@Zhukov

"LaRue MBT-2S (supposed to compare very favorably to the Geissele SSA-E)"

FWIW... The LaRue trigger face , it is far from a USGI rounded shape. The Larue is much flatter shaped ( minimal rounded corners at the outside edges )

As for trigger pull... here is a comparison from a "Dvorak TriggerScan system" between the LaRue and the G SSA ( I realize the SSA isn't the SSA-E, but it is all I got, Lol ).
I enjoy being able to have a measurement of what I am feeling.

The SSA-E has become my standard 2-stage. When they are on sale, it is well worth the money. ( Currently on sale at Primary Arms for $170 )
The SSA-X... is awesome. I have bought them $199

From this thread...https://www.ar15.com/forums/ar-15/Robotic-Testing-AR15-Triggers-Updated-5-1-2023/12-779525/

LaRue pull results...



FWIW...Geissele SSA results... As per Geissele the SSA has a carrot like 2nd-stage break... the SSA-E has a Candy Cane like 2nd stage break.
The difference between the SSA and the SSA-E is very apparent / noticable/ better to my feel.

I was surprised by how heavy the Larue felt compared to a SSA-E that I have in a .308 AR. I may end up switching them out, but I'll shoot the LaRue a bit before making a final decision.

2-stage for me as well.

They're still backordered on the barrel.

I finally got it! No sooner had I complained in this thread and I received a shipping notification. Just slapped the scope on it. Can't wait to go to the range...



I ditched the LaRue grip for a Magpul MOE K2-XL

Updated picture with better camera and better lighting.

I figured someone would notice.

It's just screwed on loosely and not timed yet. I plan to take 10 shots without it and 10 with to see if there's a difference. Heading out to the range in a bit.

Preliminary results. The 75gr Hornady BTHP round I had loaded up eons ago. They represent the max load of TAC for 223 pressure chambers.

75gr Hornady BTHP, 23.6gr TAC, no flash hider
Avg = 2750fps
ES = 105fps
SD = 37fps
Max spread = 2.20"
Mean Radius = 0.64"




75gr Hornady BTHP, 23.6gr TAC, with flash hider
Avg = 2772fps
ES = 103fps
SD = 39fps
Max Spread = 1.44"
Mean Radius = 0.41"


I did move the scope 2 clicks up and 1 click right, but the shift on POI was much more noticeable. If my shooting was consistent, then it seems to have tightened up the group.

This is a composite of a 10 round velocity ladder using 77gr SMKs/Western Powders MP518 (StaBALL Match equivalent) and Mk262 factory loads.

77gr SMK, 23.2-25.0gr MP518, with flash hider. You can see a nice, steady increase in velocity with increasing powder charge as expected.
23.2...2446.4...-159
23.4...2517.2...-88
23.6...2516.0...-89
23.8...2582.9...-22
24.0...2588.7...-17
24.2...2624.7...19
24.4...2643.7...38
24.6...2674.1...69
24.8...2721.3...116
25.0...2738.3...133
HIGH:2738
LOW:2446
E.S.:292
AVG:2605
StdDev:94
Max Spread = 1.42"
Mean Radius = 0.43"


There were no pressure signs even at 25.0gr (23.2gr on left to 25.0gr on right; 24.6gr is missing):



The interesting this is that the velocity ladder was the best group I shot all day (even with a ES of almost 300fps) and Mk262 factory shot the worst @ 2.54" max spread even though it had the best SD/ES numbers:
HIGH:2908
LOW:2867
E.S.:41
AVG:2882
StdDev:12

It certainly was a hot load, that's for sure. Here's what the brass looked like; there's a definite flattening of the primer around the edges:



The Hornady loads were "meh" at best. The fact that the 77SMKs shot well with a 300fps spread makes me think that they're bound to perform way better. Next time I go out, I will load up three 10 round loads of different charge weights and see how they do when they all run about the same velocity. I will say that I feel like I didn't shoot particularly well; seems like I flinched a lot, but maybe that was after the shot broke. By no means am I claiming that I would have turned in 1/2 MOA groups if I were "ON", but maybe 1/4MOA better? I dunno...

Some observations: At my range, while shooting slightly "downhill", the Magpul bipod is really high and I had to put a 2" ammo bow under the back WITH my squeeze bag. The LaRue trigger is much heavier than I had hoped and I may swap it out for a RRA 2-stage I have in another rifle; I don't think it's to blame either though.  I had a lot of problems the first 20-30 rounds getting the bolt to lock back and/or feeding the next round. That all went away and I had no more issues after that, even with the very low velocity of the 23.2gr charge of MP518.

I'm not disappointed and am looking forward to trying the 77gr SMK load - I think it will definitely shoot. I will also load up velocity ladders with the 69 and 52gr SMKs next time.

If you're talking about the velocity ladder brass - there are no marks on them. I just double-checked.

I removed the LaRue MBT-2S and swapped it with another rifle that had an old RRA 2-stage national match trigger - MUCH better. I'm also going to try to reposition the scope and move it forward; I wasn't getting a consistent cheek weld and have to work on that.

[ETA] Yeah - I was a moron and I can't believe I mounted the scope so far back. That was completely wrong.

Yeah, I'm not shooting Mk262 anymore.

I will second this.

I'm experimenting with 77, 69, and 52gr SMKs. Doing velocity workups and all that - it's going to take a while to go through all the combinations. I even bought a box of 77hr Berger OTM ammo at $2/round. It made me want to throw up a little in my mouth, but it's supposed to be incredibly accurate. Might as well see what expensive bullets with VV powder and Lapua match brass is capable of.

Brief update: The RRA 2-stage is much better than the LaRue. Of my handloads, most of them shot right at 1.1MOA with the 77/69/52gr loads. So far nothing stands out as significantly more accurate than the others. The Berger factory ammo was about 0.85 MOA; it figures that this expensive crap is really good. I'll continue working on my technique and post updates when I get better and find a good load. The rifle has been flawless after the initial break-in.

Here are some results from today...

My best 69gr SMK group - they mostly ran about 1.2"


Very disappointing - there weren't many groups like that. Notice the first shot had a really high velocity and it hit way high.


Ramshot TAC at almost 2900fps with 77gr SMK!


This group was representative of most stuff I shot over the last three range sessions. Didn't matter if it was 52/29/77gr:


Hands-down the best group with my hand loads. 25.0 also looked good.


Best group with TAC:


Berger 77gr OTM factory.




Those aren't all the groups. General conclusions:

• The 69gr SMK didn't shoot as good in my opinion.
• Ramshot TAC ran WAY hotter than advertised, but I did get a good group with 24.5gr. Primers were a little flattened.
• MP518 is much better with SD/ES than anything else I've tried in AR15s
• Berger 77gr OTM @ $2/round is, unfortunately, all that.

I'm going to start loading 25.1gr of MP518 and just practice with those. Might was well stick with those and standardize. If anyone wants to donate money to fund me buying a bunch of that Berger ammo, IM me for instructions.