Not all recievers are created equal
I hardly ever write a review, but this product fits and works perfectly in my Sendra receiver. Which is true mill spec. You can't blame this product for the receiver manufacturer drilling the pin hole in the wrong place. And yes a little bit matters.
This part is better than you think!!
As I have a bit of a difference in my experience with this part, I'll let it suffice to say the following: Each and every "Mil-Spec" receiver has it's own minute differences. With a thousandth diff in spec from one to another, can easily cause the binding described by others. The one I installed in a Spike's Lower was fitted properly and works as expected. The customer was very satisfied, as are the community being protected by him...
Works fine in a few NFA receivers
I have not had an issue with a few Colt A1/A2s and some other NFA RR installs. Could be a tolerance stackup in both the receiver as well as the KNS part. It is worth saving the NFA item either way.
Limited fitment
This only works on Colt. I was told by KNS Built off Colt specs. Make sure your sear pin on right side of lower is directly above your safety ( 12:00 position ). Or this will be worthless!
Not living up to the KNS reputation
KNS prides themselves on tight fit but the sear anti rotation pin was TOO tight. The sear could not rotate when installed on the KNS pin, resulting in no auto fire and uncontrollable falling of the hammer with the bolt carrier in auto. I got a few of these to have in stock, they are all going back.
VERY DISAPPOINTED
I was surprised and disappointed with this product. After using KNS products for years in both duty and personal weapons without any problems I was surprised this product did not work. As usual for KNS, it is well made. However I found the arm / plate was too long, making an extremely tight fit. There was so much tension on the pin that it caused the auto sear to bind, thus becoming inoperative. Attempted to install in 2 different Colt M-16A1's with the same result. KNS makes great products but the mensions on the 1 I received were not correct for a proper fit and function.