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Cool. Thanks Dano. Was pondering this the other day for some reason wondering if the E-carrier would be slightly lighter b/c of the segmented rail that interfaces with the upper and the longer cam pin tunnel. It is but not much.
-Jax
Seems like running a Semi carrier give you a negligible weight difference. Less than 4% difference.
I do have, what I think is, a Colt semi carrier with no bottom. “half circle”.?? But am unsure as to maker and didn’t weight it.
Also I did not have a regular LMT carrier, only the enhanced versions. I would guess not much off.
There are many variations of the semi carriers, shrouded, not, etc.
I think with a drill (holes along the side) as well as milling, one could get to 7.4oz or so… extrapolating from what i took off the LMT carrier. Perhaps one day when snowed in will think about it.
Mine has a “C” stamped on the left side, if that helps you authenticate it. ??
Cool thread, here are some of my contributions to add:
Young Manufacturing NM semi-auto - 265g
JP stainless semi-auto - 250g
Here are my contributions (all with gas key attached, and nothing else):
Rock River Arms (RRA) chrome semi-auto bolt carrier: 9.21 oz / 261 g
Primary Weapons Systems (PWS) Isonite DI bolt carrier: 10.79 oz / 306 g
LMT standard semi-auto carrier: 9.10 oz / 258 g
Joe Mamma
Just a general question about BCG’s. I have seen some designated as M16 bolt. I am planning on building a mid length/16" barrel ar. Will a M4 bolt fit this or does it have to be M16? Thanks for any help.
My contribution to the thread, carrier/key only
Core 15 M16 profile Carrier 9.38oz / 266g
PSA Premium M16 Carrier 9.34 oz / 265g
There is no such thing as an M16 bolt. What they are MOST LIKELY referring to is the carrier profile. That means a full auto carrier which hasn’t been chopped and emasculated.
Weight on a calibrated digital scale.
BCG’s, complete assembled
DD BCG, standard 11.68 oz.
DD BCG, w BCM extractor upgrade kit 11.54 oz.
BCM carrier with FN bolt, BCM small parts 11.70 oz.
‘generic’ NiB BCG - std. carrier, 9310 steel bolt, mil-spec parts 11.61 oz.
Carriers stripped (w gas-key) coming up:
Weighed on a MS-600 digital pocket scale (reliable to 0.1 gram accuracy) - all units in grams:
Bolt
FailZero m16/4 Full Auto Bolt Carrier Group (EXO) = 330.2 g complete BCG (270.3g carrier only)
LMT MRP Piston = 344.0 g complete BCG (285.2 g carrier only)
BCM = 329.2 g complete BCG (269.6 g carrier only)
Colt made these in an unshrouded FP version and a shrouded FP version.
Been seeing a lot of this monstrosities popping up lately.
Progressive Machine & Tool Titanium carrier - 5.1 ounces
Smith Enterprises Aluminum carrier - 3.85 ounces
I get the impression from this thread that some folks are seeking a lighter weight bolt carrier. If so, this is contrary to good design engineering for best reliability. One reason the AK system is so reliable is that the carrier on a proportional basis is so much heavier than the bolt head. Greater mass of the carrier is very important for reliability as it increases the probability of a full bolt stroke due to higher inertia. Instead of increasing the weight of the buffer in the M4, as is now commonly done to assist in reliable function, it would be best to increase the weight of the carrier. That is neither practical nor easy, so instead as a matter of convenience the buffer weight is increased. At least the cycle is then slowed and the bolt then feeds a fresh round with greater certainty due to the heavier buffer.
I have to STRONGLY disagree! I have been running lightweight carriers for almost 40 years with no issues. Also, on the AR the carrier and buffer operate as a if they were a single integrated unit.
This is actually a much more complicated subject than most want to know. Without going into proprietary details and direct specifics, there is a balance that happens when changing total reciprocating weights, total reciprocating weight Vs actual buffering weight, chamber pressure during initial unlocking, gas port size and location for a given length, and at least 11 other variables that I can come up with when someone else who could see with the spreadsheet i’m thinking of could see much more.
Basically, going beyond the normal balance of weights for a 20" rifle gas, you reduce the band of operating range for many of the given variables. Leave the low mass systems for their specific application.
I tend to agree with you. I know the serious three gunners run as light a BCG as they can get, but those guns are specifically tuned for such performance. For combat/field use where reliability is paramount I think what you say holds true.
The Tubb Carrier Weight System has been available at least since 2004. It consists of a flange that fits into the rear of the bolt carrier and two weights, one steel and one tungsten, either of which fits into the flange to increase the weight of the bolt carrier group. The rifle does have to be assembled and disassembled slightly differently, though.