What should I try next?

[JFrank]

Loading for 270 WIN... Nosler brass, H4831SC 56.9 gr behind 130gr AB. Last week I shot 3 groups- 40, 80, and 120 off. By far, the best group was at 120 off (.7”/ES 38) but the most consistent velocity (also by far) was with the 40 off group (1.4”/ES 11). Now, I want to further tweak seating depth (and in much smaller increments). I think I should try 35, 45, and 50 off. My question is should I tweak off the best group or tweak off the group with the consistent velocity?

MV 2860 at 120 off
MV 2840 at 40 off

Thanks for any input

There is a difference between testing and load development,
To quote a WRH ( charts and graphs are nice but show me the target)
SPJ

 

[Bc'z]

Do what works for you. I won't continue to repeat myself.

It's cool to agree to disagree.
My last post came from my personal experiences after scoring my magnetospeed a few months back.
I was shootin a confirmed load in wifes rifle
That was consistent .3" load.
Not seeing the shift of magnetospeed but seeing difference on target, on the 3rd shot there was enough movement that the first port on brake frayed edge on strap.
Grouping was over an inch.
Just saying there's more than 1 way to skin a cat. Bottom up, or top down. Take your pick.
Now maybe Dusty will chime in as to why he posted it's not needed also.

 

[JFrank]

And although some people say you can't use a chrono for load development, I completely disagree. A consistent chronograph like the magnetospeed can and is the most reliable and objective method to be utilized for developing charge weight. Seating depth needs to be shot on paper, no way around that.

I'm a stickler for recording data. I have dozens of excel pages filled with accurate notes. And what I noticed after a half decade or so is that the ladder test results almost always matched up perfectly with the chrono numbers. The flat spot on the target was also the flat spot on the chrono.

Look for your velocity over a few charge weights (approx 1% apart) to level out. Three to four rounds per. Weight will give an accurate enough average velocity.

Pick the middle charge weight and test seating in small increments. Like .002" at a time. Start touching the lands (or wherever you choose) and work out or in for about 7-8 groups. Look for the groups to tighten up or for where the poi is relatively the same. I've seen both. Smaller cartridges tightened up whereas larger calibers tended to flatten. This part is not set in stone, I only have so many calibers to test.

Good luck and remember there is no substitute for the scientific method.

Sure there is"

 

[HTSmith]

My experience with a 270W and Nosler bullets would suggest that you'll get more out of adjusting your powder charge than seating depth. There is a reason that most 270W, 130 Grain loads run in the region of 3000 fps plus. For hunting rifles I usually start at about .010 off or the longest length that will have at least 1 caliber in the neck and will feed reliably out of the magazine. Then I start working up on powder charge. My bet is you will find both better accuracy and more consistent velocity with a little more H4831.

This is also a cartridge that I got better results with magnum primers--either CCI 250 or Fed215. Just my experience. Hope it is of some help.

 

[ckaberna]

Loading for 270 WIN... Nosler brass, H4831SC 56.9 gr behind 130gr AB. Last week I shot 3 groups- 40, 80, and 120 off. By far, the best group was at 120 off (.7”/ES 38) but the most consistent velocity (also by far) was with the 40 off group (1.4”/ES 11). Now, I want to further tweak seating depth (and in much smaller increments). I think I should try 35, 45, and 50 off. My question is should I tweak off the best group or tweak off the group with the consistent velocity?

MV 2860 at 120 off
MV 2840 at 40 off

Thanks for any input

My nosler book lists that powder and bullet with a max of 59.0 grains. How high did you go in your ladder testing? As others posted do not use magnetospeed during this testing. Wait until you have load settled then check it if you want

 

[Jody Simcox]

My nosler book lists that powder and bullet with a max of 59.0 grains. How high did you go in your ladder testing? As others posted do not use magnetospeed during this testing. Wait until you have load settled then check it if you want

Went to 59...best group (and repeatedly) at 56.9/2750 FPS... 2750 resulted in best groups across other powders also (IMR 4350)

 

[ckaberna]

Went to 59...best group (and repeatedly) at 56.9/2750 FPS... 2750 resulted in best groups across other powders also (IMR 4350)

If 59.0 is as high as you want and no signs of pressure, if it were me I would go above “book” max slowly. Especially if you were not 3k + FPS. But that’s just me. Keep in mind powders vary by lot and every rifle is different. Every 130 grain .270 I ever shot liked the additional speed.

 

[Bc'z]

53.7 Rl17
I did load work for lil brothers 270 using Rl17
Velocity was 3150 with 130 ballistic tips.
This was the high node, killing primer pockets though.
Gonna take it down to next node to save brass. Should still easily run above 3000
Also ran Rl19 60 gr gave good groups but didn't tune or chronograph as 17 was showing more promise. I may go back to this load.
Trying to give you some options is all

 

[JFrank]

Here is what Nosler has listed, for what it's worth