Dave, I love the 55g Nosler BT on yotes. They seem to be a different animal compared to the 50g BT.
Part of the spice of life is trying different bullets on yotes. Key is to shoot several from different angles and at differnt distances to get an idea of how they are working for you. I am a firm believer that the factories change bullet performances as the foundries change their alloy mix on bullets. Factories buy massive quanties of metal at a time, and untold thousands get produced before the next batch comes in from the foundry with perhaps different results.
I tried the Nosler 60g sp when they were available due to the fact that we were taking big game animals also. The 60g Nosler is a great deer bullet and I am not talking about the partition, but the old Solid base. It shot holes straight through coyotes like a FMJ. The 60g Sierra HP shot groups in the 2's and low 3's with 39.0g of IMR 4350 in a 22/250, and it also shot holes straight through yotes. Perhaps the faster twists in the AR's will help this bullet open up???????
You never hear any talk of them anymore, but the Sierra 50 and 55g Semi point bullets are every bit as accurate as the 53g bergers in my custom 22 PPC's. They give great penetration on yotes, and never fail to expand. I have memories of shooting ground squirrels at 500+ yards with the 55 Sierra Semi points loaded with h335. I saw my buddy nail a ground sqirrel on the side of a tree in S. Ca at 800 yards with the 55g Semi point...took 3 shots.
Like you, I am concerned about the quartering shots coming at me and the dirty buzzards that run in like a grey hound and are high tailing it away from me which are always a quartering shot through the hind quarters. I have had great luck with the 55g Sierra's of all types with this shot in 22/250's and 223's.
The 63g Sierra in a 1-14 twist 22/250 is the Hammer of Thor on yotes, and is plenty capable of takiing out lions, hogs, and deer. It seems like that the lead tip bullets are perhaps tougher than the poly tip bullets for these quartering shots. The 55g Sierra BTHP is one heck of a bullet; jackets are controlled for accuracy like a match bullet. They do not expand quickly like a poly tip bullet.
You mentioned that you have had ? luck on the 50g BT on quartering shots. I shot a coyote in the head at 320 yards with the same bullet and it did not penetrate the skull, muzzle velocity was 4200 out of a long barrel 22/250 AI. They are meant to expand very quickly, and if more guys analyzed their kills, they would not be so talkative
on their results. Shots from the A$$ end from a lot of bullets leave a lot to be desired, especially 40g bullets.
Before I forget, the 55g Hornady Bulk bullet is fairly tough. Yes, the bullet that is only 8 Cents each. I am getting groups in my custom 223 and 223 AI in the high 2's with these bullets which is fantastic. Ojive lengths on these bullets seem to run around .004 for the lot of several thousand, again a great number considering the cost.
Good luck, and thanks for sharing the results with us!