OK. Where to start.

1. Use only Barnes data for their copper bullets. That actually goes for all makes of bullets. Pressure comes from an interesting and unintelligible mix of bullet weight, powder burn rate, voodoo, and bullet bearing surface/coefficient of friction. Let the manufacturers do the hard work for you.

2. Military brass is thicker and often-times will have a smaller case capacity than commercial. What you are actually loading is 7.62 X 51mm, not 308 brass. It won't matter, as long as you work the load up slowly.

3. Hearing powder crunch is no big deal. it called a compressed load. It happens with slow-burning powders more often, but if you are using the correct data and powder and weight, it's no big deal.

In this case, it may be.

Barnes are all-copper, and are longer in length than lead-core bullets. That's why they have their own data. Couple the reduced case volume due to the military brass, plus the reduced case capacity due to the deep bullet, and you might be overpressure.

My recommendation would be to look online (Barnes has SOME data available online, more in their manual) and see where you are before you fire any (more?) You may be fine, possibly not. Start a little lower than 10% below max since you are using the Lake City brass, and work up carefully if you have to start over. Look for the usual signs of overpressure. If you have a chrono, you are ahead of the game.

Lastly, there are a lot of experienced handloaders on this site (including myself, if I do say so) and they will be happy to answer any questions.

Good luck, be safe.

Amflyer is right. It's just a compressed load. No biggie. But I don't like them. Pat M. loaded for his .270 by filling the case level full (I forget WHICH powder!) and crimping a bullet into the case!
There is also the "drop tube" option if you're using "tubular" powder. I find it too painstaking and tedious.
Anytime I find myself with a "compressed" load, I change powders or bullets until that is no longer a problem.
I love handloading, but "compressed" loads just make me uneasy. One of my "quirks" is I only use powder charges that are more than half case capacity. A double charge spills powder out on the bench. That's an alarm to me, so I won't do it.
Pat poured his preferred powder in a glass bowl and scooped powder with the case until full. He said he liked it because he didn't have to weigh each charge! LOL!
NOT for me!

Panfry

If you're absolutely positive everything is correct, (powder charge?) I'd shoot them. They may be just the ticket for your gun. If you are apprehensive in the least, go with your "gut" and disassemble promptly.

I have RE 15 but have not tried it in a .308 win, I like it more in my 30-30.
My .308 win powder of choice for 165gr bullets is IMR 4064, second choice would be Win 748. My next lighter bullet is 110gr for which i use H4895.

Amflyer is right all the way. RL15 is not a great choice for a .308 using Barnes TTSX bullets. But you won't have to worry... you can't get enough of that powder in the case to exceed acceptable pressure. In addition to the copper adding length to the bullet, the grooves cut in the bullet add even more to the length for a specific weight.

According to my Barnes book, you can load up to 47g of RL15 but the TTSX bullet may not compress it enough so that its overall length still allows it to fit in your magazine.

You can go ahead and shoot the ones you have without worry. According to my Barnes book, they should be going about 2800 fps or more. Such a compressed load will typically not burn as consistently from shot to shot but will be Ok for hunting purposes. I'd suggest you switch to IMR4064 or Varget. IMR4895 might be very accurate in your rifle too. Always work your loads up from minimum recipes, stepping up about a grain at a time. It takes a while to do this but that also shows you what velocity is most accurate in your rifle. The fastest .308 load is often not your most accurate.

Jay,

Oddly enough, I had forgot about that. Someone asked a question about their posted pictures coming out upside down, and I rotated mine and answered "that never happens to me" or such. Not helpful, I know.

I left it because of all the quasi-political left vs. right conspiracy theory back-and-forth going on hot and heavy at the time. Sort of a digitized call for help, distress symbol, etc.

Or, just maybe, I was in New Zealand and snapped that picture of a German Shepherd. It was standing upright when I took it, but when I returned to this hemisphere...

Panfry,
Two things: Chuck that Hornady manual unless you are using Hornady bullets, period. Secondly, you will have diminished case capacity and higher pressures with LC brass. RL15 is a fine powder for .308 Win. Barnes call out 44.0 gr for 2,733 fps for a 150 TSX. Check your scale with a balance scale or Lee dipper for comparison. RL15 at 48 gr is a max charge at 105% compressed load. You better start with 44.0 and work up in .2 gr increments.