7lrm load development, what next??

[sledneck84]

hey everyone, I am trying to workup a long range load for my 7lrm out to 1000 yards. I have ran two ladder tests {different primers} on different days to try and see which charge weight to play with. it was windy both days so grouping isn't good but vertical dispertion is what I was trying to see anyways. I decided to play around with 71 grain charge and shot a 200 yard 4 shot group {see pic} and Chrono'd it to see what the ES was on the round. I feel the group size was good, around .5 moa. but the ES is at 47 which I feel could be way better. my groups out to 400 seem to be less than .5 moa consistently so it's shooting fine. i'm afraid i'm going to see a lot of vertical stringing at extended ranges is why I am looking at the ES. This is virgin brass that has been FL sized before loading. some of the necks were dinged from shipping so i'm wondering if that is making a lot of velocity difference in the neck tension. I guess i'm not sure what to try or if i'm chasing the wrong charge weight all together. any insight would be greatly appreciated as i'm driving myself crazy trying to figure out what way to go with this.

Load Info

71 grains H-1000 {blue shots}
CCI 250 Primer
180 VLD
2.660 to ogive
.020 off lands
Virgin Brass

The pictures are turned sideways. not sure how to fix it. the top of each one is the left side of the picture.

First pic is FED 215m primers
Black - 70 grains
Red - 70.5 grains
Blue - 71 grains
green - 71.5 grains

second pic is cci250 primers
red - 70.5 grains
blue - 71 grains
green - 71.5 grains

third pic is 200 yard 4 shot group followed by chrono numbers for group.

 

[jgal72]

My 7lrm shot close to the same numbers as yours. I'm using the 180 hybrid 2.704 to ogive, 71.0 of h1000, fed 215. velocity is 2950 from 25.5 inch barrel with ES of 25. Groups just under quarter moa.

 

[sledneck84]

thanks for the info. I feel like i'm chasing a ghost. lol. I worked another round of various loads today and got one to an ES of 19. That was 71 grains h-1000, cci 250 primer, 180 vld, 2.668 to ogive. I tried quite a few other things to try and lower that ES even more and it went the other way on me. not sure what I need to do. I've spent about 30 hours and feel like i'm still not there yet. frustrating.

 

[WildRose]

thanks for the info. I feel like i'm chasing a ghost. lol. I worked another round of various loads today and got one to an ES of 19. That was 71 grains h-1000, cci 250 primer, 180 vld, 2.668 to ogive. I tried quite a few other things to try and lower that ES even more and it went the other way on me. not sure what I need to do. I've spent about 30 hours and feel like i'm still not there yet. frustrating.

When I see broad swings in ES or vertical stringing (usually one and the same) absent significant temperature swings which can really affect some powders neck tension is where I look.

Before getting frustrated and moving to a new load try just neck sizing some of your once fired brass using the same load and see what that does for you.

 

[sledneck84]

I don't have a neck sizing die. would partial fl sizing with a slight shoulder bump work to try??

 

[WildRose]

I don't have a neck sizing die. would partial fl sizing with a slight shoulder bump work to try??

The way I did it for years was to partial resize trying generally to get low on the neck without quite bumping the shoulder by watching the line that is formed from the lube and moving it down incrementally till I felt like I was where I wanted to be.

If you're going to full length resize each time absent having dies made specifically to your rifle you will never quite get the full benefit of loading your own.

If it were me I'd call up the manufacturer and see what it would cost to get a neck sizing die so you can really do it right.

 

[ShootnMathews]

Use calipers and a hornady gauge to adjust the FL die to where it's bumping the shoulder back .002" on your once fired brass.

 

[Mikecr]

You should have first taken time to fire form your brass while performing seating testing.
And when ready for a ladder(with fully stable brass), you should pick perfect conditions, so that you can mind horizontal as much as vertical.
Then incremental load development around the promising, followed by seating tweaking to shape your final result.

If you're actually FL sizing the necks,, stop doing that.

 

[sledneck84]

Thanks for all the input guys. I am getting closer thanks to your advice. Since I don't have neck sizing dies I used what I have and loaded some rounds. I partially sized my once fired brass bumping the shoulder .002. I went out and shot and am now getting an extreme spread of 9 ft/sec. Groups are right at .5moa at 200 yards which I was hoping would be better but it may just be me today and not the guns fault. I am going to load some rounds and go stretch its legs out this weekend and see how they do down range. I may play with the seating depth a little bit and see if I can shrink that group up some. Anyways. That's where I am at for now. Thanks again for the help and feel free to add any other advise you may have.