7mm-08 Load with 131gr Hammer Hunter

[blueridge]

I am working up loads for two 7mm-08's with 131gr Hammer Hunter bullets. In case anyone is interested, I will show my results and progress here. Every gun is unique, so a reminder not to expect/assume similar results.

I used Lapua brass, WLRM primers, and Shooters World Precision Rifle powder (see update in subsequent post for change to Varget). The latter is supposed to be very comparable to Varget, which I was not able to obtain.

I started low with 38gr. It was a snowy day (32 deg), so I started just shooting into a bank over a chrono out the back door, looking at velocities and trying to find pressure signs.

Rifle 1: Tikka T3 Forest, 22.5" barrel, 1:9.5" twist.

gr - fps
43 - 2754
44 - 2824
44.5 - 2851
45 - 2879
45.5 - 2989, 2962
46 - 2996, 2989
46.2 - 2978, 2989
46.4 - 3008, 3016, 3016, 3030, 3018
46.6 - 2996

Loaded 46.3 and 46.5 to shoot 4-shot groups @ 100 yards.

46.3gr: 2943, err, 2943, 2949


46.5gr: 2996, 2943, 2982, 2989


Rifle 2: Savage 10, 21" barrel, 1:9.5" twist.
gr - fps
38 - 2578
39 - 2640
40 - 2704
41 - 2766
42 - 2830
43 - 2886
44 - 2930
44.5 - err (slightly stiff bolt lift)
45 - 3051 (extractor mark)

This is a new gun to me and when I mounted my standard rings and scope on the existing bases, I didn't have enough adjustment in my scope to even get on paper, so just ordered a Savage 10 specific base/ring set.

More to come . . .

 

[homers]

I got some initial load dev suggestions from Steve for my 7mm-08 with the 131 HH. Got two nodes that I need to explore, one topping out at 3100fps.

 

[JLS]

Something isn’t quite clicking, is it?

 

[blueridge]

Had very different velocities for the same charges on three different days. Emailed Steve to get his advice and he said the ProChrono I am using is the likely culprit for all of the wonkiness. Magnetospeed on the way, along with an adapter from Wiser Precision that mounts it to a swivel stud-picatinny rail adapter that will keep it from affecting poi or barrel harmonics.

 

[blueridge]

It's been a few weeks, and a lot has changed with this load development. Here's a current update:

Per Steve's advice, I switched chrono's to a Magnetospeed to ensure accurate velocity data. The ProChrono was all over the place. I also got a RCBS Matchmaster bushing die set to adjust neck tension. And, most importantly, I landed a few pounds of Varget. So I basically started over from scratch.

Goal for the first day was just to find max loads in both rifles and record velocities.

I looked up Varget load data for a comparable bullet (140gr TSX) to get a rough idea on min and max loads. I loaded 38-42 in 1gr increments to see if there would be any initial pressure signs. Used a neck bushing in the full length die to give me .003 neck tension. Bullet seating to 20 thou off the lands, followed by a medium crimp with a Lee FCD.

In the Savage, I found the velocity I wanted at 42gr with no significant pressure signs, so stopped there. The Tikka wasn't quite there at 42gr, so I continued with smaller increments until I got to the velocity I wanted. Primers were flattened, but no extractor marks or wipes.





Velocity trajectory lines with this combination were extremely consistent and predictable. Curious as to whether it was the powder or adding the neck tension and crimp. Would be an interesting test to load a few with the SW powder but this time with neck tension and crimp and see if that curve would flatten out as well.

Anyway, next step will be to shoot groups with these top charges and see how they look. If needed, start seating deeper in .015 increments and see if things tighten up. More to come.

 

[std7mag]

Interesting write up.
But kinda scratching my head.
I thought you were originally loading for the 131gr Hammer Hunter.
A monolithic bullet.
But you used load data for the 139gr Hornady Interlock. A heavier cup & core bullet.

Also, almost every mono bullet data i've seen suggests starting at 0.050" off the lands. Not 0.020".

 

[mtmuley]

Data for like weight lead bullets seems to line up with Hammers for load data. Especially Nosler data. And, as a rule they are extremely insensitive to seating depth. mtmuley

 

[blueridge]

I thought you were originally loading for the 131gr Hammer Hunter.
A monolithic bullet.
But you used load data for the 139gr Hornady Interlock. A heavier cup & core bullet.

Also, almost every mono bullet data i've seen suggests starting at 0.050" off the lands. Not 0.020".

That was in the first test using the Shooter's World Precision powder. Their load data did not have any info with mono’s, so I used the closest similar weight just to get a rough idea on where to start. In the subsequent test with Varget I used data from both 140gr etips and tsx’s to get a starting point.

Starting 20 thou off was following Steve Davis’ own load development process, as any later seating changes are then only in one direction.

 

[JLS]

I want to know where the hell you found a FCD? Be been looking for a few weeks.

 

[blueridge]

I want to know where the hell you found a FCD? Be been looking for a few weeks.

Everywhere has the 7-08 FCD. You looking for your .280 or CM?

 

[JLS]

Everywhere has the 7-08 FCD. You looking for your .280 or CM?

.280.

 

[blueridge]

Took a little longer than for some, but load development for my Tikka is done.

I found seating depth adjustments made a significant difference, despite the claims to the contrary.

43.5g Varget with .003 neck tension and 1/8 turn factory crimp gave me the velocity I was looking for (2950fps) and very low ES. I fired 4-shot test groups at 20, 35, 50, and 60 thou off the lands at 100yds that ranged from .8"-2.5", with 35 thou off being the sweet spot. That put the coal at 2.941. These were all significantly longer than my factory magazine max length (2.83), so I also shot groups with 2.78 and 2.80 just in case I could get lucky. 2.8 showed promise.

I then loaded 9 each of these top two candidates to shoot for statistically significant groups: coal's 2.941 and 2.80. 8 minutes between shots. Near identical consecutive days.

9 shots, coal 2.941


9’shots, coal 2.80


Loaded up 9 more of the 2.941 to shoot at 300:


For my hunting purposes and shooting ability, that will do. Will work out drops tomorrow and call it good.
To load from the magazine, I switched to the M+ magazine, sold with the 6.5CM, that has a oal of 2.980.

 

[blueridge]

Could never get the Savage 10 to shoot under 1.5", despite changes in powder, primer, or seating depths. I had bought it used on a whim as a winter project gun, so its history and potential was unknown. Since I am happy with how the Tikka 7-08 shoots, I am going to rebarrel this to 300WSM.

 

[std7mag]

Could never get the Savage 10 to shoot under 1.5", despite changes in powder, primer, or seating depths. I had bought it used on a whim as a winter project gun, so its history and potential was unknown. Since I am happy with how the Tikka 7-08 shoots, I am going to rebarrel this to 300WSM.

Have you tried tuning the action on your Savage?
There is an article on Accurate Shooter by a member of Savages shooting team on how to do it.
Essentially you torque the front action screw to 30-35 inlb. Loosen the rear action screw, then torque to 15 inlb.
Shoot groups going up 5 inlb on the rear screw per group going up to 30 inlb.

I'll admit i was skeptable at first. But when i saw my groups tighten up, then open up again, i had to run the test a second time.
Has worked for every Savage i own (5).

Try it! You'll like it!

Spoiler, almost all of mine shoot best between 20-25 inlb.

 

[blueridge]

Have you tried tuning the action on your Savage?
There is an article on Accurate Shooter by a member of Savages shooting team on how to do it.
Essentially you torque the front action screw to 30-35 inlb. Loosen the rear action screw, then torque to 15 inlb.
Shoot groups going up 5 inlb on the rear screw per group going up to 30 inlb.

I'll admit i was skeptable at first. But when i saw my groups tighten up, then open up again, i had to run the test a second time.
Has worked for every Savage i own (5).

Try it! You'll like it!

Spoiler, almost all of mine shoot best between 20-25 inlb.

Huh, no I haven’t. Will definitely give it a try. I already have the 300wsm barrel and SA mag bolt face ordered, but will experiment with it with the new load. Does is matter if it’s pillar and action bedded? It’s in a Boyds.

 

[std7mag]

Matters not a whit.
My Stevens 200 rebarreled in 250 Savage still likes the rear action screw at 15 inlb.
Screw got a drop of the low strength, purple Loctite.
Don't need it falling out!

 

[rtraverdavis]

Took a little longer than for some, but load development for my Tikka is done.

I found seating depth adjustments made a significant difference, despite the claims to the contrary.

43.5g Varget with .003 neck tension and 1/8 turn factory crimp gave me the velocity I was looking for (2950fps) and very low ES. I fired 4-shot test groups at 20, 35, 50, and 60 thou off the lands at 100yds that ranged from .8"-2.5", with 35 thou off being the sweet spot. That put the coal at 2.941. These were all significantly longer than my factory magazine max length (2.83), so I also shot groups with 2.78 and 2.80 just in case I could get lucky. 2.8 showed promise.

I then loaded 9 each of these top two candidates to shoot for statistically significant groups: coal's 2.941 and 2.80. 8 minutes between shots. Near identical consecutive days.

9 shots, coal 2.941
View attachment 180776

9’shots, coal 2.80
View attachment 180775

Loaded up 9 more of the 2.941 to shoot at 300:
View attachment 180778

For my hunting purposes and shooting ability, that will do. Will work out drops tomorrow and call it good.
To load from the magazine, I switched to the M+ magazine, sold with the 6.5CM, that has a oal of 2.980.

Thanks for all the reporting! These bullets sure are fun and interesting to mess with.

Did you try that significantly shorter COAL test load to ensure you were crimping in the valleys between the PDRs? I’m running into the same length issues with my 6.5mm 123 AH load with crimping. I can either go a little bit longer (which makes round cycling from the magazine iffy) or significantly shorter to get the crimp in the right spot. Still in the velocity ladder stage of load development, haven’t shot for groups yet. I’m wondering how important crimp placement really is.

 

[blueridge]

Did you try that significantly shorter COAL test load to ensure you were crimping in the valleys between the PDRs?

No, those shorter ones were just in hopes that the best shooting load would also fit in the standard magazine. The crimp on those were in front of the groove.

In the end, the best shooting coal put the crimp right where all the main folks over on the hammer discussion board say to put it: end of the crimp right in the middle of the second pdr groove.


What model gun are you shooting? Can you modify the mag lips for smoother feeding of the longer length?

 

[JLS]

If I put a HH in that groove in my .280 the bullet will end up sticking in the lands.

 

[1_pointer]

Could never get the Savage 10 to shoot under 1.5", despite changes in powder, primer, or seating depths. I had bought it used on a whim as a winter project gun, so its history and potential was unknown. Since I am happy with how the Tikka 7-08 shoots, I am going to rebarrel this to 300WSM.

That's a much taller order than folks that only shoot 3rd groups realize.