7mm WSM, 143g HH and RL22. FAST, where to from here?

Jonoton

Well-Known Member
Joined
Feb 1, 2017
Messages
189
Location
Texas
Hello,

I finally was able to shoot my first handloads for my built 7mm WSM.
Rifle details:
27" Bartlein barrel, 1/9 twist + brake
Alpha WSM magazine
Cleaned before shooting these Hammers. Maybe 60 rounds down the tube prior to today.

Load details:
New Winchester brass, formed with Forster FLS-Q dies
RE22, WLRM primers
143gr HH (they actually measure 145.5gr)

Forster micrometer seater die
COAL: 2.907"
Jump to lands: .007"

I loaded 10 rounds in .3 grain increments from 65gr to 67.3gr. Rounds 9 and 10 were in .1gr increments as I expected to start seeing pressure signs somewhere in there.

I finally got time to shoot today, and it was 95* out and breezy.
Here are my numbers, Oehler 35p:
1. 65.0gr, 3257 fps
2. 65.3gr, 3312 fps
3. 65.6gr, 3317 fps
4. 65.9gr, 3351 fps
5. 66.2gr, 3374 fps
6. 66.5gr, 3373 fps
7. 66.8gr, 3425!!!!! Fps

That 7th shot definitely felt different than the others, with a stiffer recoil. And I think the primer was pretty flat, though bolt lift and extraction were fine and I didn't notice any other pressure signs.

I didn't shoot rounds 8-10, as these speeds seemed higher than what I had been expecting even though I am not getting to Alliant's book max loads for similar weight leadcore bullets.

My research and forum data mining had lead me to hope for 3300+ fps.

I shot these at 184 yards (there was a good shade tree), not really with the intent of doing a ladder or anything very advanced. However, all of these shots had a vertical range of 1.5" and horizontal range of 2.25".

I THINK 5 & 6 went in the same hole, and i think my chrono data suggests that is a node? I was walking to the target between most shots and could not locate 6, but the prior #5 hole looked a little enlarged.

All of that said, where would you go from here?

I am leaning towards being happy with the velocity provided in the 66.5gr to 66.8gr range and loading up 5 of each to shoot for groups at 300 yards.

Thanks for reading and any advice!

Jonathan
 

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Prior to shooting #6
(As an aside, I will try a cardboard backer next time in hope of getting cleaner holes)

Edit: charges 6 and 7 both have ejector marks on closer inspection.
 

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