Need some load workup advice


Well-Known Member
Apr 21, 2012
I'm doing a workup for a 300wm and having some difficulties getting anywhere. I've done a full ladder test and can't seem to find anything that works. Hoping I can get a nudge in the right direction to get over this hump.

180gn Accubond
Fed 215m primers
Magpro powder
Winchester Super-x cases, fireformed with full case prep (neck turn was only partial though, no bushing dies uses)
Remington 700 5r 26"bbl

Accurate powders lists 85.5 grains as the max (3146fps), and a starting load of 76.9. I did a pressure workup and found that I got much higher velocities than expected and stopped at 83.5 and 3210fps. I'm a little...confused I guess is the word...because that's 2 full grains short of listed max and over 60fps more. The cases show only a slight polishing of the extractor at that powder charge, with no extra bolt lift force. About one out of every 10 or so need a SLIGHT bit more aft pressure, but once the case moves there's no other resistance. No other pressure signs w/ case or primer

At this point I don't have enough experience to know whether it's normal to get that much deviation from listed data, or should I check into the chrony's accuracy and keep working higher. The Shooters Chrony seems fairly consistant, but prints about 50fps higher velocities on the Winchester factory rounds. Seems like a plausible velocity, though, considering the drops I've verified at a few different ranges are pretty close to what EXBAL shows.

After all that, I ran a ladder test from 678 yards. The target data doesn't show any well-defined "nodes" except a slight tightening around 81 grains and another at my max load of 83.5grains. The velocity data supported a tight node around 83-83.5 (3fps ES one day and 10fps ES another day), at around 3108fps, so I figured that one was my best bet, even though it's pushing max.

Today I set up four different loads, two near the middle "node" and two near the upper node...with five shots each. Just got back and don't have a single load showing any promise. All groups (from 400yards) are around 6" plus or minus. Then I put 5 of my go-to factory round, Winchester Super-X cheapies, into a 4.1" group, with only about an inch of horizontal spread. Grrrrrrr.....

I'm not sure where to turn next...different powder? Bullet? Primer? Should I call BS on the chrony? I've shot close to 100 rounds and wasted several DAYS with nothing to show....I guess I'm still hoping that there's still hope...If someone can lend some experience I'd sure appreciate it.
Try another powder, just on the off chance there's something up with that lot of Magpro. Not saying there is, but since it's driving a lot harder than you'd expect--it's possible.

RL22 would be a good powder, with Nosler showing an accuracy node at 75.5 grains (work up from 71.5 grains).

I'm not a fan of extreme range ladder tests personally... there's just too much that can go wrong (as you've seen, with un-repeatable results when you tried the same charge up close).

Most 300 Win Mags will shoot quite well with an even 70 grains of IMR 4350, for 3000+ fps of velocity from 26" barrels. That's a max charge in some manuals, so work up from 66 grains.

I do have some h4831 on the shelf, maybe I'll give that a try. Is the IMR 4350 about the same as the H4350?

I saw your post on the IMR powders but haven't ever burned any. I'm only familiar with a couple (rifle) powders, the ones that seem to be "staples" for the 300wm: H1000 for the bigger pills or longer barrels and the others above. Consistancy is my goal, so might go for the IMR 4350 if it's good for the 180 - 210 range.

Have you tried changing your seating depths to see if that could be the problem? Your rifle might like more jump or less. My Rem .300wm seems to like to be seated off the lands quite a bit. I tried seating the bullet only .005 off the lands and my groups went crazy. It might be something to try before changing powders.
Yeah, good call. I've got em as long as I can in the magazine (with a decent buffer) putting them .090" off the lands, but still .100" longer than published max length. Maybe I'll push em in a bit and load some more before I give up on those spectacular velocities. Probably try a different method for workup as well so I don't burn so many rounds.


First off, how confident are you that the gun is capable of sub 4" groups at 400 yards? Maybe I missed it but I don't see any info on the gun. Before you go and spend more money and time on ammo is there a chance the problem could be with the gun? Are you using good cleaning methods every 20 to 25 shots?

Next, the big red flag that may or may not be causing you problems is the brass you are using. All of your components are high-end except your brass. you mention that you turned the case necks. How much variation are you seeing in the wall thickness? My experience with winchester is that the brass can be extremely inconsistent in just about every aspect. A good rule of thumb with brass is that any variation in the neck thickness will also be present in the body of the brass... so you can only get so far with turning necks. Considering how much money bullets/powder cost plus time and effort reloading and going to the range ... it's not worth trying to save money on brass. Buy good brass like lapua or norma or nosler. I have had excellent luck with Nosler brass, all of the brass is weight sorted to within 1 grain and neck wall thickness is within .001 on all of the brass.... at least with the batches that I have used.

And I would personally do the shooting for load development at closer ranges so you are not magnifying any possible human error. I normally shoot at 100 and sometimes at 200.
Here is what works well for me:

I start by establishing the seating depth that shoots most accurately with my chosen bullet using the procedure outlined on the Berger website:


I have used this same procedure for load development with Berger VLD's, Hornady AMAX's and VMAX's, Nosler Partitions, and Barnes TTSX's with great success. This has become the first step in my load development regardless of the bullet that I am using.

Once the preferred seating depth is established, I begin my powder charge workup using the OCW procedure outlined here:


The entire process normally takes about 50 rounds and two range sessions to complete. It has worked reliably for me and a handful of others I have talked to who use similar techniques.

I hope this helps you get thins sorted out...
Yes! I think that helps me sort some things out.

I started out making it short enough to fit in the magazine for hunting and forgot all about playing with the seating depth, I'll give that a whirl before switching powders.

And after getting nothing useable from doing the ladder test, I've been reading up on the OCW and I'll give that a go for sure.

Thanks for the help!!

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