Home Forums Reloading Big Game Rifles Barnes TTSX grooves..,,

I understand Barnes put those horizontal grooves on their bullets to deal with pressure and fouling issues, but how do they affect their long distance air resistance? For me 500 yards is long distance, 400 is about my maximum range. I’m shooting s .257 Roberts with 100 grain TTSXs.

"how do they affect their long distance air resistance?" do you mean the effect on BC? They don't. The BC was calculated based on the totality of the specifcations of the bullet. Now that doesn't mean that the published BC it is necessarilly an accurate but it is the published BC.

Additionally, a single BC number is always in accurate because BC changes as velocity changes. Hence, "maniac" LR shooters are always argueing about "trueing the BC to their rifle given actual velocity"

But all of the above, really doesn't matter. The only truly relevant data is actually zeroing your rifle at say 200 yards and then shooting it 250, 300, 350, 400, 450, and 500 and recording the drops.

I just meant in a general way, compared to a similar shaped bullet without grooves. It seems the smoother bullet would slip through the air better.

Mike is right, published BC is simply a number. I think Hornady on their CX line did something with the grooves to improve LR performance but the proof is with your load in your rifle.

As noted, the grooves reduce BC. This reduction is included in the published number for Barnes though as noted varies in different conditons. Some of the newer groove designs have sloped the edges of the grooves and limited number on shank to minimize the impact to BC

Lou

There's not going to be much difference between a grooved 25 cal bullet vs non-grooved from 0-500 yds. The difference in B.C's will become much more noticeable from 500 to 1000 yds.

I'd be (and am) perfectly happy with a Barnes TTSX at just about any reasonable range.

I recently checked drop at 300 yards with a 7mm 140 TTSX. I'd have to look at one to see how many grooves it has, but actual measured drop numbers coincided perfectly with book figures based on the published ballistic coefficient of that bullet.

As Lou 270 noted and GlacierJohn surmised, the grooves do reduce BC but the question is how much and is it relevant. Knowing what the drop is, is way more important than whether the drop 32" or 36" at a specific distance

On a side note, I had an interesting email exchange with Berger just last week.

Berger 308 180 Elite Hunter BC = .576 length 1.375

Berger 308 185 VLD Hunting. VLD stands for Very Low Drag; i.e., design for long range BC =.558 length 1.378

I asked what gives because that is counter intuitive. I have two bullets - the heavier longer one which was purposefully designed to be more aero dynamic has a lower BC.

The reply I got was more or less - yeah well, things don't always workout like we expect.

According to Lyman's 47th reloading manual, Chapter 22: Any irregularities on the surface of a bullet cause additional shock waves. Additional shock waves cause increased drag. So, I would think that the grooves on bullets with bands have more drag than similar bullets without bands.

I've had some issues with the Barnes TSX/TTSX/LRX grooves when using my Hornady OAL gauge. Sometimes the grooves tend to hang up on the neck of the threaded case and make it difficult to get good measurements. I've had to sand down the sharp groove edges on the test bullet in order to get it to slide smoothly. Not a huge problem but a bit frustrating until I realized I needed to smooth out the edges.