Kind of an oddball question here

[tazman]

I have a Ruger New Model Blackhawk convertible in 357mag and 9mm. It shoots well with appropriately sized boolits with both cylinders.
My question is........ How fast will the 9mm slugs be going when they leave the cylinder to enter the forcing cone on the barrel?
The cylinder is essentially a short barreled 9mm in itself. It might be about like shooting a 2inch barreled semi auto at that point.
I wonder how the extra velocity at the forcing cone effects the boolit on the way to engaging the rifling.
What are your thoughts?

[Silver Jack Hammer]

Forgive me if my comments do not address your question, I may not understand your question. The revolver's barrel cylinder gap does not really reduce pressure as it would seem to. Laboratories like Speer have published their findings that revolvers actually deliver higher velocities to their semi auto counterparts. And we know that a 4" inch barreled revolver gives higher velocity than a 2" and a 6" gives higher velocities than a 4" so the powder burn is accelerating the boolit past the barrel cylinder gap.

Another factor is how we measure pistol barrels. Semi autos are measured from the breach of the barrel, revolver barrels are measured at the face of the cylinder. So all things being equal a revolver is going to have an inch and a half more tube than a semi auto.

[9.3X62AL]

It is by no means common, but I am aware of criminals having unscrewed revolver barrels and used receiver-and-cylinder assemblies as crime weapons. 30 years ago, I could have had Cal-DOJ labs perform such testing in the interest of advancing the science for its own sake, but that was a different era--a time before refried Bolsheviks from Cal-Berzerkeley infested our State offices so deeply.

I am certain the FBI Labs have run these sorts of tests, and the results of same may be in the public domain. It is certainly an interesting idea, and while accuracy would be dismal I am sure such projectiles could severely injure or kill a recipient.

[smokeywolf]

All you would have to do is contain the brass to achieve projectile velocities which at short distances would be lethal.

[44MAG#1]

tazman,

That at is an interesting thought.
I am sure you are leading up to bullet skid going into the rifling.
Right??
This is going to be a soft vs medium vs hard vs super hard alloy thread.

[44man]

This has been bandied about forever and it was said to get the boolit as close as you can to the cone but it has not proven true.
Some gun makers have taken this so far you need special boolits and even then you are .001" from boolit pull lockup.
My fastest revolver is my BFR 45-70 at over 1630 fps and the boolit is close to 3/4" from the end of the cylinder. It is also the most accurate revolver I ever owned.
Yes, I used to have the concern too but it was from reading, not actual practice.
I would ignore it and just have fun shooting.
I suppose the most serious job I undertook for over 60 years was to prove about every word ever written about revolvers has flaws, no matter who put those words to paper.
But back then we did not have Cast Boolits to look at either.

[bedbugbilly]

taman - interesting question!

I have one for you just out of curiosity and the thought that I might run across a convertible at some time - either in 9mm/357 or 45ACP/45 Colt.

My question it this. Do you find on your convertible that you tend to use one cylinder more than the other? I'm sure both are fun to play with but I have read on many threads (usually by those that don't reload) that they like the 9mm for the point of cheaper to shoot than 357 as far as "store bought" ammo goes. But . . . you and I both cast and reload. So . . . on a 9mm/357 - I'd probably be shooting 38 Spl. (my hands can't take the abuse of too many 357 rounds - but I do enjoy 45 Colt so go figure). Anyway - as far as "shooting expense" - you have the casings, you have to use a primer for each - you can use the same boolit if desired or there might be a grain difference in weight between what you use in the 9mm - but let's say that you use the same boolit. The only difference is going to be in the powder weight and that isn't going to vary by a whole lot if you were using 38 Spl. brass. So given those things - is there one cylinder you "lean to" more than the other? Do those with convertibles end up finding that one cylinder sits and lives a lonesome life over time? Or is the additional cost of a convertible worth it?

I'm just talking about general shooting - I can see if a person hunts with one, etc. how he might switch out for the "job".

Second question - do you have to use moon clips with your 9mm cylinder? I've never really looked at a convertible as I didn't think I'd use both cylinders but it would give you another cartridge to play with and could be a lot of fun I'm thinking?

[Pipefitter]

Second question - do you have to use moon clips with your 9mm cylinder? I've never really looked at a convertible as I didn't think I'd use both cylinders but it would give you another cartridge to play with and could be a lot of fun I'm thinking?


I don't think it would be possible to get moon clips in a Blackhawk, just sayin'.

[tazman]

taman - interesting question!

I have one for you just out of curiosity and the thought that I might run across a convertible at some time - either in 9mm/357 or 45ACP/45 Colt.

My question it this. Do you find on your convertible that you tend to use one cylinder more than the other? I'm sure both are fun to play with but I have read on many threads (usually by those that don't reload) that they like the 9mm for the point of cheaper to shoot than 357 as far as "store bought" ammo goes. But . . . you and I both cast and reload. So . . . on a 9mm/357 - I'd probably be shooting 38 Spl. (my hands can't take the abuse of too many 357 rounds - but I do enjoy 45 Colt so go figure). Anyway - as far as "shooting expense" - you have the casings, you have to use a primer for each - you can use the same boolit if desired or there might be a grain difference in weight between what you use in the 9mm - but let's say that you use the same boolit. The only difference is going to be in the powder weight and that isn't going to vary by a whole lot if you were using 38 Spl. brass. So given those things - is there one cylinder you "lean to" more than the other? Do those with convertibles end up finding that one cylinder sits and lives a lonesome life over time? Or is the additional cost of a convertible worth it?

I'm just talking about general shooting - I can see if a person hunts with one, etc. how he might switch out for the "job".

Second question - do you have to use moon clips with your 9mm cylinder? I've never really looked at a convertible as I didn't think I'd use both cylinders but it would give you another cartridge to play with and could be a lot of fun I'm thinking?

Given the length of the 9mm cylinder, I can use literally any boolit I want in 9mm cases for this gun. The throats on my 9mm cylinder are the same diameter as the ones on the 357 cylinder so I am good to go with .358 diameter boolits, hence the good accuracy with 9mm. I use .358 diameter boolit in my 9mm loads for my semi-autos anyway. The cost per shot is identical for my reloads as you noted. Brass cost may be slightly less for the 9mm but the difference is minimal.
I haven't had the gun long enough yet to develop a preference for one cylinder. If I only shot 357 cases in the 357 cylinder, I would probably shoot the 9mm cylinder more as it would be more comfortable and pleasant. I have arthritis in my hands as you do but the grips I have on the gun minimize the abuse.
No need for moon clips as the cases headspace on the mouth. You couldn't use moon clips anyway as you would need to remove the cylinder from the gun to load it. There is no room for moon clips between the cylinder and frame in any case.
The Blackhawk is a single action gun after all. You punch out the spent brass one at a time with the 9mm just like the 38/357 cases.
I haven't fired full power magnum loads in it yet. I am waiting for access to a range that allows their use. I will have that access shortly.
One of the main reasons I got the convertible is the large amount of 9mm loads I have on hand. When the time comes the government takes away the semi-auto handguns, I will still have a revolver that can use that ammo.

[tazman]

tazman,

That at is an interesting thought.
I am sure you are leading up to bullet skid going into the rifling.
Right??
This is going to be a soft vs medium vs hard vs super hard alloy thread.

That was the first thought. Since the gun shoots accurately with the 9mm cylinder that is probably moot.
The other part was, if the cylinder isn't in perfect alignment, is there going to be extreme wear on the forcing cone area due to the increased velocity at that point?
Since the gun is designed for 357 magnum loads, it probably doesn't matter. I wouldn't be able to shoot it enough to wear it out anyway. The gas pressure from a full magnum charge would cause more wear than the lead boolit anyway.


Forgive me if my comments do not address your question, I may not understand your question. The revolver's barrel cylinder gap does not really reduce pressure as it would seem to. Laboratories like Speer have published their findings that revolvers actually deliver higher velocities to their semi auto counterparts. And we know that a 4" inch barreled revolver gives higher velocity than a 2" and a 6" gives higher velocities than a 4" so the powder burn is accelerating the boolit past the barrel cylinder gap.

Another factor is how we measure pistol barrels. Semi autos are measured from the breach of the barrel, revolver barrels are measured at the face of the cylinder. So all things being equal a revolver is going to have an inch and a half more tube than a semi auto.

I think you did misunderstand the question. I am not concerned with the cylinder gap or any drop in pressure at that point. My thought was that the length of the 9mm cylinder makes it act as a short 9mm barrel, giving the boolit more velocity than say a 38 special or even a magnum, at the point where it crosses the forcing cone and enters the barrel. The dynamic might be changed a bit due to the difference in speed.

[Silver Jack Hammer]

Dave Scovill removed the barrels of Colt SAA's and test fired boolits into wet newspaper to see the amout of upset the base of the boolit had with various alloys. His tests addressed the low pressure .45 Colt cartridge. He wanted to test boolit skid upon entering the rifling. Because the Colts have oversized cylinder throats he was looking for the right alloy to upset and fill the cylinder throats.

[tazman]

Dave Scovill removed the barrels of Colt SAA's and test fired boolits into wet newspaper to see the amout of upset the base of the boolit had with various alloys. His tests addressed the low pressure .45 Colt cartridge. He wanted to test boolit skid upon entering the rifling. Because the Colts have oversized cylinder throats he was looking for the right alloy to upset and fill the cylinder throats.

That is getting to the question. The difference being, the 45 colt is very near the front of the cylinder where the 9mm has quite a bit of cylinder in front of the boolit, allowing the boolit to reach higher velocity as it exits the cylinder. Also the 9mm is loaded to much higher pressures than the colt and the cylinder throats on my gun fit the boolit much tighter than the Colts did.

[bedbugbilly]

Pipe fitter and taxman . . . "moon clips" - DUH! That was certainly a stupid question wasn't it! LOL I don't know what the heck I was thinking of! Lay it on my brain has been mush this week! Don't know where my mind was at! Part of the problem is I don't have a conversion SA and dropping a cartridge into a cylinder that headspace on the throat is foreign to my normal SA shooting. Just chalk it up to "old age"! LOL

[lar45]

Back to the original question...
A look at Quickload might give a reasonable estimate.
Looking at 9mm with 124gn bullet and 6.6gns of HS-6
From a 4" bbl Hodgdon shows 1116fps, Quickload says 1155fps
Plugging in 1.6" for just the cylinder shows 828fps

[tazman]

Back to the original question...
A look at Quickload might give a reasonable estimate.
Looking at 9mm with 124gn bullet and 6.6gns of HS-6
From a 4" bbl Hodgdon shows 1116fps, Quickload says 1155fps
Plugging in 1.6" for just the cylinder shows 828fps

WOW! That is a lot faster than I was expecting! Thanks a lot for that information.
At that velocity, I have to wonder how much damage is being done to both boolits and forcing cone if alignment is off a little?

[9.3X62AL]

Good point, Taz. I didn't approach your initial question from that angle, only "as asked".

Ken Waters (the "Pet Loads" guy once in "Handloader" magazine) discussed this question at some length in an article concerning 32/20 WCF revolver loading. His view was that shoulderless round nose bullets "self-center" into barrel forcing cones much better than do sharp-shouldered wadcutter or semi-wadcutter designs. If there is an alignment problem between chamber throat and barrel, he felt that shoulderless RN castings were likely to survive any such problematic transitions in better shape than the squared-profile front bands of a Keith/SWC or WC. It made empirical sense to me, and it seems to me that the round-flat-nose of the levergun era and the present day could yield similar advantages in older, worn rollers whose line-ups might be less than ideal. Food for thought, if nothing else.

[vzerone]

I have the Ruger Blackhawk in 45Colt/45ACP. I find myself using the 45 ACP cylinder lots more simply because the accuracy of it is right up there with 1911 Gold Cup. That ACP bullet has a long ways to go through that cylinder too. So whatever it's doing there must not be any harm because like noted it's very very accurate and I get no leading in the barrel. Don't worry about bullet skid if you don't have any problems and 9.3x62AL told about what shape bullets align better.

[tazman]

Good point, Taz. I didn't approach your initial question from that angle, only "as asked".

Ken Waters (the "Pet Loads" guy once in "Handloader" magazine) discussed this question at some length in an article concerning 32/20 WCF revolver loading. His view was that shoulderless round nose bullets "self-center" into barrel forcing cones much better than do sharp-shouldered wadcutter or semi-wadcutter designs. If there is an alignment problem between chamber throat and barrel, he felt that shoulderless RN castings were likely to survive any such problematic transitions in better shape than the squared-profile front bands of a Keith/SWC or WC. It made empirical sense to me, and it seems to me that the round-flat-nose of the levergun era and the present day could yield similar advantages in older, worn rollers whose line-ups might be less than ideal. Food for thought, if nothing else.

My thoughts exactly. I have found that in some of my revolvers, the round nose and LFN designs are more accurate. I wondered that it might be the nose shape pulling the cylinder back into alignment without the boolit nose being damaged much. The 9mm cast loads I use are all TC and round nose design which might help explain why the 9mm cylinder shoots well in my Blackhawk.

vzerone---- I agree about the skid not being a factor since the cartridges shoot well. Since they are accurate and do not lead the barrel I wasn't planning on making changes to the gun.
I was thinking about strain on the gun with the boolit impacting the forcing cone/rifling at fairly high velocity.
Anything I shoot through this revolver will undoubtedly be cast as the bore is right for 38 special/357 mag. A 9mm jacketed would rattle down the barrel and inaccurate at best.

[str8wal]

The revolver's barrel cylinder gap does not really reduce pressure as it would seem to. Laboratories like Speer have published their findings that revolvers actually deliver higher velocities to their semi auto counterparts. And we know that a 4" inch barreled revolver gives higher velocity than a 2" and a 6" gives higher velocities than a 4" so the powder burn is accelerating the boolit past the barrel cylinder gap.

The BC gap does make a difference, or so my chrony says. A particular 45 acp load (230 grain fmj/4.8 grains of TG) runs about 30 fps slower from my 6" barreled Bisley revolver than from my 5" barreled 1911, even though the revolver offers 1-3/4" more length for powder to burn.

[tazman]

The BC gap does make a difference, or so my chrony says. A particular 45 acp load (230 grain fmj/4.8 grains of TG) runs about 30 fps slower from my 6" barreled Bisley revolver than from my 5" barreled 1911, even though the revolver offers 1-3/4" more length for powder to burn.

That particular comparison is highly suspect. I know your data is correct for your guns.
My point being I have done the same test with 4 different revolvers three of which had the same length barrels. In my case, two of the 6 inch barreled guns had the same velocity. One six inch was significantly slower. The 4 inch barreled gun gave the fastest velocity of all of them. Guns differ. Each gun makes it's own rules.
I was more concerned with what was happening as the boolit left the cylinder on the way through the forcing cone to enter the barrel. Was wondering if the higher velocity could cause problems.

[str8wal]

Was wondering if the higher velocity could cause problems.

I can see no reason why it should.

[str8wal]

In my case, two of the 6 inch barreled guns had the same velocity. One six inch was significantly slower.

Did you measure the BC gap on all three?

[tazman]

Did you measure the BC gap on all three?

No I didn't. At that time I didn't have the necessary tools to do that type of measurement. I wish I had.
I figured the differences were due to barrel finish and differing dimensions. I didn't know anything much about guns at the time. All I had for tools were my reloading equipment and a chrono.
They all shot equally well for me so I wondered about the velocity difference but didn't think it might be important. Unfortunately all those gun made the trip to the gun shop when my wife developed cancer 20 years ago so I can't revisit the test.

[44man]

Good point, Taz. I didn't approach your initial question from that angle, only "as asked".

Ken Waters (the "Pet Loads" guy once in "Handloader" magazine) discussed this question at some length in an article concerning 32/20 WCF revolver loading. His view was that shoulderless round nose bullets "self-center" into barrel forcing cones much better than do sharp-shouldered wadcutter or semi-wadcutter designs. If there is an alignment problem between chamber throat and barrel, he felt that shoulderless RN castings were likely to survive any such problematic transitions in better shape than the squared-profile front bands of a Keith/SWC or WC. It made empirical sense to me, and it seems to me that the round-flat-nose of the levergun era and the present day could yield similar advantages in older, worn rollers whose line-ups might be less than ideal. Food for thought, if nothing else.
WOW, full circle! I did not know Ken wrote that and I have all his books but never loaded the nine.
But everyone here knows why I don't like Keith boolits.
Gap comes up often but it has nothing to do with accuracy either, just a few fps is all. Sometimes not. Many revolvers with a large gap can shoot faster then a SS or semi auto with the same loads.
I never use a chronograph to work loads, those numbers do not make a gun shoot! They do not kill deer faster either. Leave the machine home, it will distract you from shooting groups to get readings.
I started messing with revolvers about 62 years ago but it was 1980 when I started to think, IHMSA, the greatest teacher ever. I never shot 25 yards even back at the start and 100 was common until the .44 in 1956 when I went to 200 to over 500. Elmer did affect me but he was wrong with the boolit. The cylinder must be "clocked" by the nose ogive.
Friends wanted super tight cylinders and spent a lot until they seen extreme damage. Line boring appeared as the solution but the hole is just started with a jig in the frame, still needs chambered from the rear so setup must be in millionths. Then an after market barrel is installed that might not be bored and rifled in line with the cylinder. Threads might be off. They spit barrels out of machines like springs or 1/4" bolts.
I will take gang chambering any time and some slop in a cylinder. There is not a single advantage to line boring or a tight gun. If done right you can't afford it anyway.
I did two things with my SBH, I cut the cone to 11°
and cut my mold with a boolit ogive as close to 11° I could. It has exceeded 80,000 of the heaviest loads you can shoot with zero wear. Most were Hornady bullets so why should cast have a shoulder?
Some buy a Belt Mountain pin because the pin latch is wrong and it moves out---GOOD and a good pin but then you fit to zero tolerance---WRONG! Then someone said shoot it enough to wear it in--WRONG, every boolit will be off center.
I see no problem with the Ruger .357/9mm. If you wear it, you will be 500 years old.