Troubleshooting An AR Problem

[1075tech]

A few years ago, I put together an AR for a friend of mine. I don't think caliber is important but it's a 6.5 Grendel. So, the problem is it won't shoot in cold weather. The first time this happened, I found a lot of oil and carbon on the firing pin, bolt, and carrier. I cleaned it well and by the time he took it out to shoot it again, it was warmer.

Same problem occurred again. So far, entire bcg has been replaced with one that had no issues. The trigger, a RA-140, was also replaced. He took it out the other day and put several rounds through it with no issues.

Sunday morning, he goes to take a shot and just "click". It was about 30° .

I havent seen it yet to look at it. Other than oils thickening in cold weather, what other things could it be?

 

[Calculon]

What trigger is in it now? Milspec or drop in?

 

[Carlos Hathcock]

I have a couple Grendels. Never had an issue like that. Are you "oiling" the BCG? I run an RA trigger in mine.

 

[1075tech]

Drop in. Another RA-140. When I take a look at it, if I can't find any other issues, I'll drop a Larue MBT in it

 

[1075tech]

I have a couple Grendels. Never had an issue like that. Are you "oiling" the BCG? I run an RA trigger in mine.

On the initial problem, I did find the bcg and fp to have a lot of oil on it. I'm wondering if "cleaned" it and oiled it after Friday's shoot.

 

[Carlos Hathcock]

I'm no expert by any means but I've read that over oiling is sometimes an issue. Light oiling seems to be recommended. Was there a strike on the primer?

 

[cgrutt]

Did he get any primer strike on cartridge at all? Is is factory ammo or reloads? I'd check BCG and make sure firing pin is moving freely and is within spec. Was it going fully into battery? Could be frost if any moisture within BCG. Clean everything with solvent and recoat lightly with synthetic oil.

 

[Calculon]

I had an issue with a drop in trigger (only one so far of several I have) and it was a light strike issue. Swapped it out with a 4lb Velocity precision and issue went away. I'd try another trigger first. Other than that use Slip 2000 EWL - doesn't gum up in low temp.
https://www.amazon.com/Slip2000-603...d=1606175594&sprefix=slip+2000,aps,191&sr=8-1

 

[1075tech]

FP and bolt are in spec. Headspace is correct. FP protrusion is in spec.

This is the third trigger tried. All the same though. My guess is going to oil, again, or he's not making sure it's completely in battery. Maybe riding the bolt to reduce the noise since this has been an issue during hunting?.

I'll see it in a day or two. Will have to get to the range when it's below freezing.

 

[4WHLDRFTN]

hammer spring is in backwards

 

[1075tech]

hammer spring is in backwards

In three drop-ins?

 

[4WHLDRFTN]

post a pic installed

 

[Mosinitis]

It could be a number of things. It's a waste of effort to guess without the specifics.

 

[218bee]

 

[gun_slinger_boy]

Are you saying that you're oiling the firing pin? If so that's a no no. There should be no oil in the channel or on the pin whatsoever. In fact it should be so dry that you should take some acetone or the such and clean the firing pin and channel.

 

[4WHLDRFTN]

 

[Mosinitis]

Are you saying that you're oiling the firing pin? If so that's a no no. There should be no oil in the channel or on the pin whatsoever. In fact it should be so dry that you should take some acetone or the such and clean the firing pin and channel.

Mine is always well oiled and firing pin channel is cleaned. Not only that, if I shoot two days in a row and don't clean the rifle in between, I put a few drops of oil into four accessible holes in BCG (including FP hole) and cycle the action a few times. I shoot AR almost every week for the past 22 years.

 

[repete]

Mine is always well oiled and firing pin channel is cleaned. Not only that, if I shoot two days in a row and don't clean the rifle in between, I put a few drops of oil into four accessible holes in BCG (including FP hole) and cycle the action a few times. I shoot AR almost every week for the past 22 years.

I do pretty much the same, even more so when it's a new gun. I oil them up so much that after shooting a new one I have oil spots on my glasses, people tell me that's not needed or even bad for the gun. Meanwhile my gun fires just fine while quite a few others are fumbling around trying to figure out why it didn't go BANG.

 

[Calculon]

A guy at my club literally dunks his bcg in 10W30 before heading to range. He swears by it so too much doesn't seem to be an issue.

 

[FrankenCub]

The only time I've ever had an issue with click no bang was from oil in winter. But, it was like -10. I haven't used Hoppes oil since. Mobile 1 on everything, and sparingly.
I can see frost maybe being a problem if the gun was outside, brought in enough to warm up and condensation form, then right back out in 20 degrees.

 

[holdover]

One possibility is the powder if they are hand loads, some powers are sensitive to weather.

 

[Robin]

Its' not the weather, its' the temperature. You can lose feet per second with some powders as the temperature drops. All I have read, there is no danger and the difference isn't significant unless you are in a long range target competition or perhaps are varmint hunting and taking long shots on a cold winter night. I saw a list of powders that are affected but can't find it. My favorite was on it CFE-223.
Robin

 

[holdover]

That's what I meant .

 

[FS1040]

I had an issue with a drop in trigger (only one so far of several I have) and it was a light strike issue. Swapped it out with a 4lb Velocity precision and issue went away. I'd try another trigger first. Other than that use Slip 2000 EWL - doesn't gum up in low temp.
https://www.amazon.com/Slip2000-60320-Slip-2000-4oz/dp/B00635VIY8/ref=sr_1_1?crid=3NQDEY4QHWPB5&dchild=1&keywords=slip+2000+ewl&qid=1606175594&sprefix=slip+2000,aps,191&sr=8-1

I just bought that trigger for a lower I built. I compared it to my stock M&P Sport and its a night and day difference. It’ll spoil you rotten.

 

[spat]

Its' not the weather, its' the temperature. You can lose feet per second with some powders as the temperature drops. All I have read, there is no danger and the difference isn't significant unless you are in a long range target competition or perhaps are varmint hunting and taking long shots on a cold winter night. I saw a list of powders that are affected but can't find it. My favorite was on it CFE-223.
Robin

Or maybe you work up a hot load in the winter and then shoot it in the summer and it's suddenly extra hot.

Not likely to be enough to be dangerous, you should have plenty of safety margin. But it could be enough that a load that was acceptable in 20 degrees is showing signs of being uncomfortably hot in 90 degrees.

 

[Robin]

No, it shouldn't be hot enough to cause problems, but who sits outside in the middle of January reloading bullets?
Robin

 

[spat]

No, it shouldn't be hot enough to cause problems, but who sits outside in the middle of January reloading bullets?
Robin

Well, you reload them in the house, but walk to the backyard to shoot.

Maybe they cool off quick enough, maybe not...

 

[Robin]

The properly tested and measured amount, proven to be safe, is the same, hot or cold.
robin

 

[Mosinitis]

If the bolt doesn't fully go into battery and lock, the hammer can still fall, but firing pin will not protrude from the bolt face. This is built in safety feature by design. There are a number of reasons this can happen, the most common are improperly sized brass or too much fouling in the chamber. This is the best guess with very little information to go on.