Having trouble working up a hunting load for my M70.  Using Win cases, CCI mag BR primers, and 180 Nosler Accubonds.  I've tried H1000, IMR 7828, and Magnum.  Best loads so far are 79g H1000 and 82g Magnum.  Both produce groups with four slightly under or right at an inch and a typical flyer an inch or two away.  I'm going to try H4831 next but I'm really puzzled over this one.....first rifle I've ever had this much troubled with.  Suggestions?

Frustrated in Houston  

IM sent with my hunting load.

ETA,  start at 10% lower.

My M70 likes RL22 and 200 gr nosler partitions.

I worked up a load until I liked what I saw.  I'm a bit under noslers published max for the load.

I use 72 grains of IMR 4350.  That's max or slightly over, depending on which manual you're looking at, so proceed with caution and work up.


Delivers 3000fps in my M70 with a 24" barrel.

300WM is really sensitive to seating depth and seating pressure. That itsy bitsy neck does not hold on to bullets very well if you use a bushing die and apply the typical .002" neck tension. You did not say how you sized your brass or how you arrived at your COAL, but I suspect you'll find the solution in those two areas.

Here is the same issue and a solution:

http://forum.snipershide.info/showthread.php?t=250870

Read post #9.

wasn't aware that cci made a match magnum primer? I've always heard that 215m or cci 250's were the standard for magnum cartridges? I would try some 215's. and depending how thin the barrel is you may need to allow cooling between shots. my factory sporter savage 300wm would throw shots after 3-5 rounds and the barrel would be cookin! is the barrel free floated? when it throws a shot re-check if it still free floats. could start deflecting towards the stock with the heat.

That comment on a round going an inch or two away from what sounded like the start of a pattern that would be about an inch sounds wrong.

Does the rig repeat that behavior without cleaning or by just cooling off? Or, does it throw flyers every so often regardless?

By chance, do you use this same brass prep in any other rig where it tends to exonerate the brass prep? It might be handy to track those shots with a chrono to see if they are flyers for a reason.

Have you ever had this rig do well with any factory or other hand loads at all?

How was this rig chambered, i.e., how far out to touch the lands with sample bullets?

I'm not sure if we are not seeing something as simple as the dispersion of a recipe it doesn't like, or one of several other causes.

The brass is new and was resized with FL Forster dies.

The bullets and the brass was weighed on a jeweler's scale and batched by weight.  Particular attention was given to the charges which was also weighed on the same scale.

The rifle has a chamber that is at the upper end of spec and free bore like a Weatherby.  I'm limited to maybe 3.36 COAL due to the magazine.  I have tried 3.34 and 3.355 with no apparent difference.

And, my bad...the primers are Federal 215 BR.

The rifle will shoot every 180g factory rounds I've tried into 1.5" or less.  Also, I ALWAYS allow time between shots.  If the barrel is clean I'll usually put a couple rounds through it and let it cool completely before starting to shoot for groups.  Usually takes me about 30 minutes for a five shot group.

My gut was telling me it's new brass, long chamber and powder but I'm stumped.  As I said earlier, best loads so far are 79g H1000 (4 shots at about 1 1/4" and a flyer 2" away) and 82g Magnum (3 shots into one over-sized hole, 1 about 1/2" away and a flyer about 1 1/2" away.

Both range sessions had wind of about 10mph straight from my back.  

I'm going to suggest a different approach having had similar problems with a light weight .300 WM.

Two rounds touching.  Third an inch or two away.

My problem was the stability of the rifle on the front rest.

Instead of the now classic position of left hand under the stock, try left hand stabilizing the fore end.

My insight was a light weight magnum rifle was lifting off the front rest under recoil before the bullet left the barrel when I used my usual technique.

Flyers went away when I controlled the fore end.

Try it and see.

Good luck.

I use 80.5 grs of h1000 with 180 accubonds with a WLRM primer coal of 3.5" . 81 gr is max according the nosler handbook. I also found in my load development h1000 didnt group well for me until I got to higher charges. It has given me solid 3/4" groups from a factory browing xbolt lrh. Work up slowly.

I am getting ready to start my testing with 190g accubonds.  R22 will be my powder of choice.  Mine loves max load with Sierra 190 matchkings.  Hoping I will get similar results with the Accubonds!