Just received some 450 TSX's and thought I would tinker with them in the 458 Lott.
Any suggested loads? Looking for 2350 - 2400 FPS.
I have a older Barnes manual (Pre TSX) and the only data is limited.

EZ

I've had good luck with 78-80 grs. of H4895 and 81 grs. of RL-15. These loads have given me good accuracy with no apparent signs of undue pressure in my rifle, but I have not had the opportunity to shoot them over a chronograph yet.

According to Barnes manual #3, 78-80 grs. of H4895 should get you in the neighborhood of 2350-2400 fps., but approach with caution as the newest edition of the Barnes manual lists a max load of H4895 as 75 grs. for 2220 fps.

I'm not sure how much it matters, but FWIW, I am loading to a COAL of 3.650, as my rifle has a long enough magazine and throat to allow that. I don't know if loading to the standard COAL 3.600 would cause undue compression and pressure issues with any of these loads. As always, start low and work up slowly.

Interesting that you bring up the OAL comment. I have crimped into the second ring on the TSX. Still plenty of room in the magazine of the CZ 550 action. I believe I am at 98-100% fill capacity with this load 84 gr AA 2520??
I have a little history with a 450 swift and 86 gr AA 2520 @ 2380 FPS (23" barrel) across my chrono. I did not get a response for a while so I went ahead and dropped that charge 2 grains and thought I would run it through the Chrono this weekend. I suspect the TSX may create a bit more initial pressure than the Swift.
I suspect most reloading manuals are becoming more conservative than initial publications due to law suits.
The folks providing the information have no idea what type of firearm you have or the condition it is in so they are providing conservative data.
Big difference in the old Barnes manual and the new one....

quote:

Big difference in the old Barnes manual and the new one....

Not just with the Lott, but with all calibers.

My rifle is a Ruger RSM, and like you I can seat the TSX out to the second ring with no problems at all. I started load development with this rifle at 3.600, and then moved out to 3.625 and then 3.650 with the accuracy improving at each step. I have some loaded to 3.700 that I'm hoping to try out this weekend if the rain holds off and the wife's honey-do list isn't to long

I would be interested to see what kind of results you see with your load over the chronograph, keep us posted.