It appears that it will stabilize in the typical 1:20 twist, per the Berger Calculator.
BC: 0.869 estimated (https://blackbasin.com/tools/coefficient-calculator/) (as a round nose model)
Caliber: 0.458"
Weight: 777 grains
Length: 1.645" (based on back calculating the length of a .458 diameter...
Just curious, what are you shooting with... a Deerfield carbine or Lever gun?
I've never bought from them, but Steinel comes highly recommended from a friend of mine that shoots a lot.
This is the only round I've found that checks the boxes on subsonic & expanding. I would have thought Lehigh...
It's pretty cheap actually, a few household chemicals mixed 50/50. Only catch is that your end product is a lead solution that is pretty hazardous (lead acetate, which can be readily absorbed through the skin, as well as fume inhalation risk)
What will it be going on mostly?
On paper it looks like the R9 is slightly lighter, a smidge longer and has a better "decibel rating" (whatever that means), but has limited "full auto" rating.
Their marketing says that the R9 was designed with 9mm SMG in mind, and the Resonator K with rifle...
Weird, it seems there are 2 styles out there. A bird cage design with spring, and a straight tube.
Bird cage: https://www.midwayusa.com/product/102548159 (backorder OK)
Tube: https://www.midwayusa.com/product/100406720 (discontinued)
Running through google results... I found a place that...
Hrm... based on what I see on MidwayUSA they've been discontinued. If you can't find NOS on someone's shelf, you might have to resort to a custom made part from someone like Stalking Rhino or ECCO Machine. @Hood886 can you make anything like that?
No drilling needed. They only offer the "IRM" model now... internal recoil mechanism. Not difficult to install at all. Just remove the front pin, and then the MAC upper. There's a long recoil spring you have to install in the Lage upper assembly before you mount it, and Lage provides you the...