For the really serious reloaders out there, how much weight do you give ES and SD when developing load data? I’m working on my .300WM right now and the load I’ve worked up shoots fantastic at around .5-.7 inches. The only issue is my SD is up to 22.9 and my ES is pushing low 90s. I had another load with an SD of 7.6 and ES of 21.3 but the velocity was over 100fps slower and I never shot it on paper. I’m going to Idaho in October and was told to expect potential shots of 700-1000 which is farther than I’d normally prefer to shoot but still doable. If I’m getting good accuracy out of a load with higher numbers should I stick with it or keep playing around for lower numbers and hope the new loads group well? To add some context the load with better numbers was at factory recommended overall length and the group I put on paper is measured off the lands and seated a little further out.
For a 1000 yard shot, I would prefer to have a single digit SD.
What scale are you using for powder measure? Any idea where the high SD is coming from?
Im using the FA digital scale and measuring each round by hand for powder and length so the consistency is there. Could have just been a bad day but it was a group of 25 so I guess its also possible I didn’t let it cool down enough in between shots. The shot data looks pretty consistent with maybe a few bad rounds but its still higher than I’d like. I have another 40 loaded I wanted to shoot over distance. I’ll post the data from my Garmin for each load for you to take a look at and maybe you’ll see something I didn’t.
What dies are you using? For my 300WM im using Hornady match grade bushing die and following with a LE Wilson mandrel getting .002 neck tension. Neck tension and seating depth can affect sd and es.
Im loading 180g tsx and getting single digits 2930 fps. Sd 3.2 Es 7.9 H4831sc powder
I’m using the RCBS Matchmaster dies. I running the Hammer 182 HHTs using Ramshot Grand and Peterson brass.
I hand measure all my rounds off the ogive so I know the ammo consistency isn’t the issue. At this point I’m thinking its the seating depth. After playing around with the bullets I noticed if they’re seated out too far there’s not enough tension to hold them in place and I can actually spin them by hand. I had to seat a little deeper until I couldn’t spin them anymore so I’m assuming that’s whats caused the huge spread when I went out to the range.
Im going to seat this new batch a little deeper than they were and check if that fixes things.
Expecting long shots that you indicated the ES and SD become important. If shots are 300-400yds there is not enough time for the velocity differences to make a huge difference. 1. How many cycles are on your brass and 2. Do you anneal the cases? Neck tension needs to be consistent. I have never heard of the neck tension so light that you can spin the bullet in the case once seated. IMHO that is way too loose unless I misunderstood your narrative.
These are all first loads on virgin peterson brass so I doubt its the brass thats the issue. I believe its more the design of the hammer bullets and where I had them seated was not enough surface area contacting the inside of the neck to provide enough tension. I ended up seating them a little deeper than initially and now they’re fine.
Could be seating depth I usually statt at .05 off the lands and adjust
Factory base to ogive was 2.820, I started at 2.890 based off the lands and now I’m down to 2.860
The 182 hht isnt very jump sensitive so I would change powder H1000, H4831sc, or N565 are better powders for that round.
I would try n565 or H4831sc.
Factory ammo my 300WM likes 180g accubond. Have you considered changing bullet maybe TTSX since your shooting long range, your rifle might not like hht
CJ, I also have a FA digital scale. I was getting ES numbers up as high as 70’s. I finally changed scales to FX 120i and since then my highest ES is 32. That’s the highest by far. My FA scale is just not that accurate. So, if you have someone with a second scale you can double check your powder weight with, that might help. I found the FA scale just wasn’t as accurate as the scale drug dealers and jewelers use.
double check on an old beam scale when something appears off.
I’ve had single digit SD on the same scale with the same bullet and powder but changing my seating depth is what caused the spread. I was chasing velocity so I might have to go back to my old load and hope it groups well
Intellidropper 2.0 no issues for me very consistent. My Autocharge pro was overcharging 50-75% of the time, hornady replaced it with a new one but im selling it to a buddy
Are you using the Peterson Long 300 WM brass? If not, you need to get fire formed brass for belted magnums to really start your load development.
I had a very similar issue with Ramshot powder in the past. I switched to H1000 for my 300 WM, using 185 Berger VLD Hunting bullets (I tried Berger Hybrids, Hornady ELDx and CX and Nosler Accubonds before landing on Berger VLDs). I seat long at 3.595”. My velocity is on the slower side at 2850 FPS. But, I found a good node and my SD is 6-7 and ES between 12-15. Groups are .6-.75”.
I found moving from a spherical powder to an extruded powder like H1000 or Retumbo made a huge difference for me. Neck tension and jump with the bullet I am using are also important. Sounds like you are having neck tension issues if you can spin the bullet at any seating depth.
If you plan to shoot and/or hunt at distances beyond 500 yards, your really need to get your load dialed in. With the delta in velocity you are seeing with your load, it would be reckless to hunt at distances beyond 300 yards. It’s one thing to shoot 1 MOA at 100 yards, a whole different game shooting 1 MOA at 500 or 1000 yards.
I might not have explained myself properly… when I first loaded the bullets measured off the lands and had them loaded long but with enough pressure I could twist the bullets by hand. This was all after my trip the the range with my leftover rounds that I didn’t end up firing. Once seated further into the case they no longer are able to be twisted. My assumption is the initial loads were seated too far out of the case which caused the velocity inconsistency. I havent been out to the range with the new loads yet but my rifle is getting good accuracy and velocity with the hammers and grand so depending on how the next session goes I might have to swap things up.