. Is this enough or did I do it wrong?
Thanks

 

[LRB]

I would think that you are fine with that. I could be wrong, but I was told years ago by a machinist, that three threads is enough for most all purposes. If that is all the barrel wall will allow, what else would you do? Just keep your loads within reason.

 

[Zonie]

With a 1/4-28 thread 3 1/2 threads equals .125, or 1/8 of an inch long.

A .45 caliber bore in a 13/16 inch barrel has a .181 thick wall so the length of your vent should be just slightly less than .181. .165-.180 would do.

A vent that is .165 long will have over 4 1/2 threads on it.

Either you cut the vent too short or you put a fairly large chamfer on it?

Anyway, if the vents length is 1/2 of the diameter or more (which it is) it should be safe to shoot.

 

[skwerl-eater 1]

Thank you both for your replies. The vent does have a large chamfer on it. And I plan on shooting a hunting charge of 65 or 70 grains of 3f.

 

[Birddog6]

Depends on the vent liner you use. I would not put a Ampco in it as you auto lose 1 full thread up need the bevel/seat. From what I just measured on one, if you use a Ampco you will only have 2 full threads & part of another one. The threads in the rifling don't count, you count the full threads & you need 3 min. (IMHO)
So I suggest you use a vent liner that is threaded all the way to the seat, since you have already cut the seat.
In my 13/16" .50 barrel I used a Chambers vent liner because I could get more threads & they go all the way to the seat, and I only used 1/2 of the seat as well.

 

[skwerl-eater 1]

thanks Birddog6, I think I will change it to a fully threaded liner just to be on the safe side.

 

[Onojutta]

Just don't stand on the lock side of the rifle when you shoot it. :hmm: