Rcbs 257-120-sp

[Marlin Junky]

What's required to stabilize RCBS 257-120-SP?

MJ

P.S. And what weight boolits does this mold cast in WW metal?

[Bass Ackward]

A 25 caliber bore. Some rifling in it would help.

You can't shoot that in a 35 for gosh sakes!

[beagle]

Shoots pretty well in my old M722 "Bob" in a 1-10 twist./beagle

[AnthonyB]

I have one, and some of beagle's 25-120 HP's. I just haven't made my way below 30 caliber with CBs yet - I'll save that for after I retire.
Tony

[reloader28]

Beagle
If you dont mind my asking, what are you using for a load? I have a 1-10 Bob myself.

[Marlin Junky]

So the normal 10" twist is all one needs to stabilize this thing from 1500 fps to copper patch velocities?

Not a very popular boolit, eh?

MJ

[Shuz]

I've tried this boolit a few times in several .250 Sav bolt guns down thru the years. Results have always been less than stellar, and I've had much more success with the Cramer 55A. The Cramer 55A is a nominal 100 g boolit that weighs about 105g when cast from my 3:1 (ww:lino) alloy and gas checked.
The RCBS 25-120 outta the same alloy weigh 125g sized and checked. I would expect this boolit to weigh slightly more outta "pure" wheel weights. Naturally, the more stick-on wheel weights in your "pure" mix, the heavier the resultant boolit.

[felix]

When twist is marginal, you want the heaviest boolit possible (for the given length) for starters. Sharpening the very tip of the nose will give additional help. If still no stability, grind the nose back keeping the nose sharp. Once stability is found, you might then decrease the nose some more while adding a meplat. ... felix

[beagle]

25120SPHP 122.8 WC820 13.0 1625 7.6
25120SPHP 122.8 MS4759 16.0 1817 6.2 milsurp 4759
25120SPHP 122.8 4198 18.0 1780 17.1
25120SPHP 122.8 WC820 14.0 1728 21.6
25120SP 122.6 4198 18.0 1838 11.1
25120SP 128.1 4198 18.0 1838 8.2
25120SP 128.1 Unique 11.0 1637 14.9
25120SP 128.1 4895 22.0 1709 14.6
25120SP 128.1 4895 25.0 1907 8.3
25120SP 128.1 4198 18.0 1838 10.4
25120SP 128.1 MS4759 16.0 1784 12.4 that's milsurp
25120SP 128.1 WC820 13.0 1581 16.1
Bullet Wt Powder Wt Av Vel SD

Now, these are my loads in my rifle so use at your own risk.

The best performance for me was with 4198. As you see, I'm not breaking and speed records but the 4198 loads would gibe me about 1" at 100 yards.

Those are pleasant shooting loads as well. I love shooting the Bob,/beagle











Beagle
If you dont mind my asking, what are you using for a load? I have a 1-10 Bob myself.

[reloader28]

Thank you. I dont have this mold, but was thinking of getting one. I love the 243 version.

Marlin Junky
sorry for butting in.

[beagle]

Not butting in, this is an open discussion. I also have a 25-100-FNHP that shoots well in it but when I ordered that, it was special order and a bit pricey. I think Midway has stocked a few since then but it shoots well also./beagl


Thank you. I dont have this mold, but was thinking of getting one. I love the 243 version.

Marlin Junky
sorry for butting in.

[HangFireW8]

Those are pleasant shooting loads as well. I love shooting the Bob,/beagle

Beagle,

Thanks so much for those loads. I have the mold, and as soon as I get a chance, hope to be trying these in my Improved Bob.

-HF

[Al_sway]

When twist is marginal, you want the heaviest boolit possible (for the given length) for starters. Sharpening the very tip of the nose will give additional help. If still no stability, grind the nose back keeping the nose sharp. Once stability is found, you might then decrease the nose some more while adding a meplat. ... felix

I am afraid that I don't understand the point you are making.
If the twist is marginal then a lighter bullet (shorter bullet length) is required, or so I thought. Why would you start with the heaviest bullet possible? Perhaps that is what you are saying and I don't follow your point properly.
I also don't understand how sharpening the tip will help (done manually?) other than reducing the bullet weight for a given length.

[303Guy]

I am afraid that I don't understand the point you are making.Perhaps the parethesis should be removed.
... you want the heaviest boolit possible for the given length ...This means you want to put as much weight as possible into the given length (and then as much of that near the circumference of the boolit as possible - as in smaller lube grooves and shorter ogive). The 'pointing' of the nose would have something to do with the destabilizing effect of airflow over the boolit body (or shockwave) as well has effectively shortening the ogive.