Also looking for powder recommendations

[NC FNS]

I'll be loading my first batch of 7.5 x 55 Swiss soon. It's for a K31. I've got Hornady 168gr bthp's. My Lee manual (second edition) lists 2 powders that I have on hand - H380 and H4895 - for 168gr jacketed. If anyone has any experience with those 2 powders, or can recommend a different one, please do share. Also interested in knowing what bullet types have worked well in a K31. Thanks.

Chris

[ligonierbill]

Reloder 17. The only powder I have found to match GP11.

[RC20]

Sierra lists IMR-3031* (Hornady also) /IMR-4895/IMR-4064 (Hornady Also) /IMR-4320* (Hornday also) /IMR-4350 ((Hornday also) /IMR-4831

Hornady Lists: H4895/ Accurate 4350/ VIHT N-160

R-17 oddly is not listed in Horndy that does have it in 30-06. I have found 30-06 high loads too hot for the 7.5, so starting low and working up is needed (more efficient?) it is a shorter fater case.

In the 7.5 Savage 110 I built I was getting hard bolt lift in R17 at 52 gr.

I have taken down GP-11, powder in it is a like 48.9 and identical to R-17 as noted.

K-31 does not have the cam action a bolt does so not one I would push.

I have notes of H 4350 in the K-31 of 47 gr.

I have not gotten much out of the K-31 that satisfies me, the H4350 did work but has gone off.

In the 7.5 Savage 4831 has worked at times, H4350 and working with IMR-4350 (easier to get) now.

As the case capacity is virtually identical to 30-06, any 06 powder would be worth a try, starting low of course and working up and be aware mid high is the limit.

30-06 lists R-17 up to 59.2 and that is clearly way to hot for a K-31 (and the Savage)

Nothing bullet wise like a GP-11 bullet, its just strange (no straight to the side at all, curves from tip to the change point and a long boat tail after.

My K-31 is in great shape but I have yet to get it to shoot consistently. I do have the Scope mount for it (non intrusive ) and it works well. I can't see iron sight that well these days.

I have found it a most interesting caliber, pretty much a RUM well before RUMs came to be. Highly advance case and a bullet no one has duplicated in the GP-11.

Its a shame is so niche, it would give the 06 a run for its money.

[NC FNS]

Thanks. I loaded a dozen, and have a col issue. I’ll give rough numbers, since I don’t have my manual handy at the moment.
Hornady match 168gr hpbt bullets didn't plunk at the minimum col given for 168 gr fmj, which was 3.06 if I recall. For 167 gr bullets the col was 2.9xx.
I had to seat mine at 2.90 to get them to plunk.
The powder range given for each powder I have spanned 2 grains. I loaded 3 rounds at minimum and 3 one grain higher, for both H380 and H4895. I’m thinking I’ll be okay...I plan on trying the minimum load first and looking for pressure signs. Should I worry about having to seat the bullet that much deeper?
Also, anyone have a good source to purchase bullets close to what the original K31's used? I’d prefer to load those if they’re available.

[ligonierbill]

I load 175 SMK (#2275). It is not quite as "pointy" as the GP11, but reasonably close. You do have to watch the COL for the K-31. Mine are set to 2.933. I will let you work up your own powder charge, but using Reloder 17, these go 2,570 avg/7.7 std. GP11 go 2,579 avg/ 12.3 std.

[cdoc42]

Try this. I looked on the Hodgdon web site for a load for 162gr Hornady in 7mm Rem Mag. The loads had CUP and PSI designations. I researched for a conversion and found a nice site (I don't have a link) that offered formulas for PSI to CUP and vice-versa. I changed the Hodgdon list to reflect lowest to highest CUP with 2900 fps being the baseline. The chart below is what I ended up with and is self-explanatory.

The formulas are:

CUP to PSI: PSI= CUP x 1.516 - 17902

PSI to CUP: CUP = 17902 + PSI/ 1.516



7mm Rem Mag CUP vs Velocity

Max 2900 fps CUP
Powder Load Velocity CUP base over #1

US 869 80.0 gr 2921 47693 21 0
H1000 70.0 gr 2905 49600 5 1907
Retumbo 73.5 grC 2963 50500 63 2807
HybridV 60.0 gr 2922 51057 22 3364
H4831 64.0 gr 2871 49800 -29 2107
H4350 58.0 gr 2799 49400 -101 1437

US 869 would be the first choice based on low pressure and velocity over 2900 fps

Hybrid V100 delivers the same velocity (2922 vs 2921) but has 3364 CUP higher pressure

Current inventory unfortunately has every powder BUT US 869, so the next best choice
is H1000. It is only 16 fps slower with 1907 CUP higher pressure.

[cdoc42]

I'm sorry the table did not present as it reflected on my pre-publication entry. It looked fine before I hit the post it key.

It should read Powder-max load-velocity-CUP-fps over base 2900- CUP over #1

So, let me try the first line

US 869- 80.0gr - 2921 - 47693 - 21 - 0

I was looking for the powder that had the lowest pressure and highest velocity. All but two had a velocity over 2900 fps and they were close enough that the difference in pressure directed my choice.

[RC20]

You look to have gone off track a this is a discussion on 7.5 Swiss not 7mm rem Mag?

[RC20]

The data is iffy, so you figure out what COAL is, drop off the lands .020 and go with that.

We are dealing with old guns and most of the data is for the 1911 not the K-31.

I might be able to finagle out what the off lands is for the 7.5 GP11 or at least close.

[cdoc42]

RC20- it doesn't matter which gun is being discussed- the OP is looking for powder recommendations. My post was an example of how one might do that, caliber notwithstanding.

[NC FNS]

Thanks, everyone. I appreciate the information.

Haven’t got out to the range yet. Maybe next weekend...

I’ll probably give the SMK's a try in the future, and maybe the H1000, which is available locally.