New 338 NM Build and Load Work Up Advice

[JW74]

I just had a 338 Norma magnum built and am in the early phases of my load work for it. If others here that have loaded for the 338 NM could give some feedback it would be greatly appreciated.

The rifle is built on a Defiance Deviant action with a Bartlien barrel (27” heavy varmint contour @ 1:9.3” twist).

I went with 300 grain Berger bullets to start and H1000 powder as this seems to be a very common combo in the 87-88 grain range at 2700+ fps. I started very conservatively, and the loads and velocities are as follows:

300 grain Berger Hybrid OTM
H1000
Fed 215M
New un-fired Norma brass
2.836” to ogive (0.018” jump)

1) 81.0 gn @ 2584 fps
2) 81.5 gn @ 2595 fps
3) 81.8 gn @ 2618 fps
New Lot of powder used (velocities dropped)
4) 82.1 gn 2540 fps
5) 82.5 gn 2590 fps
6) 82.8 gn @ 2585 fps
7) 83.1 gn @ 2610 fps
8) 83.4 gn @ 2620 fps
9) 83.7 gn @ 2627 fps
10) 84.1 gn @ 2630 fps

This was over a couple of range sessions. I am still ~4 grains and 100 fps below what most people are getting with H1000 and I am starting to see signs of pressure with flatish looking primers, no cratering of the primers though and no stiff bolt lift yet. All of these groups were close to 1/2” at 100 yards with SD’s from 4-12. I still have a little room to go up in charge but don’t think I will get close to 87-88 grains without high pressure. I am wondering if I may have a tight barrel and that is why I am seeing pressure earlier than most?

I also tried the same loads but substituted Reloader 33 for H1000.

300 grain Berger Hybrid OTM
Reloader 33
Fed 215M
New un-fired Norma brass
2.836” to ogive (0.018” jump)

Those loads were:

1) 91.0 gn 2559 fps
2) 91.5 gn 2574 fps
3) 92.0 gn @ 2601 fps
4) 92.5 gn @ 2610 fps
5) 93.0 gn @ 2642 fps

The Reloader 33 produced these velocities with no real signs of pressure but the groups were not as promising as with H1000 and the SD’s averaged higher at 15-20.

Thanks for any feedback or advice on these loads and further load development as it is greatly appreciated.

 

[Taylor4862]

Every gun is different, it's perfectly possible to be reaching high pressure without nudging the max book loads, I got pressure signs in every projectile/powder combo I tried in my .300 Win Mag about half way between min and max loads.

However from what I've read, primers alone are not a particularly reliable indicator of pressure, and can be taken with a grain of salt when found in isolation. The Federal primers you're using have a reputation for being soft and therefore more easily show pressure signs like flattening and cratering when there may not be dangerous pressure levels at all.

All these factors taken together, I would guess you could safely pursue your H1000 load further if you think that's what will perform best.

 

[kgoltz]

I'm using 84.3 gr. of Norma MRP powder with 300 Berger Elite Hunters. COAL: 3.622 Getting right at 2945 ft/sec.

 

[JW74]

Every gun is different, it's perfectly possible to be reaching high pressure without nudging the max book loads, I got pressure signs in every projectile/powder combo I tried in my .300 Win Mag about half way between min and max loads.

However from what I've read, primers alone are not a particularly reliable indicator of pressure, and can be taken with a grain of salt when found in isolation. The Federal primers you're using have a reputation for being soft and therefore more easily show pressure signs like flattening and cratering when there may not be dangerous pressure levels at all.

All these factors taken together, I would guess you could safely pursue your H1000 load further if you think that's what will perform best.

Taylor, thanks for the reply, that's good info. I will cautiously push ahead with the H1000 and may try a different brand of primer as well and see how things unfold. I'll keep working the RL33 up as well and see if those loads tighten up too.

 

[JW74]

I'm using 84.3 gr. of Norma MRP powder with 300 Berger Elite Hunters. COAL: 3.622 Getting right at 2945 ft/sec.

That's great velocity! How long is your barrel and are you seeing any signs of pressure?

 

[kgoltz]

Running a 28" Proof Carbon Barrel and no signs of pressure, haven't added any more powder because the guns shoots in the same hole and I'm happy at that velocity! Barrel has about 60-70 rounds down it so I expect to pick up a little more speed with break in.

 

[JW74]

Running a 28" Proof Carbon Barrel and no signs of pressure, haven't added any more powder because the guns shoots in the same hole and I'm happy at that velocity! Barrel has about 60-70 rounds down it so I expect to pick up a little more speed with break in.

That's awesome! Are you using Fed 215M primers as well?

 

[kgoltz]

That's awesome! Are you using Fed 215M primers as well?

Yes! And unfortunately Hornady Brass!!

 

[JW74]

I went out yesterday and worked up some more loads. Still working with new un-fired brass at this point and plan to pick up some Peterson brass shortly if available. Based of of my velocities I do think I have a tight barrel that is causing higher velocities and pressure at lower charge weight than most others have been reporting.

300 grain Berger Hybrid OTM
H1000
Fed 215M
New un-fired Norma brass
2.836” to ogive (0.018” jump)

1) 85.6 gn @ 2703 fps
2) 85.9 gn @ 2727 fps (stiff bolt - stopped here with H1000)

300 grain Berger Hybrid OTM
Reloader 33
Fed 215M
New un-fired Norma brass
2.836” to ogive (0.018” jump)

Those loads were:

1) 95.5 gn @ 2750 fps
2) 95.9 gn @ 2776 fps
3) 96.3 gn @ 2779 fps
4) 96.7 gn @ 2805 fps
5) 97.1 gn @ 2839 fps

No real pressure signs with the Reloader 33 other than the flat primers as mentioned before. The velocity with the RL-33 is great but the accuracy and SD's are better with the H1000. I will try some of these loads with once fired brass and also with Peterson and/or Lapua brass and see what happens. For now I may settle on 85.6 gn of H1000 @ ~2700 fps and begin working on loads with the Hornady 285grain ELD.