@S.E.G.
Better not use .308 slugs - if bullets have to be upset / obturated a lot in order to fit the barrel they won't be consistently centered, leading to drop in accuracy. I'd go for a subsonic heavy flat nosed hollow slug cast for the .303. After all, no point in powering up for a 400m kill with that minimal sight radius (though the barrel itself would not be expected to have a problem with that just because it is short!).
There is a fellow on TM selling quite reasonably priced cast .308 hunting slugs, which he size at either .309 or .310 ...suggesting they are born a bit fatter out of the mould - maybe you could ask him to sell them to you "native" even though that would need to be unlubed. Less need for lube with sub loads.
See: https://www.trademe.co.nz/sports/hun...1463273144.htm
Speaking of the sights (going back to the sten gun talk) you could remove the rear open sight and instead mount a small fixed piece of L-shape iron with a decent peephole atop the charger bridge? Not much need for elevation adjustment at those ranges and you can readily drift as well as file down the height of the fore sight post.
If you're really comfortable with open sights, you can go super-minimalistic: just file a deep "V"-notch atop the charger bridge! It could save quite a few grams of weight to get rid of that open snaggy rear sight along with the massive steel brick it rides on, and won't interfere with stripper clips.
Hope some of the above is of use to you.
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