GURPS It's Always GURPS

Out of a 20" barrel, .30-30 does 5d+1 pi with ball ammunition.

6-31 basic damage with an average hit of 18.

This is the exact same damage that 7.62x39mm does.

.30-30 gets a bit more 1/2D with 700 vs 500; and a bit less Max with 3,000 vs 3,100.

Not too different.

Like with .270, .30-30 is kind of rare in FMJ.  Conversely, 7.62x39mm is far more common in jacketed ball.

So .30-30 is far more likely to have 5d+1(0.5) pi+ for damage.

That leaves the basic damage alone, but gives unarmored things (like deer) DR 1.

So we get 5-30 penetrating and 7-45 points of damage (26 damage on average).

Your typical Whitetail has 10 HP.  26 is enough to get a death roll.

Against the vitals, the 5-30 penetration becomes 15-90 with an average of 52 damage.  Roll well and you're into auto-death.

.30-30 has killed a lot of hoof-rats so the stats appear to pass the reality-check.

Out of 26" barrels .30-30 gets 6d pi.  Longer barrels do better with ranges of 900/3,700.

6d(0.5) pi+ gives 6-36 basic damage, 5-35 penetration and 7-52 (average 30) damage.

Arguably until the introduction of .308 Winchester in 1952, .300 Savage was in the running for popularity with the American hunter.

It's loaded just a little hotter than .30-30 and doesn't have to take tube magazines into account for bullet shape.

6d+2 pi for ball with 850/4,100 for range.  It fills the gap between .30-06 and .30-30 well.

6d+2 pi gives 8-38 basic damage with an average of 23.

Again, soft and hollow-points are the norm, so 6d+2(0.5) pi+ for 7-37 penetrating for 10-55 damage with an average of 33.  Yup, that will snuff a hoof-rat.  The average body hit even gets two death rolls!

Honestly, I don't know if the deer can tell the difference.