Rolling Block Project

[chriskat]

Thought I'd start a new thread. See the thread below started by JCHannum.

So I bought this Swedish rolling block shotgun and after much consideration, discussion here and opinions from another board I've decided I'm going to rebarrel it 50/90 Sharpes. Problem is I'm having difficulty finding a barrel that I'm willing to spring for (I'm cheap).

Last night I realized that I have a Ma Deuce barrel in the shed for a .50 BMG single shot project. It's been there for at least two years maybe three. I think I found my barrel, and I like the price (already paid for).

Hopefully this will progress fast enough to be a little bit interesting to the board members. I'll try to update as I go.

Jeff

[Maine 04655]

I used m2 barrel for my Bill Holmes 50 project rifle years ago. They are HEAVY. I would be dubious about turning one down enough to be used on a old rb frame. Also the block and frame are not made for the pressures generated by the 50bmg round. If the frame and block are able to handle the pressure the only thing left to worry about is making the barrel to thin to work with it. Be Safe...

[chriskat]

It certainly won't be left .50 BMG, and you're right there will be a lot of swarf generated. Assuming, of course I can even turn that much off. I value my time at $0.00 though since it's recreation.

Assuming all goes as planned once it's a 1.25" x 35" x .50 caliber barrel blank it should be considerably lighter than it's current 24 pounds.

We'll see.

[JCHannum]

Jeff;

You might consider shopping the 50 cal barrel around on some of the sites that cater to those. You might be able to work a swap or generate enough to purchase a barrel.

Unfortunately, the cost of barrel blanks took off a couple of years ago and anything longer than 24" is pricey.

[DonT]

Not to rain on anyones parade but:
I believe the twist on 50BMG is 1X15
I beleive teh twist on a 50/90 is 1x24 to 1x30

I am really afraid if you stick the BMG barrel on the Roller you are not going to be happy with the Patterns (note patterns no groups).

Also one other thought is that the 50 BMG barrel may have, likely has for corrosion resistance and barrel life under harsh conditions, a chrome lined barrel. If so you might be in for a bit of surprise if you have not worked with a chrome lined barrel before. To say they are difficult is an understatement.

Like I said I don't mean to be a killjoy but it sucks to go to all that work only to find you the rifle works better as a club than rifle..

Also one final thought. I am not sure the Swedish RB was a nitro powder rated gun. This is not to say it cannot be used for lighter loads or blackpowder loads with cast bullets (you didn't mention what you planned on shooting in it) but I would be hesitant using jacketed with moderate to heavy loads...

DonT

[chriskat]

Jim,

I thought about selling it and using the funds for a barrel but I don't think it'll get me very close. I think I paid in the neighborhood of $150 for it as it was advertised as a "blaster barrel". The throat is eroded to the point that the rifling is nearly gone out to probably 8" past the chamber. I'll consider that some more.

Don, will be used for BP loads only no smokeless at all. It is stellite lined which appears to extend the 8" past the chamber that is terribly shot out. The remainder of the bore looks to be in good condition and is not obviously chrome lined. The barrels that Green Mountain lists on their web site:

Green Mountan 1.125" Blanks

are 1-16". I understand from the ASSRA forum that these are discontinued, although when I called Green Mountain they didn't tell me that.

You really think the twist will be a problem?

[chriskat]

I offered it for sale on 1919A4.com; I think that's where I got it. We'll see what happens.

If it doesn't work out I can always start cutting.

[DonT]

doing a quick search in google it appears shiloh is using from 1x26 to 1x36 for the 50/90. I just typed in rate of twist for a 50/90.

I know my muzzleloading barrels were also extremely slow twist as well. If it will stablize what you want to shoot thats great but you are talking about a fair amount of work with rebarreling and rechambering to end up with something that will not stablize a cast bullet.

The rifling in the 50bmg is designed to be be fast enought to stabilize a jacketed bullet, typically the rifling is not broached and not as deep. In my humble opinion if I were going to all this work I would get a barrel with cut rifling which is deeper and better suited for cast bullets or maybe even a round bottom rifling.

I know some time ago there was a fella at our range trying to stabilize a 50bmg shooting subsonic (about 1,000 feet per second) out a bolt gun he hung a 50 bmg barrel on. At 50 yards he was getting wonderful bottle shaped holes as the bullet went thru sideways. He finaly gave up the project as the twist would not stablize the jacketed bmg bullet as that slow a speed.

I would think the issue would be the same with a 50/90 and holy black but maybe not...

Just one old guys opinion...
DonT

[Bob Ford]

Using a ballistics calculator I find you will need a bullet slightly over 2 inches in length Weighing about 1100 grs and traveling at about 1500 fpm. It really calls for 1 in 18, but I think it would work. Do not think it would be fun to shoot.
Suggest leaving barrel full diameter and turning shank for threads if you try this 50 BMG barrel.

Bob

[JCHannum]

I can't offer any thoughts on twist rate, but here is a twist rate calculator to try the various combinations with;

http://webcache.googleusercontent.co....us/twist.html

Generally, the faster twist rates favor the heavier bullets. And, no, a 1100 grain bullet will not be fun to shoot.