Thank you.
IMHO a bench rest or supported rifle shouldn't need a hook.
I found information that the MLAIC long range ML matches allow the use of a 2 point sling when shooting at distances up to 600 yards. --->>>
https://www.muzzleloadingforum.com/t...g-again.11155/
"...Shooting in the 19th century did not permit artificial support, including slings. Shooters fried prone, unsupported, or from the back position.
Modern rules permit the use of a two point sling for ranges up to 600 yards (see Whitworth rifle picture above) and shooting is from the prone position. At ranges greater than 600 yards a wrist rest may be used, or the shooter can fire from the back position - as shown below..."
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.45 cal percussion rifle
Weight 12lbs (in the 19th century weight was restricted to 10lb. Modern rules permit up to 15lb)
34-36" barrel
1:18 twist
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In a blog describing a 1000 yard Creedmore ML commemorative match, a competitor mentions firing some shots supported and others shots unsupported. Each match can set up it's own rules. The fellow even posted a photo of himself wearing a modern shooting jacket while firing unsupported.
"(Official score was 20 points for both relays at 1000. I actually got 6 points supported and 15 1X unsupported...."
https://vringblog.wordpress.com/page/2/
The hook could very well be used for something else, but it's just my opinion that it's used for a sling, possibly in the prone position.
I realize that you believe that it's a bench rest rifle, and it may be.
But perhaps it could also be a prone rifle.