Advice Needed, Load Development

jstanton

Well-Known Member
Joined
Oct 7, 2017
Messages
154
Location
Texas
So I wouldn't say I'm an advanced reloader but I'm also not a beginner. I've worked up loads for my 6.5CM and 300WM with great success but my latest endeavor for my custom 7mm Rem Mag has been difficult to get my SD and ES where I want them. Ideally, I would like to see both below 25, and maybe that's unrealistic, but that was easily achieved for my other rifles with the 6.5CM being single digits on both. I'm thinking maybe this gun just doesn't like H1000 but figured I'd tap the braintrust here before changing anything.

A bit about the gun. Built by Alamo Precision its a 7mm RM on a Curtis Axiom action, 24" Proof Sendero Lite barrel, Timney Calvin Elite trigger, bedded in a Western Precision Stock. It was throated for 180gr Berger VLD bullets. Prior to load development the gun had 140 rounds of factory ammo through it.

Load components are: New ADG brass, Berger 180gr VLD Hunting, CCI 250, and H1000 powder. Loaded .020" off the lands and .002" neck tension set with a mandrel.

I am typically pretty cautious working up to pressure so I always start low. Here was my first outing. All shot over a Magneto Speed V3 in 5 shot groups. No signs of pressure.

65.1gr, 2802fps, 40.2SD, 98ES
65.4gr, 2809fps, 30.6SD, 84ES
65.7gr, 2804fps, 19.2SD, 44ES
66.0gr, 2840fps, 46.6SD, 123ES
66.3gr, 2843fps, 21.4SD, 50ES

Second outing, still searching for signs of pressure, I started on the high end of my first workup. No signs of pressure still.

66.0gr, 2791fps, 23.4SD, 54ES
66.3gr, 2815fps, 33.0SD, 78ES
66.6gr, 2855fps, 34.7SD, 80ES
66.9gr, 2841fps, 17.3SD, 48ES
67.2gr, 2859fps, 33.3SD, 67ES

Temperature and humidity were similar both days. I even tried a round with 168gr Bergers and had similar results to my first batch of 180s. I feel good about my reloading process. I throw charges with a Chargemaster Supreme and double check every charge with a balance beam. I also measure every round after seating to verify depth.

Could it be the powder and it just doesn't like H1000? Something else?
 
Here you go:

Load components are: New ADG brass
Don't even bother with the velocity stats yet. Shoot all the cases at least once before you look at it. Don't oversize the cases on the first sizing, let them grow.

Just curious, what's the best ES/SD you've ever gotten, and what did the factory ammo post?
 
I do not use new brass to start developing a load for belted magnums. I always use formed brass. Also I would just load 10 rounds increasing charge weight with once fired brass to find pressure and then go back and find a decent spot to do an OCW test. I do this with cartridges I am not familiar with. Makes it easy to find the sweet spot.
 
I would agree that H1000 is probably to slow. Ran it through GRT and it had incomplete burn rate (93%) at the end of the barrel. I ran H4831 ssc and N565 which both gave 100 bun rate. Also RL 16 and 19 may be good candidates.
 
Here you go:


Don't even bother with the velocity stats yet. Shoot all the cases at least once before you look at it. Don't oversize the cases on the first sizing, let them grow.

Just curious, what's the best ES/SD you've ever gotten, and what did the factory ammo post?
For sizing I typically FL resize with a .002" shoulder bump so that was my plan for this one as well.

Best ES/SD was 48/17.3 and 44/19.2 over 66.9gr and 65.7gr of H1000 respectively.

Factory ammo I never chronoghraphed. I sighted the rifle in with some Hornady Precision Hunter ammo and it was holding 1.5" groups at 200 yards. I used that for a few Texas hunts and to break the barrel in before I started working on a load.
 
Usual suspects have been mentioned I think

Possible powder not ideal tho in my experience 7828 is good in a 270 and 8133 In a .300 win so I can't agree that h1000 is too slow. Plus you've had success loading in other cartridges regardless of powder so….

Hows your neck tension consistency from piece to piece? That could do it. Inconsistent brass or rougher dies?
 
Usual suspects have been mentioned I think

Possible powder not ideal tho in my experience 7828 is good in a 270 and 8133 In a .300 win so I can't agree that h1000 is too slow. Plus you've had success loading in other cartridges regardless of powder so….

Hows your neck tension consistency from piece to piece? That could do it. Inconsistent brass or rougher dies?
I feel like my neck tension is consistent but I am not really sure how to check that? I use a mandrel to set neck tension at .002". Brass is pretty consistent with weights not varying more than a few tenths of a grain. Dies are RCBS competition.
 
I feel like my neck tension is consistent but I am not really sure how to check that? I use a mandrel to set neck tension at .002". Brass is pretty consistent with weights not varying more than a few tenths of a grain. Dies are RCBS competition.
Okay never mind then. Just seemed like another box in need of ticking

I realize I too don't know how to really check that but I have fiddled around with crimping vs not crimping and also with removing the expander ball all together for a much much tighter neck. Beleive it or not in my old savage 99 243 that helped (back then I was using mixed headstamps haha…maybe making the necks stupid tight evened out differences between brass). Crimping can be a good thing or a bad thing.
 
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