1867 Navy Rolling Block .50 Pistol Chamber

[Central Georgia]

I have recently acquired an 1867 rolling block pistol. The chamber is actually the full length for the 50-70 case instead of the pistol 50-20 or 50-25. The chamber does not look like it was bored out at a later date but appears as it is original to the gun. The serial number on the barrel and the wood grip is actually #25. I think since it was such an early one, that they may have reused a rifle barrel? The pistol appears to be unmolested with the proper inspector and proof makes and the correct patina and wear. I have shot it using a 300 grain projectile 25g 3f BP and cases shortened to the pistol length. It shoots fairly accurately but it will throw a flyer every 5 or six shots. Would there be any drawback to using the full length 50-70 cases and just seat the projectile deep down in the case against the powder? This would keep the projectile in the case until it engages the rifling.

[vagrantviking]

That should work fine as long as the case walls don't get thicker and prevent the bullet from seating as far down as you want. Similar to a wadcutter load.
Another option is to use a little filler between the powder and bullet. I've tried things like multiple cork wads, cream if wheat and corn meal. This works if the case walls are too thick or if you want to keep the bullet up near the lands of the rifling.

[Central Georgia]

Thanks, Yes I have used fillers before but since it would be 2/3 filler and 1/3 powder, I figured doing that might present problems of it own. I've loaded seating deep in a case before just never so deep where you are only using half of the case.

[lar45]

That's exactly what I've been looking for. Except I'd rather have the Army version

[M1871]

I have an Army 1871 and it has the correct chamber. I can not insert an empty 50-70 case in the chamber so even more impossible to load a round with a bullet. The case alone is just too long and it hits on top of the open breech block. So I'd suspect that what you have has had other changes to the action. Would be interesting to compare photos of your pistol to the one I have. What was the diameter of the bullet you fired?

I have the 1871 Army pistol and I'm interested in doing some reloading for it.
But..... I am having a very hard time finding much usable info for this cartridge.

I see conflicting info about the differences between the Army and the Navy chambers. The Army cartridges apppear to be somewhat bottle necked, while the Navy case are straight walled. I slugged the barrel of the pistol I have it it looks like a correct bullet dia would be clost to .510. Some info I have come across talks about using a bullet with a dia meter of .514 for the Navy model. But since the Army cartridge looks to be necked down I think that perhaps the bullet dia is smaller for the Army pistol that it is for the Navy model.

I'm waiting on some Cerrosafe to arrive so that I can do a chamber casting. I have the Lee 90255 50-70 450gr. .514 mold and plan on running it through the mill to shorten the bullet cavity and end up with aprox. a 300 gr boolit.

Any and all information regarding these rolling block pistols would be interesting.

[ndnchf]

I would advise against seating the bullet deep inside the case. Black powder tends to expand the bullet. Upon firing that expanding bullet diameter could be constricted as it tries to exit the case mouth which could raise pressures to dangerous levels. I think it would be safer to fill the excess capacity with CoW or some other, non compressing inert substance.

M1871 - I have done the same thing with a Lee mold. I cut it down from 450 to 350 gr. It works great in all my 50 cal guns.

[BrassMagnet]

I would strongly advise against multiple cork wads.
Using multiple cork wads in a 9.3x74R case reformed to .410 3” all brass shot shell didn’t work well. Shot shells are very low pressure and rifle brass used as all brass hulls should last nearly forever. With extra cork wads to make the load long enough to roll crimp the overshot card in place caused case head separations in only three loads. Thankfully the shotgun wasn’t damaged. Note: I witnessed this, I didn’t do it!

[mazo kid]

I also have the Army RB pistol with the long chamber. I just trimmed a couple of 50-70 brass cases to pistol specs, mostly for display.

[M1871]

Confusion Abounds

Chamber casting length * original cartridge COL size * Bullet diameter * New custom configured case

Since I started this project of reloading some rounds for the M1871 Army Rolling block pistol I have found most all information to be not only confusing and convoluted, but in some case contradictory.

The start of this thread the OP states that he can chamber a 50-70 round or perhaps just a case in his pistol. In my pistol this is not the situation. As seen in my photos I can not chamber a full size 50-70 case and the same is true for a carbine length (1.35") case. Comparing a full size 50-70 case to the chamber casting it is apparent that the full size case is too long for the chamber. So, I am not sure what is going on with the Op's pistol chamber.

I made a chamber casting of the M1897 I have and compared the results to an original .50 Rem cartridge.
original factory round. I cut down 50-70 brass to more correct length where the bullet would be much closer to engaging the rifling.

Conflicting information regarding the correct bullet diameter. Some information I have come across states the correct size should be anywhere between .502 to .514 Depending on which article you read.
I slugged my bbl and took some measurements also measured the casting I made. Difficult to do because of the 3 groove rifling. The best "guesstimate" for my pistol comes out to be about .5094. Some writers claim to be able to use bullets straight from a mold casting a diameter of .514. I seen other articles claim the correct mold would cast a .508 bullet. Yet another source offers a bullet dia of .502.
Now here's the kicker...... measuring the bullet in the original cartridge, the diameter is somewhere around .506. But that is reading a 100+ year old bullet still seated in it's case.

I'm pretty sure I have the correct case length figured out. Just not sure on what bullet diameter I should consider, On one hand for my bore, the.514 seems a bit to large and the .502 seems too small. I'm not certain on just how much over size I can get safely by with. From all I've ever learned regarding the correct diameter it should be around .002 or .004 over groove diameter.

[ulav8r]

Confusion Abounds

Chamber casting length * original cartridge COL size * Bullet diameter * New custom configured case

Since I started this project of reloading some rounds for the M1871 Army Rolling block pistol I have found most all information to be not only confusing and convoluted, but in some case contradictory.

The start of this thread the OP states that he can chamber a 50-70 round or perhaps just a case in his pistol. In my pistol this is not the situation. As seen in my photos I can not chamber a full size 50-70 case and the same is true for a carbine length (1.35") case. Comparing a full size 50-70 case to the chamber casting it is apparent that the full size case is too long for the chamber. So, I am not sure what is going on with the Op's pistol chamber.

I made a chamber casting of the M1897 I have and compared the results to an original .50 Rem cartridge.
original factory round. I cut down 50-70 brass to more correct length where the bullet would be much closer to engaging the rifling.

Conflicting information regarding the correct bullet diameter. Some information I have come across states the correct size should be anywhere between .502 to .514 Depending on which article you read.
I slugged my bbl and took some measurements also measured the casting I made. Difficult to do because of the 3 groove rifling. The best "guesstimate" for my pistol comes out to be about .5094. Some writers claim to be able to use bullets straight from a mold casting a diameter of .514. I seen other articles claim the correct mold would cast a .508 bullet. Yet another source offers a bullet dia of .502.
Now here's the kicker...... measuring the bullet in the original cartridge, the diameter is somewhere around .506. But that is reading a 100+ year old bullet still seated in it's case.

I'm pretty sure I have the correct case length figured out. Just not sure on what bullet diameter I should consider, On one hand for my bore, the.514 seems a bit to large and the .502 seems too small. I'm not certain on just how much over size I can get safely by with. From all I've ever learned regarding the correct diameter it should be around .002 or .004 over groove diameter.

Measure your chamber cast at the front, where the neck of the loaded cartridge will be, then measure the neck wall thickness of the brass at the same location. Subtract twice the neck thickness from the chamber diameter to get the MAXIMUM diameter of the bullet that might chamber. Then subtract .001 to .002 from that to get a bullet diameter that might work most of the time.

[ndnchf]

M1871 - by your groove size, I'd say a .512" diameter bullet would be a good starting point. Bullet sizing dies are availble in that size.

[M1871]

ulav8r --- Thanks for that advice. But I'm not clear on how your suggestion would differ from actually measuring the greater diameter of a bbl slug. I'm pretty confident I know the correct diameter for the bullet.. I used the wrapping the slug with shim stock method and measuring with three micrometers and a dial caliper. Getting consistent result on multiple measurements. I'll admit I am not all that knowledgeable on this topic, I do know that the bullet nose should just fall shot of engaging the rifling. I think I've accomplished this from measuring the casting. I feel that (my determined) case length is far better than what the original cartridge length would be. I intend to cast with a soft alloy so as not to create to much chamber pressure.

ndnchf --- Thanks! how about sizing down to .510 would that still be OK? .514 seem a bit to over-size. Would that still be safe?


I'm not looking of accuracy here Just wanting to be able to enjoy shooting this bit of history once in awhile.

[ndnchf]

Typically sizing down more than about .005" can cause bullet distortion. But you aren't doing precision target shooting, so thats probably fine. What bullet diameter are you starting with?

[M1871]

ndnchf --- Well, I thought I had a Lee 90255. It was ordered and then I learned it is now back-ordered. No one has that lee mold in stock. I was lucky to have come across several bullets that were cast from that Lee mold. I cut the lower two bands off the bullets to get the correct size and weight, This gave me something to plan and work with. I had plans on modifying the new Lee mold much like you have done except taking down even more meat. So I'm now looking at a mold from accurate mold that is .510 dia. at 290 or 320 grn. Or..... if anyone has another option for a suitable mold I'd consider that.

[ndnchf]

Accurate makes darn nice molds to order. That is a good alternative. Just a thought, but did you check BACO's site to see if they have bullets in the weight range you want?

[ndnchf]

BTW M1871, I'm curious about your screen name. I have a M1871 Springfield Spencer rifle

[M1871]

ndnchf --- Yes I had found a cast bullet at BACO that they actually specify for the .50 Rem pistol. But, they are out of stock. BACO also had some loaded rounds . Just too expensive. Besides where is the fun in just buying everythig one needs? This is a hobby after-all. Ain't we supposed to use our heads and hands and not just the power of our wallets.

Accurate Molds..... They do look good and can pretty much build to specs. A bit pricey and the wait time as of this writing is 10 weeks.


I also found a suitable mold at Old West Bullet Moulds but that one is .508 dia. I wrote to see if he could supply a different diameter, He could at an additional cost. His mold s "as listed" are at $135 Not sure if I want to pay the extra cost and I thing that the .508 might be too small.

Regarding the screen name..... I had an old account here at castboolits but it disapeared. So I started anew. The M1871 is the designation for the Model 1871 Army Rolling Block Pistol.

.-.

[ndnchf]

M1871 - got it, that makes sense.

I have molds from both Old West and Accurate. Both are very nice. The OW is brass and does get heavy after a while. Bernie at OW does sell bullets from his molds too. He doesnt show them all, you have to ask. Last month I bought 50 .41 rimfire short bullets. I dont expect to shoot my deringer enough to warrant buying the mold. So I just got 50 bullets. Maybe you can get some to try.

[ulav8r]

M1871, your best guess measurement of .5094 would suggest a bullet diameter of .510 to .511, or even up to .512. The measurement and calculation I suggested would indicate of .510-.511 would be a close or loose fit to the chamber.

[M1871]

ndnchf --- Oh that's good to know about what Old West might have. I'll contact him again, I'll see if he has a few bullets from that .508 mold. Although I do suspect that those would be slightly under sized. I'm thinking about inquiring about having him make up one of the .50 Rem molds that will cast closer to .512. Perhaps 514 since I can always size the bullet down slightly. I noticed that he also has sizing dies rather reasonably priced. Might even consider getting one sizing die and if need be hone it out to the larger dia, Of course I could do the same with Accurate molds but the 2 1/2 week wait time is not very appealing.


ulav8r --- Yes your stated measurements are about what I concluded. Thanks