RN vs Spitzer

I've been using the 174 gr. RN for many years now in many of my SMLE's. I even worked up a load for my single shot 303 Martini Henry that is pretty deadly. The last critter I took with one of my 303's was a couple years back, knocked down a cow Moose at about 175 yards. It went about 30 yards and piled up, no worries with the terminal performance of those 174 gr's.

Most bullet manufacturers will tell you the optimal velocity for their hunting bullets.  If your range is 200 yards look at how your choices perform at the velocity you might have with your load at that range.

Yes, would certainly be worth trying the .312 RN if .311 spitzers did not shoot well.  

Would it also make sense that owners that feel their Enfield bore is worn that the 174 Hornady RN would be a good option to try seeing that it is .312" and has more contact area than a spitzer?

HT, yes, the flat base RN 174 gr bullet will have more bearing surfaces area contact with the rifling.  That might help in a worn bore, but if your barrel is .303 to .304, the spitzers should still shoot well.   Test them both and see how they shoot in your rifle.  

Goosic,

That Sierra 180 gr ProHunter flat base spritzer bullet has never shot well from several of my No. 4 rifles, strings rounds vertical. Perhaps it’s more sensitive to barrel harmonics and you need to find the velocity it likes.  Most of my 10 shot groups at 100 yards were spread vertically about 4 inches, lateral spread was reasonable, 1.5 inches approx IIRC.

The most accurate one will be which ever one your rifle likes best.
At one hundred yards the only place you might see any different between the two is in the terminal ballistics. Round nose bullets transfer their energy quicker but you probably won’t see that much of a difference in a 31 caliber. But as you noted a spitzer will carry its velocity and therefore energy down range better than a round nose.
The other thing to consider is how much impact velocity the bullets need too reliably perform. The Pro-Hunter is a stouter bullet then the Intr-lock and should be driven faster to provide optimum performance, with impact velocities ideally above 2200 fps or so.