7x57 AI loading data

Mtnlover

I'm trying to help a friend work up loads for a 7x57AI with 140 gr. bullets. We've tried several powders, but have gotten extreme velocity spreads (200 fps+ over 5 rounds). We're using RCBS press and dies and measuring every charge within 0.1 grains. The limited data I've found shows powders as slow as H4831 and as fast as H4064. Any advice on a range of powders to try and what may be causing the extreme spreads?

DENWA

Try H4350 or better yet Varget.

Also check primer pockets and look at the primer holes very carefully.

Make sure all primers are inserted with same depth/insertion pressure.

I've got extremely low std dev with H4350 even across temps.

Oh yea, try a Magnum Primer but be careful with pressure signs.

this should be very similar to 7mm-06

mrbruce

Different neck tension will effect velocity spreads especially on old brass..
H-4350 should be, and is a great powder for the 7x57 with 140 grain bullets.
Find some of those Wolf Russian LR mag primers, they may help a lot too....

2BGood

I agree with mrbruce, check the neck tensions and seating depth.
[:)]

Mike Fink

You always get help on this forum. The only thing I can add is: use the same brand of brass,bullets, primers and powder. Consistency solved these same problems with my 7X57 Ackley. Imp.-Best, Mike

Mtnlover

Checked our mix of brass and turns out ALL Rem brass needed neck reaming and NONE of the Win brass did. Haven't clocked loads since neck reaming, but appreciate the good advice. Now, if we can just find the magic powder for this rifle.....

sandwarrior

Mtnlover,

I've had tremendous success with my standard 7x57 using VV N150, N160, and N165. Also, H4350 and H4831 Extreme. that is a 30-06 sized case and needs a powder slow enough to utilize the whole barrel length. Also, you might, on a whim try H1000. I use that in my .280 AI. It's kind of been a toss between 1000 and 4831 for velocity. Both have shown typical accuracy for the rifle.

I'm really suspecting that your best bet for accuracy will be the VV N165. I use 47.5 gr. in my 7x57. That would be a good starting point for your AI.

-good luck

Edit:

That was with 168 gr. bullets....sorry. With my other 7x57 I use 4350 behind 140 gr. and 154 gr. bullets. The 47.5 would still be a good place to start. The powder is a little more costwise, but it is very consistent shot to shot. It does vary about 100 fps from summer to winter too. I don't have the load handy so I will have to digress to what I know I did use and that was H4350X for 140 gr. BT/ACC's 48.5 gr. of VV N160. VV N165 will go a little higher. Bullets seated normal in case not out to meet the lands.