I see lots of photos posted where people show keys that are supposedly improperly staked.
The military standard is that the stakes should not distort the side surfaces, and they should result in a removal torque no less than 55 and no more than 100 inch-lbs.
I would bet that many of the “improperly staked” keys are in spec of 55-100 inch-lb removal torque, and many of the home stake-jobs are over 100 inch-lbs removal, and hence out of spec.
So before you re-stake your carrier, perhaps check to see if you can remove the screw with less than 55 inch-lbs of torque. If you cannot, then it is in spec.
Here is the issue I have with this. Colt stakes theirs from the factory and they are done with a special tool (IIRC).
Some companies stake theirs very lightly to the point that they look correct, but in fact the staking is not contacting the knurled part of the screw head and so it will vibrate loose over time.
In addition it doesn’t help that they do not even torque them to the correct spec. The manual calls for 35-40 in/lbs. and should you need to replace the carrier key the only method decribed is the field staking method which is much different from the factory method.
When I have checked questionable keys from companies like BM, DPMS and Armalite they were unquestionably not torqued and staked properly from the beginning.
If one of these set to 55 does not remove the screw, then it is ok - no matter what the stake looks like - because the entire point of the stake is to make removal be 55-100 inch-lbs (no less, but also no more):
When talking about “in spec” it is important to note that EVERYTHING needs to be “in spec.” So the bolts for the gas key need to have the correct head diameter. The holes in the gas key need to be a certain size.
So where the problem arises is when someone follows the spec for staking the gas key, but the bolt heads are undersized and the metal from the gas key never touches the bolts. This is why you have to go over the .Mil STD.
Pic is worth a 1,000 words. These bolt heads were on the small size.
I like those - as it seems useful to remove screws that were staked too much.
Generally a torque spec is computed to preload the threads to make them lock - and any more can break the bolt.
According to this calculator, you don’t want more than 46 inch-lbs. I am not sure how that jives with the 50-58 that is now recommended. Seems like the Change-7 recommending 35-40 may have been the best thing (combined with staking).
I think the right thing to do is to not over-torque them, and then properly stake them. And by properly stake, I mean work on the process until they can be removed with between 55 and 100 inch-lbs of torque. Less is bad, and more is bad.
Generally a torque spec is computed to preload the threads to make them lock - and any more can break the bolt.
According to this calculator, you don’t want more than 46 inch-lbs. I am not sure how that jives with the 50-58 that is now recommended. Seems like the Change-7 recommending 35-40 may have been the best thing (combined with staking).
