Just starting to reload lead. Have some questions as they relate to hard cast bullets (BHN 19) loaded for a velocity of approximately 1300 fps...

1. What is the "ideal" relationship (in measure) between cylinder throat, bullet and bore? As I understand, it would look like this for .41 mag"

Cylinder throat: .4105"

Bore groove diameter: .409"

Bullet: .410" SWC 210 grain (BHN 19)

Is this correct?

2. Hypothetically, if the bullet diameter was .411", or 001" larger than ideal, typically what is to be expected? Poor accuracy? Higher than normal or dangerous pressure? Leading in chamber?

Reason I'm asking question #2 is, I have some hard cast lead bullets that I bought and some that were given to me, both boxes are marked .410" but measure more like .4112". They do not "push-fit" my cylinder throats.

To add further... I was told that all lead bullets "spring back" some when sized and the oversize differences I was seeing should not raise any concern. I don't want to proceed to use these bullets if there is a safety concern, or if it is certain to result in a waste of time and effort.

Thanks in advance for your help here.

1. Sounds correct.
2. No accuracy problems. Higher than normal pressure but nothing your handgun could not handle. Leading in the bore.
If lead bullets "spring back" after sizing, the spring back is very slight. Measureable somewhere in the ten thousandths of an inch range.
Since you did not mention what handgun you will be shooting, I hope it is a Ruger. All kidding aside, you can load a few of these bullets and test them out. Being .002" over groove diameter should not make that much of a difference. Decrease your current load by at least 10% and work up to the velocity that you desire. Be alert for any unusual signs of high pressure.

Oversized lead bullets usually cause no problem because even the hard alloys are still much softer than copper and they will swage down in the chamber mouth same as in the bore. The only threats, pressure-wise, would are if the bullets were so large they expanded the case until it had no room left in the chamber to open up and let go of the bullet. The other is that leading in the cylinder will build up faster under these conditions, so you want to watch that it doesn't get so heavy that the front of the cartridge case is closed in upon. It needs that open-up room.

A common technique in accurizing a revolver is to ream the chambers to SAMMI maximum. so a tight chamber is not required in a revolver as much as it is important the chambers all be the same. I own a Redhawk in .44 Mag that shoots 1" groups at 50 yards all day long from 5 of its chambers, and 1.5" when the sixth chamber is used. I bought it at a store which had three in stock, so I was able to examine each one closely and choose the one with the best timing and centerning of the chambers on the barrel axis, as well as having the most uniform barrel/cylinder gap and a very clean crown. This gun has not been accurized other than a trigger job. A friend owns the same exact model Ruger, but he had no opportunity to compare it to others when he bought it. I could not group under 10 inches with his gun at 50 yards using the same scope and ammunition I use with mine. We sent it back to Ruger with a complaint about the accuracy and they returned it with paper showing the shop had reamed the cylinder. It now shoots around 2" at 50 yards. Not quite as tight as my selected gun, but more than adequate for hunting. A custom revolver smith would get it shooting like mine with some additional fine tuning.

Regarding spring-back of bullets: I have seen it as great as 0.0015" in .45 caliber linotype bullets. How much you get depends on both the alloy hardness and the bullet diameter. Pure lead exhibits almost no dtectable spring-back. It is well under the 0.0001" resolution of thimble micrometers in any bullet diameter up to 75 caliber, but how much beyond that it remains true, I don't know? It remains small in cast bullets up to about BHN 11-12. That is why you see this hardness range most often recommended for firelapping.

In firelapping you want the abrasive impregnated bullet to rub hard against the narrowest places, but, having been necked down by them, not spring back out to remove metal from the wide places. You would think a pure lead bullet best fills the bill, but they are so soft that propellant pressure obturates them (bumps them up) to full diameter following a constriction. So, soft lead is only good for hand lapping. On the other hand, the hard bullets that resist obturation best will spring back out following a constriction and also rub the wide spots. BHN 11-12 is the best compromise.

You have three options for best performance if you are not satisfied with accuracy. First is to send the gun to the factory with an accuracy complaint. I have witnessed this miracle twice in my life, and both times it worked out well. Once was the Redhawk, the other with a 31/2" Charter Bulldog that wouldn't stay on a pie plate at 25 yards, but came back holding 1.25" at that distance. Amazing for such a light little gun. The factory gunsmiths usually know what they are doing.

If you contact Lee Precision (http://www.leeprecision.com/cgi/catalog/browse.cgi?1137524550.1468=/html/catalog/custom.html#CUSTOMLUBESIZE), their custom service will make you a .409" sizing die for $25+$4S&H, and you can run your bullets through it to narrow them to something closer to .410" (with spring-back) and definitely under .4105". As long as your bullets are equal to or greater than (within reason) the actual groove diameter, you won't have a problem with gas cutting due to blow-by. At the velocities you are shooting, a gas check is recommended to prevent propellant gas heat from melting the bullet base. P-wads (http://www.neconos.com/shop/index.php?shop=1&cat=16&cart=39885) are an alternative.

You might look at firelapping the revolver as an alternative to reaming. This tends to reduce leading and clear up any bore constriction at the frame (which used to be a chronic revolver problem, but the manufacturers have been doing better over the last 10 years). It will tend to uniform the chambers by cutting harder on the narrow ones than the wider ones.

Finally, before you do any of that stuff, have you slugged your chambers and bore to learn actual sizes and whether you have any constrictions?

Nick

Marshall, Thanks for the quick reply. I loaded approximately 20 rounds using the 210 gr. LSWC (BB) BHN 19 over 12 grains of Blue Dot. Average velocity out of a 5.5" barrel is 1247 fps. Not light, but not punishing. Pretty easy shooting mag load. I did not get any signs of leading in my barrel, but did have a few spots of build-up just prior to the forcing cone. I suspect that this is due to the larger than desirable bullet diameter.

unclenick, I have four revolvers chambered in .41 mag. Two S&W 657s (one from the PC), One Ruger BH (5.5" barrel) and a FA 83 (6" barrel). I have slugged all bores and measured all cylinder throats with a pin gauge and calipers. They are all pretty much the same, with the exception of my FA 83 being slightly tighter (smaller). Throats measure .4105" and bores are .409".

The bullets that were given to me are machine cast 210 gr. LSWC (BB) BHN 19. They are supposed to measure .410" but they actually average more like .4112". Originally, I was trying to find a lower velocity round for practice and I tried using these bullets under 7 gr. of Unique. Easy shooting, but very bad leading in the forcing cone area. It was suggested that I try either a softer bullet, or a slower powder and step up the velocity. I tried 12 gr. of Blue Dot and it seems to work, but I was looking for a lighter load. Guess these bullets are just too hard. I also have some Keith style 230 gr. LSWC (FB) BHN 22 bullets from Leadhead. These also measure .411+" on average. I have not tried these.

It would appear that if I want a lower velocity load, I need to find a softer bullet (BHN 12). Additionally it appears that I should be looking for a bullet with a diameter of .410" as opposed to those I have.

Do you fellas think I could run the bullets I have thru a lee sizer die and get their diameter down a tad? Also do you have any suggestions where I could buy some softer cast bullets for my application?

Do you fellas think I could run the bullets I have thru a lee sizer die and get their diameter down a tad?

See my sixth paragraph, above.

Leading from hard bullets over low doses of Unique occur because the temperatures and pressure at the breech get high as the bullet tries to enter the rifling. Higher than they would pushing a softer bullet in. This gas both melts the bullet base (harder alloys typically have lower melting points than those with higher lead content) and the gas blows out into the barrel/cylinder gap as the bullet passes, splattering metal. As I also said in paragraph 6 of the first post, gas checks or P-wads will stop this.

Nick

Marshall, I did not get any signs of leading in my barrel, but did have a few spots of build-up just prior to the forcing cone. I suspect that this is due to the larger than desirable bullet diameter.

It's pretty common to get a little lead build-up in the area of the forcing cone and even where the rifling starts. As long as the leading isn't extensive. It sounds like your bullets are performing well even though they are slightly oversized. I get this with my own cast and properly sized bullets.

It was suggested that I try either a softer bullet, or a slower powder and step up the velocity. I tried 12 gr. of Blue Dot and it seems to work, but I was looking for a lighter load. Guess these bullets are just too hard. I also have some Keith style 230 gr. LSWC (FB) BHN 22 bullets from Leadhead. These also measure .411+" on average. I have not tried these.

With hardcast bullets, you have to push them a bit. They are fine for hunting applications but they can be punishing if you shoot a couple hundred of them at the range.

It would appear that if I want a lower velocity load, I need to find a softer bullet (BHN 12). Additionally it appears that I should be looking for a bullet with a diameter of .410" as opposed to those I have.

A softer bullet, around BHN 14, would be a better choice for plinking/target work. This is equivalent to the Lyman #2 alloy which is great for all-around shooting.

Do you fellas think I could run the bullets I have thru a lee sizer die and get their diameter down a tad?

You could certainly try this. I would not re-size all of the bullets until after range testing. If you continue to get leading around the forcing cone it would not be due to the bullet diameter.

Also do you have any suggestions where I could buy some softer cast bullets for my application?

You could try your local gun shop or sporting goods store. Also, www.laser-cast.com or www.nationalbullet.com bullets to name a couple. Others can be found advertising in the shooting magazines. Just make sure that what you buy isn't too hard. If you can indent one or scratch it with your thumbnail, it is soft enough.Good luck on finding a suitable bullet and load! :)

One way of looking at it is this:

No mater what size the bullet you put in the case, once you kick it in the rear with pressure, it's either (1) going to bump up to whatever size hole is at the front of the cylinder or (2) resist expansion and be gas-cut as the pressure leaks around the sides.

The first case is what I try for..a nice balance of pressure and bullet hardness so that the bullet defoms/bumps up but not so much that it slumps and acts like putty. Can't see any good reason not to have the bullet start off close to the diameter it's going to end up inside the cylinder mouths....you can kick an undersized bullet in the butt hard enough to make it slug up, but it's probably not going to do so uniformly.

With an under sized hard bulllet, or even an undersized soft bullet used at too low a pressure to bump up, will get that kind of erosive-deposit leading people complain about...plating the cylinder face and leaving globs of lead in the forcing cone and barrel breech.