Hardness vs powder coat

[archeryrob]

Does powder coat make up for hardness?

I cast a bunch of NOE 312 184 grain bullets for a gas checked round cast with 11bhn wheel weight lead for the 30-30. All water quenched tested one and it came out 14 - 15 maybe. I did a bunch with deer fat lube to load plain and I powder coated some. I did not like pan lubing them as it was messy, but they looked really cool natural. Then I powder coated a bunch and sized them all to .309 and run on 3031

Shot the gun in at 50 yards with iron sites and lead and powder coat rounds was on. At 100 yards the powder coated rounds was still on and the lead rounds where 6" low and right. Is the 14bhn too soft and does powder coat make up for this? Or is something else going on?

 

[AJC1]

PC does a good job helping protect the base from flame cutting if you have a good fit. I shoot full house 357 PC bullets with a plain base bhn 9-11. The lee chart recommends a harness double my hardness. I would love lyman or any of the big companies to publish a researched article on PC effects on internal ballistics. Not counting those chickens....

 

[archeryrob]

These are gas checked and still off.

 

[AJC1]

These are gas checked and still off.

I have a 180 mold that runs gas checks but I haven't spent any quality time with that bullet to give direct observations. Wish I could offer more.

 

[bluejay75]

I would say that 3031 pushes cast as hard as I have ever tried to push. My best guess is that they skidded. Look at the bullet base on the right. That’s what skidding looks like. It happens when your lube fails. PC will let you get away with a softer bullet.

 

[bluejay75]

Powder coat didn’t make it for the pressure I was running on the 44 magnum bullet. I scrapped that powder coat after this test. It went on too thin. Skidding happens when the billet won’t stay in the grooves. The bullet on the left is a 30 caliber bullet 12 bhn from a 308. 185 grain billet at 1820 FPS. That powder coat held up well enough that I could push a little harder. You may have to blow them up.

 

[forrest r]

I doubt it is a skidding issue, you can tell by looking at a recovered bullet like bluejay 75 stated. Look at the marks left by the lands, they will either appear wider then the lands themselves or be v shaped/wider at the nose of the bullet then the base.

14bhn alloy itself is more than enough to withstand 50,000psi loads. Your alloy is more than most likely on the brittle side simply because it doesn't have a lot of tin. This is not my chart but as you can see pc'ing bullets will anneal/lower the bhn of an alloy. This is testing ww's and letting the bullets age harden for 2 weeks.

 

[forrest r]

IMHO:
You're looking at a lube issue. Huge differences between the same bullet that is traditionally lubed VS pc'd. The difference between the 2 and how they affect the bullet.

With traditional lube:
You hit the loud button and "BANG", the bullets off to the races!!! The nose of the bullet moves forward and starts to spin in from the lands. The middle of the bullet is expanding in the freebore. (This is why you size your bullets to the diameter of the freebore in a rifle.) The rear of the bullet is moving strait forward. Between the nose locked into the lands & twisting and the bullet expanding/grabbing the freebore and the back of the bullet pushing. This causes rotational torque to the bullets body and this is where any skidding will start/happen. The base of the bullet will bump up to the size of the freebore as it moves forward and then enter the leade of the chamber getting sized back down and starting to spin with the rest of the bullet. At this point the bullet itself will start to compress at it's weakest point/points, namely the lube grooves simply because the bullets diameter is smaller/weaker then the main body of the bullet. This causes the lube in those grooves to be hydraulically forced outward and forward. Small amounts of hot gas will get by the gas check and that pressure will also force the lube outward and forward. The lube will not only protect the bore from leading, it also acts as a gasket aiding in sealing the bullet/bore fit. (Remember GASKET). The lube does this the whole length of the bbl.

PC:
It's already everywhere it needs to be & simply needs to be thick enough to withstand the rotation torques of the load along with the compression of the bullet to be affective. I've found that 2/1000th's" + pc coating has worked in every firearm/load I've used pc'd bullet with.

The difference between the 2:
Traditional lube is a balancing act between the bullets hardness, the pressure of the load & the amount/type of lube being used. Change the pressure of the load, how slow or fast that pressure is exerted on the bullet affects it's performance. With a pc coated bullet the pressure of the load doesn't matter. PC will seal the bbl no matter what the pressure or how fast/low it's applied.

 

[forrest r]

50yds is really a poor indicator of what a load or cast bullet is performing. But there are things that can be learned from any testing. These are 10-shot groups @ 50yds shot over a chronograph.

Traditional lube (bens red/soft lube that is mainly grease) 45/4510 tumble lube also and a gas check installed 1329fps load


Same bullet that has been pc'd along with no gas check installed 1391fps load


Same bullet cast from the same alloy/same day. Same powder/rifle/primers/cases/etc. The traditionally lubed bullet had a gas check installed to aid in sealing the bbl/better performance. Yet the pc'd bullet without a gas check outperformed the traditionally lubed bullet velocity wise.

This is an example of the balancing act that the alloy/load pressure/lube that traditionally lubed bullets have to go thru VS a PC'd bullet. The pc'd bullet was faster simply because it was more efficient (that GASKET thing). These bullets were cast from a 8/9bhn alloy.

 

[forrest r]

The lee 312-160 tl bullet is an excellent bullet for testing traditional lubes VS pc. It doesn't hold a lot of lube but tumble lube can be appied/added as needed.


I cast up a bunch of the lee tl bullets out of a 14bhn alloy that had equal parts of tin/antimony. Sized them to .310"s & loaded up a bunch of loads using traditional lube VS pc doing 10-shot groups @ 100yds using H335 for the ladder tests.
The PC'd bullets


The traditionally lubed bullets



Two things happened:
The PC'd bullets were faster
The PC'd bullets were more accurate

The traditionally lubed bullets were lubed with a harder lube, LBT blue. There just wasn't enough lube there. I retested the 36gr and 37gr loads adding the 45/45/10 tumble lube to the already traditionally lubed bullets that had the LBT lube. HUGE difference!!!!


Gained a little more velocity (that gasket thing) but more importantly, the consistency/accuracy came back

 

[forrest r]

Playing around with a beater s&w 629 looking for 25yd plinking loads that would do minute of golf ball @ 25yds. I used 5 different bullets that were cast from the same 8/9bhn alloy with 1/2 of them being traditionally lube (ben's red) and the other 1/2 pc'd then sized to .430". Used 5 different powders doing 1/2gr jumps in the ladder tests.

Same brass/firearm/alloy/sizing die/primers/powder/etc Traditionally lubed VS PC'd accuracy testing
It ended up:
3 VS 13
Out of all the loads tested 3 of the traditionally lubed bullets would do 1 1/2" 6-shot groups or less @ 25yds. The PC'd bullets had 13 loads that would do 1 1/2" or less 6-shot groups @ 25yds.


The 3 VS 13 difference is because of the lube/alloy hardness/lube combo that has to match up with traditional lubes to make them efficient/accurate. The pc'd bullets are not bound by the same rules.

This is why I believe you have a lube issue with your traditionally lubed loads. Soft lubes are excellent for target & low pressure loads. When you start stepping into the high pressure load arena wax based lubes tend to perform better then oil/grease based lubes.

 

[forrest r]

If you like the looks of the cast bullets why not buy a clear pc.

 

[archeryrob]

Forrest, I just thought the naked bullets looked cooler as I like old school muzzle loading and I shoot my 45LC bullets that way also. I also started with 11bhn lead and only got 14 bhn with water quenching. No substantial changes like that chart showed. Most of the lead I used was wheel weights and reclaimed bird shot.

The load is 29 grains of 3031 and GRT says 2009fps as I do not have a chronograph. The lube is the same lube I use for muzzleloaders and it is 3/4 deer fat (pretty stiff cold) and 1/4 beeswax. The deer fat is pretty stiff cold, but I bet it melts down fast when any of the heat from the powder contacts it. So I assume this is my problem.

 

[forrest r]

Clear pc leaves the bullets looking as cast, actually like the looks myself. If I ever burn up the 3# of john deere green I have laying around I'll end up buying clear.

A simple test is to take a wax like johnson's paste wax and smear/coat your already lubed bullet with it and re-test. Test some with jp wax as the only lube also, just make sure you get a good coat on the bullets with your fingers.

A pc'd bullet is a good way to test the traditionally lubed bullets/loads. If they both fail it's a alloy, pressure, bullet size/fit, or bullet design issue. If the lubed bullet fails, it's the lube. Which could be not enough, too much, or too oily for the alloy/pressure of the load. When pc fails it's typically not thick enough, the heating process used to cure the pc annealed the lead or the process of putting the pc on failed (under cured).

The fact that 1 bullet worked with your load and the other 1 failed is telling you where to look/test/modify.

I wish you the best of luck and take my hat off to you. Pushing cast bullets hard/fast isn't as easy as it sounds. You've made excellent choices in bullets and the caliber to use them in.

 

[archeryrob]

Thanks, I got 75 still in lube and think they will be my "Thick in the woods" hunting rounds or plinking short range rounds until they are gone. Or I'll see how much trouble pulling one is and melt them down and recast. I have 100 powder coats in a mtm box, sized and waiting to be seated.

Maybe some other day I'll experiment with lube and I'll settle for powder coated rounds that can kill deer for now. I guess i just got educated that all lube is not adequate.