416WSM on Siamese Mauser & 416/348Ackley Improved on Martini

[Grumpy gumpy]

I spoke to the stock supplier, and his opinion was that the grain and quality of the blank did not need the wrist reinforced. Especially if I pillar bed the tang screw an ensure there was some clearance around the action and bottom metal tangs.

Bottom metal tangs? Usually it’s the rear tang of the receiver that is a problem, no clearance there and it acts as a wedge
Gumpy

 

[BlueFlyer]

Loaded up the first lot of cartridges today. The Siamese Mauser was setup for a cartridge OAL at 2.940" and to be just clear of the lands I set these at 2.950" using Hornady 400gn Interlock RN. This gives me a little more space in the case over standard WSM action. The base of the bullet is just out of the neck and into the shoulder.

I started at 53gn and have stepped up in 1gn increments to 60gn of AR2206H. White River Magnum primers, never heard of them, but that was all I could get. Anyone have any experience of White River Primers?
The 60gn load is not compressed. Now I just have to replace the screens on the Krony and get to the range. But there are a few domestic duties before that happens.

 

[BlueFlyer]

Got to SSAA Eagle Park range today. Yesterday was 104f and today today was 64f, AR2206H has a stabaliser in the formulation to minimise the influence of ambient temperature. After today's results I am starting to think that AR2206H might be a bit slow for the 416WSM. If you look at the table below the increase in velocity with increase in charge weight is a diminishing return. The charge weight is increasing by 1 grain and the increase in velocity is getting smaller. This indicates to me that the increased charge is being burnt out of the barrel - what do you think?
The loads are NOT compressed and the base diameters and primers are indicating that the pressures are low. As others have mentioned (375WSM using 68gns) it might just need more powder?
The base dimensions for 53gn & 54gn were measured immediately on ejection - then I realised that the warm shells would measure bigger.
Next I am going to keep increasing the charge and see if I can get an increased pressure & velocity.
If that does not work then I will go with a faster powder.

Not sure about the 56gn & 57gn results, but my electronic scales did reset at that point. I use a Lee powder measure to under charge the pan and then use a trickler to bring the load to weight.
All cartridges we single loaded into the chamber to maintain OAL, as I cannot crimp the bullets into the case at this point.

 

[Grumpy gumpy]

I would have thought that in a large volume case with a big pill, 2208 or possibly 09 would have been better, less of a pressure spike
Gumpy

 

[Rule 303]

I would try BM8208. You have a large exit hole for case capacity so a faster powder may well be the go. When I started reading this thread I was thinking 2206H would be the place to start. These may well change with different weights.

The 35 Sambar runs 2209 for 225 grains and heavier pills. Can use 2208 or 2206H with 200 and lighter pills. 2206H being the best.

In the 416 Rigby with 400 to 450 grain pills I best result from 2209. I have used 2206H with lighter bullets but because of the case volume I would not recommend this as you can not get very good velocity out of it. Way smaller case and it is a different story.

 

[BlueFlyer]

I would try BM8208

That is where I was thinking of going, as it is a relatively small case capacity compared to the bore. Bit like a 358Win on steroids.
Remember I did not use a 416WSM reamer, the reamer was/is 416/348 Ackley Improved. It has a slightly longer body due to the 40deg shoulder (wsm is 35deg) and a longer throat. If you look closely there is a slight fireforming of the shoulder. Headspace is the neck to shoulder point on the unfired brass.

 

[BlueFlyer]

Did a bit more research today, trying to get some more pointers on powder selection. I read some articles on the 400Whelan and 416Taylor. All referred to H4895 as a preferred powder with excellent results.
H4895 is AR2206H packaged in a different container.

Looks like I need to get the charge up around 68gn. Need to keep going up in 1gn increments. I am going to use my old Lyman balance scales to weigh out the loads rather than the electronic scale that reset half way through the session.

 

[Rule 303]

I was thinking you had maxed out on the 2206H. Keep going and in 1 grain increments. 1/2 a grain in that size case is just wasting powder, primers and bullets. Not sure what velocity you are hoping to achieve.

Re crimping. Lee will make a custom Factory Crimp die for you, I had them make up one in 358Rum for me. However if you want to save time buy one of their off the shelf 416 factory crimp dies and just stick yours in from the top. Yes it is doable. I tried it after reading about it on here from memory. It is not as precise as it is not held squarely by the shell holder.

 

[BlueFlyer]

However if you want to save time buy one of their off the shelf 416 factory crimp dies and just stick yours in from the top. Yes it is doable.

So rather than place the shell in the holder and pushing it up into the the crimp die, you feed the loaded cartridge in from the top and then activate the crimp in the normal way.
I could also machine up a slip ring to go onto the neck and bottom out on the shoulder to control the depth the cartridge and keep it square. Thanks for sharing the concept.

 

[Rule 303]

So rather than place the shell in the holder and pushing it up into the the crimp die, you feed the loaded cartridge in from the top and then activate the crimp in the normal way.
I could also machine up a slip ring to go onto the neck and bottom out on the shoulder to control the depth the cartridge and keep it square. Thanks for sharing the concept.

Correct.

However I would prefer the your other method. Just a hack like me does not have the skills or equipment to do that.