Sharing a recent experience/email with Geissele CS.
Recently acquired a URGI 10.3 which came with the Super 42 and H3 buffer. Pretty much immediately replaced one of the tungsten weights with steel to make the buffer an "H2". Installed with a LAW adapter, I was finding operation to be sluggish with .223 ammo and that the bolt wouldn't lock back even with some 5.56 options, primarily 55gr. I did experience a couple short stroking malfunctions especially in cold weather.
I've been exchanging a few emails with Geissele CS, but the TL;DR is that the LAW adapter adds 2 oz to the BCG and changes the recoil dynamics. Currently running with the Super42 and a "Carbine" buffer (removed all three tungsten weights and replaced with steel), and now cycles all ammo I've tried so far. Curious if others have had similar experience.
From Geissele CS:
Thank you for the update. The law tactical folder does have a space that adds a few ounces so It would not be a true H1/H2/H3 and additional tuning would be required. Would you be able to tell me if it is now running in the H1 configuration?
My latest response:
Thanks for following back up. I did exchange one of the tungsten weights with steel to make the buffer a "H1" with the super 42 spring. I found that function was improved, but that the bolt would still not lock back consistently on the last round, depending on ammo. Federal M855 worked without issue, but cycling was sluggish and locking back was inconsistent with 55gr Wolf Gold .223, 55g Federal AE .223, IMI M193, CBC M193, Speer Gold Dot 62gr and Gold Dot 75gr. What surprised me most was that Federal Mk318 62gr OTM would not consistently lock back. I am running unsuppressed and brass ejection is somewhere between 4:30 and 5:00.
According to LAW Tactical's website, the buffer extension weighs 2 oz. Exercising some google-fu:
Carbine buffer weighs approx. 3.0 oz
H1 buffer weighs approx. 3.8 oz
H2 buffer weighs approx. 4.6 oz
H3 buffer weighs approx. 5.4 oz
H4 buffer weighs approx. 6.8 oz
So with the LAW adapter the overall weight of the cycling system (less BCG) is:
Car + LAW = 5 oz (between H2/H3)
H1 + LAW = 5.8 oz (>H3)
H2 + LAW = 6.6 oz (~H4)
H3 + LAW = 7.4 oz (>H4)
Since the Super 42 is an extra power spring, I'm guessing that an H1 buffer plus extension at 5.8oz, heavier than an H3 - is causing the issue. Next step is to try to replace the last tungsten weight in the buffer with steel to make it equivalent to a standard carbine buffer, which would put the total weight of the buffer and LAW extension between a typical H2 and H3 weight, which would be within the recommendations for a 10.3" with carbine-length gas system. Unfortunately I don't have a suppressor to test, but I wonder if the 5oz combined weight would be a pretty sweet spot between suppressed/unsuppressed.
If you like I'd be happy to report back after the buffer swap and range trip.