.30 caliber Boolit design

[Marlin Junky]

What I struggle with most when designing a boolit is the lube groove configuration and I'm wondering if there's been any recent research regarding this aspect of boolit design specifically for .30 caliber (or other small bore; i.e., .22"-.32") rifles. I want to get a couple high BC (approx. .400) molds cut for my '06, the first one shall be a PB design to be followed by a similar one with a gas check. The .400 BC requirement isn't all that difficult with noses in the 7/16" long neighborhood, with .190" meplats as long as the boolit weight is in the 190-200 grain range (about 17/16" overall length). What I'm having trouble with is "guessing" whether short grooves and/or driving bands are better than long ones. I don't want a bore riding design so I've decided on a long secant ogive sitting on top of at least 60% bearing surface.

MJ

[Ben]

You are WAY OVER my head !

[Marlin Junky]

You are WAY OVER my head !

Nah, it's not that complicated.

OK, here's another way to approach it... how much lube should a rifle boolit carry? A half grain? More? Less? Let's assume one has already determined their ultimate boolit lube.

MJ

[Ben]

I just shoot em', I don't design them.

I leave that to smart folks like you.

Ben

[leadman]

If you look at the Lee 230gr mold that Midway sells this may help you out. It is a tumble lube design and I have fired it with and without a gas check with no leading. It does not hold much lube.

[41 mag fan]

I just shoot em', I don't design them.

I leave that to smart folks like you.

Ben

I'm the same as you are Ben, let the smart ones design so i can have the pleasure shooting them!!

But I will give MJ one piece of advice i do know...the lube needs to go all the way around the boolit!!

[badbob454]

http://castboolits.gunloads.com/showthread.php?181277-lee-blackout-309-230-mold-bc
better than .400 mold

[Marlin Junky]

I just shoot em', I don't design them.

Ben

Ben,

Speaking of shootin' 'em... have you tried my 15 grains of 4759 load yet behind your pointy 190?

MJ

[Marlin Junky]

http://castboolits.gunloads.com/showthread.php?181277-lee-blackout-309-230-mold-bc
better than .400 mold

That's nice if all one wants to do is shoot inanimate objects... I need a meplat for varminting. Yes, it certainly doesn't hold much lube... way less than 1/2 grain to be sure. BTW, what twist was that boolit designed around? I do like the boat tail concept. How practical is checking it though? Most importantly though, how does it group?

MJ

[Ben]

Ben,

Speaking of shootin' 'em... have you tried my 15 grains of 4759 load yet behind your pointy 190?

MJ

They are loaded and ready to head to the range.

Ben

[shooter93]

MJ I'm not sure there is an answer...certain calibers needing this or that amount of lube considering all the factors that get tossed in the mix. With some of the newer lubes I believe most of us over lube though. Figure the best resters are shooting respectable groups at higher velocities and some of them only lube the area just above the gas check. I've taken Tom's advice...Accurate Molds....on several molds and I maybe able to cut back some with experimenting but the don't seem to be way over lubed.

[fecmech]

MJ I want to thank you for starting this thread. I've always been in the dark as to the difference between a tangent ogive and a secant ogive. After reading your thread I decided to get off my butt and learn what they were and the difference between them. I don't plan on designing any bullets but at least now I know the difference and even learned of the hybrid ogive! I now have just enough knowledge to be dangerous![smilie=1:

[Marlin Junky]

MJ I want to thank you for starting this thread. I've always been in the dark as to the difference between a tangent ogive and a secant ogive. After reading your thread I decided to get off my butt and learn what they were and the difference between them. I don't plan on designing any bullets but at least now I know the difference and even learned of the hybrid ogive! I now have just enough knowledge to be dangerous![smilie=1:

Becoming dangerous is the first step in your journey, weed-hop-pah. :bigsmyl2:

MJ

[Marlin Junky]

Come on Ben... show me the group! :kidding:

MJ

[Shiloh]

You are WAY OVER my head !


I just shoot em', I don't design them.

I leave that to smart folks like you.

Ben

LOL.
No offense Marlin Junky, but you are a lot more analytical than my comprehension can take. Like Ben, I rely on folks a lot smarter than me to design boolit molds.

Shiloh

[Marlin Junky]

I wish I had named this thread differently... something like, What does it take to get plain base, small bore, boolits to shoot accurately?

I shot a bunch of .30 caliber plain base boolits through my 30-'06 today and my groups with 11.5 & 12.0 grains of Blue Dot were smaller than those shot with 14 & 15 grains of 4759. The Blue Dot shoved the .311", 199 grain boolits about 50 fps faster too. Is the key to shooting PB boolits accurately, burning the powder charge quickly so there's a limited amount of gas leakage near the muzzle; and, if that is the situation, what should the boolit base look like; i.e., how long or thick should it be?

I'm going to retest using 7625 and have a feeling the faster powder will shoot even better, assuming I can maintain the same boolit hardness and velocity. My alloy is BHN 14 and according to QuickLoad, I haven't broken 12K PSI yet. My lube is MML.

MJ

P.S. I'm not offended, Shiloh. Hell's bells, my wife has called me way worse than that. Does this mean you're not going to read my posts anymore?

[Chicken Thief]

So you want BC then you want meplat.
What 'bout this:
http://castboolits.gunloads.com/showthread.php?190050-Ness-30cal-safety-slug&highlight=ness