M&P15 OR ST-T2 SPikes tactical Buffer

Question for anyone out there who is familiar with the ST-T2 Spikes tactical buffer. I recently purchased an ST-T2 buffer. Not that i was having issues with my 2 month old M&P15 OR; just that I like to tweak and make things better if possible. Haven't shot the gun yet with the new buffer. In the 2 months I've owned the gun, I've put about 800 rounds through it. About 500 rounds of Russian steel case and about 300 rounds of PMC bronze.

Now; I've heard that the M&P15's are "Over-Gassed", so I figured the ST-T2 buffer would be a good addition. Heavier than an "H" buffer, but lighter than an "H2" buffer.

My question is: Has anyone had any issues with short stroking their M&P15? Especially anyone who has used the ST-T2 buffer, and/or if you shoot Russian Steel case ammo? Thanks... Mike...

I've heard also that the M&P15OR was overgassed, and that the ejection was a little strong. I haven't seen any dents on my brass or anything and haven't really noticed any signs of being overgassed. I've not tried any other buffers, I think the standard buffer is fine.

Are you having problems with short stroking?

Is that russian steel case ammo corrosive?

No Problems with short stroking or any rim issues. Probably don't need to replace the buffer. I'm just a "Tweaker" and like to make things better. No worries.

As for corrosive ammo. You're not going to find any corrosive ammo out there. They haven't made corrosive in decades. Don't let anyone tell you differently. Even my military ammo I buy for my M1 Garand stopped making Corrosive ammo about 50 years ago. The thing about the russian ammo is that it's "Steel Case". That's not a problem. it won't hurt your gun or anything. However; it doesn't expand as much as BRASS. As such, it will allow a little blow back past the case in the chamber. Therefor, a little more powder residue/carbon will build up in the chamber. Simply means you need to clean your rifle more often. i say "More Often", because there's actually people out there that go 500+ rounds without ever cleaning their rifle. Then they complain when cases sometimes stick in the chamber. If you shoot a lot of steel case ammo, just clean it more often. I always clean mine after a couple hundred rounds, so I never have problems anyway. Steel ammo is about $4 a box of 20. excellent stuff. If anyone tells you it will hurt your gun or is trash, they simply put: Have no idea what they're talking about.

Anyway; most people who have changed the buffer on their M&P15 haven't had any problems with short stroking, so that's good. I was just wondering if anyone put in an ST-T2 and was using russian steel case ammo. An ST-T2 is heavier than an "H" buffer, but lighter than an "H2" buffer. It should be fine. Should smooth out the action a bit and be easier on the bolt. Guess we'll find out this weekend.

I knew there wasn't supposed to be any corrosive ammo out there for a while, but i'd read that the russian steel case was corrosive. I don't use the russian myself, and since you used it just thought i'd ask.

Whose "they" that say the rifle is overgassed? I'd ask you what your signs of excessive bolt carrier velocity are, but you state the rifle has no issues. I think you have a solution in search of a problem.

Which direction is your brass ejecting and how far?

who are you addressing?

I said that I had not noticed any overgassing or ejection issues.

The OP.

...

Dragon88 said:

Whose "they" that say the rifle is overgassed? I'd ask you what your signs of excessive bolt carrier velocity are, but you state the rifle has no issues. I think you have a solution in search of a problem.

Which direction is your brass ejecting and how far?

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I don't have a solution in search of a problem. Actually; I don't have a problem. Is the M&P overgassed? Yes. I will look it up again, or you can, but the mil-spec gas tube port hole is i believe: .062" for a carbine. For a MID size, the port size is .073. However; the M&P is set up with a carbine gas system, but still has the .073 gas port. Now most times this is not a major issue; because 90%+ of anyone who is shooting a civilian AR style rifle, is shooting .223 ammo and not 5.56, (Which has greater pressure). As such; a little over-gassed is not a problem. Even if you shoot a lot of 5.56 ammo, it's not a major problem. Most specs give a variance for a 16" barrel to have a port diameter of between .062-.078. But the reason for the variance, is because most there is carbine length, mid length, and rifle length gas systems. Most 16" barrels, SHOULD have a "MID Gas system". But many, like the M&P don't. They have a Carbine length gas system. But the gas port is sized for the Mid Gas system.

Again; this is not a major problem. With most .223 ammo and even some weaker ammo like some of the russian, it ensures you'll never short stroke. You'll notice it a bit more with REAL 5.56 military ammo. For me, it's not because I have a problem. I simply like to tweak. As such, I got an ST-T2 buffer. It doesn't use weights that independently shift as the bolt recoils against it and into the spring. It has tungston shavings/powder, to has a smoother and more gradual shift. Also; it's about 4.2 oz compared to a standard carbine buffer that is 2.9-3.0 oz. So; the standard carbine buffer is expecting "X" amount of pressure of gas from a mid length gas system. Instead, it's receiving more gas, because the gas system is a carbine instead of mid-length, but it has the gas port diameter of the mid-length which is larger. Pretty basic math. shorter distance, larger hole, more gas. Means it's Over-Gassed. But again; for 99% of all people, it is not and will never be a problem. For a tweaker, we care. We tweak for smoother operation. I was just wondering if anyone here was using the ST-T2 buffer with any russian steel case ammo; which overall tends to be a little lower velocity than american brass ammo, and definitely less pressure than military 5.56 ammo.

Again I ask, which direction is your brass ejecting and how far?

Dragon88 said:

Again I ask, which direction is your brass ejecting and how far?

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Why does that matter? Why do you "Ask again". I think i was quite clear in saying that my rifle; currently stock; is not having any issues. AT ALL!!! I'm simply "Tweaking". I do that a lot.

But if you MUST KNOW; my empties are shooting into a nice clean pile at the 4:00 position, about 7 feet away. And just anticipating the new buffer; because I haven't shot it yet; but having a lot of experience with AR's and heavy buffers in other AR's; I would anticipate that the new buffer would have the empties going closer to 5:00 and probably closer to about 5-6 feet away.

You posted the thread, now you aren't interested in input? Your ejection pattern is giving you information you aren't heeding, but you appear to be the expert so enjoy your "tweaking".

Accually there is a gas problem with every 16" barrel. Which is why there's a large variation systems trying to compensate for the shortened gas tube. With the m16's original design it had a 20" barrel. When the shorter barrels came about it through the system off. That why ars' some times experience stuck shells or broken extractors, because pressures haven't dropped before the bolt comes back resulting in the empty literally being ripped from the chamber.

...Also, my rounds eject @ 2-3 o'clock

Foxtrot said:

I knew there wasn't supposed to be any corrosive ammo out there for a while, but i'd read that the russian steel case was corrosive. I don't use the russian myself, and since you used it just thought i'd ask.

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I use Tula, and I've shot a few thousand rounds of it with both my S&W and a home-made AR with a stainless barrel.

I use a H2 buffer, a blue sprinco spring, and a full-auto BCG in my S&W. Tweak away.

Dragon88 said:

You posted the thread, now you aren't interested in input? Your ejection pattern is giving you information you aren't heeding, but you appear to be the expert so enjoy your "tweaking".

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You are correct. I started this thread. And Dragon; while I appreciate you trying to provide input; you aren't providing the input that I am looking for. If you care; here is a nice picture of ejection patterns of an AR15/M16 rifle. Now, the only problem with this, is you have to dig a little deeper. Why? Because in many modern AR's, including new M&P15's, they have a brass deflector on them. This will alter to an extent, the ejection pattern. Most notably, it can be a bit misleading on short stroking. But then again, there's normally feed issues associated with short stroking. Normally, if short stroking is suspected, that easy enough to determine by simply loading 1 round in the magazine, and seeing if the bolt open lock engages after shooting the one shot. So currently, my pattern of 4:00 is actually a normal ejection pattern. But again, as I mentioned previously, I and most people shoot .223 ammo and not 5.56, so there's less gas pressure to begin with. And I also said that I wasn't currently experiencing any actual problems. "Unless you think a 4:00 ejection pattern isn't correct". Now; do I think I'm the "Expert" on AR's? No. Not at all. But I am very knowledgeable and experienced with them. But I do appreciate you trying to help. Here's a pic if you care.

BeginingOfTheEnd said:

Accually there is a gas problem with every 16" barrel. Which is why there's a large variation systems trying to compensate for the shortened gas tube. With the m16's original design it had a 20" barrel. When the shorter barrels came about it through the system off. That why ars' some times experience stuck shells or broken extractors, because pressures haven't dropped before the bolt comes back resulting in the empty literally being ripped from the chamber.

...Also, my rounds eject @ 2-3 o'clock

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BOTE: Not sure what type of ammo you are shooting, but if it's pretty hot; e.g. 5.56 mil surplus; that could be the reason for the 2-3:00 pattern. And that's actually still not really bad. If it ejects there for ALL ammo, you probably could use a heavier buffer to slow the cycle down a little. It would be less stress on the bolt; eject a little later; and feel smoother. (Not like .223 really recoils/kicks much anyway).

My main concern, and the reason I started the thread, was to see if anyone using the M&P15 had a heavier than carbine buffer, and was shooting Russian ammo. See if there were any issues. Jsimmons is using an H2, which is slightly heavier than my ST-T2, and he's shooting russian Tula. (I've shot a lot of that). Curious as to what his ejection patter is.

Normally, when tweaking, I go with the theory of go with the heaviest buffer/spring that will consistently cycle your bolt, doesn't short stroke, and will lock the bolt back at the end of the magazine. I have a carbine buffer and an H3. With that, I can mix and match the weights and make an H, H2, or H3. However; I bought the Spikes Tactical ST-T2 that doesn't use traditional weights. So there's no real way of experimenting. It's simply try it and it works or it doesn't. I was just looking to see if any other M&P15 users were shooting russian (Usually weaker ammo) and using an ST-T2. But Jsimmons H2 is close enough. If he can chime back in with his ejection pattern or any issues that might seem like short stroking, (Which I doubt, because he would have said something negative), but any additional info would help.

Unfortunately that chart is not accurate.

Dragon88 said:

Unfortunately that chart is not accurate.

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No suggestions as to what is?

BeginingOfTheEnd said:

No suggestions as to what is?

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I don't want to hijack anyone's thread. However with your described ejection pattern and lack of issues, you do not need to make any changes at all to your rifle.