I wonder what the collective opinion is for the required telescopic sight eye relief for medium bore rifles?

I am thinking of recoil levels from .300 Win Mag through .338 Win Mag upto 9.3x62 and .358 Norma Mag.

Barness states in his book Optics for the Hunter that a minimum of 3.5 inches, ideally 4 inches should be the goal for rifles like the .338 Win Mag.

I have read on various AR forums, posters using 1-4x22 Meopta scopes, nominal eye relief of 3 inches, on rifles like the 9.3x62. Those with CZ 550 rifles in .416 Rigby seem to prefer the Leupolds for their long eye relif. However, Barness states that eye relief also depends on whether the shooter 'stock crawls'.

There are a number of high end German scopes with more than 3.5 inch eye relief:

Schmidt & Bender 1.25-4x20, 3.75 inches.

Schmidt & Bender 1.25-4x22, 3.5 inches.

Gerhardt - Nickel 1.5-6x30, 4.9 inches.

New Zeiss 4x32 MC, 4 inches.

New Zeiss 1.8-5.5x38 MC, 4 inches.

The Austrian Kahles scopes in 1.25-4x22 offers, I believe 3.5 inches, but I do not think it is as good as the S&B scopes.

I checked some of my scopes for eye relief this evening. The results were:

S&B 4x36, West Germany (i.e. old, circa 1982), nominal 3.3 inches

Gerhardt - Nickel 4x36, nominal 6.5 inches (But this was a special request custom job direct from the factory)

Zeiss 6x42, West Germany, nominal 3.2 inches

S&B 6X42, nominal 3.2 inches

Habicht Nova 4x32, nominal 2.88 inches.

I have a 90mm (3.6 inch) relief on my Zeiss Victory Diavari 3 - 12 x 56 mounted on 9,3x62 and 8x68S and it works for me...

3.5 inches for a minimum and 4 inches is better. I don't think I'd have a problem even with a .416 and 3.5 in.

The worst 'ding' I have had was from a light weight, 22 inch barrelled Remington .30-06 with a synthetic stock. Ouch!

Fortunately, it was not my rifle. However, my first rifle, a .270 Steyr Mannlicher Mod M, with the 4x36 S&B mentioned in my first post, gave me repeated crescent shaped scars if I did not pay attention.

I have a habit of stock crawling. And I think the Steyr Mannlicher, with the S&B 4x36 was a bit light for Norma 150grn .270 rounds and awkward shooting positions.