Coating the bases of plain base boolits

[colonelhogan44]

Has anyone ever coated the base of a plain base boolit with something such as a high temp paint, or similar to emulate a gas check and allow it to be driven faster? Does this idea even have any potential to work?

[Echo]

No potential whatever (IMHO). The boolit is in contact with the hot gas of propulsion for maybe a thousandth of a second - No time to melt anything.

But you might try it out, and report your findings here.

[Bret4207]

A GC is made of a material more resistant to gas pressure erosion than any lead alloy. But it has to fit to work. Someday for kicks take a GC desing and size the gas smaller than normal to simulate and undersized GC in an oversized barrel and put a hot load behind it. Most times you'll get leading like the GC wasn't even there. With that in mind I don't see how paint will help you. Some fillers work to slow the ability of gases to reach the boolit base. That might help you.

[Bob Krack]

Has anyone ever coated the base of a plain base boolit with something such as a high temp paint, or similar to emulate a gas check and allow it to be driven faster? Does this idea even have any potential to work?
Good idea - except the problem is not that base melts in any manner at all.

The problem is that the hot and ionized gases flow around the boolit and wash many many molecules of alloy from the sides of the boolit and deposit most of them on the bore of the firearm.

Bob

[XWrench3]

The problem is that the hot and ionized gases flow around the boolit and wash many many molecules of alloy from the sides of the boolit and deposit most of them on the bore of the firearm.

you hit the nail right smack dead center Bob. that is why we slug each barrel twice (one from each end) to size the boolits to the barrel. if the boolit fits, and you are not trying to ger rediculous with the speed/pressure, you will not have much trouble with leading.

[44man]

Has anyone ever coated the base of a plain base boolit with something such as a high temp paint, or similar to emulate a gas check and allow it to be driven faster? Does this idea even have any potential to work?
Every answer you got is correct. I have shot PB boolits to 55,000 psi.
You have the wrong idea of what a GC does. It protects the sides by stopping boolit skid that opens gas channels with softer boolits. You can exceed the skid so that a GC also fails. That tells you that you need a harder boolit to start to grip the rifling before the GC is reached.

[colonelhogan44]

Thanks for the education. I'm fairly new to this whole casting business, and have never used a gas check.

[damron g]

Has anyone ever coated the base of a plain base boolit with something such as a high temp paint, or similar to emulate a gas check and allow it to be driven faster? Does this idea even have any potential to work?

I leaded a 30-06 rifle barrel intentionally and cleaned it with a PB bullet that i added a goober of lube to the base.It cleaned it right out with no scrubbing.Shot the bullet at 800 fps,took 4 shots.An old timer showed me this one and i thouhgt it wouldn't work,but it did.

You can use something called a "P" check that is cut from poly coffee can lids that allows you to drive PB bullets a bit faster with better accuracy.it is seated with a special hand seater before the bullet is seated into the neck.You can take old Lyman GC's (or sized Hornady) and seat them behind PB bullets upside down and it works lust like it had a GC.A bit of trouble,but i tried it anyhow.
i tried gluing different materials to the bottom of 30 cal plain base bullets last year and never got any magic results from it.The "P" checks always worked better,but i still don't use them much as i hate the extra step.


You should try your theory out, we may learn something.Keep us posted


George

[Bret4207]

Every answer you got is correct. I have shot PB boolits to 55,000 psi.
You have the wrong idea of what a GC does. It protects the sides by stopping boolit skid that opens gas channels with softer boolits. You can exceed the skid so that a GC also fails. That tells you that you need a harder boolit to start to grip the rifling before the GC is reached.

I think it's more logical to theorize the GC performs several functions- stopping skid, blocking gas flow, scraping previous leading away, making the base stronger. I don;t believe there is any "one" thing a GC does.

[Larry Gibson]

I think it's more logical to theorize the GC performs several functions- stopping skid, blocking gas flow, scraping previous leading away, making the base stronger. I don;t believe there is any "one" thing a GC does.

Bret just shot a 10X:-)

Larry Gibson

[44man]

I think it's more logical to theorize the GC performs several functions- stopping skid, blocking gas flow, scraping previous leading away, making the base stronger. I don;t believe there is any "one" thing a GC does.
All are correct. Stopping skid is what blocks gas flow.
But if you also get the boolit fast enough at the start and lead is too soft for it, the check will also skid and the barrel can then get full of leading. You don't want gas to get past the check.

[colonelhogan44]

So, Theoretically, hardening your alloy would reduce skidding and allow for Plain base slugs to be driven faster.

[geargnasher]

So, Theoretically, hardening your alloy would reduce skidding and allow for Plain base slugs to be driven faster.

Yes.

I'll add one more thing to Bret's list: A gas check protects the edges of the boolit's base upon muzzle exit, too, thereby reducing wobble induced from uneven gas jetting.

Gear

[Bret4207]

So, Theoretically, hardening your alloy would reduce skidding and allow for Plain base slugs to be driven faster.

Yes and no. Hardening alone is nothing if the boolit doens't fit in the first place. And then you have to consider WHY is it skidding? Is it because the alloy is not tough enough to handle the pressure, because the pressure curve is wrong and pounding the boolit into the barrel and a slower powder and softer launch would fix that, because the barrel has mechanical issues like uneven lands and grooves or a rough forcing cone that rips the boolit apart, because alignment issues are causing tipping or probably another dozen reasons I can't think of.

Sometimes simply water quenching your boolits will "fix" the problem. Other times it just exacerbates the problems. Observe, experiment, change one thing at a time, write it down! My alloy and your alloy will never be the "same". All we can do is give general advice, this isn't a science, it's an art.

Also realize that we have an issue with definitions here. "Harden"...what exactly does that mean? Add tin? Add antimony? Add both? HT? WQ? Are you going for a harder or tougher alloy? How will it react under compression? It's a c rap shoot isn't it? What's your base alloy and size? Is it "soft", "medium", "hard" or "really hard"?

Look, I'm not trying to confuse you or make this any harder than it has to be. But simply saying "if I make the alloy harder will it let me boost the FPS?" is kind of like asking "Will this aftershave make me attractive to women?" Answer- yes, no, maybe. And every answer is right...and wrong. It worked for my brother, and sorta worked for for my cousin Ed, but it didn't work for me at all. And that's just the way things are.

[geargnasher]

Bret, I was just assuming that when a person asks "theoretically", they are assuming an "all else remaining equal" position, or at least that all the other things like size, launch pressure, and bore condition would be correct enough not to affect the factor in question. In the real world, you're of course absolutely correct with "yes and no". That's why we have threads like "do boolits swell up on firing " that have post counts nearing four figures. Opinions, facts, observations, conclusions, impressions, hearsay, naysay, plate tectonics, you name it will get as many different responses as those responding in a lot of cases because we are each working with individual guns, components, and conditions that are similar but never identical. Like you say, what works in your backyard might not work in mine. However, the basics are pretty well understood and agreed upon by experienced casters/loaders/shooters and I think a "Troubleshooting" sticky would be very appropriate.

Gear

[Bret4207]

Sorry I got so wordy Gear, I just hate simple answers to complex problems that turn into advertising hype, ie- harder is better.

[44man]

Bret is correct in that fit is first. You don't want the boolit to change shape in any way and that includes expanding to obturate.
I don't use super hard lead as I explained and most is just WW metal.
Needing a softer boolit for expansion in some guns show a PB will just scatter shots but the same design with a gas check brings back accuracy.
The gas check is wonderful but if you don't shoot too fast, like a .45 Colt, .44 or .475, then you can just water drop WW metal and shoot PB just fine. These calibers kill with harder lead but as you speed them up in a rifle, etc, then you start to need expansion. Softer lead is needed and that is where a GC really comes in.
If you shoot paper or steel, then why worry about shooting the best alloy your gun will shoot? Just work with the gun to see what does best. GC's are expensive being made from unobtainium so if you shoot paper with a PB, just find what is needed to stop skid at the base.
I shoot a PB, water dropped WW boolit at better then 1600 fps out of my BFR 45-70 with 1" accuracy at 100 yards but I dare not shoot a deer with it. Air cooled starts to NEED a GC and I REALLY need one with a 50-50 alloy.
I catch thousands of boolits and one glance tells me what I need to do. Some GC boolits have as much lead on the check as was used to make the things. That showed me the boolit failed to start turning and it continued past the check as land marks on the check were too wide.
If you have boolit failure, that little piece of copper will not instantly grab the rifling.
If you shoot steel you need "hang time" on the plates so don't get carried away with lino, etc. Too hard is no good as the boolit turns to dust on impact. Use only enough hardness or toughness your gun needs.
Yes, a boolit that skids full length HAS failed! [smilie=s:

[curator]

Another feature of shooting cast boolits without gas checks to protect the base is that the pressure bearing on the boolit base can and does cause it to soften. This is called pressure fusion and is usually the reason soft boolits lead in high pressure rounds like 9mm and .40S&W even if they fit properly and have good lube. OP wads and fillers can reduce this some but simple paint can't.

[damron g]

'I shoot a PB, water dropped WW boolit at better then 1600 fps out of my BFR 45-70 with 1" accuracy at 100 yards "

two shot groups<G>

[mpmarty]

I'm sure I could push a 450gr cast boolit to over 2500fps in my bfr 45/70 but unless I'm facing a charging Tiger would never want to. 350gr at 1700 or so is all the fun I can stand.

[44man]

'I shoot a PB, water dropped WW boolit at better then 1600 fps out of my BFR 45-70 with 1" accuracy at 100 yards "

two shot groups<G>
Five shots from sandbags. No pictures on this computer but have a few downstairs.

[Treeman]

Many years ago there was a company marketing something they called "soft gas checks"-It was a wax mixture that came in sheets. You could use the cartridge case mouth to cut a plug then seat a bullet over the "check". Reportedly they worked well-I never tried them. My personal theory regarding LLA /Xlox working so well (I love the stuff) is that A. The bearing surfaces are lubed(Some LLA actually stays on the bearing surfaces during bullet seating/ and pulling) . B the base is coated(Thus forming an ablative surface that shields the lead and may flow into any gas leaks forming at the base seal.)

[Bret4207]

Another feature of shooting cast boolits without gas checks to protect the base is that the pressure bearing on the boolit base can and does cause it to soften. This is called pressure fusion and is usually the reason soft boolits lead in high pressure rounds like 9mm and .40S&W even if they fit properly and have good lube. OP wads and fillers can reduce this some but simple paint can't.

Thanks for the definition and proper term. I've referred to it as gas cutting or erosion, depending on where it occurs, but I think this is the "melting" so many falsely believe in. I have a theory any shallow voids int he base will exacerbate this issue also.

[Bret4207]

Many years ago there was a company marketing something they called "soft gas checks"-It was a wax mixture that came in sheets. You could use the cartridge case mouth to cut a plug then seat a bullet over the "check". Reportedly they worked well-I never tried them. My personal theory regarding LLA /Xlox working so well (I love the stuff) is that A. The bearing surfaces are lubed(Some LLA actually stays on the bearing surfaces during bullet seating/ and pulling) . B the base is coated(Thus forming an ablative surface that shields the lead and may flow into any gas leaks forming at the base seal.)

In theory anything between the gas column and base will work, in practice it just isn't that simple. For decades a graphite disc, I forget the brand name, placed between powder and boolit or bullet was a standard trick. It seems to have died out.

[Dollar Bill]

I was just reading Philip Sharpe's Complete Guide to handloading last night. The section had to do with lubes under the base of the bullet. If I remember correctly (and that's a big IF), he had started the practice as a teenager (which would have been around the turn of the century - the last century). Using petrolatum as a standard lube because he nothing else, the pet contaminated the powder so he had alot of misfires. Searching for a better lube eventually lead him to better lubes but also to a regular grease gun modified to produce a sheet of lube to use under the bullet. The other method was to melt the lube in a pan and dip a glass jar in it, then cut strips of lube off the jar. He gave some to Elmer Keith who found under bullet lubes usefull in the early 220 Swift experiments. He originally was only getting about 2-300 rounds out of a barrel (J bullets). Addition of the lube under the base of the bullet extended the life of the barrel out to 600 rounds or so.
Not that this has much to do with the question at hand, except that under base lubes or soft checks can be used successfully in some applications. It may help in this case.

[44man]

Five shots from sandbags. No pictures on this computer but have a few downstairs.
This is a can with 5 shots through the hole in the top at 100, shot with the 45-70 BFR. Other holes are from a rifle. I had to set the can back up after every shot.
Vision is the only limit. I tried to shoot a small group on paper the other day by taping a can to the paper. I could not see the stupid thing but had the first 3 in an inch. Vision went haywire and the next two were left but were very close together. I changed the target but it was worse. I do better with a can on top of the rail. I can set the red dot on top of the can that way.

[44man]

I shoot thousands of PB boolits and recovered ones do not show what some of you talk about. No extrusion, only some powder dirt. Even the sprue cut has not changed. These were all shot with heavy loads at high pressures.
Nobody has ever proven that lube seals a boolit. It can't, it wont and fit with a lead seal is all that works.
PB taken to 55,000 psi look no different and a few of these might be those I tested.
If I wipe the bases clean, they look as cast.

[pdawg_shooter]

Why not eliminate the whole problem, just paper patch. No leading because the lead never touches the barrel. Jacketed velocity and accuracy.

[Dollar Bill]

Nobody has ever proven that lube seals a boolit. It can't, it wont and fit with a lead seal is all that works.

I've heard and read alot of debate of this subject for 30 years now. I can't prove it one way or another but a similar type application comes to mind where a lubricant does seal a bore, and that is the piston engine. It's a fact that, although there are compresion rings to seal the bore, they ride on a film of oil. They have to to prevent metal to metal contact. The oil control rings regulate the thickness of the oil film. That's why piston engines always consume some oil: it's on the cylinder walls during the combustion cycle.
Just something to think about, FWIW.