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Posted: 1/27/2003 9:00:16 PM EDT
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You may remember a few months ago, I was wondering why I was getting some fail to fires out of my SAR-2.. Hitting the primer hard and leaving a good dent in them but no bang on a few rounds.This was the first time it has happened in three years. Well, do you know of a good way to check the headspace in it? Thanks! 
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The only way I know is with a set of Manson guages. (about $140). How old is the rifle? If it is out of the warranty period, I would first try to contact CAI(I will look for my contact info) If it is out, instead of spending the $ on a set of guages I would contact Troy about re seating the barrel. LMK what you decide to do maybe I can offer some advice....since I have been down that bumpy road! |
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I'll tell you a rough way to do it if you need peace of mind. Remove your FCG and install a un fired round in the bolt head and insert into chamber. Rotate the bolt and check the space on the rear of the bolt lugs.(both l/h and r/h) The bolt does not need to be installed into the carrier. Just make DAMN sure that you have the fire control group removed. Depending on how much slop is in the locking up of the bolt, this should give you a relative indication on the headspace condition. It should lockup tight as it rotated into battery. You may also want to remove the extractor and firing pin to facilitate this primitive headspacing procedure. It would also give you a chance to inspect the firing pin for binding. I have seen some that have accumulated crap in the firing pin channel that could cause problems. Rot's suggestion on getting Troy to headspace it is a fine idea. Just make sure that it is, before you send it off though. I have a gut feeling that many of the CAI SARs may be out-of-tolerance. |
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gotta dial indicator? feeler gages? if so, an unfired round chambered should show no more than .010" gap to the bolt face. at that point it is too close to an unsafe condition. more typically, the allowable gap should be .003-.004" for a new rifle. ak's tolerate long headspace conditions better than some other designs, but safety comes FIRST! since you aren't mentioning extraction or ruptured case problems, i doubt headspace is the issue. since you are stating that you are getting acceptable primer strikes and depth, i doubt that firing pin protusion length is your problem. nor do i suspect you have hammer/firing pin contact problems. at this point, i'm leaning towards crap in your firing pin hole, which can be flushed out with solvent (kerosine or mineral spirits) and a high pressure air gun. also, swith ammo sources/brand and see what happens. |
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Well, I did what hbarski said. The bolt with a live round seemed pretty tight when locked up in battery. Although there was a little bit of jiggle when it was locked up, I'm guess it was the extractor and the rim of the round doing that jiggle (please correct me if I am wrong) I guess I will have to take it to the range this weekend and give it a good few hundred rounds. My G/F was the person firing the SAR-2 when it was not firing right. I noticed she was using the butt of the Magazine sometimes as a rest, could that have made the rounds not fire in any way? Well, thanks for all your help.Hopefully I can get this running without any further problems again! |
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". Although there was a little bit of jiggle when it was locked up, I'm guess it was the extractor and the rim of the round doing that jiggle (please correct me if I am wrong)" m4, there MUST be 'some' clearance in the locked up bolt/trunnion in order to allow for the ammunition's manufacturing tolerance. the question is "how much" clearance is there. this is not something that can be felt for. it has to be measured accurately. that said, i still think your firing pin should be looked at. |
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Ditto on what Campy said, cause I KNOW firsthand, that a crushed primer can work its way into the firing pin channel. You can also add some electrical tape to the back of that cartridge one strip at a time to slowly buildup the clearance. Keep refitting it until it is a good battery closure, then get out your dial calipers and see how much tape it took and that will give you a "ballpark" idea on what you are dealing with. |
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