Cast bullet diameter with revolvers

[brasshog]

I have a newly acquired Ruger Blackhawk 41 mag with a 4 5/8" barrel produced in 1977. Today I slugged the barrel using the Lyman #410610 cast with WW+2% Tin (220 gr) that was sized as cast at .412. I used this boolit without a gas check seated at the hardness that I shoot most often because it is the mold that came with the gun and I will be casting for it initially. The cylinder sized the projectile down to .410 as expected. The barrel sized (with obturated/swollen boolit) in at .4115-.4120 with the last inch being tighter than the muzzle (nearing throat). My question is in regards to the barrel versus the cylinder size. I doubt that a .410 sized boolit will hit the barrel and get any real accuracy with cast with it's .412 sized barrel. I noticed that on some custom gunsmiths sights they offer a service for "shooting cast bullets". Is this a modification to the cylinder for correcting an issue such as this ?

The mold is producing a boolit with an outer frontal band (above crimp) diameter of .411, a inner mid band diameter of .412, and a inner lower band above the gas check at .411. I'll have to buy some new powder and I'm questioning the accuracy potential as is before I spend the money. I understand that a short barrel isn't going to have the sight radius of a longer barrel for accuracy. What are your thoughts on the barrel diameter vs the cylinder throat with either cast or J-words ? It seems that I have a limiting factor in the cylinder throat. Thanks in advance for any suggestions or advise.

I have provided examples below for an explanation
224811

224812

[Moonie]

Contact Douguy to have the cylinder honed to the proper diameter for cast. He does great work and is very reasonable. You only have to ship him the cylinder.

[Rcmaveric]

It doesn't matter how many driving band sizes a bullet has, once it gets sized down by the cylinder throat. They will all be the same diameter. Then that undersized bullet will rattle down the rest of the barrel while all the gasses blow by. I would recommend some pin gauges or slug just cylinder, forcing cone, and muzzle so that you can accurately compare with definite measure rather than "Feels Like". So unless your hand is calibrated i wouldn't trust feel. Just tap in a soft slug and nock it back out the other way.

With a .410 chamber, your gun will never be accurate. If you did fix the chamber, then your forcing cone or beginning end of the barrel is swaging the bullet down to smaller than the muzzle.

The swaging down starts in the cylinder throats. Then the bullet jumps the gap into the forcing cone. The forcing cone swags the bullet down to the barrel dimensions. Some guns, the barrel constricts near the muzzle. FortuneCookie 45LC has great video explaining this on youtube.

[Outpost75]

Your revolver may have thread choke also from the barrel being over-tightened in the frame.
Lapping will help.

[brasshog]

Your revolver may have thread choke also from the barrel being over-tightened in the frame.
That's a good point Outcast. I hadn't thought of that. Now that I look at it the boolit was hard to move at exactly the area where the frame and barrel meet.

RCMaveric...The "feels like" comment was in reference to the initial resistance due to the swelling of the boolit and engaging the threads thus suddenly becoming easier until I hit the frame area but I see your point and agree with you on it. I will pursue it further tomorrow as I get the chance and post the results. I'll have to figure out how to slug just the first inch or less since I can't hammer it in easily from that position. Also, my thought was "How can a J-word ever be accurate in this barrel with a .412 size ? Aren't they all .410 for the most part ?". Thanks

Thanks for the referral Moonie. I sent him a pm.

[DougGuy]

If you have a plastic cleaning jag, put it on a cleaning rod and patch it tightly into the bore with paper towel or cotton cloth, and see how much effort is required to keep the jag moving as you push it. Any change in resistance along the way is caused by a change in bore diameter. If you push the jag along the bore and you feel a series of bumps, the "Lawyer Warning" is often rollmarked so deeply into the side of the barrel that it will raise a series of ridges inside the bore and you will feel them with the jag. If the jag gets harder to push where the barrel meets the frame, you are feeling thread choke. If the tension against the jag is moderate, you have a slight choke. Maybe .001" to .0015" if the jag stops and you have to beat it the rest of the way, the choke is severe, and may be as much as .003" or more.

If your jag moves smoothly, you should have a BIG GRIN on your face when it pops out of the forcing cone!! Me, I would be dancing a jig if it was my gun!

If you use this test on a medium framed New Model gun, you may find the jag moves smoothly and evenly all the way down the bore because Ruger has refined their production processes and is producing some of the finest fit and finished sixguns that they have EVER produced. The lawyer warning is faintly imprinted on the bottom of the barrel, and they are generally not clocked into the frame as hard as large frame guns, I really like the medium frame offerings for this reason.

[brasshog]

Thanks for the information Doug. I received your reply pm. My NM Blackhawk is pre-lawyer and thus does not have the mark. I'll try the jag tomorrow after work and post the results.

[Hick]

I just size my cast 0.001 over and let it go at that (0.358 for my S&W 38 Special and my Ruger New Model Blackhawk in 357 Magnum). Never slugged the barrels or had any special work done. They don't lead and I can hit things out to 50 yards easily, even out to 100 yards off the bench. Maybe my standards are too low, but it seems to me that we overthink this at times.

[Wayne Smith]

For future reference if you are using a micrometer for measuring - use pure lead for slugging. Bi- or tri-metal alloys will spring back and your measure will be too big.

[DougGuy]

I just size my cast 0.001 over and let it go at that (0.358 for my S&W 38 Special and my Ruger New Model Blackhawk in 357 Magnum). Never slugged the barrels or had any special work done. They don't lead and I can hit things out to 50 yards easily, even out to 100 yards off the bench. Maybe my standards are too low, but it seems to me that we overthink this at times.

Not everyone is afforded the same amount of success with cast boolits until they examine what the cause of some of the issues is. The majority of Ruger single action revolvers have undersize throats which may work well with factory ammo, but not so well with cast boolits. Here is where the throats need to be larger so that the cylinder itself does not become a multi-port sizing die as you fire the gun. This is accepted as the norm in most calibers. It's not overthinking at all to choose to have the cylinder throats "dimensionally corrected" when the before and after range reports show a noted improvement. I have YET to see a degradation in performance or accuracy from having this done.

As far as sizing .001" over, what are you measuring that you arrive at your final size? If you size greater than throat diameter, there is *zero* chance that your boolit will exit the front of the cylinder larger than the throat itself, and if your cylinder is tight as many are, you will be delivering a slightly undersized boolit to the bore, REGARDLESS of what you size to in the beginning.

[brasshog]

Wayne-I was going to use pure lead when I slugged it again to re-check everything. Thanks for the reminder. I wasn't considering the spring back when I first slugged it.

Hicks-This weapon is primary role is woods back up, range time, and hunting next year. Most hunting is within 30-50yds but my standard is a 6-8" group (perfect day at the range) at 100 yards (with j-words) from the bench with open sights. I have achieved this in the past with 357 mag (10" T/C Contender & Dan Wesson 6") and 44mag/445 Super Mag (Dan Wesson 6", Ruger NM Super Blackhawk 7.5", & Colt Anaconda 8 3/8") with longer barrels so I may have to settle for a slightly larger group due to the shorter sight radius and my slowly diminishing eyesight due to age. I load my pistol hunting rounds the same as any benchrest shooter would for a rifle match by sorting for interior water capacity (weight), weighing each boolit, inside and outside turning of the brass, etc...ect...I'm not a progressive stage press kind of guy or have an issue paying $400 for a set of rifle dies versus the normal sets if needed. Processing brass and loading is my "Zen" if you will. I guess it's similar to an OCD issue with me although I don't have OCD. I HAVE to slug the barrel, measure everything, and get it "just right". If I make a bad shot on an animal I want to know that it is the user and not the tool. I just see a possible potential for any accuracy issue and want to resolve it if possible before I start this long process again especially since this time I will be trying to hold that standard with cast rounds which I'm admitingly less familiar with.

Rcmaveric-Thanks for the information about pin gauges. Now I'll have to get a set eventually lol

[Mal Paso]

Rcmaveric-Thanks for the information about pin gauges. Now I'll have to get a set eventually lol

MSC Direct has a set of .251-.500" pin gauges for $100. The minus set is KB86463023. Reg price $223. It was one of the first reloading tools I replaced as sizing and reloading dies are often Not The Size Marked.

PM me if you have trouble.

[DougGuy]

-or- you could order singles from Meyer Gage Co. You would need .409" through .414" in half thou increments to cover the 41 caliber and this will insure you have fine measurements, i.e. half thousandth steps, which is much more detailed than .001" increments. This would be 11 gage pins, they are about $2.60 each and it will qualify you for their $25 minimum order. If they cost more than that, stop at .413" because this is about the upper limit unless you have a cylinder that Bubba reamed out with a wooden dowel in a drill motor and some 80 grit paper at the kitchen table!

[John Boy]

The SAMMI nominal bullet diameter is 0.410 ... so, take it from there

[brasshog]

Hmm DougGuy. Interesting idea on how to "fix" this problem at the kitchen table [smilie=1: Maybe I can try to......Nope ! :lol:

[fredj338]

I would open the cyl throats. I have a RBH ss that had 0.450" throats. I only shoot lead bullets & accuracy was good but never great & it leaded early at any vel. After opening the throats to 0.452" shooting a 0.452" bullet, groups were cut in half & leading virtually gone.

[DougGuy]

The SAMMI nominal bullet diameter is 0.410 ... so, take it from there

This is for j-words as we know them...

[brasshog]

Ok test results. After taking everyone's input and my questioning of my method of wisdom (or lack thereof) I rechecked the dimensions today. Using a pure lead 452 round ball I first checked the first inch of barrel at the front sight. I then removed the projectile after marking it for orientation. I did this by placing a wood (oak) dowel rod section in the barrel before loading the ball and pushing it back out. Measurement was .41200 with both of my dial calipers. I then re-inserted the ball and pushed it by hand using a T-handle cleaning rod section and was able to push it to the frame area where it gained resistance. I marked the rod and removed it to verify ball location. It was at the frame as suspected. I pushed harder and it popped out of the forcing cone. Measurement was approximately .41125 (minus 3/4 of one thousandth inch on the dial from .412). I took the same ball and then loaded it into the cylinder. I had to use a hammer and rod to get it through and it measured .41000 (dead on .410). Test was repeated with similar results.

Findings: It appears that Wayne was correct in that I had spring back from the initial test due to a tri-metal boolit. Looking at the two they were miles apart in smoothness. The .410 is insufficient for my use and the cylinder throat will have to be opened up. I'll send it to DougGuy as soon as I have the extra cash.

Today's question: Since my Lyman mold 410610 is dropping at .412 should I change alloys to try to get better fill out or just buy a different mold that is .413 and size boolits to .412 or .413 as need for testing ? My hope is that since this firearm is of low round count (hasn't been fired in twenty years) that the wear at the frame area will slowly open up and consistently allow .412 sized boolits down the barrel in time.

[Char-Gar]

Contact Douguy to have the cylinder honed to the proper diameter for cast. He does great work and is very reasonable. You only have to ship him the cylinder.

This is The Solution. I had a Ruger 41 of the same vintage with the same problem. I sent it back to Ruger three times and they never did anything about the disparity. A cylinder that has smaller throats than the barrel groove will never shoot cast bullets to any satisfactory level.

[brasshog]

I agree Char-Gar

[DougGuy]

was able to push it to the frame area where it gained resistance.

The amount of resistance you encountered doesn't sound severe enough that firelapping won't ease the boolit's passage, and may get rid of the choke completely. I would firelap this one after the cylinder throats have been honed, lapping boolits will work much better than through .410" throats.

[brasshog]

I agree DougGuy. I was considering firelapping it once I get it the throats enlarged. I tried your suggestion with the patch but didn't really notice any restriction hence why I chose to use the soft lead ball. I figured that if I could push it by hand after the rifling was engraved upon it that it would be easier to detect. When I did the same thing with the tri-metal boolit it was a beating and banging process with more so at the frame. I also noticed that once free of the frame the soft ball simply pushed out as easily as it had started.

PS-I appreciate all of the input, suggestions, and recommendations that everyone has offered. Thanks again.

[blackthorn]

MSC Direct has a set of .251-.500" pin gauges for $100. The minus set is KB86463023. Reg price $223. It was one of the first reloading tools I replaced as sizing and reloading dies are often Not The Size Marked.

PM me if you have trouble.

Thanks for the tip on where to get those pin gauges! I have been looking for a good long while and every time I found some the Co. did not ship to Canada. I did a search using your information and found that MSC Direct has an outlet(S) in Canada. My order is placed. Thanks again!