Inconsistent Nitro Conversion.

[Certus]

Hi,

I'm a new member of this very interesting and informative forum living in the United Kingdom.

I have a Ruger Old Army which has been converted to use nitro powder and shotgun primers. I was advised to use 4.5 grns of Herco behind an Alox lubricated .457 round ball.

When this load works consistently it sounds right and is very accurate, but I'm getting quite a few weak discharges and have noticed unburnt powder accumulating in front of the muzzle.

I would have thought either the ball is not seating tightly enough or the powder is not burning fast enough. As already stated, the ball is the recommended .457 dia and I can see a ring ring of Alox coming of after seating, but not really a lead ring as with my BP revolvers. I have also tried ball from different makers with no difference in the results obtained. I realise that it's important to use a 'Flake' type shotgun type powder in these conversions to prevent finer powder disappearing through the primer hole, but wondered if a slightly faster burning powder than Herco such as Unique might help the situation.

Any thoughts would be much appreciated.

Regards
Brian

 

[4V50 Gary]

Are there hotter shotgun primers out there?

Can you post pictures of the new nipples?

 

[Ricklin]

???

No ring of lead concerns me.

Have you slugged the bore of your Old Army? Cylinder bores?

Have you confirmed the diameter of the balls with calipers?

I have no experience with nitro conversions, I would think that shaving that ring of lead is significant.

 

[Hawg]

If it's not shaving lead the balls aren't tight enough. I would be concerned about them moving forward under recoil and locking it up. I do not think that is your problem with weak discharges tho. I would tend to think powder contamination is the culprit.

 

[HiBC]

I know nothing about your conversion,and I don't even own a cap and ball.
Please take my comment with a grain of salt.
A standard ,traditional cap offers a very modest ignition.The cylinder is not significantly pressurized before the powder ignites.
I speculate that the initial event of firing the shotgun primer produces enough pressure to unseat the ball and drive it into the barrel with no powder present.

In a cartridge revolver,a strong roll crimp offers resistance to assist ignition.

You don't have that.You have a small amount of "press" fit from forcing the ball. I don't know,but maybe a well fitted conical bullet would help. Perhaps even a hollow base to obturate.
The primer fires before the powder lights,and I suspect the primer is driving the ball out of the cylinder before you get good ignition.
If you can,I'd try the least powerful primer available.

Another difficulty is that your combustion chamber volume will be quite large relative to your smokeless charge. A small qty of powder scattered over wide area will not ignite as well as a charge with some load density.
Black powder and smokeless operate with completely different rules.Black powder requires a full cylinder,100% plus load density. Nearly all fast pistol or shotgun powder will (if ignited) provide quite frisky pressures at very low load density....but not necessarily consistant ignition. When the transition from black powder to smokeless was made,cartridge cases became much smaller.The 45 ACP was scaled to provide 45 Colt performance with smokeless.
Many shotgun powders require a wad pressure preload for good ignition.The don't work well loose.

Pistol and shotgun powders tend to not be forgiving.I would hesitate to experiment .
I cannot,and do not,make a load recommendation...but I suspect Hogdon Trailboss might be a good place to look.

Another powder I have seen recommended for load density in cartridges such as 45 Colt is Nitro 100. Its a bulky,fluffy powder with a high nitroglycerine content. ....but I cannot make a load recommendation.

I suggest contacting the gentleman who did your conversion and asking him what loads he intended,or a tech rep at a powder company.

 

[Centurion]

Never heard of it. How does it function? It is a new cylinder or a conversion from the original one?

 

[B.L.E.]

I would imagine it's a custom made cylinder made to use 209 shotgun primers, with its own firing pins similar to the cartridge conversions sold in the United States.
It's a United Kingdom thing due to their laws making the ownership of modern revolvers nearly impossible.
Smokeless powder relies heavily on the primer not only igniting the powder, but also getting the initial chamber pressure up into smokeless powder's efficient burning range. That's the main reason it doesn't work well in normal percussion muzzleloaders using nipples and caps.
A tight fit is important, and so is consistent bullet seating depth. Do the chambers have stepped bores so the bullet stops at the same place when seated?
Herco is a pretty slow burning powder for this application, a .457 round ball only weighs 143 grains. Slow burning powders in low power loads tend to be erratic. Bullseye or 700X might be a better choice.
Also, some primers are hotter than others. Federal 209A primers are said to be hotter than some of the others.

 

[bedbugbilly]

Never seen one or had experience with one - but off hand - if you aren't shaving lead when loading, you may be having gas loss on ignition - already addressed above.

Another issue may be powder placement - try a tighter ball and on you've loaded it, pint the muzzle upward and give a quick shake which should position powder closer to the primer - a combination of powder placement and perhaps the primer may be part of the problem. Good luck and be safe.

 

[Certus]

First of all thanks to all who have replied for their constructive and helpful feedback. I mainly shoot reproduction black powder revolvers, but had this revolver converted as it was already a modern design and dispensed with the time consuming clean-up after shooting. I must admit I prefer the black powder experience so haven't spent too much time experimenting with this nitro conversion.

The Ruger was converted some twenty years ago and has had the primer pockets machined out to accept 209 shotgun primers. A fabricated plate fits behind the cylinder which holds the firing pin with the whole assembly then being inserted into the frame in the normal manner.

A bit more research suggests that due to the burning characteristics of the slow burning powder the charge should be increased rather than decreased.

Next time I visit the range I will increase the load incrementally from 5 to 6 and 6.5 grns of Herco and see what happens. I have also sourced some ball of .460 diameter and some slightly faster powder (Unique), so still some options to pursue.

I will update this thread with any progress after trying the above alternatives.

Regards
Brian

 

[Ricklin]

Load one cylinder only

Hi Brian,
You might try loading just one cylinder and run that round over a chronograph.

You could then try a full cylinder to check the velocity of the remaining rounds.

 

[Centurion]

So it is what I supposed...the original cylinder with nipples changed to fit 209 primers. I have a pair of Piettas (one a Colt Army and the other a NMA) with cylinders with some kind of internal chamber's step and always wonder why...
Maybe while being not the original intended purpose this kind of cylinder were the ones used to convert it from BP to Nitro powders...

 

[4V50 Gary]

Drop a chunk of brass down the chamber. Then pound in a lead ball halfway. Invert the cylinder and shake over a box of sand. The brass will pound out the ball. Mic. the ball. Whatever it reads, add .001 and use that size ball.

 

[rodwhaincamo]

Wouldn’t he want more driving hand length that what little that would add? I’ve only heard of one using a near chamber diameter projectile when using bullets/conicals as they have driving bands to hold it in place by friction.

Also having more friction would delay the projectile moving slightly increasing the pressure, no?

 

[Hawg]

Drop a chunk of brass down the chamber. Then pound in a lead ball halfway. Invert the cylinder and shake over a box of sand. The brass will pound out the ball. Mic. the ball. Whatever it reads, add .001 and use that size ball.

That's not enough for a round ball. I would say at least .003

 

[B.L.E.]

I'm curious, is this what you are using? I'm tempted to try them myself for no other reason than the fact that most sporting goods stores rape you when you buy #11 percussion caps.
I wonder if they ship to the U.S.

http://www.anvilconversions.co.uk/index_files/Page13768.htm

 

[B.L.E.]

Never seen one or had experience with one - but off hand - if you aren't shaving lead when loading, you may be having gas loss on ignition - already addressed above.

There may also be a possibility that the chamber mouths have been coned by a reamer. This swages the ball to a smaller diameter rather than trimming it by shaving lead and actually results in a tighter fit. It also makes the starting of square based bullets easier.

 

[Certus]

Hi,

I'm off to the range on Friday to try a few more options and hopefully improve the reliability of the Ruger.

I will update the post with any progress and also have a go at uploading some pictures of the conversion for anybody interested.

Regards
Brian

 

[4V50 Gary]

Thanks BLE.

 

[Certus]

Hi,
First of all here a few pictures of my Ruger nitro conversion revolver which allows me to load the gun with the cylinder in place rather than having to remove it to load using a small press which is normally the case on UK conversions or purpose made muzzle loading nitro revolvers.

I tried increasing the load in small increments from 5 to 6 grns of Herco at the range today. The heavier loads grouped higher, but still suffered from the presence of some unburnt powder with the occasional light discharge. A definite improvement this time though as the 5 grn load grouped into 4" at 25yds unsupported with the fewest light discharges. I will now try a faster powder and some .460 ball to see if things can be further improved.

Regards
Brian

 

[AKexpat]

Brian, welcome to the forum!

I have never heard of nitro loads of which you speak. By nitro, are to speaking exclusively about smokeless powder? I have always been a fan of Hercules Red Dot powder and chamber pressures with that powder have always been mild in skeet shotguns, but I have never loaded it in pistol calibers.

I completely agree with previous posters who think you are using an undersized round ball if not shaving a thin ring of lead when loading it into the chamber front of the cylinder.

Smokeless powder is a different animal than BP because it burns differently, progressively, as compared to one explosion with compacted BP. Since you are not using a well-seated/crimped projectile in a cartridge case, your cylinder is taking the place of that and needs to be addressed accordingly with a tightly seating ball/conical.

Just my $.02 worth.

Jim