Range Report: 120 TTSX AR-Comp

[sneaky one]

L-52- let me know your thoughts on the LRX.. I see-something -maybe- in that unit? Tools, sent me back- some TTSX 120 units, I tweaked them, then sent a few back as 105's-- w/ 3 factory grooves in them., and a few as , 100, & 95 grn. units. I have been searching-Lutz moeller- the bullet designer = I found the english version. The mighty Grrr, just can't take the same abuse as the AR-10. Thanks for your support, on these awesome pills! The GMX, needs a frontal redesign for the Grendel loading-@ a lighter wt.- It's close, not perfect though. I still take that 95 grn. round hunting each fall., mseric was there to see the test results- last Oct.- he was wowwed!, to say the least. Did you get a 6.8 PRI. mag. yet? If so, can it run a 2.31 loaded round? I think it can, after a round file rub- vertically-per column,,, frontal tip area- -internally. Poish the plastic, before the oal comes online-you want smooth bullet tip contact area. If you can tweak that mag-let us know, or send it to me- I'll find a way, D.

[LRRPF52]

All my Cproducts mags will take 2.305" COAL, I found. I have 600 Hornady SST's to play with for a while too.

[Hoot]

Being a determined person with 15 bullets left, I decided to go outside of conventional wisdom and do a brief experiment to implement the greatest neck tension without severe or exotic crimps. The technique of seating to the lands is not new and in the case of the Barnes TTSX, generally a path neither taken, nor recommended. Despite my better groups coming at loads of 26 and 26.5 gr of AR-Comp earlier, given the unknown variable of monolithic bullets with no jump, I loaded my three runs starting down at 24.5 gr. to hedge my risk.

Interesting results followed and not the kind that show up on YouTube in a bad way. They actually made me wish I had had more bullets to have gone a step or two higher in charge.

First off, in my barrel, which employs a standard 6.5 Grendel chamber, I encounter the lands with the 120 TTSX loaded to a COL of 1.31 inches. That will not fit into my magazine, so I carefully removed .06 inches of tip from all the bullets, leaving them with a rounded finish on the half tip remaining. That gave me .7 gr more powder room in the case for what that's worth. This endeavor put to rest the question that if I could achieve greater neck tension, could I get AR-Comp cooking a little more before the bullet started down the bore and possibly net more velocity for the same powder charge.

Here's the velocity results:



Not a significant increase over the middle experiment with net increases of overlapping charge weights of about 2.5 %

Resulting groups looked like this:



My gut feeling was that about the time I ran out of bullets, it was just starting to get interesting. Also, the faint ejector imprinting I was intermittently getting the the two previous runs stopped. Primer edges were rounded and there was no untoward casehead growth. IE no signs of pressure issues. Admittedly, this was a small sample base, but if your magazine allows seating the 120 TTSX to the lands, I see no ill effects with AR-Comp. Faster, more dense powders may not be as tolerant.

So in closing this experiment, AR-Comp, which works well with some other 6.5 bullets and no special accommodations, does not seem like a good match for the 120gr TTSX if top velocity factors into what you're using them for. The combination certainly seems capable of delivering good groups though with a little accommodation.

I retreat to my lair to ruminate on this experiment and debate whether to use a different bullet this coming deer season, different powder, or both. I saved one 120 TTSX for my reference bullet collection drawer and may just take it out, load it up and dump it into a string of water filled milk jugs (my default expansion test setup) to see if the combination is worth the effort it takes to make them get along. There certainly are other lead-free choices at our disposal.

Respectfully submitted,

Hoot