I'm loading a Cooper 280AI with 150gr Barnes TTSX. I've heard they require a good jump.

Other hunting bullets (Nosler Accubond and Hornady VMAX) in other calibers I have (30-06 and .223 Rem) I am loading about 0.025" from the lands.

What is a good starting point for the Barnes on the 280AI, any suggestions? I was thinking of starting with .050" off the lands.

I'm going to try loading with H4831SC and IMR7828SSC and hope to find a load that gives me good velocity and accuracy with this bullet.

.07 to .08

Yep

I know Barnes says start'em at .050" off, but if your magazine allows it, start at .010" and work up with your powder. When you get the velocity you want, start moving back from the lands continuing to check velocity( it should decrease as you get farther from the lands and you may have to increase your powder charge. Try to keep your velocity the same as you shorten OAL. You will find your rifles preference. It may be at .010 or even .100" or more. Usually it seems to be different for every rifle for which I have loaded. It a rare magazine that will allow loading in the .010" range, but don't dispare, usually the sweet spot is farther away from the lands and sometimes I have found two OAL's that shoot well.

I have the same rifle and chambering. I shoot the 140 ttsx. I can check my OAL. If the ogive is the same on the 150 grain, the OAL will be the same. I actually never really played with the length. I had a previous gun in the same chambering so I just used the same length and it works great.

I seat the 130gr TTSX .030" off the lands for my 270WSM.

Start them at bottom of top groove.

I find .030"-.070" works best when operating in the upper range of acceptable charges.

Pressures do some strange things as you go longer and shorter, since you are changing case volume. QuickLoad is handy to see the difference.

A previous poster noted pressures and velocity will decrease as you get away from the lands. I can tell you this is not always the case.

130gr.TTSX 308 - .060-.065"

.050" to .080"

Kiss then work from there, assuming your mag allows. If not then start at mag constraints and work back from there.

Anywhere from .08-.01'' off of the rifling.

Have a 243 with a Shilen barrel that likes them jammed

Amazing how often that works.....

6x45, 260, 7-08, 270, and 30-06 have all been that way for me.

In my experience, both T/TTSXs like to be seated deep. I do what other suggested, start at the bottom of the last groove and work up. Below is my 257 Weatherby Ultramark at 200M seated as described:


And my McMillan stocked pre-64 in 300 H&H. Same distance:

I've solved forty odd rifles for X/TSX/TTSX bullets. Most are pretty easy. Some can be real problem. I have learned that if I start at about .050 off, work up to pressure or until the groups start to come together. If I don't have sub inch groups then I move up to .010 off and normally start moving back .010 at a time. I have one rifle, a .223, that likes them slightly jammed. Some rifles like than way, way off, more than .125 Not nfrequently, rifles like them at .010 off.

Seating depth quite often is the difference between sub inch groups and 3 inch or larger groups.

I've seen it. Only bullets that I ever needed to kiss were 75's and 68's in 223AI. Quite different bullets than Barnes, but that's what it took. Always thought it was a VLD thing, but the 260 liked a leap. Guess nothing is carved in stone.

No one can truthfully tell you. Only you gun knows. Spend the time and workem up don't be lazy.

My most accurate load (160 TTSX) is at 2.82 (mag limit). Touching the rifling is 2.974. Second most accurate (185 TTSX) is the same.

Between me and a few friends that load them, all gave better groups between .040-.060 off...I'm sure there is a good reason Barnes reccomends starting a .050 off!

I used to start by grazing the lands, but now start .050 off. Weatherby cartridges I'll typically start at mag length.