Les in Wyoming
Well-Known Member
I went through a lot of headache developing my 300 wm load. I could not get Bergers to shoot as accurate as Hornady ELD-m. My load is a 208 gr eld-m with 77.5 H-1000 and .090 jump. Hope this helps as a reference.
Verticle Spreading and load development help - where to go from here?
- Thread starter fnlights
- Start date
Help Support Long Range Hunting Forum
Stgraves260
Well-Known Member
- Joined
- Sep 1, 2009
- Messages
- 942
In your vertical/ latter test keep the bullets the same off the lands. So say .015 off the lands. Then load some up with your powder as such. 71 - 71.5 - 72 - 72.5 - 73 - 73.5 and so on. Go up 1/2 grain increments. I like to go back to 300 yards while doing this. After each shot mark the bullet impact so you don't get confused on what powder charge was used. Pick the ones that are closest together. After you decide the one you want then start messing with the seating depth.
Stgraves260
Well-Known Member
- Joined
- Sep 1, 2009
- Messages
- 942
Stgraves260
Well-Known Member
- Joined
- Sep 1, 2009
- Messages
- 942
drborsos99
Active Member
If changing the powder charge weight, changes the chamber pressure, how can changing the seating depth, not change chamber pressure? Isn't chamber pressure and velocity directly correlated?
SSG Graybush
Well-Known Member
You should load 30 thou jump and shoot a ladder from 74 to 76 grs at .2 increments look for a speed node, a flat spot, a spot where the speed stays the same. And look for pressure. A good node is were the fps ES is less then 20 fps across .4 grs/ 2 shots or more. Load the middle of that node/powder charge. And then test your jump again at 5 thou increments and since 30 thou jump was best before go up and down from there, 20, 25 30, 35, 40. When you shoot these you should see a pattern to follow to the best load. See ocw and Satterlee load development videos.
jerry moore
Well-Known Member
if you want velocity i would start 2grs under max & work up 1/2 gr incr get acceptable fps work on seating depth good luck
You did good on the seating test on low low powder. Now you need a chronograph. The best thing to do is load 1 bullet at say 72gr, then 1 at 72.2, 72.4 and so on. There will be a flat spot where your fps is similar like 73.5 gr is 1650 fps, 73.7 is 1652 fps and 73.9 is 1657 fps. The area that you get a flat spot where the fps is really close together will be where you want to go back and fine tune with 4 or 5 shots to find the least amount of spread in fps.
cabelasken
Well-Known Member
The vertical group could be solved by tuning the powder charge to the barrel whip. A thin or a long barrel can amplify the vertical stringing. I had the same issue with a #2 contour barrel and when the powder I selected did not achieve the velocity and accuracy desired, I experimented with different burn rate powders to get closer to the velocity and accuracy I wanted. I've also found that with a perfectly aligned custom barrel that seating depth sometimes is not as important aa tuning the powder burn rate and/or powder charge.
Cliffhunter
Well-Known Member
I did a load development on a 300 WinMag last summer for a friend. Are use the 210 grain berger bullet. I got as high as 79 g of H 1000. Slight cratering to the primer. So I backed off and use 78 gr. I like a big slug for hunting but a 180gr bullet might perform better in a 300 winmag.
QuietTexan
Well-Known Member
Seating depth does affect chamber pressures, but to an extent there is an inverse correlation between internal case volume and pressure, with velocity as a constant - meaning as case volume increases and velocity stays the same, pressure decreases.
Direct from Bryan Litz: "In fact, the extra powder you can add to a cartridge with the bullet seated long will allow you to achieve greater velocity at the same pressure than a cartridge with a bullet seated short."
I say to an extent because you can jam a bullet into the lands or seat it so short that you force other issues not strictly speaking related to the internal ballistics of a cartridge because they're outside the scope of normal. Stupid things, like seating a 115gr VLD into a 6BR case to where a caliber-ogive is at or below the case mouth (so about .25" too deep), or loading something so long to the point the bullet is set back into the base a tenth of an inch and compresses a max load when you beat the bolt down. One the jump is so illogically long that the bullet even getting out of the neck poses a problem, the other you've basically built a bomb. So there is an assumption here that you're coloring close enough to inside the lines.
Last edited:
Wolf76
Well-Known Member
I use this same combo in my 300 wm/215/nosler case. My coal is long and I'm well north of 77 grs. My last 8# jug of h1000 was slower than the pervious 1# cans. Needed almost a full grain more to achieve the same speed.
Well... there's a lot of info and great tips. If I may help? I'll keep it as simple as possible. You can start at 70.5 and load one bullet .3 grains hotter each time until you see pressure (ie: 76 or more) Be careful!!! Use your corny! This OCW test will show you a node where the MV will flatten out over 3 or so shots. No target needed. Yes I said no target required. Just the chronograph. Choose the middle load of the three and then do seating depth testing starting at max mag length or .005 off of jam. Load 3 shots per string same depth then .003 deeper for the next string and so on.The node will show itself here. You are looking for the groups to tighten then open watching yet again the ES& SD's of each string. Target required here in conjunction with the crony. You are tuning for barrel harmonics now. When the best 2-3 groups are found across approximately .006 of jump, use the longest seating depth that is visible minus .001. This allows you to stay in the node as your throat erodes. Good luck!
