Four Questions about projectiles

[The Dixie Diarist]

Hello All, first post here.

First question: I was doing the math and it seems that (for a .45LC or ACP) a 200gr. cast lead bullet has more muzzle energy than a comparable 230 or 250 gr. cast lead bullet. I was using the formula of muzzle velocity squared x bullet weight in grains / 450411 = muzzle energy in ft-lbs. I calculated this for both Long Colts and ACP's using Lee's reloading data for Titegroup. Is this so, and if so, is there any advantage to a 230 or 250 gr. projectile?

Question Two: Is there any advantage between a truncated cone and an rfnp assuming the meplat is the same? If so, to which does what advantage go? (If it matters I have a SigSauer P220R and a Uberti SAA w/ a 4-5/8" barrel.) I know about the advantages of SWC's, so you don't need to give me that as I am already considering those.

Question Three: as I am still considering using 230 and 250gr. cast lead projectiles, can anyone give me a loadout using Titegroup for either of these weights in .45LC and/or .45 ACP?

Question Four: What is the difference between a Keith and Thompson (?) SWC?

 

[Jon_Snow]

Welcome to THR Dixie,

I'll answer the questions that I can and let someone smarter than I answer the rest.

1) While your units are incorrect it is true that at the muzzle, lighter bullets will often have more energy than heavier rounds. As you noted, energy increases with the square of velocity. The advantage of heavier rounds is that they lose their velocity more slowly, so as the round travels downrange, it retains more energy than a lighter round. At some point the heavier round will have more energy than the lighter round.

2) I think you meant RNFP. If so, I think the assumption that the meplats are the same is not a very good one. TC's generally have smaller meplats and I believe, feed more reliably. As for ballistic differences, I can't say.

 

[cheygriz]

At pistol ranges, the lighter faster bullet beats out the "pumpkin roller" for energy every time. For the light bullet to lose enough energy to be surpassed by the pumpkin roller, you'd need to exceed any practical pistol range.

If you're looking for effectiveness against a living target, instead of the truncated cone or RNFP, go to a 185 or 200 grain jacketed hollow point, loaded to +P.

 

[Walkalong]

We could debate bullet weight until the cows come home. I like 200 or 230 Gr in .45 vs 185 Gr at higher speeds.

SWC's are for target shooting, so who cares how fast they are going?

In general, the bigger meplat bullet will work better to kill game when using cast bullets.

 

[cheygriz]

I agree. The bigger meplat is definitely more effective in killing game with cast bullets.

But why use a cast bullet? A JHP is more effective still for anything you're going to hunt with a .45 ACP.

as foir the light v heavy, I also like the 200 graion in .45. Preferably the 200 Speer "Flying Ashtray," JHP.

 

[243winxb]

A 230 or 250 gr. projectile will penetrate deeper than a 200gr depending on the yardage that it makes contact at, when starting at the same fps. Velocity can change over long distance, so Ballistic Coeff. comes into play on different bullets. Look at Lees molds here for Coeff. > http://www.leeprecision.com/html/catalog/bullmol2.html Loading data can be found here > http://data.hodgdon.com/cartridge_load.asp

What is the difference between a Keith and Thompson (?) SWC?

Keith-lswc , lead/tin alloy, being harder than pure lead, .430" diameter. Made for cartridge revolvers Thompson- Maxi ball, pure lead, soft, used in muzzle loaders over black powder. It can not be used in a cartridge firearm as the base is undersized for easy loading Is this what you are asking ??

 

[floridaboy]

I think that the OP may have meant Thompson designs of cast bullets. I have a Lyman mold that casts a 255 gr, .44 SWC/HP, gas checked slug that is a Thompson design. The only thing that I don't like about it? Single cavity mold. But I've never seen a hollow point that wasn't a single cavity.

 

[Jesse Heywood]

Titegroup with a 250 gr 5.7 to 6.2 gr. If I were loading a 45 Colt for plugging people I would prefer a big, heavy, flat nosed wadcutter. I wouldn't care about penetration, I would want trauma. as for what is in mine right now, it has Silvertips. It makes for less work for the lawyers later.

 

[243winxb]

floridaboy, thanks. Ray Thompson, i googled it.

 

[The Dixie Diarist]

Thank you all for the responses. I cannot reply to them on my lame little phone:banghead:, but here at the library - when I can get in here - is a different story.

I think, for pistol range use then, the 200 grain cast lead is my choice and my RNFP's will do just fine, although I may yet go for a 230gr. TC or a 250gr. SWC or RNFP...

Thanks for pointing me to Hogdens site for the load data, too.

Deo Vindice,