1858 different point of impact

[Warhorse]

I have a R&D conversion cylinder for my 1858 Remington in .44 to shoot .45 Long Colt cartridges.

 

Much to my surprise, with the conversion cylinder the point of impact at 25 yards was over a FOOT higher than when I used the percussion cylinder. Both groups were about the same size, roughly 3" diameter.

 

The .45 Long Colt cartridges are Black Hills Cowboy loads. The percussion charge is about 35 grains. (Can't remember charge exactly, set the fixed charge tube a very long time ago, but it nearly fills the chamber with just sufficient room to properly seat the round ball.)

 

Any bright ideas why this should be so?

 

I have not yet taken the time to experiment with different charges for the percussion cylinder. I suspect that the heavier charge in the percussion cylinder is the likely reason for its lower strike. A lighter charge would allow a little more time for recoil response to affect the bullet trajectory. Does this sound right?

 

 

Warhorse

[Colorado Coffinmaker]

Yup. Point of impact is directly related to the weight of the projectile and it's velocity. POI is also effected by barrel time of the projectile. Cartirdge rounds with a different powder charge, bullet weight and barrel time are going to have a much different POI. Physics.

 

Coffinmaker

[Doc Coles SASS 1188]

I believe that some of the R&D cylinders are not bored in line with the barrel but at a slight angle to allow room for the rim of the 45 colt. As such, the bullets are changing angle a bit when they enter the barrel which has to have some effect on ballistics. It might not make them shoot worse, but it could result in them patterning in a slightly different place. Having said this, the biggest difference is probably from the difference in load, bullet weight and bullet tension between your cartridge and cap and ball loads.

[Adirondack Jack, SASS #53440]

I know how to fix the disparity. Ya need to shoot a load a LOT closer to the RB ballistics. Doing that will mean a light bullet and a reasonable velocity. Pards tell me they get near identical performance in a variety of conversions using 150ish grain bullets such as the EPP-UG and C45S cases. As always, YMMV.

[Smithy]

I have not yet taken the time to experiment with different charges for the percussion cylinder. I suspect that the heavier charge in the percussion cylinder is the likely reason for its lower strike. A lighter charge would allow a little more time for recoil response to affect the bullet trajectory. Does this sound right?

 

Sounds just about right to me Warhorse. I had an eclectic assortment of POI results during my conversion, but I also went from round ball to 300 grain cast big lube bullets to 200 grain cast Corbin lubed bullets which I am now shooting and shoot to my POA which works for me so I'm not complaining at all. Smithy.

[Driftwood Johnson, SASS #38283]

I believe that some of the R&D cylinders are not bored in line with the barrel but at a slight angle to allow room for the rim of the 45 colt. As such, the bullets are changing angle a bit when they enter the barrel which has to have some effect on ballistics. It might not make them shoot worse, but it could result in them patterning in a slightly different place. Having said this, the biggest difference is probably from the difference in load, bullet weight and bullet tension between your cartridge and cap and ball loads.

 

Howdy

 

Yes, in order to fit six 45 Colt rims into the diameter of the 1858 cylinder, the chambers are bored at a slight angle, they are not bored straight. That is why a R&D cylinder for the '58 can hold 6 rounds, yet the Kirst cylinder for the same round will only hold 5 rounds. The Kirst chambers are bored straight to the bore, the R&D chambers are bored at a slight angle.

 

HOWEVER............the actual angle the chambers are bored to in the R&D cylinder is less than 1/2 of one degree. This amount is so minor it has virtually no measurable effect on the accuracy of the guns. In fact, with their R&D cylinders my two Remmies are the most accurate 45 Colt revolvers I own. More accurate than my Rugers or my Colts. The reason they are more accurate is because the chambers are bored more precisely than either of those other two brands. In fact, when I load 45 Colt I keep one of my R&D cylinders on the bench as a 'cartridge gauge'. If a 45 Colt round will fit into my R&D cylinders, it will fit into my Rugers or my Colts. If a crimp is a little bit too 'bulgy' it may not want to seat completely in my R&D cylinders, but it will still seat in the Rugers or Colts.

 

The angle is so slight, it has virtually no effect on the accuracy of the gun. It is no problem for a bullet to redirect itself less than 1/2 of one degree as it clears the forcing cone.

 

Far more significant is the weight of the projectile and the powder charge. Don't forget, a 44 cal round ball only weighs around 150-160 grains. In addition, a round ball is only held in place by friction across the tiny cross section where it is shaved as it enters the chamber. A 200 or 230 or 250 grain bullet mechanically locked in place by a crimp will cause far more recoil which will cause the muzzle to rise more while the bullet is still in the barrel. Even with the same powder charge, that will cause the bullet to strike higher than the round ball.

[Warhorse]

OK. Thanks to all for the input. You have verfied my basic premise on the different POI problem.

 

I believe that my next step is to experiment with different powder charges on the percussion cylinder. There's not much I can do about bullet weight there using round balls and conical is far more trouble than it's worth. My objective is to have the revolver shoot reasonably close to POA with both cylinders, if possible. I would rather not have to change sight settings when I change cylinders. (Yes, I have the target model with adjustable sights.) This is not a match gun, I only shoot it for fun. I just like consistency in my artillery.

 

I don't currently plan to reload .45 Long Colt as I don't shoot that enough to bother. My main match guns are .357 NM Vaqueros, with which I am quite pleased. I also use the same caliber in my rifles. (What was that about consistency?)

 

 

Warhorse

[Nate Kiowa Jones #6765]

OK. Thanks to all for the input. You have verfied my basic premise on the different POI problem.

 

I believe that my next step is to experiment with different powder charges on the percussion cylinder. There's not much I can do about bullet weight there using round balls and conical is far more trouble than it's worth. My objective is to have the revolver shoot reasonably close to POA with both cylinders, if possible. I would rather not have to change sight settings when I change cylinders. (Yes, I have the target model with adjustable sights.) This is not a match gun, I only shoot it for fun. I just like consistency in my artillery.

 

I don't currently plan to reload .45 Long Colt as I don't shoot that enough to bother. My main match guns are .357 NM Vaqueros, with which I am quite pleased. I also use the same caliber in my rifles. (What was that about consistency?)

 

 

Warhorse

 

 

If you ever plan to reload there are some 165 gr 45's available. I agree with DJ. Heavier bullets pushed at about the same speed as the lighter bullet will cause muzzle rise. Even in some rifle. Almost ever one that I've dealt with that has the 454 casul 92's in the 16" carbines end up putting on taller front sights to compensate for the muzzle rise.