First off, I’m not a ballistician or an engineer or anything special at all, but I did stay at a Holiday Inn Express last night…
And I apologize, the title of your thread has to do with barrier rounds with similar ballistics of GMM and I saw some posts on BC and MV, I’m assuming you are at a PD in the US so I’m writing from a standpoint of short range open or barrier applications from a LE viewpoint so I base my ammo selections on POA/POI, accuracy (short distance), TB, and performance in LE specific applications and not in tech specs or long distances/factors. Again, I have very little knowledge of that kind of info. Any knowledge I have (which is very little) is confined to the LE application of precision shots of 308+ calibers.
Secondly, everyone here is very knowledgeable, smart, and has a ton of experience so absorb all that they have offered. That being said, and you probably already do this but if you haven’t already I would encourage you to go out and build a windshield holder out of a couple sawhorses and a res window holder out of some stands and clamps. Any windshield replacement shop will give you all the windshields you want and res glass window businesses will donate windows to LE for testing in my experience and with some goodwill. Get a bunch and then shoot your duty and a bunch of other different types of rounds through glass for yourself and your supervisors/agency. Stack cardboard targets on stands behind the glass every couple feet or so as a cheap way to see what each one does as far as separation, spawl, glass frags, and bullet behavior. We also check deflection and as a result no longer take that into account for our POA. Our ghetto method for that was to have a shooter staged and rifle safe, keeping the rifle parallel to the end aiming target. Shooter aims through the glass and we place a 1” dot on that rear target as his aiming point. Then via radio we place a 1” dot on the windshield at his direction so that it is lined up in the exact same spot/plane (as best we can) as the rearmost aiming end dot. We are trying to eliminate any shooter induced miss that we may interpret as bullet deflection by glass angle or rake. Once those two dots are set we then fill in the space between them with cardboard targets starting right behind the glass all the way back to the rear target. Then when shot is fired we can see where the round hit on the windshield in reference to the dot there and compare to the impact at the rear dot. As you know we rarely see every round fired punch the very center diamond of the target dot every time, and when aiming through the windshield at a dot behind it and firing, how would we know if the round on the dot behind the glass was high or low or left or right due to possible deflection or shooter induced? This way we can compare the two (impact in relation to dot on windshield compared to impact in relation to dot on target behind windshield) and make a deduction. Plus the targets in between show all the behaviors and pieces and travel/path of the bullet and bullet/glass pieces. I’m sure tons of guys have been doing this already but we only started doing it a few years ago after a training course where someone said the military tested glass deflection in a lab setting and found there really wasn’t any, at least in our application/distance with specific barrier rounds.
So we wanted to see for ourselves and this is what we came up with and we’ve found (again, our opinion/observations only) that there was little to no deflection given a good barrier round at a target behind windows at pretty big distances (20+ feet behind windshields and 30+ feet behind res windows) with a ton of induced angle/rake, so we removed that thought or worry or factor from our minds on our very specific/limited application. Obviously there are tons of factors of caliber, bullet composition, speed, etc but with the ruag tactical and T1 etc it’s not a factor or thought for us now.
Disclaimer: This discussion only applies to our 308/338 barrier rounds fired at glass in specific situations, NOT firing pistol or carbine rounds of all types from inside out of cars or vehicles and bullet behaviors in those instances, if that makes sense. And this pertains to average/standard res windows and windshields only, other glass types (commercial, fire rated, commercial laminated and plexiglass etc) are a whole other ballgame. For that go to your bigger commercial glass outfit and ask for samples of glass they put up in schools, gov buildings, commercial places (banks, 7-11’s, etc.) and shoot those as well and then get a 338…
Now for more info/opinions:
My ammo supplier said that the Federal LE 308T1 has been discontinued. T2 is their (federal’s) only LE barrier round now for 308 that I know of. I think Speer is part of federals parent company? But honestly I’ve never tried their GDSP 308’s that come in 150 or 168.
And I’ve been told that Ruag’s tactical has changed or is changing to a 164 from a 163? I don’t have any of the 164’s yet though, just 163’s.
And another disclaimer, (my opinion only!!!) I’m not a Hornady TAP fan at all. Any kind of TAP. We’ve tested/tried it and did not work for us in particular. I’m not talking TB or barrier performance but POA/POI, FTF and accuracy in our guns. But they do have the 165 GMX that some folks have and/or use for barriers. I know it works for lots of others though so you can prob disregard all that info. And apparently Terry can shoot good groups with it!!! But for us we have 14 guys/guns and we have to pick the ammo that shoots best overall for the group and Terry made them so they shoot federal very well but we haven’t had much luck with Hornady from FTF’s to accuracy etc. we shoot with lots of outside agencies at our trainings and when they all switched from TAP to federal T308T they said it made a big difference and they haven’t looked back. But all guns are different and some shoot stuff better than others. Our guns can prob shoot tap just fine we prob just F’ed it up, cause Terry showed above that his guns shoot tap very well!
It’s all anecdotal and individualized but in our testing we saw (again, our opinion only) too much going on with the T2 through window barriers (residential glass of different types as well as windshields etc.) and we weren’t comfortable with it in its application of shooting it at a suspect with an innocent right next to them and in close or not so close proximity to the barrier. But I know a ton of agencies use and like the T2’s. The T1’s did much better (again, our opinion only) but weren’t as accurate overall. But we used T1’s up until recently due to how it performed through glass specifically. But due to the T1’s accuracy, POA/POI in conjunction with our open air rounds of GMM and T308T we wanted to explore a change and ran some more tests.
The Ruag Tactical (glass barrier) rounds performed the best by far and hold a very good POA/POI in conjunction with GMM or T308T (at least in our guns, all KMW’s) and shoot small groups as demonstrated by Terry’s pic above. We made the switch from T1’s to the Ruag barrier for our 308’s. We also shoot the ruag (and always have) out of our 338’s at Terry’s recommendation. I’d shoot all ruag in our 308’s if we could, if money were no object. But unfortunately it always is.
Be prepared for extreme sticker shock on ruag Ammo pricing. We are fortunate and have a lot of support and a good Ammo budget but I just bought 1500 rounds of Ruag 308 Tactical barrier (apparently in 164 now but I haven’t gotten it yet) and paid $6,345 for it. That’s $4.23 a round for 308. And that was the best price I could find. But for the kind of shot you might be taking in that situation with a barrier round in my opinion price is no longer an object. Plus for training and purchasing you probably won’t fire a ton of your barrier rounds all the time so my thought process was to get the best barrier round possible and price be darned, whereas your open air rounds which are fired for most quantity/volume during trainings, traps and other scenarios, is where price becomes an issue due to quantity fired and the federal rounds are really really good and priced right.
Irritatingly, the other issue I ran into is that the ATF now considers the 308 ruag all copper barrier round to be AP based on their definitions so I had to submit a FET, dept purchase order, and a ton of other docs on this order. Which is funny because the 338 tactical, same exact construction (as far as I know) as the 308 tactical, is not considered AP by the ATF unless that has changed recently. I was told it has to do with 308’s being a “pistol” capable caliber and that’s why they consider it AP in 308? I personally have no idea, just some info I was told.
Anyway, get a bunch of ammo and go shoot some windows and figure out what works best for you and your gun and your agency/application.
Again, I’m absolutely not an expert at all, just a regular yahoo so if anyone thinks I’m crazy I’d probably agree with them.
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