In the Single Shot Rifles sub-forum I posted about my early #2 RRB in .44 rimfire. I've put a centerfire block in it and am now in the reloading phase, so I thought it best to start a thread over here.  The original discussion can be found here:

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The centerfire version of this cartridge is very similar to the .44 S&W American, but a little longer.  I determine the case length by seating a bullet in the breech. Then backing off .015".  I ended up with a case length of .965".  All other case dimensions are equivalent to .44 S&WA.  To start out I purchased .44 S&WA heel bullets from BACO. I made cases from both 303 Savage and .41 Magnum. Both worked fine, but the .41 Mag rim is a bit small and will occasionally slip past the extractor.

This was my first time out with the 140+ year old rifle. My goal was to verify proper functionality, collect chronograph data and see if the bullets flew straight.  I was successful on all accounts.

After a lot of research, I made up four loads to start, 10 rounds each.

Load #1 was 22.0gr of Swiss 1.5, lightly compressed, my home made black powder lube in the exposed lube groove. 303 Savage brass, WLR primer.  This gave an average velocity of 1023fps.

Observations:  This shot well, but I had one light hammer strike. Cases extracted easily.
 
Load #2 was 13.0 gr of Blackhorn 209, lightly compressed, my home made smokeless lube. 303 Savage brass, Fed 215 LR magnum primer.  This gave an average velocity of 931fps.

Observations:  This shot well, but I had one light hammer strike. I think the LR primers may be a little too hard for this rifle. Cases extracted a little harder.
 
Load #3 was 16.8gr of Reloader 7, filled to base of the bullet, my home made smokeless lube, .41 Magnum brass, CCI LP primers.  This gave an average velocity of 1023fps.

Observations:  This shot well, no misfires. Cases extracted easily. The avg. velocity was exactly the same as load #1 with Swiss 1.5. The agrees with what the late John Kort said.  That a case full of RL-7 closely duplicates the original black powder loading velocity and pressures in pistol size case.  I've had the same experience with .32-20 and .32-Ballard XL.  

Load #4 was 5.0gr of Unique, my home made smokeless lube, .41 Magnum brass, CCI LP primers.  This gave an average velocity of 807fps.

Observations:  This shot very well, but case mouths were not sealing. Potentially the most accurate load.

Continued...

surely better than a pocket knife!  nice work on your part  best  art

Last night I went to prep the fired cases and found they are a bit out of round    It seems this rifle had a rather sloppy chambering job. Fired case on the left, neck sized on the right. Visually, the chamber looks fine. But this can't be good for accuracy.... 

I got looking at a pile of Lyman/Ideal 427098 bullets I cast a while back for a 44-40. Noticing the similarity to the BACO heel bullets I bought, I thought hmmm, maybe I can make them into suitable heel bullets. I put one in the lathe and turned the base band down to .412". That left .150" long heel - the same length as the BACO bullet heel. So I made up a dummy round and it chambered fine. So I turned 39 more 

It looks like you're on a roll. I'm very much enjoying your posts and progress. 
Lee Gibbs Pres.ASSRA 

P.s. when you're done you should write it up for a journal article.   Please!

Second trip to the range today with this rifle. My goal was to see if the Ideal 427098 bullets that I lathe cut heels on would work. I'm pleased to say they did.

The rifle's groove diameter is .430", the bullets were the same size. Usually I prefer bullets .001- .0015" over groove size. But this is what I had on hand. They were cast of 40-1 alloy, which helps. 

They drilled nice straight holes at 50 yds, so I'm very happy with that. The biggest problem is my aging eyes and the original barrel sights.  It really seemed to like the Old Eynsford 3F and Unique loads. It grouped well despite the errant shots that are my fault. It does show good potential. I'll make more 427098 here bullets 

What would be the point of Remington deliberately reducing the groove diameter to .430?  A proprietary cartridge?  Or is this simply reflective of a time when tolerances held to 1/100th of an inch were still considered "good"?

Bill Lawrence

ndnchf wrote on Apr 27^th, 2020 at 11:10am:



I need to make a slight correction.  The "B - .440" above means bullet diameter, not bore diameter. I missed the abbreviation legend on my first read.  But along the same train of thought, I've seen the .44 S&W American bullet diameter listed as both .440" and .434".  So was there a change in bore size, or was the .440" bullet just made overly large to account for a variety of bore sizes from different makers?