HP Bullet Design

[rodwha]

A fellow on the Rem 1858 forum has created a BP HP bullet and has/will create a ram with a HP pin to preserve the integrity of the cavity upon loading. I’ve been wanting to modify my current designs as I see their preferred powder charges don’t change despite projectiles used so I figure instead of fillers I’d fill the excess with lead.

I like a wide meplat as these will penetrate and still create a large wound, which is something I’d want for things like hogs. But I’ve figured a HP version might well be good too (I’d buy an additional loading lever assembly).

What comes to mind is the old Flying Ashtray of Speer. These bullets performed quite well well before these premium offerings we see today. So I’m thinking I’d want to create something along those lines. I know the cavity was wide and deep, but I see differing ideas of what the cavity itself looked like. Some seem to claim it was a straight walled cavity whereas others seem to show the more typical tapered cavity. Without a jacket I’m wondering how thick I’d want/need the initially lip to be. Seems you wouldn’t want it really thin. Right now my meplats run 0.375” on a .452” (after its run through the barrel) bullet. The main bullet weighs 195 grns but with modifications I’m assuming it’ll be somewhere between 205 and 220 grns as a solid and maybe as low as 180 with a huge cavity, if I go that route. I don’t necessarily want to give up too much penetration, though I figure what works on a man will work on a deer well enough, especially as ours are rather small.

I intend to allow for a cereal box cardboard over powder card, another ~1/16” for powder charge variation, and ~1/16” under the chamber mouth as it’s been shown bullets get gas cutting.

I intend to go back to Accurate Molds and send it from there to Hollow Point Molds (?).

Thoughts? Ideas? Recommendations? Anything else to consider?

This is my 195 grn bullet:

http://accuratemolds.com/bullet_detail.php?bullet=45-195C-D.png

I’m likely going to ream my chambers again from 0.449” to maybe 0.452” as my grooves are just slightly over 0.452” on my Pietta NMA. Bullets don’t need to be grossly oversized as with a ball so I’ll reduce the diameter from 0.456” to 0.453-4”. I also want to increase the length and diameter of the base to help keep the bullet centered upon loading and help put some more mass into the chamber reducing the OAL of what’s protruding (I already had to modify the loading window even for my shorter 170 grn version at 0.400”).

Since the chamber walls will be that much thinner after reaming again, as well as increasing the mass, I think it prudent to decrease the top driving band length. I’ve used a weighed 33 grns of 3F Olde E, though I broke that measure and will be reconfiguring the accurate charge, so pressures aren’t higher than with what’s common.

I’ve also debated reducing the meplat from ~83% to 78-80% as some feel above 78% and it can create aerodynamic issues at longer range and I feel the itch for a Remington carbine. But then others claim this is false, and we see plenty of long range handgun hunters using very wide meplats successfully.

Side note for reference:

From what little chronographed results that I’ve found my charge and bullet are within the .45 ACP realm of 350-425 ft/lbs. Some claim it could be a little higher.

I’m intending on a 4 cavity mold with only 2 of them hollow pointed so that I can load 3 of each and be prepared for about anything.

[Good Cheer]

T'were I designing a hollow point for a percussion revolver it would have to be heavy enough to assure penetration whether it expanded or not. My experiment with full wadcutter design showed me the necessity of preserving both boolit mass and powder mass. But if it was going to be a hollow point I'd make it a big flat with a cup point with little lip.

What I've come up with is that preserving the available powder space and using a nose design with enough weight that provides penetration is how you're gonna maximize the kill power for a percussion revolver, for the very same reasons that black powder loadings in early cartridge revolvers were loaded that way. They just did what worked best.
A slightly reduced flat point seems to penetrate best. So if it was me I'd use a boolit with no lube grooves that slipped into the chamber and sheared on the front (same thing I always end up with). But here's the kicker; make it a nose pour and have the boolit length changeable with an adjustable length base plug. That way you could experiment with lead length versus powder column length and see where the optimum was. Kind of a blunt force sort of approach.
http://i.imgur.com/LrWje1B.jpg (https://imgur.com/LrWje1B)

[Good Cheer]

Was thinking just enough reduction on the nose initial contact with target as to help penetration.

[rodwha]

I’d still want a line groove as I’d shoot a lot in a range session. The lube groove I designed is fairly minimal. I might reduce it a little if I decide on it being specific to just my NMA and not also work for my ROA with the longer barrel and stouter charge. It would be a little more ideal I suppose, but I like the idea of one mold for both guns. But then that all might well change if I decide to modify my ROA, one being to deepen the chambers (I assume it’s accurate powder charge will remain the same).

The NMA has more excess room. I could likely get 210-230 grns of solid lead in there which would increase the weight of the HP as well. I’ve also considered seeing about modifying those chambers as well. Ream to .452” right up to the bolt stops and square up the remaining portion. Wouldn’t likely add much though, but it would add a little more to the projectile.