Drawbacks to semi-auto bolt carriers?

[Northridge]

There have been third party tests previously posted here showing that a heavier reciprocating mass has reliability benefits for M4 style AR type rifles (e.g. carbine length has system)

Without repeating all the details, the two key benefits are:

a) more mass in the BCG and buffer increase inertia and delay unlocking and extraction which allows a bit more time for chamber pressure to drop and the fired case to shrink thus reducing extraction effort. This reduces failures to extract.

b) more mass in the BCG and buffer increase momentum while stripping and chambering a new round which enables the rifle to overcome fouling and other factors (lack of lube, dirt, carbon fouling, bent rounds, etc)

Stronger recoil spring also helps.

[Northridge]

BCG and buffer mass aids in reliable extraction and chambering.

[Disciple]

The difference in mass between LMT style semi and full carriers is inconsequential, much less than the difference between buffer types.

[bruin]

The weight difference is minimal...

I've weighed both, it's about 0.3 oz difference.

Sent from my Pixel 3a XL using Tapatalk