Need powder recommendations

[Ian]

Here's the MP 30 Sil as-cast .3125" pounded into the .3108" throat entrance of a saami .30-'06 throat. note several things: First the lead rings scraped off by the sharp edge of the fresh throat entrance, and how the noseof one point stayed straight even though the unsupported base collapsed to one side, and the other on the far right did not...which makes a perfect example of what we mean when we say "crooked launch". Also note how metal from the oversized front driving surface folded back as designed into the lube groove, accomplishing the task of filling the chamber neck space and staying straight when moving the first few thousandths, yet folding up like an umbrella as it morphs into a land/groove sized projectile. When fired, the lube displaced out of the groove spreads out to fill the gap between the case mouth and end of the chamber, creating a sort of bridge which aids the oversized rear band and gas check funneling into the throat. Sometimes, even if the throat entrance is too small, the lube pressure up the groove and will keep the lead from shearing off like that, instead pushing the displaced lead into the nose rather than scraping it off.

When actually fired, the transformation is even more dramatic because the pressure on the bullet base transfers up through the core of the bullet, causing the nose of the bullet right were the land marks are in the picture to balloon and expand to full groove diameter nearly to the ogive. All this happens in the first half inch of travel, and it won't happen to good effect if the alloy isn't of the correct ductility for the pressure applied, and the nose of the bullet doesn't fit the throat in such a way that it will align itself point-on before and as the nose bumps up into the grooves.

This is the hard way to launch a bullet, and takes a lot of work to find the right alloy, quench hardness, powder, and other details to get it to happen correctly without having a wobbly ball of putty going up the pipe. But, with some rifles, it's the best way to HV because of tolerances we have to deal with. Sometimes, with sharp throat edges, we get leading and don't know why. Those lead rings should tell you one possibility...your bullet is too big, but, it may not shoot well if it's any smaller due to excessive chamber neck clearances, and the proper alloy and lube can fix that.

 

[Brad]

Ever pound the same bullet sized .310 into the throats of same rifle? Would be interesting to see the difference.

 

[35 shooter]

Wow, pictures really are worth a thousand words.

 

[Ian]

Ever pound the same bullet sized .310 into the throats of same rifle? Would be interesting to see the difference.

yes, but have baby in lap and that's the only photo I could find without getting up and going to other puter. .311" in that rifle (.30 xcb) doesn't scrape lead off and puts 50/50 +1% tin, water quenched and aged, to 2650 fps and 1.25moa groups no problemo. you done even more with same iirc. tite throat helps. in m1a .312" is better, even w/ .3105 throat b/c chamber neck is like .343 vs .337 of xcb.

 

[Brad]

I will have to do a pound salt to see what the throat is like on the 06. I have dies for .308- .312 so size is not a problem.
In my XCB I used .309 or .310 with same results.

 

[Will]

Shew there’s a million things going through my head when I stop and really think about what’s going on here.

The bullet on the right looks great except for the bend starting in the narrowest part of the bullet at the grease groove. Looking at this I can definitely see why a loverin style bullet works good.

Looks to me like the hardest part is going to be keeping the bullet base straight to the bore while all of this is going on. I can already see I’m going to have to buy a neck turning device of some kind in order to have 100% support in the case neck area.

The only chance I see for the bullet making it to the bore straight is if the case neck has absolutely a perfect fit and doesn’t allow any area of less resistance for the alloy to move to.

 

[fiver]

Walter the 311 thing is something I was going to suggest you try in your rifle versus .310 anyway.
mine make 311-3115 I just measured 4 of them in a couple of different places.

 

[fiver]

you can just point it the right way.
if you do that and combine the alloy/design thing I outlined earlier you'll go pretty far up the ladder.

I guess there is no point in getting into different way's to raise up the centerline of the bullet to the centerline of the barrel right now.
but that's really the quickest way to work around many of these problems right from the beginning.

 

[Brad]

Things like not removing the flare on the case mouth?
Ideally the brass is thick enough to take care of the problem on its own but often it isn't.
I know the 375 has lots of neck clearance, it was made as a dangerous game rifle where reliability trumped accuracy.

 

[fiver]

bumps and bulges in the right place can certainly help.
hard to tell by just pulling the bolt and looking towards a light.

 

[Will]

I’m excited to do a pound cast Monday I’ll definitely post pics. I’m really curious how big my chamber is in the neck area.
Good thing is I have lots of different types of 308 brass. Some of the WCC (military brass) I have has really thick brass in the neck area. These things are a bear to resize even after being fire formed. All that extra thickness may come in handy.

 

[fiver]

just so everyone knows I don't do any of this stuff I rely totally on luck... and a faulty chronograph I sent back to china and had them off set the speed by 175 fps.

 

[fiver]

 

[Ian]

Will, neck turning doesn't work miracles, though it can help. Just because your neck walls are uniform doesn't mean they have any way to keep the bullet base straight when the powder lights off. The case neck blows up to fit the chamber before the bullet even moves, leaving the base swinging in the breeze and whatever gap there is is room for the base to go sideways...or rivet. Minimizing these tolerances can sure help, but isn't the only way. Having a little bit of jump, and a chance for the bullet nose to hit a lot of surface and get straight quickly, before the case neck blows up and all base support is gone, helps. Some people like to call that "wiggle room", and it's totally necessary in some arrangements. Uniforming necks by taking off the thick part helps even release , but I believe there is a general error in the line of thinking that you can possibly eliminate all tolerances and perfectly fit everything to the point that the bullet will go perfectly straight without changing form....unless you breech seat.

At HV the whole game changes. You can't get away with the things that give you good results at 1500 fps. Tolerances will bite you unless you eliminate them or find workarounds, and the old trick of getting a tight bore-riding bullet and just jamming it in the lands and calling it a day won't cut it, either. Well, actually it can, but you still have to smack it so hard it blows up to the same form the self-aligners do anyway for best results. Giving the bullet some breathing room for an inertial head-start, and room to easily move forward into the throat before pressure gets so high it bends the base, are things that sometimes help get the bullet straight with a lot of neck tolerance.

 

[Ian]

just so everyone knows I don't do any of this stuff I rely totally on luck... and a faulty chronograph I sent back to china and had them off set the speed by 175 fps.

You mean like my laptop that I sent back and had that "half moa" key installed on?

 

[Brad]

Fiver, is that you?

 

[fiver]

hey now just cause BS JR said I was a internet celebrity makes it so.
and that guy is wearing some type of shoes, I got at least 2 more weeks before I gotta put shoes on.

 

[Brad]

Those aren't shoes, those are fuzzy kitty slippers. I'm sure yours are adorable.....

 

[fiver]

you know,,,, I have never had a pair of slippers.
it's never occurred to me to buy some.

 

[Ian]

Current conditions @ my house...