HELP WITH IZHMASH CM-2

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RED RAIDER
Posts: 82
Joined: Mon Nov 05, 2012 2:52 pm

HELP WITH IZHMASH CM-2

Post by RED RAIDER »

My daughter shoots a Izhmash CM-2 Cadet. She is having a problem with the firing pin/Trigger. I don't pretend to be a gunsmith and can't solve this problem.
When she pulls the trigger about half the time the gun will click, but not fire. There is no mark where the firing pin made contact the bullet. Open and close the bolt and try again, it will fire this time.
I adjusted all the creep out of the trigger and it helped. It now probably only happens 10% of the time.

She is shooting indoor smallbore matches (NRA & USJOC), and this aggrivation may impact her scores. Any of you have suggestion on what I need to do to the gun?
Tim S
Posts: 2018
Joined: Mon Jan 03, 2011 11:33 am
Location: Taunton, Somerset

Re: HELP WITH IZHMASH CM-2

Post by Tim S »

Light strikes are usually a problem with the firing pin or its spring rather than the trigger. Had all cartridges been hit, then it could be faulty ammo, but since this isn't the case, it points to the firing pin/spring. As a first step, disassemble the bolt (see here for instruction http://rimfirecentral.com/forums/showth ... p?t=234769) and thoroughly clean and degrease the inside of the bolt body as well as the pin and spring. Sometimes bolt internals are coated with a rust-preventative grease which can gum up the pin so it doesn't strike correctly, not to mention the crud and grease from bullets that find their way inside. When you reassemble the bolt, you can leave the insides oil free, but a thin smear of grease on the cocking cam (the V-shaped notch by the handle) will make bolt lift smoother.

If this doesn't work, and assuming that the firing pin and spring are not obviously damaged. then you may need to investigate whether the firing pin or spring are worn, so the pin strike the case hard enough, or even reach it. It's not uncommon for springs to loose some of their power through use, especially if the bolt is stored cocked. Measure these and compare them to others from another rifle of the same make that is known to work. If the measurements don't match, look for a new pin and spring. Springs are not normally expensive, so you may want to replace the spring anyway.

If you have headspace gauges (or can borrow them) measure the headspace. This is the gap between the bolt face and the barrel face; it should be 0.042in-0.046in, any larger and the firing pin may not hit the cartridge rim deeply enough, if at all. Headspace that is too large can also lead to inconsistent ignition even when the firing pin/sping are working OK, as the cartridge isn't seat againsty the barrel face as the bolt closes, and can move forwards when struck by the firing pin, absorbing the blow. You need a set of graduated gauges, not just go and no-go gauges as these only tell you that headspace is within the minimum and maximum SAAMI limits, not the exact headspace. You may need to remove the extractor claws from the bolt when using the gauges to get a true reading.
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