Using Jacketing Reloading Data For Cast Boolits?

[shotstring]

My understanding is that generally jacketed bullets build higher working pressures than cast bullets due to the greater bearing surfaces of the metal jackets. From this, I would assume that as long as the cast projectile wasn't terribly oversize, you should at least be able to use reloading data for jacketed rounds without getting in too much trouble. Is this in error? I have reloaded tens of thousands of handgun rounds using this principle, but they were never max loads and the cast alloy was always the same and the calibers were very few.
Still, due to the shortage of reloading data for cast boolits, being able to use jacketed information safely for comparison sake in building up a load would certainly be a tremendous help.

But I don't want to do this at the risk of creating a dangerous load, particularly in rifle calibers. Anyone have any information to share on this?

I understand that cast boolits will reach a point where they are stressed to the point of excessive leading and accuracy will go out the window. I am not talking about that - just the safety factor that lets you try jacketed data without worrying about doing physical damage to yourself or your gun while you look for that point where the correct alloy, diameter, powder charge etc brings you to the point you wish to arrive at with little or no leading and outstanding accuracy.

[pumpguy]

It's my understanding that we should use a little less powder than the jacketed loads. Lead obturates better and fills the barrel better. Jacketed has much more blow by. Do not count on me for this. I am not 100% sure this is true.

[454PB]

Cast boolits of the same weight will usually produce less pressure than jacketed, but never assume anything. Work loads up the same as you would with any change in component. Be extra cautious with any change in cartridge capacity due to increased seating depth.

[Pepe Ray]

Probably I shouldn't assume but, could it be that you do not have a Lyman reloading manual?
Pepe Ray

[Shiloh]

Probably I shouldn't assume but, could it be that you do not have a Lyman reloading manual?
Pepe Ray

If you don't have this manual, It is a must have.

The Lee Modern Reloading book has a formula on reducing jacketed bullets loading data for cast. I'd get the Lyman Book.

http://www.midwayusa.com/eproductpage.exe/showproduct?saleitemid=823498&t=11082005

Shiloh :castmine:

[leftiye]

Jacketed data is usually safe PRESSURE WISE to use with lead boolits. An equally important question is if it will shoot accurately. Accuracy generally goes south with anything but the lightest leading, and maybe then too. Lead of any persuasion cannot withstand as much pressure as jacketed bullets can. If you want to run around in circles cussing- shoot pure lead boolits at magnum pressures out of a revolter (or anything else for that matter). Shoot enough that the leading gets really bad before you stop.

[Leftoverdj]

I cheerfully use jacketed bullet data with cast bullets as long as the jacketed data is relatively low pressure, under c. 35k cup. Past that pressure level, it's difficult to impossible to get cast to shoot. Folks who know more than I may be able to do it, but I'll stick to what I can do.

I have very little respect for the Lyman Cast Bullet Handbook. The data may be safe enough as to pressure, but it is chock full of loads that I know cannot shoot accurately. There has not been a major revision in 40 years, and we have learned a lot about cast bullet performance in those forty years.

To be fair about it, the pistol data ain't all that bad. It's the rifle data that drives me nuts.

[shotstring]

No, I don't have a Lyman book yet, but will have soon. Even so, knowing logically the difference between how jacketed slugs and cast slugs perform makes it much easier to work up a load without having to guess so much if bullet weight changes due to alloy or what a given mould throws. In all honesty, I think too much emphasis has been placed on reloading data not being correct unless it involves using only the projectiles listed by the given manufacturer. I believe reloading manuals were written for safety but also to sell the manufacturers product. I have used the Speer reloading manual all my life, regardless of what primer, what brass or what brand of bullet was used without ever having any signs of excess pressure appearing. Often used Hornady jacketed, even though the listed loads in the Hornady manual were far below the Speer loads as far as powder charge.

I try not to believe everything I hear unless it also makes sense logically but then I try not to be crazy or dangerous either, and always check for pressure signs as I work up a load. But I did extensive testing on a bullet made from a reverse hollowbase wadcutter that was bored out, serrations cut in the edges to create petals on impact, and a stainless steel screw inserted into the wadcutter raising the weight from 146 gr to 158 roughly, coated the thing with teflon lube and drove the bullet at maximum 357 velocities exceeding 1300 fps. That is soft lead driven down the bore at Mach3.

Yep, it sometimes leaded badly, but as this was a defense round, it didn't matter because you were only going to shoot a few rounds at any given time. In the accuracy department, it was a tack driver. So leading does not always translate out to poor accuracy, at least on the short term.

So if I don't have cast bullet data that closely approximates the boolit and powder that I am using, it seems logical to use the closest jacketed data as a starting point safety wise. Since what I understand about lead boolits now indicates that they often perform better at lower velocities, it would seem to be a good idea to start at the lower listed velocity range.

I'm sorry for rambling a bit here, but I have seen so many reloading manuals where the maximum listed loadings are just plain wrong. I trust the experiences of people more than I trust manuals and that is why I am asking you who have had tons more experience than me in this area and probably a lot more on a given load then the person that put the manual together. If using jacketed data is either dangerous or ineffective, then I shouldn't be doing it. Otherwise, I don't see why not.

[VTDW]

This is a great thread for me. I have been using JB data for several years with cast boolits but I shoot the Marlin Big Bores and the fps isn't that great. I have one of the new Marlin Express .308 MXs which operates in the 40,000 psi range. I am waiting on a sizing die from Buckshot before loading up the .30 caliber boolits I have cast for it. I will take all this great advice under advisement as I proceed.

This place is a Godsend!!

Dave

[Leftoverdj]

This is a great thread for me. I have been using JB data for several years with cast boolits but I shoot the Marlin Big Bores and the fps isn't that great. I have one of the new Marlin Express .308 MXs which operates in the 40,000 psi range. I am waiting on a sizing die from Buckshot before loading up the .30 caliber boolits I have cast for it. I will take all this great advice under advisement as I proceed.

This place is a Godsend!!

Dave

You're in fat city, Dave. All Marlin did was re-invent the .300 Savage. There's a ton of data available, both cast and jacketed.

[bhp9]

There is simply no substitute for using a chronograph as the published loads for anything, whether they be lead or jacketed sometimes are no where close to what your gun is giving you velocity wise. A good rule of thumb is to keep the velocity below 1,900 fps.

Remember to that working up loads for say a 24 inch military barreled gun and then shooting them say out of a military 29 inch gun will boost velocities so if you were shooting at 1,900 fps in the shorter barrel and then dump the same load into a long barrel gun, your velocity increases and your groups will often “go wild

[yeahbub]

Cast boolits of the same weight will usually produce less pressure than jacketed, but never assume anything. Work loads up the same as you would with any change in component. Be extra cautious with any change in cartridge capacity due to increased seating depth.

454PB's right. Shotstring, I've had it go both ways. Sometimes the obturation would be great enough to momentarily hinder accelaration, thus showing higher pressures than a jacketed bullet of equal mass. With bullets of similar bearing length and driven within book limits, there's rarely any problem. In my experience, the softer the bullet, the more evident the differences in pressure signs will be. More so when nearing maximum pressures. When no cast data is available, I use low-end jacketed data to begin load development and haven't run into any problems.

[IcerUSA]

I got a little info from an area gent that said to start at 85% of a condom load and work up from there , so far seems to work well .

Just my $.02 minus inflation, taxes , and ????


Keith

[Buckshot]

.................You can pretty much use jacketed data load for load with equal weight cast in any of the rifle cartridges with max velocities of around 2200 fps. Most common would be the 30-30, 30-40, 35 Rem.

.................Buckshot

[NVcurmudgeon]

.................You can pretty much use jacketed data load for load with equal weight cast in any of the rifle cartridges with max velocities of around 2200 fps. Most common would be the 30-30, 30-40, 35 Rem.

.................Buckshot

Exactamente, Rick! In the muzzle velocity range of the cartridges you mention, plus down to the .45/70 level, I use jacketed data for cast loads. But reaching up into the .270, .308, .30/06 jacketed area is out of my comfortable velocity zone, so I still use .30/30, Krag, and .35 Rem. jacketed data as a starting point in larger capacity, higher pressure cartridges for starters. Good way to stay out of trouble ; o )

[sav300]

In Aus there aint that much casting and loading data and the one book I found has a good collection of load data is Lee,it has a section for lead and in with all other loads there are lead loads.
I am wary of SMALL charges of FAST powder and do not use them.My load in my 300 savage 165 hard cast (bought em) 30gns BM2 =2070fps =2in at 50 yards thru a 2 1/2 power scope.
Lionel
:castmine: yea!

[VTDW]

You're in fat city, Dave. All Marlin did was re-invent the .300 Savage. There's a ton of data available, both cast and jacketed.

Thanks for that tidbit of information Leftoverdj. It should prove invaluable to me.:drinks:

Dave

[mooman76]

In Aus there aint that much casting and loading data and the one book I found has a good collection of load data is Lee,it has a section for lead and in with all other loads there are lead loads.
I am wary of SMALL charges of FAST powder and do not use them.My load in my 300 savage 165 hard cast (bought em) 30gns BM2 =2070fps =2in at 50 yards thru a 2 1/2 power scope.
Lionel
:castmine: yea!

Have you tried the Lyman manuel for cast data. They have allot more and better data than Lee. That's what I use almost exclusively!

[mooman76]

I think Leftiye has it right. I don't think it is so much unsafe as long as you work up as usual as it is the type of powder for accuracy. When you do find powder data it is mostly powders you would't or couldn't use with jacketed rounds!