Powder coating question

[gman]

That's interesting on the sizing diameter Ian. I have been sizing to the same as traditional lube. I may have to try that on some rifles to see if that will improve accuracy.

 

[Ian]

Gman, it's a different ball game than bare lead. You want (as with any bullet system) to minimize bullet distortion, but with bare lead bullets the surface is very soft and cannot withstand any bouncing around in the throat without getting a side smeared off, so wee have to fit and support our bare bullets very well and coax them along through the liftoff process so they don't get crooked in the throat or case neck. This means bigger bullets usually shoot better, particularly if they are "big" in the throat area and fit with minimal clearance.

We know copper jaxketed bullets can rattle around in a throat like a BB in a boxcar and jump fifty thousands of an inch or more to contact and still shoot reasonably well because their tough, slippery gilding metal jackets don't deform all that easily and let the bullet funnel into the throat with minimal distortion. Also, they have to be small, groove size or even smaller, so that the jacket isn't sliced clean through or pressure raised too much squeezing the bullet through the throat and into the bore.

Powder coating is a sort of jacket. It's very, very thin, but very tough and slippery. What this gives you is a happy medium between copper jax and plain monolithic lead alloy. The tough, slick skin can tolerate a more loose throat fit and can self-align off of one side or the other of the ball seat without sustaining as much damage as an uncoated bullet can, but due to the soft base metal beneath, there is a limit to the ability to self-correct. Also, you only need enough bullet to achieve obturation of the bore, and no more, so a half-thousandth to two thousandths press-fit into the rifling is plenty to do that without moving more metal than absolutely necessary, and thus preserving the coating and doing less bullet deformation in general.

I run my .45 ACP bullets at .451" due to a couple of tight-throated modern pistols in the armory. They shoot great. They also shoot great in my famous, reverse-tapered Kimber 1911 with the .4525" exit-end groove diameter.

 

[SierraHunter]

Need the thermometer.
It sounds like undercooked. You can overcook the coating too. Don't shoot the undercooked bullets not only will they lead your bore they will powder coat it to. It's really difficult to remove, trust me. 1" per hour of barrel to clean out.

What size do you want your final bullet to be? What size lead bullet does it shoot well with standard lube?

I remember Felix having a concern about how hard the PC would be to remove if a barrel got fouled with it, since we have no polymer solvents.

I've been having really good luck with this Ruger 300 blackout at .310"

 

[SierraHunter]

Ok, couple things.

First off Harbor Freight powders are epoxy powders, are pretty low-quality, coat too thick for a lot of things, and like all epoxies are a lot more brittle than the Polyester powders most of us use. Inability to flex can cause leading as more lead is exposed when the engraves cut into the bands.

Second, there are two reasons I do not spray my powder, but instead use the Airsoft bb shake/bake method: Spraying can and does put uneven thickness on critical areas like the side of the nose, and sprayed powder doesn't adhere nearly as well as impact coating does. If you dust the powder off of an impact coated bullet before baking, you'll notice that the surface will have a bead-blasted appearance due to the powder abrading the soft lead oxide coating and texturing the base metal. Possibly for this reason, when using Polyester TGIC powder, the coating usually adds only about one to one and a half thousandths of an inch to the bullet's girth.

Third, I've found out so far that most of my rifles and handguns like their PC fodder to be about halfway in between what I'd normally size them to and what nominal, jacketed bullet diameters would be. For .30-caliber, for example, .309-310" covers the bases, depending on throat entrance diameter and neck diameter.

That's good stuff to know, thank you. I'm using the shake and bake method, but with green air soft BBs because I had them on hand for some reason. How many bbs do you use in your container?

 

[SierraHunter]

So I just tried a few of the bullets that I cooked at higher temp. Much better. No shaving of the lead. 9.5 BHN with 16.5gn of H110, and no leading, but too dark to try for accuracy.

Where is a better place to look for powder?

 

[fiver]

see smoke 4320 over at the other site.
he has starter packages with the black BB's and all.
there are a couple of other places like powder by the pound and one or two others.
just pick a plain shiny color and go with it [green black blue]

 

[yodogsandman]

Smoke4320 over at the CB forum.

 

[Ian]

Smoke makes it easy. If you know what you want, powder buy the pound has it and prismatic powders also. Spring for the containers with screw-on lids, they're worth the extra couple of bucks, trust me. You want Polyester TGIC, and you DO NOT want to breathe even a little of the dust because the TGIC crosslinker is a five-alarm carcinogen, mutinogen, will make your kids have nine heads, etc. Nobody seems to point that out with that type of powder, but they work great for bullet coatings. Avoid epoxy and Polyurethanes. Avoid anything below 80% gloss or it won't stick via shake/bake.

I used Crosman yaller bbs because someone gave me an unopened 5K jug of them years ago and like him, I've been trying to find a use for them unsuccessfully until I decided to PC bullets. Member L1A1Rocker picked up a container of the black heavy ones for me and they do work better, mainly because powder sticks to them whereas it doesn't stick to the others. Whatever you have will work fine, it's mostly in the technique of shaking anyway.

For containers, it doesn't matter the shape or the material as much as is made out. Still, not a bad idea to buy the semi-rectangular #5 food storage containers with the silicone lid seals and four snap flaps. They can take a beating and need to without leakage.

I've only seen one AR-15 BLK chamber that would take .310" bullets without shaving. Most have a tight entrance at around .309-.3095" so I size .3092" for everything and have no issues. Haven't had a chance to load for a bolt gun yet, and as long as the .308 Winchester exists I probably never will even want to.

 

[SierraHunter]

The handi rifle I have will only chamber a .311", but the Ruger will take a .313"

One advantage to the bolt gun is pressure. I load this thing way beyond published with no problems what so ever. Even the handi rifle has trouble with loads the Ruger shoots just fine.

 

[freebullet]

Mmm...careful there. I'd be inclined to switch to a 308 or 06 vs. testing beyond regular data. While the gun might take it some eventually, it wont.

Do be careful with the powder. None of it is helpful to human respiratory systems.

 

[Rick]

Mmm...careful there. I'd be inclined to switch to a 308 or 06 vs. testing beyond regular data. While the gun might take it some eventually, it wont.

Do be careful with the powder. None of it is helpful to human respiratory systems.

Wise advice.

In several decades of handloading I've found for the most part the book listed max loads are pretty accurate. Add in that it's quite rare for the max load to be the accurate load making risking things such as a fine firearm, your eyes, hands etc. just not worth it.
.

 

[Ian]

The handi rifle I have will only chamber a .311", but the Ruger will take a .313"

One advantage to the bolt gun is pressure. I load this thing way beyond published with no problems what so ever. Even the handi rifle has trouble with loads the Ruger shoots just fine.

Never load bigger than the throat entrance diameter if you expect the bullets not to shave off the coating. I have a hard time believing that even Ruger made a 300 BLK throat entrance .313". There isn't much chamber neck clearance in most BLK chambers, either, so watch loading too fat of a bullet in there. Overloads with tight chamber neck clearance is a recipe for case head failure and inadvertent brass-jacketed bullets and neckless cases.

Though you didn't specify, a Handi rifle is having any "trouble" with pressure, particularly with that tiny case head, you went WAY too far. Remember, the SB2 frame was factory-chambered for things like .270 Winchester and 35 Whelen, which off the top of my head have something like 60K+ psi ratings with the .473" case head.

 

[SierraHunter]

When I first got the Ruger (well before the handi rifle) I worked up some loads with 165gn Hornadys using WC820. I've got it at 16.5gn and I've shot several groups under 1/2" at 100 yards with this load. No sticky bolt, no flattened primers, no shiny case heads, so I figured good to go. When I first got the handi rifle, I tried firing a few of those loads in it and it was stretching primer pockets. I only fired 2 in the handi rifle, and have not fired any loads that are for the ruger in it since (don't plan on keeping handi rifle either...trigger is terrible)

Anyway. The biggest PC bullets I've tried so far are .311", mainly because that is the only size I have for a sizer die. I want to order a .308" so that my finished bullets come out at about. .3095"

 

[Ian]

Order a .309" die if you want them to come out .3095". Or order a .308" and spend 30 seconds with sandpaper to adjust to your liking.

Sounds like the Handi has a tight throat.

 

[SierraHunter]

One more question I have. How many bullets do you guys do at a time with the shake and bake?

 

[Ian]

50-75, doesn't seem to matter the size of them. 1.25 bbs thick on the bottom of the container is about right for what I do, to answer your earlier question. Everyone will have a different container preference and that will affect bullet count and bb proportion somewhat.

It's difficult to describe the shaking technique that so far works best for me, but I'll try. It's a sort of tossing motion while shaking back and forth, trying to get the powder airborne each time and a hard slam at each end of the stroke, while holding the container at a slight angle up and away from me. Imagine an elliptical exercise machine, that's the motion. Somewhere near the end I give the container about ten hard up and down shakes and then some more light tosses, trying to get the powder to settle over the bullets with a good dusting, then a little side-to-side gently to knock off the excess, then pick with tweezers, tap on the side of the container, and set on their bases to bake.

 

[SierraHunter]

Ok. So on the note of the toxic dust. Do.you guys any kind of respirator when working with the powder? Much like one you would wear for silica or asbestos?

 

[Ian]

Not a respirator, just a GOOD particle mask. If you're careful, there won't be any airborne dust at all, but stuff happens, containers leak a little sometimes, sometimes you open the lid too fast and a light cloud of it woofs up right when you stick your face over the container for a good look at the bullets, etc.

 

[freebullet]

P or n rating of 95-99 would be my recommendation.

An exhalation valve is worth the extra cost.

I use a p99 respirator with pancake filters when I spray.

You can't breathe solids.

Was doing tumble pc without bb's. To much time for my volume needs though.

 

[SierraHunter]

I just found a container that is about 6 inches around and 10 long with a screw on lid, and is made of #5. I'm gonna put this on my old harbor freight rock tumbler frame I think..