Undersized Boolits, what to do?

[mtnbkr]

Some time ago, we're talking close to a year, I bought some powdercoated cast 30 caliber bullets from a vendor I cannot recall.  After tossing the receipt and forgetting who I ordered from, I got around to measuring them.  The lower driving band is right at .308 and the upper band is .3075.  I've spot checked several and this is consistent.  That's too small.  For a normal cast 30cal bullet, I would expect .309 minimum, preferably .310.  My next smallest caliber is 6.5 or .264, so I can't even resize these (might get away with that if I had a .280)

The bullet design is a gas check design, but is not equipped as such because it was powdercoated, which is supposed to be closed to jacketed in terms of its ability to withstand gas cutting.

So, install gas checks, tumble lube, and hope for the best or toss them into the melt pot and recast them as something useful (I have a shiny new brass 32cal mould from Mihec that I need to break in)?

These are 215gr bullets.  My plan was to experiment with some subsonic loads in my Savage Hog Hunter 308Win.

Chris

[230RN]

Depends on what you're doing with them (hunting v target shooting), I wouldn't worry too much about 5 / 10,000 of an inch on the diameter of the front band.  In other words, 2 1/2  ten-thousandths on the radius.

Load 'em up (and probably gas-check them, which will size the rear to .308") and forget it.  Powder-coated lead (and probably its alloys) will probably upset that 0.0005" on firing and fill the grooves anyhow.

This, assuming you aren't firing them out of a .311 "30 caliber" rifle.  Even then it wouldn't make a lot of difference in practical accuracy anyway.  Some folks load .308 bullets in the .311 diameter "7.62" X 39 cartridge  and the "7.62" X 54R cartridges when they can't get .311 bullets without too much detriment.

And that's 0.003" difference in the diameter.

Terry

Note: 7.62mm = exactly 0.300 inch

REF:
http://www.gunsandammo.com/reloading/reloading-the-7-62x39/

[mtnbkr]

This is just "experimentation" and not for any serious purpose.  I wouldn't even call it target shooting since ultimate accuracy isn't the goal.  I'm mainly just seeing what I can do with the 308win.  The rifle has iron sights, so I'm not going to be shooting sub 1" groups regardless of the load.  However, I don't want to waste powder and primers if there's no hope of potential accuracy.

I haven't slugged the bore, but this being a modern 308, it should be ".308".  I'll give it a try.  Worst case, I get to scrub lead out of my barrel. :)

Chris

[230RN]

"This is just 'experimentation' and not for any serious purpose. "

Then load 'em and shoot 'em even if you don't gas-check them. If the bullet weights come anywhere near matching the rifling, you may be pleasantly surprised by the accuracy... if you don't go for earth-shaking velocities.

Heck, I even tried loading # 4 buck shot in .243 Win cases as an experiment.  But the experimental results were:  "Don't bother trying to load #4 buck into .243 cases."

Terry

[mtnbkr]

Twist rate is 1:10, so I'm pushing the envelope a bit, but not too far.  Ideally, I'll find something that will give subsonic velocities and "plinking" accuracy.

Chris

[230RN]

215gr. seems to be stretching it for a 1 in 10 rifle in the .308 Win cartridge unless the nose isn't too pointy.

I suspect you'll get keyholing at subsonic velocities.  But I've been wrong before.

[mtnbkr]

It'll be stretching it, which is why I was concerned about the size and the affects on accuracy. 

The bullet is a flat point bullet and isn't very long for the weight.

Chris

[brimic]

Try them, they might surprise you.

[Triphammer]

What's the Brinnell hardness?  Depending on hardness & chamber pressure they may obturate & resolve the undersize issue.  And, 1 in 10 is the standard 30-06 rifling for a 210 gr bullet. The .308 standard had been 1 in 12 but you see 308s in 1/10 commonly now.
Here's a rabbit hole of cast bullet information.

http://www.lasc.us/FryxellCBAlloyObturation.htm

[mtnbkr]

I tried loading them up this morning and found they were too blunt to chamber (my 308 has a relatively short throat) unless seated VERY short in the case.  Between that and them being undersized, I'm just going to toss them in the melt pot and turn them into something useful.

Chris

[Perd Hapley]

Wouldn't undersized bullits mean that you can fit more of them in your 30-caliber clip? That would make your assault murder rifle even more horrifically powerful.

[brimic]

You can try to partially resize the front 2-3 driving bands down enough that they will chamber...
I had to do this with some 6.5 mm boolits I made with a custom mould. The downside is that you need a RCBs- style sizer to accomplish this and you have to do it by feel.

Melting them down is probably the best thing to do at this point and recast them with a mould that fits your needs as closely as possible.

[zxcvbob]

Did you try loading some of them short enough to feed?  I'd expect them to obturate (sp?) and work just fine even if slightly undersized.

[Gewehr98]

Ditto. 

I would've gone with seating them short enough not to engage the rifling, and shooting them.

Cast boolits tend to obturate or "bump up" from the chamber pressure, sealing the bore pretty well. 

Since you're only sweating a few tenths, I doubt you'd have any problems.

This is an exaggerated example, but you get the general idea:

[AJ Dual]

Yeah, unless they're of a really hard alloy they'll probably obdurate decently.

Load a few up and test.

[mtnbkr]

I'm familiar with the concept of obturation, but wasn't sure it would work at lower velocities and hard rifle bullets (was planning on 1000fps, give or take).

I'd have to load them to about 2.5" (standard 308Win is 2.8" COAL) to get them to chamber due to the ogive.  These are practically RN bullets and the Savage's chamber is fairly short.  That extends quite far into the powder column and renders what little load data I can find moot.  I can't get any bluntish bullets to go over 2.8" COAL before jamming up (Speer 200gr Hot-Cor can only be loaded to 2.8").  

They're already an experiment due to the weight (240gr), then add on the undersized diameter, having to load them very short, and the fact that many were outright crap (wrinkles and such), it's just not worth my limited range time.  Just too many variables... They'll be added to the pot for my next casting session.

Chris