My results at the range with 51.5 grains of Reloader 15 and 120 grain TTSX at .050 off the lands was less than spectacular for accuracy. Anyone with advice on this load would be appreciated. Remington mountain rifle.

I also have a Rem 700 MR, but restocked into a B&C Ti stock & bedded well; shoots 51gr of RL-15 & 120 TSX into 5/8-3/4".

I seat all Barnes bullets to a very light kiss to .010" off.

But it shoots pretty much everything into 3/4" or better, all loaded to the same throat clearance.

In spite of what some on here claim about the need for seating Barnes bullets with a sizable jump to the lands, in the half dozen or so rifles I developed loads with them for, all have shot just fine kissing to .010" off the lands.

YMMV

MM

Try changing seating depths or try some with H4350. I thought of trying that bullet in my 280 AI. However, I am having excellent results with the 140 ttsx and the 145 lrx

Your rifle doesn't like either the bullet or powder. Now you know...

I'd try a slower powder like Ramshot Hunter, Re-19, IMR 4831, or H4350. I've had excellent results with all of the above, even with sensitive bullets like the old Barnes X, the Swift-A-Frames and the Hornady Interbonds.
What I've found if you want to seat the TSX close to the lands is that you need to start at least 10% below the listed maximum charges. At .050 off the lands, loading data for such bullets is tha same as it is for cup and core bullets. E

Well, that's a sensible place to start for sure, but with the TTSX & TSX grooved bullets seated to kissing or just off the lands, it no big deal to usually end up at the same loading weight as is used for C&C bullets...........lowering pressure was the purpose of the grooves in the bullets as compared to the solid shank on the original X bullets.

MM

My custom '06 didn't work out like that. Seating them deeper decreases pressure and velocity. E

I got the range yesterday and using your recommendation of 0.01� off the lands things tightened up considerably. Using the same load of 51.5 grains of RL 15 and the increased COL put 5 shots just within an inch square, which is probably close to the best I can shoot so a better shooter might be able to reduce that. I am more than happy with the results so thanks for the recommendation.

I also loaded 5 rounds out to 0.07� off the lands while 3 out of 5 were very good there were a couple of flyers. There was no discernable velocity variation between the 0.01 and the 0.070 so have to assume no pressure change either. My original plan was to use the RL 17 with the 120 grain TTSX but haven�t been able to obtain any lately and as I had the RL 15 on the shelf it is what I used, also in an older Barnes manual I see the RL 15 was the powder of choice for 120 grain. Currently I am using 140 grain TTSX with RL 19 as my deer hunting round but may change that to the 120 grain given current success.

I have not been impressed enough with RL-17 in the 3-4 guns I've tried it in to get enthused about it & have discontinued any further work with it.

I also use RL-19 with the 140's & have been very happy with it.

But I killed a WT deer with a 120 last year & it performed perfectly, but since I am usually hunting mule deer & elk at the same time, I usually just carry the 140's in that case.

MM

That 120 gr. TTSX will work on about anything you would want to shoot with a 280. I have used it a lot in the little brother (7mm-08) and wouldn't hesitate to use it on elk. I have yet to find a whitetail that it won't shoot thru from any direction although I don't azz shoot them. It is uber.........

My AI version sings with H4350 and the 120TTSX.