Large or small firing pin.

I have a model 16 pre Accu-Trigger 270 WSM. I need to know what size firing pin it has. The new head I found says it's for a small firing pin. Are they talking length or diameter? I'm looking to make a 270 WSM-450Bushmaster switch barrel rifle. Is it even possible with the WSM action?

Diameter. I'm not sure how well, or if the 450 will work in the short action.

I was thinking that the 450 was shot out of an AR. That would make the length of the action fine. Extraction may be a different story.

Keep in mind the 450 & wsm require different bolt heads. A second bolt would be my choice with this switch barrel combo. Or disassemble the bolt on every switch. My "barrel trial rifle" is a LA, but I have 3 bolts for it (small rifle, reg & mag). Shoots everything from 221 fireball to 7mm mag!

Measure the firing pin on the tip end, the section before the tip end diameter. Small 0.090" large 0140". also get the cross pin to match firing pin.

People have been making the 450BM using Savage Axis and 110 short actions for years now.
I still need to know if a WSM reciever will work with 450BM and what is the diameter of the WSM firing pin. Surely someone here must know the answer. You were a faster typer short round. Thanks for answering my question on firing pin diameter. I may have found another issue with using the WSM reciever. It has a fixed ejector and the new head that I found is the pin type. Does anyone know if there are slotted heads for the 308Win diameter rim as the fixed have a slot in them.

Receiver will work for the 450. Bolt as is will not.

I don't recommend trying to make a switch barrel for the 450bm. It's gonna cause a lot of aggravation. The 450bm does not feed well from a standard mag. I have built hundreds of them, and the mag must be modified in various ways to get it to feed properly. ALso, as said, the bolt head for the 270 wsm and the 450bm are different, so you would also need different bolts for each. THerefore, you will have to switch bolts, mags and barrels... what's the point?

Foxx,
That's all I needed to know. I'll keep the 270WSM as is. I own a Ruger American Ranch in 450BM already. Maybe I can find a used short action reciever to work with. I was wanting a longer barrel and less twist on a Savage action. I guess it will be down the road before I will be able to make it happen.