Since this thread got revived I figured I would add what is hopefully a little more clarification to my post #57 above.
You probably already have all this figured out but I pulled some bullets from ammo this morning to hopefully give everybody a better visual.
The ogive of the original SMK 168gr BTHP is the secret sauce. It is very forgiving across a large variation of chambers and throats. Pretty sure nobody has to dig deep to see its history as the benchmark for consistency and accuracy.
When Sierra introduced their first .30 cal. tipped bullets several years ago, they were under a good bit of pressure from the shooting community to improve their BCs to at least pretend to keep up with Berger. They bent to the pressure and changed the ogive of the new tipped match bullets to more of a secant style to bump up the BC and branded them Tipped Match Kings / TMK.
It did increase the BC but at the cost of having a less forgiving bullet.
Everybody that has purchased TMKs to reload since they were introduced has noticed that they are definitely harder work up accurate ammo with compared to the original SMKs.
Today's current TMKs still have that new secant ogive style whether you buy them as components to reload or purchase factory ammo with them.
The image below shows an original SMK BTHP next to the TMK
View attachment 8516477
If you concentrate on the shape forward of the bearing surface on both, you can see the difference in profile. It doesn't look like a big deal but it surely does make a difference in how the bullets enter the throat consistently without being picky about "jump".
When Federal decided to move on the T308T project, they knew they wanted a bullet that was tailored for consistent terminal performance on soft tissue. They mandated that the bullet retain the original Sierra MK ogive and also a hard polymer tip to assist with feeding reliability especially in semi-autos. Sierra sells a butt load of bullets to Federal so it was not a big deal for them to agree to make an SKU specific bullet for the new loading. They produced the bullets for Federal but as far as I am aware, Sierra does not offer this bullet in component form for reloaders to purchase.
The image below shows an original SMK BTHP next to the new bullet made for the T308T.
View attachment 8516484
You can see that they retained the same ogive.
Since Sierra had already named their polymer tipped bullets TMK and TGK, Federal elected to call the bullet Tactical Tip to avoid any confusion.
I find it ironic that the newer Tactical Tip made for Federal is actually more of a true "Tipped Match King" than Sierra's own TMK of the same name.
As a final comparison, the image below shows in order L to R: Hornady ELD TAP, Federal/Sierra Tactical Tip, Sierra MK BTHP, Sierra TMK
View attachment 8516488
**The green tipped TMK is a 175gr. All other bullets are 168gr.
I couldn't lay hands on any 168gr TMK at the shop but I know the ogive is identical between the 168 and 175, so it should be a valid visual comparison for purposes of this post.
I'm not sure the shape of the bullet had anything meaningful to the terminal performance.
From what I've been told and seen it has more to do with manipulating jacket thickness, lead core hardness and bonded vs non-bonded.