Author Topic: Cimmaron 1858 NMA with Howell 5 shot conversion cylinder  (Read 5686 times)

Offline GeezerD

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Cimmaron 1858 NMA with Howell 5 shot conversion cylinder
« on: January 02, 2019, 08:36:18 am »
I recently purchased a Cimmaron / Uberti  1858 Remington replica with the intention of making it convertible from C&B to cartridge. As I received it, the bolt timing was such that it dropped about .025 to .030 before the cylinder locking slot in the cylinder. After firing about 25 or 30 shots, the cylinder locking slots were peened enough to prevent the bolt from locking the cylinder. I corrected this issue by taking a small amount off the bolt leg and now the bolt drops a little over one bolt width before the locking slot.

When I received the Howell 5 shot conversion cylinder, I found that the hand was too long by about .025 preventing it from engaging the cylinder ratchet. After shortening the hand, the 5 shot cylinder operates like it should. After removing the burrs on the C&B cylinder locking slots, it now cycles great with both cylinders.

I discovered that the bolt width is about .004 -.005 less than the locking slots in both cylinders. Will this create any problems ? Opinions

                                                                                                                                                    Thanks, GeezerD
« Last Edit: September 08, 2019, 08:19:20 am by GeezerD »

Offline Coffinmaker

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Re: Cimmaron 1858 NMA with Howell 5 shot conversio cylinder
« Reply #1 on: January 02, 2019, 10:26:20 am »
Hi Geezer  :D

Actually, you have solved both of your problems rather well.  Often (most often) when installing an R&D conversion cylinder, the OEM hand is too long and must be a few thou shorter.  This will usually leave the cylinder a Smidge (technical term for "just a tiny amount" ) short of full lock up.  This occurs when cycling the action very softly and S L O W L Y.  When cycled as you would shoot the gun, the inertia of the rotation of the cylinder will cause it carry up without problem.

"Your" Bolt width will not create problems.  The important part is the bolt FITS INTO the slots without hinderance.  That tiny amount of movement in the cylinder is not a problem.  Atz the reason revolvers are designed with a forcing cone.  Have fun with your Rem.

I ever mention I hate Auto Correct!!
« Last Edit: January 03, 2019, 06:48:55 pm by Coffinmaker »

Offline GeezerD

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Re: Cimmaron 1858 NMA with Howell 5 shot conversion cylinder - UPDATE
« Reply #2 on: January 27, 2019, 10:29:14 am »
After some shooting with the 45 Colt cylinder installed, the accuracy is a bit disappointing. The groups at 25yds using a rest, were 6 inches or more. I ended up installing a 45 Colt conversion barrel from Cimmaron with a groove diameter of .451 and it reduced the group size to under 3 inches.

I will be opening the percussion cylinder chambers to .453 diameter and use .457 diameter round balls which should help with the accuracy  when the percussion cylinder is installed. -------------------- GeezerD

Offline Coffinmaker

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Re: Cimmaron 1858 NMA with Howell 5 shot conversio cylinder
« Reply #3 on: January 27, 2019, 10:47:41 am »

Geezer,

A most excellent plan.  Having the projectile exit the cylinder 001 to 002 over groove diameter should give excellent accuracy.  How deep do you plan to counter-bore the chambers??  Were it I, I'd go all the way down to give full flexibility to seating depth for the ball and playing with the powder charge.

Offline GeezerD

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Re: Cimmaron 1858 NMA with Howell 5 shot conversio cylinder
« Reply #4 on: January 27, 2019, 11:43:55 am »
Since I will only be removing about .002, I will take it as deep as possible. Also, since the throats of the 45 Colt cylinder are .454 a larger bullet diameter may help. The ammo that I have been using is Fiochhi Cowboy 45 Long Colt which is probably loaded with .452 diameter bullets. ------------------------- GeezerD

Offline Coffinmaker

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Re: Cimmaron 1858 NMA with Howell 5 shot conversio cylinder
« Reply #5 on: January 29, 2019, 11:43:16 am »

Geezer,

That should most certainly get it done. 

Whatcha been up to??  Haven't actually hear from ya since you scratch built that '76 Kit.  ::)

Offline GeezerD

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Re: Cimmaron 1858 NMA with Howell 5 shot conversio cylinder
« Reply #6 on: January 29, 2019, 12:35:01 pm »
Since the 1876 project, I have been mostly building traditional black powder rifles. Current projects are a 54 caliber fullstock flint Hawken and an Early Virginia  45 caliber percussion longrifle. Early Virginia and percussion don't belong in the same sentence but I am building it for me and I can't shoot a flintlock worth a hoot.

I know I can't forget it but I am surprised that you remember the 1876 ordeal. Most of the stuff that I have been doing the last few years have been to help preserve my sanity during retirement. -------------------- GeezerD

Offline GeezerD

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Re: Cimmaron 1858 NMA with Howell 5 shot conversio cylinder
« Reply #7 on: January 30, 2019, 09:47:07 am »
Since it is -16 degrees this morning, I decided to spend the day in my shop. I discovered an easy way to open up the chamber diameters in the percussion cylinder.

I used a 7/16 to 15/32 inch adjustable reamer turned by hand in each chamber. Adjust it until it just starts to cut and turn it in as far as possible in all 6 chambers. Then adjust it a bit larger and turn it in to all 6 chambers again. It will follow the factory chambers and removes less than .001 at a time.

I did remove about 1/4 inch from the bottom end of the reamer shank to allow it to cut a bit deeper in the chamber. It opens the diameter down to about 3/4 inch.

These reamers can be found on ebay and cost between $10 and $15. -------------------------- GeezerD

Offline Coffinmaker

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Re: Cimmaron 1858 NMA with Howell 5 shot conversio cylinder
« Reply #8 on: January 30, 2019, 02:56:02 pm »

Yep.  I hear ya.  I take on just enough work to keep me from going completely over the edge.  Don't work on Cartridge guns at all (gave up the FFL) and kind of specialize on Pietta Cap Guns.  Fun Stuff.  Plus I build myself the Cap Guns I always wanted and never had the time to do.  More fun Stuff.

Offline GeezerD

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Re: Cimmaron 1858 NMA with Howell 5 shot conversio cylinder
« Reply #9 on: September 08, 2019, 08:01:00 am »
 Moved to classifieds
« Last Edit: September 08, 2019, 08:18:38 am by GeezerD »