.45-70 barrel length

[Andrew Wyatt]

I'm rebarrelling a remington rolling block saddle ring carbine in .50-70 to .45-70, and I'm vacilating on the barrel length to use.

The current barrel length is 22 inches, and the whole package is about as long as a 16 inch barrelled AR with an A2 stock.

I do not want to go longer than the current barrel length.

I'm seriously considering lopping the new barrel off at 16-18 inches, but i'm not sure how much velocity i'll lose.

any thoughts?

 

[dick w. holliday]

i used to have the gun you have....mine was a 45-70 and i guess because the action was so short the gun always looked too short to me......i definitely wouldn't go any shorter but i personally would go longer.....i'm sure somone will comment on powder burning rates and all that but for me i want all the barrel i can get....i currently have a Browning BPCR with a 30" tube and i wish it were longer.....that long sighting radius really gives you an advantage with iron or tang sights.....just my two cents worth......Dick

 

[JohnKSa]

Sight radius is certainly an issue, but velocity loss is not.

The 45-70 doesn't lose very much velocity when barrel length is reduced.

I saw one test where the barrel length of a 45-70 was reduced from 28 to 18 inches. Velocity difference was 120 fps.

The way it makes sense to me is that once that big bullet starts moving, it leaves a lot of empty bore volume behind it due to the large bore diameter. The expanding gases from the powder combustion can't fill that huge empty space fast enough to keep accelerating the bullet significantly.

The smaller the bore, the bigger the velocity loss with barrel length loss. The bigger the bore, the less length matters to velocity.

 

[Tom Matiska]

Are we talking about a vintage action that is limited to the original black powder pressures? John, was that test with smokeless powder?

Tom

 

[Andrew Wyatt]

The barrel is new manufacture, but the rest of the action is not.

I pretty much plan on shooting smokeless only in it, since I don't really want to have to clean all that crap out of the barrel.

This carbine will be rather neat when i'm done with it.

 

[JohnKSa]

Tom,

Excellent point.

The test was using smokeless powder and fairly hot loads. If I recall correctly, this was a 350 grain bullet pushing 2000fps in a modern lever gun.

I don't know enough about black powder to make any comment on how it might change things.

Good shooting,

John

 

[AC]

I sure wouldn't go shorter than the original length or you'll lose too much sight radius.

Is the .50-70 barrel in shootable condition? Have you purchased the .45-70 barrel yet?

The .50-70 has always struck me as an interesting round to have. A fellow I know has an original Sharps carbine .50-70 that someone at some point in time relined to .45-70 so a reline job is a possiblility if the barrel is bad.

 

[Art Eatman]

In my ignorance I ask: Can the rifling of the .50-70 barrel be recut, and then use slightly oversized bullets?

Art

 

[Andrew Wyatt]

the original barrel is unrecognizeable as a rifled barrel.

There are major pits and "frosting" over 100 percent of it's surface.

when we shot it with handloads consisting of .510 diameter lead projectiles (500 grains, i believe) from a rest, it would not keep minute of IDPA sihlouette at 50 yards.

I'll not be losing much sight radius, because i'm mounting the rear sight 3 inches farther back on the barrel than it's current position.


I'm honestly not sure the sight radius on something like this is much to worry about, since it's primarily a short range gun.

 

[Art Eatman]

If the current barrel seems too long, why not start with a 20" and then maybe cut it back, later?

If it's primarily to be used as a "fun-gun" for inside of 100 yards, I doubt any velocity loss will matter...

, Art