Unburnt powder when reloading hammers?

[Ross1147]

So have a first for me. Trying to reload for a .458 SOCOM and a 250 grain Shock Hammer. Reload data is all over the place when searching online, so I started with Nosler max load data for a 300 grain bullet and IMR 4198 (40 grains). I full length sized virgin brass and loaded the SH to the first grove and 1/4 crimped using a Lee crimping die. Also using CCI 300 large pistol primers in an AR-15 with a 16.5" tromix upper.

So, I loaded 3 at 40 grains and went to shoot them at 50 yds. Abysmal group, just about 2" (of note I forgot to crimp these, didn't realize until I shot). Speed was 1820 fps. The brass looked great, so I started to work up (all crimped from here). At 41 grains speed was 1859 fps. 41.5 grains registered at 1871 fps, but there was a very slight ejector mark the primer looked like it was pierced just slightly.

Contemplated not shooting the one I loaded at 42 grains, but curiosity got the best of me. When I shot this one the bolt didn't lock back? It had locked back on every other load. Speed was 1914 fps. Brass looked great, no ejector mark, no primer flattening, no pierced primer. But, there was unburnt powder in the acton and in the barrel? It's not a ton but it's there, see pic.

Of note these 3 shots grouped just under an inch. This load is compressed. Assuming if I add more powder it will lead to more unburnt powder?

Do I crimp more? Change primers to LRP (I don't have any large pistol mag)? Add more powder to compress more? Just be happy with group and ignore unburnt powder?

Where to go?? Thanks!

Ryan

 

[sedancowboy]

At 40 grs of powder I would want a Large Rifle primer if it were me. You might need to back off a little and work back up as the Large Rifle primer is hotter than a pistol primer.

 

[Ross1147]

Yeah, I was thinking that as well. I think the SOCOM case is designed for pistol primers. Read somewhere you have to deepen the pocket a little to prevent slam fires when using LRPs? Easy enough, at least easier than trying to find large pistol mag primers!

 

[Seabeeken]

Try a heavy crimp

 

[cohunt]

Hotter primer and more crimp-- you said 1/4 crimp-- try 1/3 maybe even 1/2

 

[QuietTexan]

Add more powder to compress more? Just be happy with group and ignore unburnt powder?

Faster powder, spherical powder, or live with it if it shoots. Heavy crimp only works to a point to try to increase starting pressure, so since you're compressed already if a 3/8 crimp doesn't make a significant improvement then move to a spherical and/or faster powder.

The bore is so large vis-a-vis case volume that pressure falls off much faster than the same case volume in a smaller bore, that's what causing partial burn of the kernels. Using IMR 4198 the bullet is ~3" down the barrel when pressure drops enough to affect burn. Running IMR 4227 (faster) and H CFE BLK (faster/spherical) the burn is much more complete in the first 1" of barrel, so the increased volume cause by the large bore diameter doesn't as much an effect to kill the burn sooner.

Look at how the red pressure curve narrows with the faster/spherical powders. I set the loads up so that they all get to the ~30k pressure line - velocity doesn't drastically change with any of these choices, just the timing of pressure before the bullet moves down the bore and increases volume.

All the normal powders for heavy subs should work to some extent here - IMR 4227, H110, Lil'Gun, SW Blackout, CFE BLK. Some will have lighter densities than others, I would stay with ones that are on the 101% side and not the 80% side, but that's because I like to crush the powder column slightly under Hammers in general.

 

[Varmint Hunter]

I'm running 34.5 H110 under a Hornady 250 MonoFlex with a LPmag primer. Velocity is at 2,000 fps and it will drop 3 rounds under 2" at 200yds every time. I'm shooting a full factory RRA rifle.

I can easily exceed 2,100 fps with Lil'Gun but the accuracy just wasn't there.

 

[Ross1147]

@QuietTexan thanks for that! I knew 4198 was a little slow for a 250 grain bullet, I use it for my 530 grain subs. Didn't think about it not burning it due to bore diameter and pressure drop. There's a local shop that has a pretty good powder selection. May have to give them a visit. I'm going to try a few of the tips above as well. Trying to see if I can get these SHs to maintain the 1800 fps to a reasonable distance to use on deer.

 

[Varmint Hunter]

@QuietTexan thanks for that! I knew 4198 was a little slow for a 250 grain bullet, I use it for my 530 grain subs. Didn't think about it not burning it due to bore diameter and pressure drop. There's a local shop that has a pretty good powder selection. May have to give them a visit. I'm going to try a few of the tips above as well. Trying to see if I can get these SHs to maintain the 1800 fps to a reasonable distance to use on deer.

Keep us posted. I'd be very interested in your findings. I'd also be interested in the 250SH in a 45-70.

 

[Len729]

Yeah, I was thinking that as well. I think the SOCOM case is designed for pistol primers. Read somewhere you have to deepen the pocket a little to prevent slam fires when using LRPs? Easy enough, at least easier than trying to find large pistol mag primers!

They have the large pistol mag primers at MidwayUSA for $99

 

[Ross1147]

Local store was loaded down with powder and primers, so I picked up some H110 and some large pistol mag primers. I'll report back with my findings.

Ryan

 

[Ross1147]

Sorry for being MIA on this post. The kid I was going to take hunting ended up failing 5 classes and his mom said no hunting for him! So the gun ended up going to the back of the safe. Was bored today so I took it out and shot a couple more rounds.

First couple shots were with 42grn of IMR4198 and WLRP. I had to deepen the primer pocket to safely fit the LRP. It increased speed by around 50 fps, but there was still unburnt powder in the action and down the barrel. There were slight ejector marks on both the cases.

Next I tried a few with H110 and GM115M primers. I loaded up 3 at 34.5 grns. All 3 shots were between 1991 - 2001fps. Much closer to the speeds I was looking for. Downside is all had ejector marks, but on a strictly hunting load I'm ok with that.

Went to Sterlok and entered in the numbers. According to that, speed will be below 1800fps by 32yds? If I can assume the SH are only guaranteed to open at speeds above 1800 fps (like all hammers) this is not a good bullet for this round. Would be better off just using my crossbow! I'll probably just save the rest of these bullets for my 45-70 and switch over to the 325 FTX for supersonic hunting.

Ryan