In the process of getting a 6.5mm - 300 Win Mag built. It will have a 1-8 twist barrel & be finished in the 24 1/4 - 24 3/8 range. Neck is throated to have a COL with a 140gr Accubond of 3.550.

Looking for powder suggestions & load charges.

Retumbo, RL25, H870, AA8700 & US869 are the slowest powders I have in the cabinet.

For those of you who shoot this cartridge I'm looking for a good baseline.

This will be a deer hunting rifle.

An accurate 3150 - 3200 FPS with a 140gr is my goal.

Thanks

I believe 3200 fps will be pretty easy to achieve, US869 and RL25 should get you started. Start with 264 Win Mag charges and you should be able to go past there a bit.

Here is how they stack up beside each other.



It's done! It finished at 24 1/2" barrel length. .298 neck. Simple neck size & trim to form brass from 300 Win Mag. My wife picks it up for me tomorrow. Now to find the magic load. A pressure free 3200 FPS with a 140gr should be easy now

I hope she is good now. On his test fires he ran it up to 65gr IMR 4350 which is 9gr over max 264 WM data. Bolt lifted fine & primer was just starting to crater, so things look promising.

Well it was -31 this morning when I put it to paper. Today was our last day of Whitetail season, so I wanted to load it with something accurate & fast enough so I could just put it to paper & continue on my day hunting.

Last night I pondered where to load this thing at. I decided on 79gr H870. Why? I figured this would be enough powder to get me some speed & not get me in trouble. I also sized & loaded the two test rounds after the build to see if I was going to have a once fired issue again. Bot rounds fired & extracted no problem. Here is what it did. Keep in mind it was -31 & the shooter may have rushed a bit. Mind you I do like what I see



Top shell was the 2nd shot after a horizontal & vertical adjustment. The first shot hit the target beside this one (not shown). The next 2 were fired after another correction & the last three were after another adjustment. I am not sure why the rifle wandered a bit back to the left? There was no wind it was just bloody cold. After the 3 shot group I made one more correction to the right & fired at the other target (not shown) & it was dead center of the top dot. Good enough to go hunting. Man what a muzzle flash though

The chrony did not work in the AM, but I did set it up when the sun poked out for 1 cold bore shot. 15 feet from the muzzle gave me 3274 FPS Judging by the group I think I may be pretty close. Some tweaking when it is warmer out & we should be in the ballpark.
I did neck size one round when I got home and put a primer in the case. Primer pocket still very nice & tight. Not like some reloads I have done over the years The re-sized shell goes back in the chamber like nothing

Here is the load details

Hornady 300 WM brass necked to 264 & trimmed to 2.610
Federal 215M Primer
79gr H870
140gr Accubond
COL 3.530. 20 thousandths off the lands.
.295 neck before firing & .298 neck after firing.
.514 at the expansion ring.

Nothing to shoot at today, not even a coyote Had one doe tag left, but in -31 weather it was going to have to be big to get my hands dirty.

So far all looks good.