I didn't imply there was a single ammunition for any of that. I'm merely stating that many of the responses are assuming terminal performance is only an open air situation. When in fact, most engagements are going to have a very high potential to be a through barrier engagement.
Obviously we could continue on with things past just defeating those barriers and into what happens after penetration such as the spawling each type produces and how that does/does not restrict your ability to engage depending on the scenario. As well as what you mentioned about needing a different system or successive shooters for some types. But that's training much later down the road.
The above poster asking why anything larger than a .223 is needed is a good example.
Our team (3 dept combined), and two half sister depts, used the ASA guidelines for ammo, and we have 5 sniper shootings among the depts. I'm an ASA member and have all their data and understand their reasoning. And glad they will support you in court, just in case.
However, (as Derrick says), I have no trouble with using fgmm, bc I did it for 17 years... based on FBI position papers, training, and support. FGMM is still the back up ammo when the distributors can't supply eldm fast enough. Or...
Now, if TC will do a position paper on the "new" fed ammo, I'd switch to that tomorrow. Just sayin...
BC, if you read all this, you will discern that TC isn't sold on eldm, and you will see TC and Dave mention soft Hornady brass, and you will see me mention a two year horribilus test w eldm and ar10's... AND not mentioned b4 today, but, that soft brass would shave & lock up the ejector plunger in our test ar10's in 5 rounds..
And, yes, I have three of the heaviest buffers ever made, a collection of adjustable gas blocks, and had a bolt carrier weight system sitting in a parts box after those two years of frustration. AR10s are back to almost stock conditions and shoot fine with fgmm 168/175, 118LR, any US ball ammo, and some lots of Hornady black.
We have one case of eldm ar we are testing now... results aren't ready to report... one DD glitched with it....
Why the emphasis on ar10's and eldm ??? That is part of the original post request for info and type of ammunition.
The answers have strayed far far far from that.
In our departments AI's, I have no problem with any of the acceptable picks of sniper ammo out there. It's not in question at all. Zero..
Pick the most accurate of the acceptable ammo and practice practice practice, then practice some more... replace the barrel as needed, repeat. Repeat until hell freezes.
And yes, we have a couple of semi autos. . None of which have the dependability of the bolt guns. And we have a 5 year continuing experiment with them since eldm non ar ammo created this nagging doubt and the question the original poster posed here. Just sayin..