Law Tactical Folding Adapter Gen 3-M BCG Extension and Angstadt Arms UDP-9 BCG Plug Weight Comparison

After doing my review of the Angstadt Arms UDP-9 9mm AR15 pistol, a lot of people asked if I had problems after replacing the BCG plug with the Law Tactical BCG extension.

Short answer: no. If that’s all you care about, you can stop reading.

Long answer, with background:

The UDP-9’s BCG has a metal plug inside of it.


In order for the Law Tactical folding adapter (Gen 2, 3, or 3-M) to function properly, the user must install a BCG extension on the back of their BCG.

Therein lies the potential problem. In order to install the Law extension, you have to remove the plug from the UDP-9.

Angstadt Arms UDP 9 and Law Tactical Folding Adapter-0

Some people were concerned that this change in mass would cause reliability issues. In my test firing with several kinds of ammunition, I never found this to be the case. I test fired the UDP-9 with WPA, Brown Bear, Federal HST 147gr, Aguila 124gr, and 115gr brass cased reloads.

I have gotten more and more questions about the weight differential, so I asked Rich Angstadt from Angstadt Arms to weigh the plug for me. It weighs 3.3 ounces.

I weighed the three extensions from my different Law Adapters (I don’t own a Gen 1).

Generation Weight (oz)
2 2.12
3 2.16
3-M 2.16

I tested the 3-M in the UPD-9 and never had a problem. Given that the mass is the same, if you own a Gen 3 or a Gen 3-M, you’re good to go.

I am unable to confirm if the 0.04oz difference between the Gen2 and the Gen3/3-M bolt carrier group extensions would have an effect in the UDP-9. I’m guessing “no,” but I am unable to verify.

Perhaps one of you out there has a Gen 2 Law Tactical folding adapter and a UDP-9? Our community is probably the best chance for such a combination. 😉


About the Author:

Short Barrel Shepherd Short Barrel Shepherd is a regular guy and works to make Web sites and mobile apps easier for people to use. He spends his free time attending fight-focused firearm, knife, and combatives training, motorcycling, writing, and playing games. His daily carry is a Glock 19 pistol and an AR15 .300 Blackout pistol in a backpack.

1 Comment on "Law Tactical Folding Adapter Gen 3-M BCG Extension and Angstadt Arms UDP-9 BCG Plug Weight Comparison"

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  1. Brian Hawkins says:

    The standard 9mm buffer weight is 5.4-5.6 oz. If you need to add more weight (for silencers, etc), you can move up to the Spikes ST-9X at 8 oz ($55) or the 9Q-T at 12 oz ($150).

    I doubt that the negligible weight difference between the Gen 2 and the Gen 3 Law Tactical folder extensions will make much of a difference as long as the
    bolt (with LT extension) + buffer weighs 1 lb 7 oz or more.

    If you really want to know why your 9mm blowback bolt + buffer needs to weigh at least 1 lb 7 oz when weighed together, here is the science:

    Hope this helps.

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