In the product description, you mention how it was basically just pulled from the FAL cut's.  Have you done any reliability / extreme performance testing with them to see if there is a difference from a non cut carrier?  Is there a situation where the cuts could result in a loss of reliability?  I have a fear of say a rifle submerged in dirt, getting dirt collected in the cuts leading to loss of friction.  A non cut rail leads to a better seal with the receiver against the ingress of dirt and foreign matter.

I was thinking the same thing when seeing the KAC sand cut bolt carriers. The cuts must let foreign debris into the action more, but gravity will assist in letting it fall through the cuts. The only real place for sand to accumulate through would be the ejection port if it was left open. I think that if an AR was submerged in viscous mud, the mud would have an easier time entering the upper receiver with these cuts and decrease reliability. These remind me of both the FAL and the Sig P226 when they made the sand cut rails in the 90's. The sig idea was a failure since it allowed the frame rails to crack easier. The FAL obviously was much more successful with these cuts. The British and Israelis both utilized sand cut FAL's which came from direct testing in the 1950's.

I think the idea in an AR is less useful because of the way the rifle is sealed much better from the elements. The FAL has a larger gap between the carrier and the receiver top cover as well as no ejection port cover. There exists a much larger possibility for sand to enter the receiver so having a way to remove it would be beneficial. The sand cuts on a FAL are also deeper and larger than those on these AR carriers.

I think that in an environment where blowing sand was common, these would be useful. In a temperate environment like most places in the US, I believe it would be more of a detriment since you are more likely to get materials with smaller particle sizes in your receiver from water bodies like swamps, river mud, etc. The smaller particle size materials would more easily enter through the sand cuts and increase friction on the carrier.

My 2 cents as an engineer is that these may be more beneficial in a desert environment like Iraq, etc, but marginally at that. I think the sand cut carriers are more for salesmanship than anything. The KAC carriers are tough to find anywhere right now. My guess is people buy them because they look cool (which they do). The KAC design also has an interesting history as it was designed and tested, but ultimately did not make it to production. I think KAC came to the same conclusion as I did and decided to drop it. Now they have realized the market for them and are producing them for the civilian market. I don't believe they come in any SR-16's but I may be wrong on that.

The same stock in some SR-25s and Gov issued SR-16s.  Never came with a commercial gun from them though.  If the cuts are only beneficial for say sand, but are a detriment in mud and decrease reliability in those circumstances, then I would not be in favor of them.

The sand cuts in our carrier were designed to be able to help drive any foreign debris out of the action.  Where the cuts are located and the angle of them allow for you to cycle the debris out of the action.  The cuts are located on all of the load bearing surfaces of the carrier so if debris was to enter the action these cuts would aid in driving that debris out where on a standard carrier that debris may end up lodged in the action and increase wear & friction.  We also offer our sand cut carrier with a NTFE - Nickel Teflon Finish in order to aid in lubricity & function.  This coating works in conjunction with the sand cuts to really help deliver a product that will continue to preform in harsh environments.

Bear in mind, these features are here to help the rifle preform better and be as reliable as possible in adverse conditions but no feature or product can take the place of maintaining & protecting your rifle from harsh elements when possible.  The Israelis knew how important protecting the action was and created a top cover with a PORT DOOR for the FAL knowing that the sand cuts weren't the only answer but rather part of the bigger solution.

Thanks, Mike
DS Arms

I've been using my KAC sand cutter extensively. Even going so far as to see how long a suppressed SBR would go without lube. Made it to 2k rounds before the dry, rough gritty sounds of me racking it was too much for me to stand and I had to oil it.

I believe that the cutter rails actually served far more useful in dealing with carbon buildup than sand or dirt and foreign matter. I fully expect that it could have kept on going had I not broke down and drenched it in oil again.
20181021_005735 by B A, on Flickr

@mbf11

I just ordered one of your NTFE sand cutters. Can you tell me if the gas key fasteners are grade 8? Thank you.