Won't fire in cold.

MNyoteHunter

New member
Got problems with my new ar I built for coyote hunting. It won't fire in the cold. Cost me a pair of coyotes Monday night. It was 15 below zero and I tried to fire it 3 times and nothing just light primer strikes. Took it in the warm house over night and it fired just fine. Pulled the bcg out and cleaned everything real good and tried swapping the firing pin. Left it in the 3 below garage overnight and it wouldn't fire again this morning. I've put another ar in the garage before work and I'll see if that one fires tonight and try swapping bcgs to see if that's the problem. What else could be causing it to not fire only in the cold? Aero precision upper, larue predatar barrel, bcm fde bcg and ke arms drop in trigger shooting hornady 75 grain hollow points.
 
Try completely disassembling your bolt and remove all oil from the firing pin and through-hole of the bolt. I have had the exact same thing happen in Minnesota. Now before I hunt in the colt I make sure the firing pin and bolt are dry.

The firing pin has SOOO much surface area going through the bolt that the oil in extreme temperatures tends to absorb much of the hammer strike.
 
What kind of lube are you using? Maybe completely take apart the bolt and hose it done with carb cleaner get it completely clean and line very very lightly with atf or synthetic motor oil. When I say very lightly I mean barley any.
 
Mpro7 oil. I cleaned the bcg and firing pin yesterday. I put a light coat of oil back on it. Like a couple drops on the whole firing pin then smeared it around with my finger. Should I try running the firing pin and bolt completely dry?
 
A couple drops on just the firing pin might be to much. I think maybe put a couple drops on a part towel and spread the paper towel around them just wipe the bcg and stuff done with the towel so the stuff just has barely a light oiled feel to it. Make sure to wipe out the upper receiver too make sure the upper isn’t full of line too.
 
Back when I shot a bolt gun I always ran it dry in winter. I now do so with the AR firing pin. You can't shoot at so many coyotes that it will wear anything out...at least I never do!
 
I run mine with hornady one shot in the cold. That much oil on the firing pin is probably slowing it down causing the light primer strikes. Try cleaning it and using a dry lube or run the pin dry.
 
Same thing happened to my buddy two nights ago. Luckily I implored him to test out his gun in the cold, it's a brand new 6.8 he just put together. We made a set and heard nothing so I went back to my car and grabbed a cardboard box, he was freezing cold and begrudgingly waited for me to set up the box so we could shoot. His gun didn't go off, I hit within 3 inches of where I was aiming from a seated 250 yard shot resting the gun on my knee.

Clean everything off, soak in brake parts cleaner or carb and choke cleaner if you really want it clean. I run lube all winter long, my favorite now is 2 stroke engine oil, the cold does nothing to it and it keeps all the dry carbon junk from caking on, just wipe the old oil off and all the carbon comes with it.
 
Originally Posted By: dtechTry completely disassembling your bolt and remove all oil from the firing pin and through-hole of the bolt. I have had the exact same thing happen in Minnesota. Now before I hunt in the colt I make sure the firing pin and bolt are dry.

The firing pin has SOOO much surface area going through the bolt that the oil in extreme temperatures tends to absorb much of the hammer strike.

X2
 
Frog lube freezes dang near solid.

More people should try the synthetic 2 stroke oil, best bit of advice I've ever gotten from a pawn shop owner... I replaced a part on my 1911 yesterday and lubed it well with 2 stroke oil and reassembled it, let it sit out in 0 degrees then fired a few rounds and no problem, I actually had the lube still spattering onto my hand after shooting.

Just got in from hunting tonight in -12 and the AR bolt is operating by hand like it does in 50 degrees, I can't get the bolt to catch even a little and when I took the BCG out I could shake it back and forth and hear the firing pin sliding back and forth no problem.

 
Originally Posted By: midwestpredatorSorry guys but I disagree with running these dry. What you need is a dry film moly lube from Birchwood casey if you don't care about the label specifically stating for use on firearms there are several other brands with a quick Google search.

This is a great source of info on moly lube and its properties.

https://www.ws2coating.com/mos2-dry-film-lubricant/

Bigtommy brought up the Hornady dry lube earlier. I've been trying to get my hands on a can of that stuff but it's never on the shelves at any of the shops. I havn't seen any moly dry lubes around but I haven't looked very hard.

There won't be much of a problem with a couple shots out hunting but there's just no reason to not use lube.
 
A dry lube is probably a fine idea much like coated bearings and valves in a max effort engine. As a matter fact maybe there would be a market for coated bcg parts. However I cant imagine you can cause any significant wear on an AR shooting at coyotes. If I didnt have a quality dry lube I would prefer dry.
 
The problem I have with running a dry carrier group is the receiver race way. Aluminum is a soft metal and most carriers that i have looked at are not a polished smooth finish on the runners. Its not like your going to wear a hole through the receiver by going no lube but it will in fact excelerate wear. If i was out hunting and had issues I would for sure hose down everything with carb cleaner or whatever is available and get back to hunting but I just don't see it as a long term solution to hunting in the cold.

The reason I don't like oil on semi autos is that it does not stay put. A good coating of moly film stays where its needed. Try some, I think you will like it.
 
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I like a light coating of Sea Foam Deep Creep on all my guns including AR's all the time even in extreme cold. Never an issue. I buy it at NAPA and use it on a wide variety of different uses. It even says right on back of the can "It will not let guns freeze up in cold weather" Works for me...
 
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