It's been a while since I've done one, if I remember correctly , the only "trick" is you need to compress the mainspring and insert a pin to retain it.

Might have to go and refresh my memory.

 

I noticed that there are two holes on the bottom of the bolt. One is in the bolt itself and one in the firing pin. Maybe if I align the two and then insert a pin.....?

 

I do think you've got it, like I said (ok, typed) it's been a while since I've had mine apart.

With the main spring fully compressed, you'll see a pin that holds the rear stiker knob on.

There are shims between the cocking cam/bolt knob and the bolt body. Those control headspace. Upside, a shim kit is available at Numrich pretty reasonable if here was any call to adjust the headspace.

 

Here is info from an old post at Jouster.com

This is not my post so take it as it is-I feel that anything helps rather than the risk of chasing parts or breaking parts if you don't know what you're doing first time around.

If any of you folks have been wondering about an easy way to take apart the bolt of your new CMP H&R M12, I might be able to help. I wanted to get my bolt apart to clean it out good, and to repair a couple stuck extractors.

First of all, to remove the bolt: 1) Lift the bolt handle. 2) Take the safety off. 3) Pull & hold the trigger with one hand, then push forward on the bolt release lever (left side of receiver in front of the rear sight base). 4) With the bolt release lever held all the way forward, release the trigger & slide the bolt out of the receiver.

The extractors can be removed by pushing them out far enough to get a small needle-type tool under them. Further prying on the extractors, along with a small push with a screwdriver from the firing pin side, should be enough to pop them out. Watch out for a flying extractor plunger.

Now, with the bolt in the cocked position (as it came out of the rifle), hold the main bolt body and slightly turn the bolt handle so that the cocking piece (end of the bolt) moves slightly out of the notch in it was resting in. A gunsmith screwdriver, or small, flat, piece of brass (around .280" x .060" works great) can be put in the notch the cocking piece occupied and cammed to lift the cocking piece off the bolt handle. The cocking piece has to be lifted enough so that a .080"-.090" pin can be dropped into the hole midway up the bottom of the bolt. That will hold the firing pin in place and the flat brass (or screwdriver) can be removed. An alternate method is to hold the upper rear bolt lug against the corner of a workbench so that the cocking piece is free to move, and push on the sear surface of the firing pin (do yourself a favor, use something soft like brass - be forewarned!! and no, I didn't bugger my bolt).

With the pin in the hole in the bolt, the cocking piece pin can be seen and driven out. The cocking piece, bolt handle, and headspace washers (should be obvious to all - don't loose any of these washers) can be removed from the bolt.

With the bolt removed, the firing pin spring retaining pin can be seen. A special tool, .210" in diameter, around 1" long with a .100" wide slot, .100" deep will make the rest of the bolt take-down and re-assembly much easier. Slide the tool into the back of the bolt and turn it until it straddles the spring retaining pin. Pushing in on the tool will relieve the pressure on the pin and it will be easy to drive out. The pin can be driven out without the tool, but it will be much easier with it and you won't have to wrestle with removing a pin punch. Re-assembly is much easier with the tool. Also, a C-clamp or vise used to compress the tool into the bolt makes things a cinch but use some brass on the front of the bolt to avoid nicking or damaging it.

Re-assembly is in the reverse order. The only tricky part is lining up the slot on the special tool with the hole for the firing pin spring retaining pin.

 

Craig - These sound like correct way to disassemble the bolt. OK, I haven't done it yet, but I can see it in my mind, which is a start.

I got my M12 yesterday, the action was a filthy mess. The previous owners may have taught marksmanship, but they certainly didn't stress maintenance. This may be a good thing though, fewer damaged parts may result needing repair.

The dual extractors are pretty interesting, althought the corresponding grooves in the barrel and bolt are packed with fouling.

 

The extractors are a pain-clean them well

My M12 has new extractors because some folks including me had extraction issues when we got their rifle-not sure if wear did it or what. Anyway after 100 rounds or so they won't extract an unfired round-that match chamber engages the bullet tightly. I plan to check heaspace with a set of match chamber guages. I never have any problems extracting a fired round or a unfired round before the bolt closes on it.

Good luck, they are a great rifle for the money.

 

When I was cleaning mine I did notice that cleaning the breech is going to be a pain in the arse. It is way up there in the receiver and hard to get to. The two extractor notches are kinda hard to get to also.

On the other hand, the build quality looks to be #1.

The headspacing washer (shim) is a neat idea. I've never seen a rimfire with that feature. Maybe it is common on all target rilfes though.

 

Official CMP Bolt Disassembly opinion (Thread)

From: CMP South Armorers [mailto:armorers@odcmp.com]
Sent: Wednesday, March 15, 2006 12:36 PM
To: Davis, Brad C(Engineering Information Services)
Subject: RE: M12 Bolt Disassembly

I personally like your idea of blasting it with WD40 to get the grit out rather than dissassembling it. John

-----Original Message-----
From: Davis, Brad C
Sent: Tuesday, March 14, 2006 10:24 AM
To: armorers@odcmp.com
Subject: RE: M12 Bolt Disassembly

Thanks John.

I want to clean the bolt to clear the grit and grime from it's internals. If there is an alternate method to clean it please let me know. I have considered blasting it with WD-40 or Brake Cleaner to clear the gunk, then follow up with Break-Free CLP.

Do you have a suggested cleaning method other than a total break down?

Thanks - Brad

​

From: CMP South Armorers [mailto:armorers@odcmp.com]
Sent: Tuesday, March 14, 2006 9:14 AM
To: Davis, Brad C(Engineering Information Services)
Cc: lwilliams@odcmp.com
Subject: RE: M12 Bolt Disassembly

Sir, these are used rifles and they do not come with manuals as we dont have them. Bolt dissassembly is much more difficult on the H&R mod 12 than most, and we dont recomend it unless something is broken. If you really need to know you can call me at the # below and I will help you.

THANKS!
John Mclean-Armorer
CMP South Armorers
Civilian Marksmanship Program
1401 Commerce Blvd.
Anniston, AL 36207
Phone: (256) 835-8455 Extension 36
Fax: (256) 835-3527
Email: armorers@odcmp.com

-----Original Message-----
From: Davis, Brad C(Engineering Information Services)
Sent: Monday, March 13, 2006 10:04 AM
To: custserve@odcmp.com
Subject: M12 Bolt Disassembly

Good Morning,

What is the procedure for disassembling the bolt on the H&R M12? I just received my M12 and did not get any kind of instruction manual for the H&R M12. Was I supposed to get one?


Many thanks,

Brad Davis