Reloading for a 458x2

[mbarasing]

Hi everyone,

I just loaded up some Woodleigh 405 flat-nose into cut-off 300wm brass to keep the 458x2 fed. My goal is to find subsonic loads from N320 and Red Dot. I haven't shot any yet, but I have ladders worked up in N320 from 17 to 20gr and with Red Dot from 15 to 18gr.

But a question came to mind about my max pressure. Is it safe to assume my max pressure is the same as it was from the original 300wm parent case (SAAMI 64,000 psi)? I have been playing around with GRT and while I don't yet know how accurately it predicts for this rifle, it is fun to play with. GRT predicts 60kpsi and >1870 fps with Woodleigh 405 using 56gr of 4227 and it comes with 41 ft-lbs recoil.

Merry Christmas to all, and to all a good night.

[Larry Gibson]

That would be a probable assumption for the cartridge case but what is the rifle action?

[mbarasing]

That would be a probable assumption for the cartridge case but what is the rifle action?

Bergara Premier SA.

[mbarasing]

[Larry Gibson]

Good to go at 64,000 psi for which the cases you use are rated. Be careful though, the powders used in the 458x2 to reach that psi are going to be a lot quicker burning than those used in the 300 Win Mag. A little bit of the faster powders can go a long ways pressure wise. I found that out loading Jacketed Barnes SPs to 2300 fps in my Siamese 45-70.

[Sgt H]

The 458X2 is going to have a case capacity pretty close to the 45-70 and 450 marlin. The 15-18 grains of Red Dot is going to be supersonic. 11-12 grains should get you in the 1050-1100 fps area with a 400 grain boolit.

[mbarasing]

The 458X2 is going to have a case capacity pretty close to the 45-70 and 450 marlin. The 15-18 grains of Red Dot is going to be supersonic. 11-12 grains should get you in the 1050-1100 fps area with a 400 grain boolit.

We will see... one thing I should mention is that I only have 9" of barrel.

[mbarasing]

Once I have the subs to my liking, I will try to find loads for supers, probably with vv110 or imr4227 or the like. With the 9" of barrel, I think I could get above 1,800 fps with 405g and maybe above 2,100 with 305g.

[Sgt H]

Larry is correct on a little bit of faster powders going a long way pressure wise. I suspect your 18 gr load of red dot and 20 gr of 320 are approaching if not over 50,000 psi. According to data I have 16.5 gr of Unique (slower than red dot or 320) is right at 40K in a 45-70 case with a 400 grain boolit. I will bet the case capacity of the 458X2 is a bit less than the 45-70 and will raise pressure even more. I would be very careful with those loads.

[mbarasing]

Larry is correct on a little bit of faster powders going a long way pressure wise. I suspect your 18 gr load of red dot and 20 gr of 320 are approaching if not over 50,000 psi. According to data I have 16.5 gr of Unique (slower than red dot or 320) is right at 40K in a 45-70 case with a 400 grain boolit. I will bet the case capacity of the 458X2 is a bit less than the 45-70 and will raise pressure even more. I would be very careful with those loads.

I think you and Larry are correct and I have overcharged these loads. I will start with lowest loads and record the speeds and watch for pressure signs. Thanks for the help, as a new reloader it is appreciated. I will report back here how it goes.

[mbarasing]

I found in GRT that when I created the 458x2 cartridge, I did not adjust the H20 capacity correctly. Thanks to Sgt H and Larry calling me out, I found the mistake and corrected it. My brass held 72.2gr of H20. With the case capacity adjusted GRT revealed I had overcharged my ladders (none over pmax, but all supersonic). I pulled bullets (kept the lowest charges) and now have N320 from 15-17gr and Red Dot from 13-15gr.

I will let you all know what speeds I find. Thanks again.

[mbarasing]

Woodleigh 405gr Subsonic Load testing, 12/29/23
Bullet Woodleigh 405gr, FN 30B
Weight 405
Length 1.02
Drag G1
BC 0.25
Primer CCI 200
COAL 2.45

Powder Red Dot
Charge (gr) 13 14 15
Velocity (Predicted) 1068.3 1111.6 1153.9
Velocity (Chrono) 1012 1066.1 1123.7
SD 5.1 3.8 2
Spread 9.8 7.5 3.6


Powder VV N320
Charge (gr) 15 16 17
Velocity (Predicted) 1071.8 1111.2 1149.9
Velocity (Chrono) 1058.5 1110.5 1154.7
SD 2.4 3.9 6.9
Spread 5.1 9.5 13.6

Your mileage may vary.