Hi All,

I was looking on the Barnes site earrier, and noticed that on the TSX, there are two different additional suffixes for the bullets.

Some are TSX BT
Some are TSX FB

Does anyone know what the BT and FB each mean and what is the difference in performance?

Rgds,
FB

Fallow Buck:

I will be most surprised if they don't mean:

FB = Flat Base
BT = Boat Tail

Jim

BT = Boattail
FB = Flat Base

Boat tail bullets carry a higher ballistic coefficient than a flat base of the same weight/configuration. Higher BC equates to less wind drift and slower velocity loss per unit distance.

I've had many rifles shoot flat based bullets into tighter groups than the corresponding boat tail alternative. In fact, most 100/200/300yd benchrest competition winners in the US today are winning with FB bullets. From a performance perspective, it might be best to try both and see which your rifle likes better.

BT = Boat Tail
FB = Flat Base

In theory, a BT bullet will have a higher ballistic coefficient than a comparable FB bullet (all other things such as caliber, weight etc. being the same). So in theory, a BT will not loose as much in elevation at longer range. In practice, the differences are minimal - e.g. 1" at 300 yards, a difference too small to matter in the field.

- mike

P.S. note collision...

If my memory hasn't completely failed, boat tails started as a military design to stablise bullets at very long range when vellocity had dropped below the speed of sound. With that in mind, I'm not surprised that there doesn't seem to be any systematic advantage to using them for hunting or target shooting. It seems to be a case of what an individual (rifle and/or shooter)likes best.

Dean

The only advantage I have ever seen in a boat tail is they seat easier when reloading! I have found FB bullets to be more accurate at 200 to 300 yards...The boat tail will have more detrimental effect on the throat of a rifle according to benchresters and varmint shooters who shoot more and faster than most of us hunters.

quote:

The only advantage I have ever seen in a boat tail is they seat easier when reloading! I have found FB bullets to be more accurate at 200 to 300 yards...The boat tail will have more detrimental effect on the throat of a rifle according to benchresters and varmint shooters who shoot more and faster than most of us hunters.

Ray,

Some believe this is even more so with monolithics where the obituration is harder than with softs and if extreme velocities are milked from the gun then the condition is exacerbated. The scorching flame go in between the boat tail and the bore and acts like a blowtorch.

Do you argee with these statements?

Chris

quote:

The boat tail will have more detrimental effect on the throat of a rifle according to benchresters and varmint shooters who shoot more and faster than most of us hunters.

This is only a factor if the bullet is undersize for the bore and allows gas to blow by the bullet in the transition through the throat. This gas cutting applies to both flatbase and boattail bullets but, with the shorter bearing surface of a boattail, compared to a similar weight flatbase bullet, undersize boattails will allow more erosion of the throat. If a boattail or flatbase bullet expands radially as a result of the forces accelerating it and seals the bore properly, there is no difference in throat wear between the two styles. Pressure and heat then builds equally on all surfaces within the closed system until the bullet unplugs the bore at the muzzle.

Bullets with low engraving pressure have the advantage that the expanding volume is created more rapidly and the pressure curve peaks with the bullet further down the bore. Pressure in the throat is lower and flame cutting is less. The initial pressure rise and heat is distributed over roughly three times the surface area inside the bore compared to bullets with high engraving pressure. Bullets that exhibit lower engraving pressure can be used to achieve speeds significantly higher than other bullets weight for weight and still result in much less wear and flame erosion of the throat and first section of the bore at those elevated speeds.

The reply to your post below is here.

Throat erosion happens so fast that the major effect is right at the back of the bullet with a long sloping boat tail - the wedge between the bullet and the freebore. This is more so in harder monolithics, as the scorching flame goes right in there. A flat base monolithic is thus the wiser option; I guess it speaks for itself.

If you shoot monolithics that allow blow-by with big-case calibers, combined with hot loads (adding as much powder as you possibly can), and preferably it should be an over-bore cartridge, then you are set to achieve sterling throat erosion quickly. Simply put ... as much powder as possible at the highest pressure level will do the job for you.

Getting my drift ...

Chris