Revolver boolit design

[subsonic]

Since I started playing with Mountain Mold's website, I started thinking about revolver boolit design.

I DON'T WANT TO ARGUE KEITH VS LBT IN THIS THREAD!

What I want to discuss is the rest of the boolit.

How much driving band should be out of the case and why.
How many lube grooves/driving bands and how thick and deep?
How much lube should it carry?
Where should you put the crimp groove and why?
How many calibers long should it be considering twist and velocity?
And what happens when you add a gas check.

Any takers?

[Piedmont]

Dan has an articles section on his site. I suggest you read his article on just this subject. Dan did one for me and I specified a .080" front band instead of a .100" and included a bore ride. It worked out perfectly in that particular Ruger and had the band been .100" it would not have chambered when crimped in the crimp groove.

[44man]

Since I started playing with Mountain Mold's website, I started thinking about revolver boolit design.

I DON'T WANT TO ARGUE KEITH VS LBT IN THIS THREAD!

What I want to discuss is the rest of the boolit.

How much driving band should be out of the case and why.
How many lube grooves/driving bands and how thick and deep?
How much lube should it carry?
Where should you put the crimp groove and why?
How many calibers long should it be considering twist and velocity?
And what happens when you add a gas check.

Any takers?
Ouch, most of my best shooting boolits are accidents.
Are you really going to make me think? I don't think I can answer.
I can with some to start, SOME of the boolit should enter the throat to just center it to the bore but there is no measurement and even a small amount is enough.
Lube grooves? I find 2 to 3 better then one big one even if lube quantity is the same.
Nose length is only for what fits the cylinder with some room to spare.
I have seen a gas check increase pressures with one boolit, yet do nothing with another. Most revolvers do not need the expense.
Any boolit length can be shot as long as velocity can be achieved for stability. That does NOT mean a heavy boolit needs shot faster but just enough without making pressure too high. Usually lower velocity then a lighter boolit. It is never how fast but where is spin correct. Increase boolit weight and length and the caliber will not be able to stabilize. It is better to stay mid range with boolit weight.
I consider max loads for stability too much with a boolit that uses under max for stability best. Any boolit that starts to open groups with max loads is the better choice.
If you need max or over max, the boolit is too heavy.

[Lloyd Smale]

the problem with that is like 44man hinted to. You can do everything the way youd think it should be and the bullet can be a dud. You can take a very good bullet and change just one thing just a little and turn it into a dud. We ran into alot of that when having lee try to copy proven designs for us and even some from the other mold cutters we deal with here. About your best bet is to take a proven design and take some good measurements and hope the guy cutting it has the same idea as you and knows his tolarances have to be exact. Heck ive even seen when replacing the same mold from the same company a small change completely changes the bullet. Look at the lyman 421429 and all of its variations.

About the only thng i can say ive seen over the years is it just seems a bit tougher to screw up an lfn then any other design. But then ive had lfns that werent great too. I too agree with 44 man on the bullet groves to an extent. I think if you are the type that uses softer alloys two lube groves is superior to one big one as it probably helps in keeping the bullet from deforming. But with harder alloys i dont think it make much differnce. A gas checked bullet may not be more accurate but ill say it seems that they are more forgiving in non custom guns like rugers ect that dont allways have the best tolarances. If anything they been easiser to find the final good load with then plain based bullets.

Ill add one more thing. I wont even get into the lfn vs wfn argument but through the years ive found that putting a big metplat on swc is about a a guarantee that the bullet will be a dud. One last thing as sure as i am on my opinions your no doubt goint to find people who are going to argue that im wrong. You have to keep in mind that everyone has a differnt gun, everyone will have a prefered alloy and what works for some doesnt work for others. Also bullheaded guys like me dont tend to wonder much from whats worked for them so no doubt my answer isnt the only right one or wrong one for that matter.

[44man]

Yes lloyd, I have made dud molds too. Usually it was because I made lube grooves too small. Maybe drive bands not right????
Boolits have been exactly the same as my good ones with that one exception. No I don't know why and the boolits do not lead the bores.
Just something! Duds are EASY to make.
Meplats, not so. I have zero problems with more or less.
Keith---YES, more problems and I just quit with all of them. Not the meplat size, just steerage to the bore and cylinder alignment.
I have been sent hundreds of semi wad cutters for all guns and any left will be melted down to make good boolits.
My .500 JRH boolit was another luck thing. I set 5 shotgun shells on end at 50 yards and with 5 shots I shot all into the bases. I did not find all from the weeds but all were hit.
I just can never say what is perfect. I am not about to tell you the GG angle has to be so many degrees or a drive band has to be .0000001" within specs or to ever draw you a picture.
But if you can do this with a semi wad cutter, you have a great load.

[44man]

By the way Lloyd, my boolits are PB, I refuse to pay the price of the stupid things anymore.

[inthebeech]

I don't think you can go wrong with any of the time-tested designs from the reputable mold makers. My guess is that the folks who claim that "this or that bullet design just won't shoot out of my gun" are the exception.

It looks like you're trying to design a bullet.
It's been done for you.
WC's for targets out to 50 yards.
SWC are a good compromise / do all bullet.
Grab a mold, cast it properly, size it properly, know your gun's dimensions.
Praactice sound trigger control, grip, sight picture.
Enjoy the tight groups.

[Heavy lead]

Some plans do work out though, I have a GP100 that was throated correctly and was very accurate, problem was I needed a boolit to fit it, so using Dan's online design after reading his writing on boolit design I designed a terrific .357 boolit of 180 grains for it I couldn't be happier with, just so happens to work terrific in a Marlin lever gun too, I guess on accident, my main issue was I could have no longer than a .5 front drive band, so I used a bore rider design and stepped in with no actual length of bore ride, so the tangental ogive was at .350 that started immediately in front of the front band which was designed at .358 and drops at .3585, the step is minimal and the boolit fits.
As far as the rest, it does have a gas check, and the other two bands are .8 if I recollect correctly.
Before this I was using the NOE design which was accurate but had to seat it above the crimp groove to make it fit. I made the nose slightly shorter than the cylinder would hold.
I'm no expert, but it worked for me.

[MtGun44]

You are asking all the questions that Elmer and Veral answered, but you seem
to want to get different answers, I suppose. Apparently you are rejecting existing
designs and want us to tell you what the "real" answers are, but not refer to some
of the best designs out there that have solved these problems.

Have you actually read Keith and do you understand what his designs were
intending to do? If not, you might learn some from reading about his
experiments and his efforts to solve these same problems. The LBT designs
use a different solution, and Veral's book makes his case for his solutions
to the design problems. If you haven't read both Elmer and Veral on their
designs, you might learn a bit from reading what they said. Then you can
choose which approach (or neither approach) seems to work for you.

Maybe I misunderstand what you are attempting, but I am confused. It seems
like "I don't want to use a piston engine, but I need you to tell me the best
way to power a car, and no arguing over V8 or V6". Seems like you're both trying
to reinvent the wheel and assuming that there is only one good answer out there,
but it must be different than the previously used solutions. This is confusing
when it is known that several different approaches (Keith and LBT) are fairly
successful in many guns.

Best of luck, have fun experimenting, and maybe you will find a perfect design.

I have had a lot of very good results with Keith designs and some very good results with
LBT designs.

Bill

[44man]

Too much is made of boolit design trying for the perfect boolit when all that is needed is correct, proven stuff.
The easiest way is to shoot all of the good boolit maker's boolits until you find what you like, then have a mold made.
Like my 45-70 BFR, I have made 3 molds and all shoot plus all these other boolits that run from 317 to 478 gr plus a 300 gr Hornady. Might be a few missing from this picture, all I had on hand.
I just can not say one is better. Some were down to 1/4" at 50 but they were just 3 shot groups, yet I have shot 5 shots in 3/4" at 100 with many of them. Vision has become my enemy. I recently set up a 1-1/4" rock at 100 and blew it up but had to put a paper plate behind it.
All were shot with a 4 minute Ultra Dot, I don't know what a good scope would do.
It is more about making a revolver shoot first, not so much where a GG is or what meplat you have.

[subsonic]

I have read Keith, Veral, Beartooth, and the stuff on Dan's forum.

I guess this is all cut and try or copy.

I AM trying to design a boolit for the .500jrh, and there's just not much out there that will physically fit and provide what I think is enough lube.

But here is a more direct question, how does the width of the front driving band affect skid? Or does it?

[44man]

I have read Keith, Veral, Beartooth, and the stuff on Dan's forum.

I guess this is all cut and try or copy.

I AM trying to design a boolit for the .500jrh, and there's just not much out there that will physically fit and provide what I think is enough lube.

But here is a more direct question, how does the width of the front driving band affect skid? Or does it?
Not much, skid is controlled by hardness/toughness of the alloy. Stop skid at the base, all else matters little.
Strange that my best boolits have a very small base band too. Soft lead can't do it, think jacketed. So many say soft to expand to obturate but it is a crutch with a splintered shaft. Sure you can shoot putty balls but why?
Here is my boolit again, just a copy of a good one. Nothing special at all.

[subsonic]

Thanks again for the good pic. I assume no leading?

Putting logic to work makes me think that a wide front driving band would have a better chance of stopping skid than a wide base band would. And if there is enough driving band or bands to stop it before the base, the base band's job would be very easy and only need to work like a piston ring.

Jim, have you caught many boolits with narrow front bands like your JRH?

And does that tiny front band bridge the taper (lead?) cut in the chamber from the case mouth to actually reach the throat?

[44man]

Thanks again for the good pic. I assume no leading?

Putting logic to work makes me think that a wide front driving band would have a better chance of stopping skid than a wide base band would. And if there is enough driving band or bands to stop it before the base, the base band's job would be very easy and only need to work like a piston ring.

Jim, have you caught many boolits with narrow front bands like your JRH?

And does that tiny front band bridge the taper (lead?) cut in the chamber from the case mouth to actually reach the throat?
The boolit does enter the throat a little. Yet it is confusing because my boolits have age expanded to .5017"-.502" and I can not push them through the throats yet the rounds fall in the chambers.
I shoot other calibers like the .44 with boolits well under throat size.
Yes, I catch many boolits to study.
Here are two boolits, one with no skid but the .475 shows a lot but it ends at the base. That is the important place.