The 40 and 45 grain pills are what the Hornet was designed around, and will give you the best results. I've shot some of the 34-grain bullets, but accuracy hasn't been very good from my 1894CL. It's a 218 Bee, so who knows, the Hornet might like them. I'm currently testing the 46-grain Speer in my Bee, and early results are promising.
Usually the longer the bullet the faster the twist needs to be. Look at the .223/5.56 NATO-----the heavier bullets are for rifles with 1in9 and 1in 7 1/2 twist rifles. Your rifle should be fine with 40 & 45 gr. bullets. It is a small case and designed for lighter weight bullets to get more velocity.
Here is a chart I found from an old archived post on another site giving the bullet length to barrel twist. Do yall agree with these figures?
I've attached a SAAMI chart for the .224 diameter bullets.
0.355 to 0.368 1 in 25
0.369 to 0.384 1 in 24
0.385 to 0.401 1 in 23
0.402 to 0.420 1 in 22
0.421 to 0.440 1 in 21
0.441 to 0.463 1 in 20
0.464 to 0.488 1 in 19
0.489 to 0.516 1 in 18
0.517 to 0.547 1 in 17
0.548 to 0.582 1 in 16
0.583 to 0.622 1 in 15
0.623 to 0.669 1 in 14
0.670 to 0.722 1 in 13
0.723 to 0.785 1 in 12
0.786 to 0.860 1 in 11
You might want to recheck your barrel... I'd be very, very suprised if unless it's a custom aftermarket barrel that it's a 1/12" twist.
Almost all factory Hornets built before 1970's were with a 1/16" twist. Ruger made a change to 1/14" in the mid '70's when they chambered the #1 and #3 rifles in .22Hornet.
I had a T/C Hornet in the mid-70's that was a 1/16" twist. I never tried anything heavier than a 45gr bullet in it.
In the mid '80's I had a Ruger #3 that had a 1/14"twist, but had a messed up .22K-Hornet chamber and wouldn't shoot anything straight.
I've had two Ruger 77/22's. The first was a light weight sporter and wasn't accuracte with anything. The 77/22 I have now is a 77/22-KBZ (heavy bbl Stainless w/24" heavy bbl.).
It shoots 55gr or lighter bullets decently. Best accuracy is with the Sierra 40gr HP "Varminter". However, with the 50gr Hornady SX and Acc#1680 will occasionally give "bench-rest" type groups. I haven't found out what the variable is except perhaps different lot# of bullets.... Not even the same 5 cases will give repeatable results. But yes, it is wind sensative.
If you truly had a 1/12" Hornet, It would probably shoot up to a 60gr bullet w/o tumbling. I have a Rem. M7 in .223 with a 1/12" bbl that will shoot well (sub 1.5moa at 100yds) with a Sierra 65gr BtSpt as well as the Hornady 55gr V-max. Sierra recommends at least a 1/10" twist for this bullet. However, my Remington M700 in .22-250 with a 1/14" twist bbl will key-hole with a 65gr Sierra and won't hit the target at 100yds with a 60gr Hornady V-max. Accuracy with the 55gr Ballistc Tips is 'so-so" at ~1.5", but this same rifle with a 55gr Sierra flat-base or boat-tail SoftPoint and any number of powders willl shoot 1-hole for 5-shots at 100yds (0.3's-.4's)
I've also seen the Hornet be particular about seating depths. You might try seating the bullets out touching the lands with full-length sized brass. My "carbine" would only shoot groups (as contrasted to "patterns") with this combination of technique. This causes the cartridge to "lay" consistently in the same position eliminating the error of an out-of-round "non-concentric chamber.
Hornets can be "cussedly contrary" about what they will shoot. Mine for instance loves the Remington/Hornady 33gr v-max over #2400 at a wide range of powder charges/velocities, but give it Win296 or H110 and it "pukes" them all over the targets..... And wants all ammo "full-length sized.