Why don’t more bolt carriers come with sand cuts in the rails? I know Colt made a mod to their Enhanced M4 competing in the IC adding them and I have seen a SR-25 carrier with them, it seems like a good idea to have them allowing for a place to move sand to without interferring with the bolt carrier.
Why? When I tested various ARs by shoveling sand into them, they didn’t stop working. I don’t see this as a pressing problem, and i can see a lot of potential “sand cut” designs creating problems.
Cuz it’s largely nonsense. 
Because they enhance reliability in sand, at least in the SR-25 they did. Colt also added them when allowed to make mods to their rifle before the next phase, they also chose to add sand cuts in the rails on the bolt carrier.
It honestly seems like a feature more would use. So long as there is enough rail to stabalize the carrier you shouldn’t have issues.
There is already a lot of room around the carrier for sand… the only way to know for sure if it would be an improvement would be to do a load of testing, but absent that, if it’s not broke…
Around the carrier yes, but those parts are free floating. The rails stay in constant contact with the upper, adding cuts on the rails allows sand to be moved to areas where space would exist for sand to accumulate.
Thats why I mentioned the SR-25, they proved to increase reliabilit in that rifle according to a post from KevinB so why not the M4
General care and cleaning of the rifle like everyone who is serious already has proven to be ample enough. Running recessed areas would just create places for sand to stick and build up, as well as be a good place for mostiure to hang out. Like others have said, there isnt a point in fixing an issue thats not an issue in the first place.
If the carrier rides on the rails, then the areas around the rails are the places sand would get shoved to, so if you look at it that way it already has sand cuts.
If anyone is looking for an example of “if it ain’t broke…” this would be it.
But good question, don’t stop inquiring.
My thinkin is something like this.
On a standard carrier would leave room for sand to filter to and reduce friction. While cleaning of course fixes alot of issues I am all for small changes that increase the ability of the AR system, something like sand cuts would do that. Its part of why they were added in that rifle.
The FAL and SR-25 benefited from sand cuts, so why not the AR system.
Probably won’t hurt (unless the extra cuts create lots of sharp corners to work as stress risers) probably won;t help enough to notice.
But watch out, the mil-spec guys will have fits. :nono:
This is Colt’s new carrier for the Enhanced M4 that they modified for the next stage.
No rough edges, they do a ramped lead in to the rails from the sand cut, this is on all 4 rails and makes perfect sense to me.
LMT enhanced carrier has the same bearing cuts. (as the Colt carrier sinlessorrow posted) They introduced them sometime ago…
Another benefit of the sand cuts is that the grooves retain lubricant.
Typos brought to you via Tapatalk and autocorrect.
Makes sense, since its a liquid it will hold between the carrier and the receiver in that area like water does when 2 surfaces are in close proximity. That is another huge benefit of keeping the lubricant where it is needed.
If LMT did that with their enhanced carrier, it’d be the tits.
They did…or used to, the main issue I have with the LMT carrier is it really only works in the 14.5"-16" guns, I would prefer a carrier that functioned in them all.
Another thing to note is I wonder if there is a possibility that Colt could do this with their standard carriers for the M4 if it proves to work and no IC is selected(haha). They could possibly do something like a TDP update? yes or no?
The LMT Carrier has always had sand cuts.
The Colt sinless pictured has multiple recesses for the sandcuts.
My LMT e-carrier only has one on each end of the rail.
Benefits & disadvantages of both designs as far as moving dirt away from the rail interface?
LMT’s design appears it would aid in drag reduction.
-Jax
It has like one per side. And it’s not that large. Not KAC style sand cuts.
This is what I was pondering. Are they sandcuts or designed to just reduce friction?
-Jax