Arsenal Molds 30. Cal HVTH1

[Ian]

I don't think the whole bullet will flow, but it might draw out in the middle.

Tin forms an intermetallic bond with antimony in approximately equal molar amounts, creatng a strong, tough, but malleable lead alloy due to its fine grain structure and small shear planes.

A low-antimony alloy will extrude and draw quite easily because of the large shear planes (think of it as a deck of cards). Too much antimony by itself in lead makes a hard and brittle alloy, but when tin is added the result is more malleable, like stiff putty. However, the tin/antimony intermetallic puts up a fight when you try to cram it through a smaller hole, creating much resistance and internal frictional heat as energy is applied to change its form. Heat weakens the alloy. Low-antimony alloy will extrude with much less resistance, less force needed on the bullet base, and while building less internal heat. The catch when using a tin-starved alloy is the surface of the bullet is relatively weak and cannot take as much abuse without deforming when banging around in the throat at odd angles.

My thought is that powder-coat adds just a hint of tough, slippery skin that helps the bullet guide to center and engrave (a little = a lot here), thus allowing a much softer alloy than normal to be used without the bullet totally losing its form when kicked in the pants. Tin may or may not help the bullet maintain its form, it depends on a lot of things like how much the bullet is being squeezed, how much jump, how steep is the pressure curve of the powder, how much engraving resistance and inertia the powder is working against, and so on. The slick paint changes the dynamic one direction, the tin changes it another. Only shooting will tell us for sure whether these things are for the better, or not, and you can bet wvery situation will be different so it isn't likely a firm guideline can be easily established here.

 

[popper]

Dang Spin, now I gotta try the 185gr without GC PCd in the BO pistol, low fps. Just PCd some on Yoshi copper bake and grill mat she gave me (well used) She gets her roll of NS Al foil and parchment paper back. Absolutely NO sticking. No sign of wear on the mat from hot plate. Even wiped a couple spots of PC off where I had rearranged the bullets before cooking. No residue! I used HF red in 308 sprayed before I got the Smoke's stuff (applies better) and found no difference shooting. HF is epoxy, other is poly.

 

[Spindrift]

@Ian, thanks for a very educational post. So, it might be that the tin-rich alloy might be counter-productive with this bullet... I’ll shoot them with an open mind, and carefully record results. I might learn something, either way.

Popper, that mat sure sounds very good! That BO pistol sounds like great fun, wish I had one....

 

[Ian]

I’ll shoot them with an open mind, and carefully record results.

Please do, we all will learn something valuable. I'm not making predictions, just sharing some observations. Not many people have experimented with alloy very much to see what effect the various constituents have when using paint, and this information wil prove very valuable.

 

[fiver]

the alloy is gonna move no matter what alloy we use.
..................................................................................................................
yep.

I think everyone has read enough posts explaining why different ones do different things and why it is so important to match the alloy to the bullets design.
K.
what we do with the powder is influence the 'where' it happens in the sequence of events.

 

[Ian]

Annnnnnd then we change the way the powder burns by adjusting seating depth, neck tension, primers, alloy, and bullet shape. So many inter-related variables that the mind boggles. Just going from traditional lube to powder coat usually requires a size reduction, softer alloy, about 5-8% more powder and/or going a couple ticks faster up the burn chart to equal same.

You know, I just realized my .308 hunting load grouped considerably better when I went from straight wheel weight alloy at about 12 BHN to the same mix bumoed with almost 2% tin (about a 2.5/2.5 alloy) at 14-ish BHN aged. I just shrugged and wrote it up as the alloy being a little more tough....but it could well be the grain structure change as much as anything. I had added the tin strictly to make the HP bullets hold together a little better at high velocity but they shot betrer too so win/win.

 

[Spindrift]

What I’ve planned, is to move down the burn chart, using slower and slower powders. Find the node just before accuracy fails.
At some point, I’ll get to a powder that burns consistently just around the point when the bullet fails. I’m thinking this load level will be interesting for some alloy testing. I’ll start with lubed bullets, then compare some PC bullets with the two different alloys.
The purpose of this little experiment is just to try to learn something.
The next powder will be Norma 200 (~Re7). Then Vectan Tubal-300 (~4895), N140 (~Re15) and N150 (~4350).

 

[Ian]

Sounds like a plan! That ought to keep you too busy to waste time in drinking establishments for the rest of the summer

 

[Spindrift]

Yep, it should keep me off the streets for a while. Hunting season is drawing near, so it might take a while before I can finish this. But I will, sometime

 

[fiver]

you have a good baseline to work from.

it kind of odd/cool that you can set a max pressure with one powder then do nothing but move the bar down the pipe by extending that pressure window further and further.
after doing it a few times you start to settle down and notice a trend in the powders you use and a couple of favorites really start showing up for a few different reasons.

 

[Spindrift]

I hope to learn a bit more about both my powders, and alloys. And have fun along the way

 

[popper]

Spin -that nuclear lead is good stuff, kinda saving mine. I can elaborate my alloy/PC/powder experience in 308 AR10. I use the 31-165C, just a tiny groove for displaced metal (I started with 165B - LG type). First #2, did just OK. Reduced tin worked best. Now I use no tin, just replace with copper. and some shot for arsenic, WD after cooking. Great fillout. I find H4895 works best, 40.5 gr gives MOA @ 100 and close @200. Few yrs back I shot at a yard sign, hit the support steel wire(14 ga?) and cut it in half. Only found the GC that was bent a little with some powdered alloy in it. I say powdered but I had to scrape it out. Don't know if the bullet fractured or not, never found it but was testing the same alloy in 40sw shot into a rock pile (same day) and recovered TC was pretty much cylindrical and 95% weight retention. One actually had a 2 length nose where it had hit hard and one side of nose was 1/4" shorter. I also tried ~1% zinc in 40sw, then added 1% Sn, then added 1% Sb. Until I added the Sb, all sized too small, leaded barrel and tumbled but at 7 yds, very accurate and mucho expansion. I used alox for those loads, aircooled. lube groove bullet which disappeared when hitting the target sideways. Been working my way down to softer alloy (started ~4% Sb) and 50/50 (~2% Sb) AC in the 30/30 works good. HT is slightly better (29gr LeverE). Summation - I haven't found a need for any tin. If you want expansion, 1% zinc at lower fps works fine. Oh H335 results in 308 cast were not that good, Rx15/4895 worked better than varget, ARcomp or 8205xbr.
The 10" BO pistol is a blast, I need to chrony the load but works great to 50. Need to put a higher power scope on it to try 100. Running low on SRP so using 30/30 and 308 now as got a get together in Ar with family and I know the GKs want to shoot it. We use a LOT of ammo on get togethers. Last time I went through 100 box of 40, same for 9 and they used 2 of the frontier 223 'ammo' boxes. First time I shot a 223. Not much impressed. IIRC they shot several 9 blaser boxes too. In 1 1/2 hrs. i didn't even have a rifle for that one. Watch out Sylamore - we gonna have fun.

 

[popper]

I realy like the BO pistol. Makes a great compact truck or 4 wheeler gun. 50 yd 357 mag performance in a 6# 10 or 20 Lancer mag (I added a linear comp and use 3x scope) that I can single point sling off the back for walking in the field. A good 3x RD would make it lighter, as would a thinner barrel. My barrel is a budget HBAR KAK 1:8. I changed the tube for a brace as the tube was rough and made my cheek sore. Could even use 110 vmax for yotes. Hot 150SPP are slightly harder to handle but very accurate. My cast load is ~ 8$/100 with roto alloy, bout 2$ more than 40sw..

 

[Spindrift]

Thanks for the info, Popper. I’ve never tried adding copper myself, but it’s on my list of possible future experiments. Interesting that you’re getting such good results with no tin. Might have to pick up some copper sulphate and try it out. I have a small Lee pot that is unoccupied.

 

[RBHarter]

If you're berm mining , copper plated anything but 22 LR especially , you'll get copper that way at about half of your tin value . .5% is a big change in bullet toughness .

 

[popper]

IIRC, Fiver and BadgerEd got me into it. Even though we had some heated discussions, it does work.

 

[Spindrift]

Today, I shot a couple of groups with powder coated HVTH1- bullets in my Schultz & Larsen 30-06. I have had good results with this bullet and rifle before, but have only tried with lubed bullets.

The powder today was Vectan Tubal-5000, a medium/slow extruded single base powder. I tried 41-42 grs (starting load for jacketed). The scope is adjusted for my jacketed moose load (POI 2 inches high at 100m).

I am pretty happy with these initial results. With a bit of teaking, I think I’ll find a good load, with a very relevant point of impact.

 

[fiver]

there's always gotta be one doesn't there.
course I don't think anything with fur is gonna notice you missed by an inch.

 

[Spindrift]

I would have some really astonishing groups, if I could only disregard the fliers

These bullets where some that I cast a few years ago. Next time, I’ll try some bullets slightly more enriched with tin, and maybe of better overall quality. Since they were cast by a more experienced version of myself.

 

[fiver]

just use another paper plate with a hole cut out where you want the group to show through.
or cut the group out minus the flyer and mount it on another piece of paper.
the flyers disappear like magic.