Front or rear detent pin?

If front, the detent should have been a PITA loading it into the channel before you were able to slip the detent past, and into the receiver channel.

If the rear, then you should have loaded the piviot pin slot to the back), installed the detent, installed the spring, then slowly lowered the stock down to make sure that the spring was forced/retained into the receiver channel.  Best guess on the rear detent/spring is that they may have been loaded backward (detent towards the stock), or the back of the spring did not compress into the receiver channel, and is now the tail end of the spring is kinked between the receiver stock and butt stock.

www.ar15.com/content/guides/assembly/lower/

Going to have to come straight out with it,
Hesse when belly up due to producing and selling some total crap items.

If the pivot pinhole in the receiver was drilled too large, then you are screwed trying to use the standard takedown pin. Even if you added a spacer in between the spring/detent to increase the tension to the pivot pin, as soon as the pin cams when opened, it’s still going to fall out.


The only thing that comes to mind is one of the wedge type pins that you would need to use an Allen wrench to install/remove as a permanent solution to the problem.

http://www.bushmaster.com/shopping/gunsmith/artp.asp

Now having posted the pin, and you seeing the price, if the receiver was one of the less than stellar casted unit, best to just leave the pin as is without the detent and spring.  You can use a Accuwedge to increase the tension of the upper to the lower, and this in it’s self will hold the pivot pin in place when the pin pushed is all the way threw.  As for the reason that I mention this cheap band-aid over using the $40 dollar pin is that the Hesse receivers are know to crack at the rear where the receiver extension installs.  If/when this happens, you can use the $40 you save by not buying the pin and just buy a New quality replacement receiver for under $100.

http://www.fulton-armory.com/AccuWedge.html

P.S. Guys, why do I always have to be the one that pisses on every ones parade. Just once, it would nice if someone else would step up once in a while to pull the trigger.  I understand that I took the job of being mod and all, but enough of these deathblows to the Newbies and no one will every being showing me the love.

Added since you will want to check the size of the pivot pin, and the receiver pivot hole size before your final decision.
http://www.biggerhammer.net/ar15/pins.html
http://www.ar15.com/content/manuals/lowerBlueprint.pdf
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www.adobe.com/products/acrobat/readstep2.html