Hey guys, I’ve been a lurker up until now and have searched the forums as much as I could, but I can’t seem to find an answer.
I picked up 6 of the LaRue MBT two stage triggers from LRT over the last few months and I put them in 6 different lowers (2 Aero M4E1s, a Spikes Tactical, Aero Gen 2, 2 PSA) and noticed that there is some “play” with the trigger pins in the holes when pulling the trigger in the first stage (whether on safe or without safe) for 4 of the 6 trigger’s lowers. they move back and forth a slight bit in the hole when it’s pulled/released and while I know people talk about excessive slop being bad, I didn’t know if this amount of play was acceptable or not. Interestingly enough it doesn’t happen with a mil-spec trigger in the same lower (I’m wondering if it’s due to a single stage trigger putting more tension on the pins vs. the first stage of a 2 stage trigger where it might be “looser” tensioned and more visible), or any other lower with my regular single stage triggers either. Just the MBT triggers. Now they’re not flopping around in the hole or anything, and you have to look closely at the trigger pin fairly close to see it shift, but I just wanted to know if this is normal, or whether it’s excessive slop and I’d need to go up to a 0.155 or 0.1555 diameter pin to take up the slop as I think Mark supplies 0.154 pins…(all the information I could find on here and TOS was about EXCESSIVE play, but no information on how much was acceptable and how much was excessive). Below is a video I made just a few inches away from one of the the lowers to show the movement.
I just wanted to know whether this is just me being OCD and overthinking it due to ignorance, or an actual issue, or if other people noticed the same thing on inspection. I know that different lowers can have slightly different tolerances, and if maybe one of the lowers had this I would have said “huh, maybe it’s out of specs”, but it fits mil-spec triggers just fine without it shifting in the hole that I can SEE and it happened on one of the M4E1s, 2 of the PSA Safe/Fire lowers, and a Spikes Tactical Snowflake lower doing the same thing. As I said, I’ve never seen this before, and these are my first 2 Stage triggers so I haven’t had any experience outside of Alg ACT or BCM PNT or basic mil-spec triggers
I have several MBT-2S triggers in as many different lowers. I have yet to have an issue with pin fitment in any of the lowers. All of my lowers are within spec. BTW, none of the lowers of which I have MBT-2S triggers installed are Aero Precision, Spikes, or PSA. They do include McKay Enterprises, Quentin Defense, Nodak Spud, C.M.T.S., and Del-Ton for now.
I have 4 MBT’s installed in two PSA, an Aero Precision Gen 1, and an Aero M5 .308 lowers. None of them have the movement shown in your linked YouTube video. I don’t really see any pin movement in any of my lowers.
I don’t know if the movement shown in your video is significant or not.
interesting… it happens with 4 of the lowers (both PSA, the Aero M4E1 and the Spikes) in nearly identical fashion. The other M4E1 shows no movement and the Aero gen 2 FDE doesn’t either. The strange thing is that a mil-spec trigger in the same 4 lowers will show ZERO movement whatsoever …
the 4 aren’t wildly flopping around as you can tell, and you do have to look at them from about a 12-24 inches away to notice, but still, kinda weird that 4 lowers from 3 manufacturers from different purchases show the same “issue”
Thanks for replying, in my OCD researching the last few days I stumbled across that article and think I understand MOST Of it. However, I couldn’t seem to notice if my particular issue was addressed in that writeup. For example, I’m well aware of the slight left to right shift of axis pins (that happens with most every lower I’ve seen), and get that there must be a little bit of a gap in there (e.g., you don’t want the pin literally locked metal to metal along the pin hole walls to allow slight rotation), but I wasn’t seeing anything about the slight “back and forth” movement I was showing, and I was just concerned that the amount shown would be considered excessive wallowing in the hole. Again, if I misunderstood something in that post or missed something due to ignorance please let me know, as this particular thing is something I don’t have as much experience with (triggers)
That was his answer when people wanted to know the deal with his BCGs, so it seemed fitting here as well. No “hard ons” here for any dudes, sorry that he gives no answers when people ask questions and he berates them. If you want to white knight for him, that is on you.
Since you didn’t think it was helpful, I’ll comment to the OP that he should return the trigger and get a Geissele.
I have MBT-2Ss in Centurion, Colt, Mega, and Aero M5 lowers. They all exhibit different degrees of movement. I bought the first one 10 months ago, and didn’t notice the movement until I installed one 4 months ago.
I pulled the components out of a Colt lower and replaced the pins with factory Colt pins. The very slight (only visible at a certain angle under good light) movement exhibited with this lower didn’t change. Oversized pins might eliminate the movement, if they’re able to pass through the receiver, but the movement is so slight that I’d be very surprised if it has any affect on the HA Aluminum.
lol, I did the EXACT same thing. I didn’t notice it until I saw a youtube video of some moron installing a G2S trigger and his pin movement was pretty crazy. I just looked at my MBT-2S out of curiosity because they were both 2 stage triggers and noticed my movement. As you said, it’s fairly slight and you have to be up close and look at it in the light to see it, but it’s there.
and I did the exact same thing with the pins too. I yanked the pins from a BCM ELPK I had lying around for a future build and it didn’t do anything for the for the wobble. even though with the PNT in place it wouldn’t wobble at all. Just bizarre
and to Stick. Ironically I have three Geisselle G2S triggers and a G2S-E on the way just because I got them for $99 shipped ($120 for the G2S-E) just to put away for future builds. I’ll swap em in and see if that tightens anything up or not
OP - I have 3 MBT’s installed, and one waiting in the dugout. I just got all three out of the safe and checked them, along with 7 other rifles.
The only one that showed absolutely no vicible pin movement - trigger or hammer - was the MBT in my LaRue 6.5 Grendel which I built using the Ultimate Upper Kit and a LaRue lower.
However, if you hold your finger over the trigger pin on any of my lowers you can feel the trigger movement.
The only lower that I checked that showed visible trigger pin movement was one with a Geissele SD-E installed into a lower made by Greg Sully’s company. This rifle is the one I put the most rounds through, at least a couple thousand on the SD-E trigger, with no problems of pin walk out - which shouldn’t be an issue anyway with properly installed FCG’s.
I copied and pasted this from Iraqgunz several years ago:
MILSPEC Colt holes are .155, not .156 and not .154. The reject for them is .163 and there is a specific gage for that and it looks nothing like what you are using.
LaRue notes this: This trigger only works with Small Pin Lower Receivers/.154
I just walked out to the shop and took the trigger pin from an MBT (the hammer pin is shipped installed into the hammer) to measure it. Using a non-digital caliper, measuring numeous places I got .154 using the machined flats on the jaws, using the ‘caliper’ ends of the jaw I got between 153.5 (eyeball - my dial is thousandths) and .154
So, if you are at the upper end of spec on your receiver, I would guess it is possible to have the visible movement.
I think to be sure you’d need a set of pin gauges to measure your receiver’s trigger and hammer pin holes.
I wonder what impact the firing of the weapon will have on the lower pin openings and the trueness of the hammer / trigger assembly. Are anti-rotation pins compatible with that trigger and would they stop the movement?
This is why some people lock down their trigger pins. It shouldn’t have to be done, but it doesn’t change the interest in them. KNS was one of the first.
Interesting. The MBT-2S I have installed does not exhibit the described movement in a Centurion lower.
Is such movement going to gradually cause enough “damage” to the lower that it would become a problem? I’ve never been sold on the KNS pins, and I believe Geissele addresses their use as unnecessary.
I’m not White Knighting for anyone. I happen to like both my Geiselle triggers and my MBT’s. Based on price I’m putting MBT’s in builds that will be around (in the family or friends).
Mark LaRue may be an asshat, I don’t know the guy. I think most of us have fit that description, at some point, in some way. That doesn’t detract from the fact that my experiences with LaRue Precision/Tactical have been positive.
I think that is exactly what is happening in most of these cases. A mil-spec .154 pin is going to have a looser fit in a .163 hole than in a .156 hole.