ballistics help

[beekeeper]

OK to start out I shoot only cast bullets!
Am working with some surplus powder WC860. using AA8700 load data.
Shooting an 8x57MM Mauser ( Milsurp barrel twist unknown)
Using 56 grains of powder.
200 grain BRP bore rider bullet sized to 325 and copper gas check

Second set of reloads uses a NOE 215 grain loverin cast bullet sizes to 325.

I am unable to keep the bullets in a 12 inch circle at 100 yards.
An 8 inch circle at 200 yards
At 300 yards had a lot of vertical stringing( up to 14 inches)

All brass is Milsurp brass (EW43, originally 30/06 )
All brass has the same weight.
All brass holds the same level when loaded with 56 grains of powder.
Brass neck adjusted with a lyman "M" die and seats with 2 thousandths pressure and is crimped with a Lee factory crimp die.
The recoil is about the same as factory or Milsurp ammo
Did not chrony it

I know some of the problem is me as I get frustrated with bad performance but it is not all my fault.
Is there a point where a bullet begins to stabilize and until then it does not perform?
If I try out to maybe 400 or 600 yards will I get any better performance?
Anybody have any idea where I can get ballistic data?

beekeeper

[Fyodor]

The bullet should be stable at 100 yards. I've heard about bullets that need some time to fully stabilize, but that effect only appeared under 50 yards. Maybe you should chrony some rounds and see if you have strong deviations.

[Steve]

Interesting. I agree with fyodor, chronograph some. I want to say when I used to shoot cast in the 30-06 if I went above 1200 fps accuracy suffered. It's been too long ago, at that time I thought I didn't need to write anything down bacause I would remember it.

[RBHarter]

The 8x57s lean toward 1-9 twists you maybe over spining the bullet. There are several threads on castboolits regarding this that just make my head swim. The very short version is that an 8mm in 1-9 over about 1900 fps begin to deform from centrifical forces ..... I have a 1-9 7mm which comes in to best groups at 2210-2230 fps. I have a couple 1-9'' twist 30-31 cal that will shoot above 1900 but I loose all hope of hunting w/them because they have to be too hard.

You may be able to shoot harder cast to get what you want or you may have to back them down.

[Ranch Dog]

Yeap, when you have these kind of issues you really need to get back to the basics. What I immediately see is no reference as to what pressure your loads are generating and what alloy the bullets are cast from and what treatment, if any, was applied during or after the cast. To me personally, velocities in regards to cast bullet success, doesn't mean much until I start sending them out the barrel over 2500 FPS. Until then, the pressure behind the bullet matters; is it appropriate for the alloy?

With accuracy at issue, cast bullets or jacketed bullets, I also think it important that every shot be over a chronograph. If, for instance, velocities are all over the place there is not much reason to worry about twist rates, bullet alloys, or much outside of handloading basics until the FPS is consistent.

One thing that I would do, is bring the distance in until you have the MOA you hope to achieve. MOA is MOA, I see guys that will shoot a 2" group and 25 yards and go right out to 200 or beyond. That results in a lot of wasted ammo and frustration. I only shoot at 300 yards here on the ranch but if I'm working on a new load combination for that distance, I need to see a ragged hole at 25 yards before I move to 50. I work this in increments out to 300 yards.

I have a berm at 250-yards and some people question me about it. Given the velocities we shoot cast bullets out, 1900 to 2500 FPS, a lot is happening from 200 yards out to 300. A lot of the projectiles are going subsonic during this leg of the journey and I believe that this is the point where the effects of bullet stability enters the picture. I also believe the bullet stability is a lot more complicated than the simple, silly Greenhill formula. This is where the quality of the longitudinal stability at the center of gravity yields to the center of lift. The transition back through the speed of sound is quite turbulent and only a stable bullet can survive.

Where I would start is with an understanding of what my alloy is and what pressure not to exceed. If you cannot generate pressure data with the WC860, set it aside and use a powder with documented properties. I would start from scratch across a chronograph at the 25-yard berm.

I tired WC860 from Bartlett a decade ago but gave up on it very quickly. I simply was not pleased with the pressure it generated. A standard deviation and extreme spread is calculated during pressure trace testing and the same that I said for velocity can be applied to these results. If pressure it is all over the map through large deviation spreads, acceptable accuracy is not possible. My hope with WC860 was to generate a load table that could be used for my various rifle cartridges but quickly realized that was not going to happen so I gave near a 8# jug of it away.

[RBHarter]

Here's a couple of links that spell it out better than I can,as far as centrifical force bullet failure goes anyway. There are of course 50 other variables to give you fits.

http://castboolits.gunloads.com/showthr ... city-chart

http://castboolits.gunloads.com/showthr ... Chapter-II

I have enough examples of 1 sort or another to both credit and discredit the above but I tend to agree having 30 cals w/1-9,1-10,1-12 twists and 8mm/32s w/1-9 and 1-10+ twists some of them just get it done and some not so much . My 1st choice would be to back the loads down until the 100 yd groups closed or try a harder bullet . WCWW or AC Lino 75/25 w/pure or 50/50 w/WW next try it water cooled then straight Lino . This is fine for paper maybe even coyotes but much past WCWW will shatter on even 1/2'' ply wood.

[beekeeper]

Thanks RD,
That is the point I am at now except I have not found anyone that wants the WC860 so I guess I will just stuff it in the back of the cabinet or use it for fertilizer.
Had never played with any surplus powders so thought this would be a good one to be my one and only try.
If I could of made it work it would of been great for me but not to happen.


beekeeper

[RBHarter]

Don't bury it to deep I'm due to pass by your front door to see my daughter and grandson........