With it being the start of a new year, I decided I would see if I could put into practice some info I had browsed in an internet forum over the Christmas holidays. The information provided the specs and some suggestions for making a barrel nut wrench for the 15-22. The information indicated that there was also a vendor on e-Bay selling the wrenches for about $25 (although you needed to add an extension to it before using it). I opted to see if I could make a wrench and remove the barrel from my M&P 15-22.
The torque specs for the barrel nut, according to information on
the S&W user forum, is 20 foot pounds or 240 inch pounds. As such, it
doesn't take much to get to 20 foot pounds and the PVC pipe is strong enough (at
least so far) to handle the torque.
Using some painter's masking tape, I laid out the cut pattern
on a piece of 3/4" (inside diameter) PVC pipe cut 18" long. My goal was to
remove everything white that laid between the pieces of tape. The tape
going around the pipe dictates the depth of the cuts which is ultimately the
length of the 4 teeth. My teeth average about .180" long. The narrow
strips of tape provide for the width of the teeth. That measurement
averaged about .170".
Using a cutoff wheel on my Dremel tool and a small file to help clean/square up the cuts, this is what mine looked like when I was done. Try to keep those teeth spaced equally around the edge of the pipe. They should be 90 degrees apart from each other. You could do the same thing in metal but I didn't have any metal around and the PVC won't scratch anything on the barrel.
In the wrench info I found, the person used JB Weld to attach a 3/8" drive socket into the other end of the PVC pipe. This allowed him to use a torque wrench when tightening the barrel nut.
So you are wondering how does it fits?
Here is the fit of my home made "pipe wrench" <grin> with the already removed 15-22 barrel nut. OK, so the teeth are a little longer than they need to be.....but it works. I can always cut some off but it is tough when you make them too short.
To remove the barrel nut, start by removing the handguard spacer from the end of the handguard. There are four clips (one of them is circled in yellow in the above photo) equally spaced around the end of the handguard. Push the clips in while gently working the spacer out of the end of the handguard. I used a small screw driver to help apply a little prying pressure on the spacer while pushing each clip in.
Slide the spacer off the end of the barrel. Slip your new
barrel wrench down over the barrel and engage the four slots in the barrel nut.
The barrel nut uses standard threads so "lefty loosey" removes the nut.
One of forum users reported that their barrel nut was just barely snugged....as
in almost loose but not quite. All the more reason to make this wrench and
Unscrew the barrel nut....yes, it is VERY finely threaded and
takes quite a few turns. Slide the barrel nut off the muzzle end of the
barrel. The handguard is removed by gently pulling it forward, away from
the receiver. Note that the barrel is removed by gently pushing it out
through the back of the receiver. If you have shot your 15-22 for a while,
you will probably find, as I did, a good layer of powder fouling around the
front of the receiver where it mates with the barrel.
Here is the forward end of the receiver where the barrel protrudes through from inside of the receiver. S&W uses a metal insert in the polymer upper receiver. There is a wide and a narrow key, on the receiver, that mates with two corresponding notches in the handguard.
Assemble the parts in the opposite order you removed them. Place the barrel into rear of the receiver, ensuring the feed ramp is positioned towards the bottom of the receiver. Slide the handguard over the muzzle. Align the notches in it with the receiver. Carefully thread the nut onto the barrel. DO NOT bung up the threads! Torque to 20 foot pounds. Having hand torqued the spindle nuts on my Jeep's Warn hubs for a lot of years, I have a pretty good idea of what 20 foot pounds feels like. I didn't use a torque wrench on the barrel nut.
So....there is a little more info concerning the M&P 15-22. As with everything on my site, I'm not responsible for your using this information and possibly screwing something up.
4x4 Off-Road Homestead Firearms RC Flying