Well; just got back from the range about a half hour ago. Only got to shoot 240 rounds. There's no time limit; I have a yearly membership - $75; but it's the first real warm day we've had in a long time. There were a few others wanting to get onto some of the 100+yard bays. Just being considerate. I do love that about Wyoming. We don't need as many rules/laws. We're just really into being considerate. (Hell, we don't even have a range officer. Just don't shoot each other). Anyway; I digress.
Anyway; of the 240 rounds, I shot 100 Tula .223 steel case; 100 Barnaul 5.56 steel case; 20 rounds of PMC Bronze .223; and 20 rounds of Military 5.56 I took off the stripper clips. Put the Spikes Tactical Buffer in prior to going out there.
Ran perfectly. Just like I has hoped and expected. FWIW: All cases ejaculated exactly where they had in the past with the stock buffer. At the 4:00 position. Still enough gas pressure, that the bolt locked open after the last round of every magazine. I use 4 USGI Mil Surplus 30 round mags with Magpul Gen III followers; and 5 Thermold LE/Govt use 20 round mags. (I've been using Thermolds for about 10 years. If you get the "LE/Govt use only", I've never had 1 failure. For $3.99 per magazine, I love them).
I do feel that the recoil on the rifle was a little softer. I know that could be just perception, but I don't think so. I've only owned this gun for LESS THAN 2 MONTH. (Got it for Christmas). But I've now put through it about 1000 rounds of ammo. I sort of know how it felt with the original stock carbine buffer. I noticed something else, which I can't really decide on yet. Normally; even with a .223/5.56, while I don't flinch, I usually "BLINK" after the round goes off. That is just normal. At least for me it's normal. Today; even with a pretty windy day; I was able to sight in through the Red-Dot, take the shot, and not blink at all. So I really do believe that the recoil is softer. Not necessarily less; just softer. Maybe smoother is the right word. Is the change DRAMATIC compared to the original Carbine buffer? No, not dramatic. Sort of like the analogy I gave earlier with working on cars. It's a "Feeling" that you get when you tune the motor a certain way. Can't really explain it; just that you know it's better or right.
Anyway; I'm happy with the Spikes Tactical ST-T2 buffer. 2 things I like. 1) My perception/feel is that it's slightly smoother/softer. Again; it's a perception that I can't quite put my finger on. 2) More importantly; the more counter weight that you can add as resistance to the bolt coming back from the gas, and yet still have it go back far enough to eject the rounds, feed properly, and lock the bolt back after the last round; mean less wear/tear and stress on the bolt. That, no matter what, is a good thing. I could probably use an H3 in the rifle, but I'll stay with this for now.
Oh; and DBR. I've been rebuilding cars (Only old carb type without modern electronics), for about the last 30 years. Of course I use vacuum gauges, tachs, etc... My point was, that once I set it for "Book Specs", I would put all those tools away and "Tweak" the rest. Usually by Ear and Feel. I've moved from the Jersey Shore to Texas to the Rockies in Wyoming and New Mexico. "Tweaking" is a necessity with carbs. You simply can't tune such a car strictly by timing and vacuum settings. But that aside; the same with the AR. Without a high speed camera, there's no way to know for sure if there's bolt bounce. It didn't "Feel" out of place. While not select fire, I ran off a half of a magazine with bump firing. No issues there either. Can some rifles with an ST-T2 experience Bolt Bounce? Yes, most definitely. So can a Colt, BCM, DD, or any other with an H, H2, or H3 buffer. And some have. Even in the videos, some did. But there can never be a blanket statement that "X" brand of buffer WILL CAUSE Bolt Bounce. That's simply not accurate. Just like saying "Y" brand buffer will NEVER CAUSE Bolt Bounce. Again; an ignorant assumption. Bolt bounce has as much to do with timing, gas pressure, and spring tension as it does with the buffer. And that's part of the compromise that the M4/Carbine model came up with. Shorter stock; shorter barrel; use a lighter buffer, but a heavier spring. Try and reduce the gas pressure.
Anyway; I don't know if my M&P15 has any bolt bounce. I've never filmed it, and probably won't. It's not full auto, so I know that I won't have any operational problems. I also know that it's virtually impossible for a semi-auto with bolt bounce to hurt the rifle/bolt at all. (Not considering the amount of stress on the "Bounce" isn't even a fraction of the stress on the initial slam forward when it's chambering the next round). So it's really a non-issue. I understand the concerns in a select fire situation. But in a semi-auto situation, which 99.9999% of all of our are, I think we're discussing a solution to a problem that does not exist.
But for me, the ST-T2 seems to be smoother. I like my physical body reaction to the firing and recoil. I like even my perception. And it's ALWAYS a good thing if you can add more resistance to the bolt blow back, if it continues to eject, feed, and lock back properly. So for me; it's good-to-go.