I have a Stevens 44-1/2 that I’m converting from .32 Rimfire to center fire.  The firing pin channel is drilled straight, with a concentric firing pin tip impacting the rim area, so any conversion of the pin would require some kind of offset tip or even an offset firing pin channel redrilled.

Would it be possible instead to make a link with longer spacing to raise the block and thus the firing pin up closer to the center of the bore?  It looks like there is only a 25-30 thousandths’ difference.  This isn’t a rebarreling, just a liner in the original barrel.  I could dress the breech face slightly if the block goes too far forward as it rises, but of course I couldn’t go too far.

I tried to search the Forum, but the Search device doesn’t accept / or\.  Kind of tough to find fractional model numbers with that restriction..

This is my first R to C conversion on a 44-1/2, and would appreciate anyone’s experience in the matter.  Thanks in advance.

Bent_Ramrod wrote on Feb 19^th, 2018 at 9:45pm:


No experience, but I'd assign first priority to retaining & modifying the original block if at all possible; once the gun is put together with a modern replacement block, to me it ain't the same.   

BR
I have a similar rifle and decided to move the firing pin because I couldn't think of any use for a 32 RF breech block. This also saves the work of fitting a new breech block.
My barrel is in reasonably good condition, so before lining it, I decided to see how it would shoot. I chambered it for the 32 H&R Mag as a test but haven't shot it yet.
After the firing pin is moved, I had to plug and move the firing pin retaining screw as well. 
Some of the breech blocks are apparently hard enough to require carbide tooling but the two that I've done (32 RF & 25 RF) were successfully machined with cobalt tooling.
Otto

I actually measured this time and indeed it looks like the center of the RF hole to the mark which would be the center of the CF hole is more like 0.170”.  If the barrel is loosened slightly so the breech block can be pushed up flush with the bottom of the receiver, the c-to-c distance is more like 0.115”.

So maybe I’ll drill the firing pin channel out to 0.228” and make a new link that raises the breechblock all the way.  Then I’ll have to dress a few thou off the breech end of the barrel to allow the block to go all the way up.  An offset firing pin tip will be necessary , but it runs at an upward angle with a kind of “whale snout” profile, so it should hit close to center.

Much less straightforward than Winchester conversions for sure.  Thanks for the experiences.

You're right - nominal displacement of the pin hole is .173" give or take.  My .140" is the CL of the pin body, the rest coming from an offset tip.

I've been boring the pin channel out to .250, using a carbide end mill, and angling the new bore to gain additional offset.  This keeps the back end in line with the hammer.   

New firing pin is then made from 1/4" 41L40 round so that I can heat treat it.  I have a trick for setting the new angle using a stepped pin held in the 1/4" collet that will then hold the mill. Can't state dimensions until I know the exact diameter of the existing pin channel.   

This is for 44s and Favorites, where raising the breechblock is not an option.

Modifying the original breech block avoids the problems of offset firing pins and functional changes caused by different link lengths. Having CPA install and fit a new CF breech block would be the easiest but I'm not sure if a CPA breechblock will always slip into place and function without some fitting. Modifying the original fitted breechblock should be less expensive, especially if you do the work yourself and is a satisfying DIY project.
After the original 32 RF firing pin hole and body are plugged and the new CF tip location is marked, I've found that the new firing pin body angle is easily located using a drill in the lathe headstock and a live center in a .062" temporary firing pin tip hole. It helps to have a shallow center hole in the proximal end of the original firing pin body plug and to have the plug start just below the original location, so that the hammer strike is unchanged.
In making the new firing pin, you might also consider adding a small FP retracting spring, although it may not be needed in the 44 1/2 action.
Otto

It all remains to be seen, I guess.  I'll make some dummy links with variations in hole spacing and see what happens.

Of the three real links I have (including the stock one on this rifle) the spacings are 0.511", 0.512" and 0.502".  Not enough difference to really get an idea of how far the block will rise.  I suppose some area of Shop Math would cover this, but I was math challenged even in the regular areas.  I'll just have to go out and try it.

Unlike the 44s and Favorites, the link on the 44-1/2 doesn't bear much, if any, load on firing, so a minor change in web thickness shouldn't matter.  But there should be some room under the block.  Even the Favorites I've reworked had enough room under the block to make a thicker web in the link, if necessary.  The main interference with the 44-1/2, I think, would be the plunger in the center of the lever.

I used oneatatime's tip and looked up the ASSRA 44-1/2 on Google.  I'd participated in a discussion with someone in Tasmania (?) who had a 44-1/2 with the block sagged down almost 1/8" lower than the frame.  Didn't remember any of it till I saw it again.