Matt,
I just looked at
www.gunsinternational.com at the .577 NE rifles listed.
They ranged from 12 pounds, some-odd ounces, to about 15 pounds.
I did not read the regulation for each but I understand there were at least two loads which these huge rifles were built for.
Seems like we can presume the higher powder charge/heavier bullet load of course called for the heavier weight rifles to be built and the opposite for the lighter load version.
I once fired two rounds from a vintage J. Wilkes made .600 NE double, and I believe the owner told me it weighed 16 pounds but he may have said 18, I just do not recall any more.
All I can say is that, firing those types of weapons tend to risk breaking the indicator needle off my fun meter.
I would not be afraid to try a .577 NE but, I do not know anyone who owns one.
No doubt it'd be too much for me to fire more than a couple shots before developing a king-sized flinch.
The same guy who owns the .600 NE (Cal Pappas) also has a .500 NE that weighs close to 12 pound and I found it to be within my recoil tolerance level, when firing it from standing position but that .500 was about all I can shoot for several shots and still be smiling.
My best guess therefore is that a .577 NE, or bolt action wildcat equivalent, should weigh about 14 pounds ?
Re: When firing the aforementioned .500 NE double I was right at the ragged edge for my recoil tolerance but still within my comfort zone with it for a few shots in a row and I confess to loading my .500 Jeffery down to a bit below that with the same 570 gr bullet (11 pound CZ bolt action).
So, there will be no .577 NE, firing full house 750 gr bullet loads in my future.
Even if I could take the recoil of multiple shots during training sessions, I am no longer man enough to carry such a heavy rifle up and down the hills all day and still be snappyquick with it when needed.
I will however live vicariously through your experiences with this project you describe.
Out,
Velo Dog.