Author Topic: How much up is too much up? (Read 911 times)

trotterlg · « **on:** May 31, 2013, 02:47:49 PM »

I have been considering a new project. I am thinking a RF WSM (this a newly announced high velocity .17 RF) To do a stub I am thinking of putting a GM blank muzze first in a dead center in the head stock and then offsetting the breach by an amount about half the diameter of the rim of the new round. I would then contour the barrel and make the stub portion and thread it with the breach offset so the fireing pin on a CF frame would strike the rim. This would result in a bore that is angled up (about 1/8 inch in 20 inches or so) when stubbed into a shotgun barrel. I would make up a tool to hold the bore centered when chambering it. I know that this would end up with a few thousants more head space at the bottom of the cartridge than at the top, but it is a RF so the brass will never be re-used. Result would be like a scope base set up for long range shooting with a couple of MOA of elevation built into the barrel. What do you guys thing? Have I had too much to drink tonight? Larry

wolverine_1 · « **Reply #1 on:** May 31, 2013, 03:08:42 PM »

Would seem getting a Versa Pack barrel would be more efficient.

YRUpunting? · « **Reply #2 on:** May 31, 2013, 03:10:08 PM »

Go for it Larry! I bet a .17 caliber version of the Versa Pack would sell for at least what they're asking for a Colt Carbine in the classifieds these days.

petemi · « **Reply #3 on:** May 31, 2013, 03:16:06 PM »

Ya lost me somewhere Larry, but I'll take a sip. Seriously, given the little I know, I don't see why it wouldn't work. I'm not much given to rim fires or 17s. You obviously won't reload them, and in my experience, I can reload some center fires cheaper than buying RF ammo. I'd rather shoot our .32-20 than Patty's .22 mag. Thanks again, I love that little rifle. I had it out this evening looking for chucks.

Pete

jeepmann1948 · « **Reply #4 on:** May 31, 2013, 03:20:02 PM »

Would using the shotgun stub chucked with the proper amount of offset in a 4 jaw chuck and then bored provide the necessary offset for the rim fire and still keep the headspace true?Just conjecture here. A 410 barrel should have enough material in it I would think.
Again thinking can be a dangerous thing on my part
George

Ranger99 · « **Reply #5 on:** May 31, 2013, 03:26:22 PM »

well. . . there's really only
one way to find out

wtroger · « **Reply #6 on:** May 31, 2013, 03:46:19 PM »

Yep that will work. Have you though about offsetting the entire barrel the needed. .165 thousands

Dinny · « **Reply #7 on:** May 31, 2013, 03:50:44 PM »

What about rechambering a 17 HMR barrel with the hopes it will fire afterwards? I have a barrel and rf receiver waiting for the pressure data, reamer, ammo, and hope that it works. If it doesn't work, can my barrel be rechambered again to a CF 17 that would work on one of my other SB2 receivers?

Thanks, Dinny

trotterlg · « **Reply #8 on:** May 31, 2013, 04:41:05 PM »

I have done an offset barrel before in the 5mm Winchester Mag, it was a very big problem to machine the way I did it, used two offset bushings as I recall. Boring a hole 4 inches deep (the length of the stub) offset would be quite a task on my machine, I did do a Versapak barrel once and made up collar that was turned round to hold it with the bore centered and the muzzel offset in a 4 jaw chuck. I am trying to find something with a few less parts and steps that will still work out. And, Yes, the 17 HMR barrels work fine rechambered to CF, I have a 17 FB reamer that has done a few and I made up a Hornady 17 Hornet reamer and done some. Larry

Tractorsaw1 · « **Reply #9 on:** June 01, 2013, 02:33:02 AM »

I'll take it!... o wrong forum. So you are talking about shifting it up or down instead of boring the stub on a slight angle? I kinda gave up on this one, but maybe theres hope yet.

trotterlg · « **Reply #10 on:** June 01, 2013, 07:28:01 AM »

I am talking about only offsetting the breach end in the lathe and then coutouring the barrel, the breach end would end up with an offset bore and the muzzel would have the bore in the center. Larry

bikerbeans · « **Reply #11 on:** June 01, 2013, 02:54:00 PM »

I like your idea Larry. Are you going to have to cant your scope base to keep it from shooting too high?

BB

trotterlg · « **Reply #12 on:** June 01, 2013, 03:19:44 PM »

I was thinking it would end up being like the scope bases that have a little down built into them so that your scope adjustments are more centered at logner ranges. When I get some time and there is ammo for the new 17RF I may just make one up and see the errors of my thoughts. Larry

nanuk-O-dah-Nort · « **Reply #13 on:** June 01, 2013, 07:04:20 PM »

Larry, bear with me here, I'm thinking out loud.

When you contour the barrel, the barrel will look normal, and the bore will be offset by 0.xxx degrees.

now, as I'm not a machinist, and I don't play one on TV, this may not make any sense.....

When you contour the barrel, leave it as fat as you can on the breech.

now, when you set up to thread, can you offset it the same degree, so your threaded stub is on the same angle, so the bore is straight, but the barrel points down that 1/8 over 20?

you can thread it a thread long, and face the breech off with files.

I'm thinking that because the barrel is tapered, you'd not even notice the drop.

you'd have to time it pretty well spot on, but because you won't chamber it until you have the stubbing completed, you can have a couple cracks at it.

then there is no issue on Headspace, OR sighting requirements.

trotterlg · « **Reply #14 on:** June 01, 2013, 07:10:31 PM »

You have it right except I would have the bore pointing high to make up for bullet drop, that would put the bore low at the breach. The barrel and the stub would look normal, not lkie a versa pack. Larry

bikerbeans · « **Reply #15 on:** June 02, 2013, 01:23:51 AM »

If I did the math right in my head, the .165" offset works out to about a 25 moa increase in POI on a 24" barrel.
BB

jedman · « **Reply #16 on:** June 02, 2013, 02:06:46 AM »

Larry, I have been thinking of making a RF stubbed barrel for a older M 48 .410 shotgun I have. These don't have a transfer bar, My idea was to just remove the firing pin and drill out the bore that the pin sits in straight thru to the breechface at the same angle and tap it 5/16 24 thread.
Then thread a piece of 5/16 drillrod screw it into the frame and redrill it at the angle needed to strike the rim , this would be the pin setting closer to square to the breechface then angling downwards the way it is currently.
Then just stub the barrel on center , modify the ejector, then ream the chamber .
It may never happen as I have way to many other projects to finish but seems possible it could work.
jedman

blind ear · « **Reply #17 on:** June 02, 2013, 04:26:20 AM »

If the muzzle crown is square with the bore will the crown be out of square enough with the outside barrel surface to be noticed? ear

redleg11b · « **Reply #18 on:** June 02, 2013, 12:56:26 PM »

Dinny, 17AH / 17H should be able to work.

I think the best bet for the project would be to offset the entire stub, but i have no practical experience in this matter.

gcrank1 · « **Reply #19 on:** June 02, 2013, 04:01:46 PM »

I agree, turning the proper f-pin offset on the breech end of the stub, fitting to the stub and then contouring/blending the lines should be more satisfactory. A good friend has done a number of vintage 32RF and 25RF rifles to 22LR this way so he doesnt have to rework the f-pin.
FWIW, imparting an 'out of square breech' in a build is iffy to me; variations in breachface squareness via caseheads has been shown to affect accuracy. You can check your cases for this with a simple fixture and dial indicator, use 'perfect ones' or at least mark the cases and index them when chambering. Group size differences can be significant (oh no......another secret out....

).
YMMV