Well after what seems like years I(actually it has been 2 years since I had the barrel chambered) I finally got my 380PDK to the range.

The case was formed from Howell Basic brass left at 2.65" 260gr Accubonds at 3.36" water capacity of the brass was 83.5grs. The cases in this picture are left to right a 375Whelen, a 380PDK using a necked up unfireformed 340PDK case(the 340PDK is formed from 280 brass), a 380PDK using Howell basic, a 380Howell and 375H&H. The 380PDK using Howell brass actually has about a grain less net capacity than the 280 based case but sure is a heck of a lot easier to build. The longer neck also allows me to use the cannelure and full magazine.

As a point of reference Federal lists their 375H&H 260 accb as 2700fps, Hornday lists their normal 270gr interlock as 2700 my own accuracy load for my 375H&H is 2715fps with a 270CT.

I tried 3 different powders IMR4895, Varget and RL15. I elected to stop at 110% capacity and when I started to see a very(per my calibrated eye ) flat primer. As it happens when I called it a flat primer QL called the pressure in the 63-66,000psi. To be fair I checked QL after the fact. I elected to call the load prior to flat as max. I did end up pulling some unfired loads. Velocity was the average of 3 rds.

Varget
Charge Velocity
60 2501
61 2540
62 2585
63 2615
64 2661
65 2692 Primer flat

IMR4895
60 2533
61 2574
62 2612
63 2665
64 2694
65 2747
66 2777 Flat!

RL15
60 2485
61 2521
62 2560
63 2609
64 2647
65 2696
66 2730
67 2750 Flat

I was using only an aperature sight at 100yds but 65 & 66 grs of RL15 formed a nice 2" grouping so next plan is to mount the scope and play with RL15 & Imr4895 for loads in the 2700fps area.

I did shoot some light bullets and I'll post that data after I get it transfered from my notes to a spreadsheet.

Impressive!

That wildcat of yours absolutely ROCKS!!!

Great power and range to boot!

John

So you are getting 2 more grains capacity than the 376 Steyr.

Seems the Steyr loads are a good source of load info.

300 @ 2450 seems reasonable.

Seems you are getting 338 win mag performance with a larger bullet. It makes sense since the 338 has an 86 grain capacity so the larger bore and shorter bullet will play the catch up game.

I think the 375-06 variants getting 300 @ 2400+ like the 375 flanged are such an under appreciated rounds able to kill anything within 300 yards and DG in DG range.

Congrats!

Thanks guys. I've been very please with my testing of the 380&400PDKs. All my smaller PDKs as well as the 416PDK were built using Norma 280Rem brass. The orginal plan had been to see what I could get from a 06(280) based case. As I got older or was it lazy I elected to use Cylinder brass for the 380&400. As I've stated loaded to the same OAL I actually end up with about a gr less NET capacity. However it is easier and I can now use the cannelure if I so choose.

What I like about them is they are DIFFERENT. Can they do anything that a 404J or 375H&H do? nope. My 400 does actually beat historical 404J and 450/400 loadings and even modern factory. Since it is a 06 based case with just a touch of filing in the shoulder area of the MKX mag box I can get 5 down. Giving me a couple extra over a normal H&H and 404J.

As I've stated before I designed my case orginally as a 280 and then went both ways down to 240 and up to 416. Only 15+ years later did I hear about Rcoky Gibbs. Then a few years later the Howell series from AHR came on the market.

Boom Stick I have three sources listing Steyr capacity as 75.9, 77.23 and 80. Net capacity gain from my case gives something in the range of 2.5 to almost 7grs depending on what volume you use. 2450 for a 300 might be a little lite in a 24". I haven't used a 300 but my buddy has the sister 380PDK and he is just under 2600.

Heck even the non improved case like the 375Whelen or the brown/whelen would take care of about anything you wanted to kill. My case sure isn't overbore so I leave no capacity on the table. Most max loads I've used calculate in the 105-107% volume range I have not gone above 110%. However most of that can be achieved with only a drop tube and very little bullet compression.

The 380 Howell ammo, brass and dies are available from AHR. If you want a 400 version talk to Z-hat about his .411 express ( it is his 411 hawk lenghtened to use 2.65" cylinder brass).

Can you imagine a "Tanker" Garand chambered for this.
It would be just incredible.

John

sweet Paul! just fantastic to see another catter having a plan, a great design, and sticktoitativeness!

i have generally found oncefired steyr cases to be about 80-81 gr .. so i use 80 as my personal reference