Revolver cylinder clearance.

[legs748]

What should the clearance be between the front of the cylinder and breech on a MLR? There is an appreciable delay between the bang and target impact on my .36 at 25m, like shooting an airgun. Out came the feeler gauges and there is between a .006"-.010" gap for the gas to escape from, does this sound excessive?

[FredB]

No--it is exactly what it should be.
Try putting some powder in.

Fred

[Sim G]

No--it is exactly what it should be.
Try putting some powder in.

Fred

Ditto....

What charge are you using? It should be more akin to .32 S&W than sub 12 ft.lbs.

[pnuk]

Are you using artillery style elevation? :-)

[legs748]

No--it is exactly what it should be.
Try putting some powder in.

Fred

Ditto....

What charge are you using? It should be more akin to .32 S&W than sub 12 ft.lbs.

13 grains of fine, thin lubed wad, .375 ball. Manual lists 12 grains as max?!?

[DaveB]

No--it is exactly what it should be. Try putting some powder in. Fred

Ditto....

What charge are you using? It should be more akin to .32 S&W than sub 12 ft.lbs.

Actually with a slightly compressed load a .36 Navy should be able to get that 80 grain ball up to around 950 fps, which puts it on more a par with a .380 Auto/9mm Kurz, than a .32 S&W.

Interestingly, I have never weighed the powder charge in any of my three .36 Navy repros (a Pietta 1851 and two Uberti 1861s) - I just use an old .38 Special case as a dipper for Pyrodex P or Hodgdon 777.

[Sim G]

Actually with a slightly compressed load a .36 Navy should be able to get that 80 grain ball up to around 950 fps, which puts it on more a par with a .380 Auto/9mm Kurz, than a .32 S&W.

Interestingly, I have never weighed the powder charge in any of my three .36 Navy repros (a Pietta 1851 and two Uberti 1861s) - I just use an old .38 Special case as a dipper for Pyrodex P or Hodgdon 777.

You're only going to get close to that sort of velocity with 30gns by volume of Pyrodex P. The maximum load for 777 is 20gns by volume, which will give around 830fps.

Interestingly, 777 is not a B/P substitute per se, but a nitro powder that can be used in muzzle loading firearms. It is a "hotter" powderthan real black or Pyro, designed to give superior velocity in B/P hunting arms. Hodgdon warn against any deviation what-so-ever from their loads with 777, as it can give dangerously high pressure spikes. You might want to swap that .38 spl case for a powder measure....

[DaveB]

I have never weighed any of the charges I use. I simply determined (back in the 80s) when I got my Pietta what volume of FFFG black powder the chambers in the cylinder would hold (while leaving room for the ball to slightly compress the charge of course) and found a handy measure that equated to that volume - a .38 Spl case with a handle soldered to it which now that I come to think about it (30+ years later), I may have cut back very slightly to get the right volume. When I switched to Pyrodex, because they said it replaced B/P by volume I used the same measure. By then I had a powder flask and I had cut the tube to deliver the same volume as my earlier scoop. When 777 came along, again they said it was a replacement by volume, so I continued using the same measure.

Now you have me curious - I think I'll weigh a couple of charges when I get home, just to see what the weight of the charge actually is.

I have never chronographed these loads either, but when I was actively shooting cowboy competitions the poppers were borrowed from the IPSC section of the club and were supposed to be calibrated for the IPSC minor calibre power factor. I found I could knock them down about 80 per cent of the time with hits in the upper half.

[legs748]

My 13 grains equates to .9cc or three scoops from a .3cc lee dipper.

[Sim G]

I have never weighed any of the charges I use. I simply determined (back in the 80s) when I got my Pietta what volume of FFFG black powder the chambers in the cylinder would hold (while leaving room for the ball to slightly compress the charge of course) and found a handy measure that equated to that volume - a .38 Spl case with a handle soldered to it which now that I come to think about it (30+ years later), I may have cut back very slightly to get the right volume. When I switched to Pyrodex, because they said it replaced B/P by volume I used the same measure. By then I had a powder flask and I had cut the tube to deliver the same volume as my earlier scoop. When 777 came along, again they said it was a replacement by volume, so I continued using the same measure.

Now you have me curious - I think I'll weigh a couple of charges when I get home, just to see what the weight of the charge actually is.

I have never chronographed these loads either, but when I was actively shooting cowboy competitions the poppers were borrowed from the IPSC section of the club and were supposed to be calibrated for the IPSC minor calibre power factor. I found I could knock them down about 80 per cent of the time with hits in the upper half.

Unless you're going to weigh B/P, the actual weight of the sustitutes don't matter. It's how much space, hence volume, that the specified amount of B/P takes up. This is why you really need a measure. Or even just borrow one to make sure. I don't have a .38 spl case so I can't check it and give you a guestimate.

Either way, the maximum charge you can get into a modern percussion .36 revolver is around 27gns of Blackpowder, which still allows for a .375 ball to be seated. To get a maximum charge of Pyrodex, you'd set the measure at 27gns and pour Pyrodex into that so the load is 27gns of Pyrodex, by volume. The actual real weight may only be 23 or 24 grns when placed on a scale.

Now even though we can go to as much B/P or Pyrodex that we can get into a chamber, we can't do that with Triple 7. Hodgdon state a maximum load of Triple 7 in a .36 is 20gns, by volume. So then we would set the measure at 20gns of Blackpowder for a max in 777, by volume. The actual weight on a scale may only be 17gns...

So lets just say that your .38 spl case is bang on 27gns of Blackpowder. Using that for Pyrodex is no issue, as 27gns by volume is perfectly safe and usable. But, if like the two former powders you are using the .38 case to dispense Triple 7, you are around 30% OVER the maximum charge.

So far you may have just been fortunate. Triple 7 is know to behave very unpredicably outside of Hodgdon's data. Even the use of a single wad is important as it gives the required compression with the stated load, that allows the powder to burn as expected.