Gun sluggish/problems chambering in "cold"

AR/M4 AR Technical Discussion
1

Looking for some explanation of what’s going on here and why, as well as the solution. I have a feeling it’s simple, which has made me hesitant to ask about this, but as with anything else involving firearms, I know if I’m having this issue then someone else is too.

When the temp drops a bit here in the Houston area to what we consider to be a “little cold,” which is in the 40’s and 50’s (Northerner’s feel free to insert smart ass comments and jokes here:p), sometimes my guns have issues clambering a round when I’m either initially making ready or performing a speed reload.

For example if I hit the bolt release on a fresh mag of 28 rounds the bolt gets stuck halfway and only chambers 1/4 of the round. Obviously charging the gun will induce a double feed so I’ll either strip the mag and try again (in which case it’ll likely happen again with the next round) or I’ll pull the CH back a half inch or so several times as need to finally shove the rest of the round in the chamber. Once I get most of the way the forward assist can be used if necessary. Then I commence firing.

Sometimes though, from there even though it gets shoved into the chamber the damn bolt doesn’t even grab ahold of the round’s rim, so it’s literally loose in the chamber. Although that rarely happens.

Even manually charging the guy when reloading a full mag, whether it’s from a closed or open bolt, it’ll get hung up halfway sometimes.

This literally only happens in the cold, with the exception of one time when my gun was completely dry because I forgot to lube it on TD 2 and 3 in my recent TAPS class and dirty as hell with almost 4K rounds, some suppressed, through it.

But other than that one time, my guns are always nice and wet with Slip 2000 EWL. Always. I added some lube to my already-wet BCG/CH/Upper a few weeks ago when this happened, and it did seem to help barely get the job done, but even without a mag inserted and just racking the CH back and forth it seemed so damn sluggish. My friend was also with me and was shooting my other gun (both guns are BCM 14.5 mid-lengths, but this has happened in the past with 2 SBRs as well), and it had not even 500 rounds on it yet and felt mostly the same, once again it was nice and wet, too.

And although it may just be coincidence, this only seems to happen after the sun sets at night (I shoot a lot at night) in the 40’s/50’s (doesn’t usually get colder than that), not during the day even if the temp is the same.

So wtf is going on here? Possibly mags? It’s also occurred with brand new GI mags as well. I went ahead and changed the RE spring/buffer spring on the gun with 4K rounds, even though it was only a half inch shorter than a new BCM one. Try a different lube other than the Slip 2000 EWL?

2

What brands of parts are you using?

3

On the primary carbine I’m talking about its a complete BCM lower, H buffer, buffer spring bought from BCM, BCG BCM and 14.5 middy upper BCM as well… So yeah, a few BCM parts!:smiley:

BTW mags were PMAGs.

4

FYI here is a vid I made last week or so showing how nasty the gun was before I cleaned it. Boring vid really, but skip to 1:40 to start getting an idea of condition of the gun.

http://www.youtube.com/watch?v=tkpElVRqDak&feature=youtube_gdata_player

Maybe I should start occasionally taking the whole BCG out so I can squirt plenty of lube into the whole upper instead of just locking to the rear to lube? I dunno. Seems like such a stupid ass lame problem though.

5

Even the most super duper sythentic lube will thicken when cold.

6

Yah but 40-50 degrees Fahrenheit?

7

Yep, it happens.

You already said you had the BCG good and lubed so that’s Part 1. Part 2 I have never advocated until I experienced the same issues as you described several times: lube the action spring/buffer/inside of the receiver extension - take your pick.

I’ve never told people to lube this area before (and I never did it before either) but it seemed to work to keep my gun stripping that first round off and chambering it consistently. Guns that have done this to me include Colt 6920 and DDM4 with NHMTG 30 round aluminum magazines loaded to 28 rounds.

Cold, wet weather usually does it, 30’s and 40’s.

8

Good to know, thanks for the info, brother. Nice to know I’m not crazy or weird after all :slight_smile:

I’ll give that I try next time I’m out in the frigid Houston winter temps. :smiley:

9

Seems to me that it doesn’t have enough spring tension to reliably cycle in all conditions.

4k is getting up there on spring cycles and it is probably borderline weak.

Try releasing from full recoil vs bolt stop to see if there is any difference.

I’d try replacing it with a new spring to see if that resolves the issue.

Lubricating the spring may work, but I don’t feel that is the best way to restore proper operation.

I may do some tests with various springs to determine the minimum distance the bcg must be retracted to properly chamber a round.

My A5 was able to do it with the front edge of the carrier lined up even with the center of the port door.

10

Measure your free spring length.

11

While spring length might be an issue lubing the action spring usually does the trick. Cold weather wreaks havoc on guns, especially those that are towards the edge of reliability. I had to do the same as Jay with a 16" Noveske N4 Mid (H2 and Wolf) and a 11.5" DD (H3 and Wolf) to get 100% function.

12

Sluggish is inherent in that config.

13

Going to a lighter lube like Remoil for the cold might help as well. Or Mobile 1 0W30.

14

I was going to say measure/change your action spring but I just re-read and saw that you did that. Cold weather can affect elasticity which would lower your spring constant but I can’t believe that it’d be a problem on a new action spring.

15

I areas that “aint supposed to get lubed” I typically use a silicone spray lube. that tends to help assuming the area was clean and dry to begin with. make sure your parts are compatible with silicone tho.

I kinda dumped a lot of the fancy go fast lubes (twl, militec, CLP, LSA, Wear check, Weapon shield, White lightning etc etc…) in favor of a simple quality synthetic motor oil like a 0w20 in winter, and a heavier 15w40 in summer.

for grease a little product called Hob-E-Lube has one of the highest shear ratings you can get in a grease. It’s used in model trains where the viscosity cant be so high that it slows everything down but it must have a high film strength. Some engineer somewhere checked the specs and tested it for use on the SKS sear which is difficult to lube and make smooth with typical greases. It’s cheap and awesome.

funny thing tho… I still use tetra gun lube to smooth up any action that is giving me grief. it’s amazing what it does.

I wonder if the gun parts are shrinking and causing binding due to temperature change. some attention to wear areas with some polish (?) might help.

16

Doubtful.

17

40-50 degrees is not cold. It might be cold perceptually to you warmer-climate guys, but it’s not cold for the operating system. Your gun should not require any lube adjustments, special applications, or any change from normal PM at that temperature. It’s performance should not vary at that temperature. If it does, and you are using known-good GI spec parts, your gun is broken and needs more detailed in-person inspection and diagnostics that can’t be done via the net.

If we were talking about temps much lower than that, freezing or below, that might be a variable. Up here in the northern tier, too many guns run well without special treatment to even think about temp in this case.

18

Not sure when I’ll be shooting at night next, hopefully soon though. I’m just gonna play with things one at a time. Now that I cleaned the hell out of it and also changed the spring, I’ll see how it goes.

If trouble arises, I’ll wipe off the BCG quickly with a rag and apply regular Slip 2000 lube instead of the Slip 2000 EWL. Wondering if the EWL might be too thick, although that doesn’t really make sense to me considering it’s not even close to freezing temps. But worth a try I suppose. Then the next step will be lubing the buffer spring if needed.

Just in case I’ll also ensure I use several different mags if I have an issue, before doing anything. Not sure if dirty mags or weak mag springs could have any effect or not.

After my next range trip at night (I swear to Christ it only happens at night for some damn reason!) I’ll post my results. Thanks everyone for your input.

19

Thank you. I thought I was the only one.

20

Interesting thread, thanks for your candor with the problem OP.

This might really steer me away from the 14.5 middy as I often venture into the mountains in 0F weather when shooting in the winter (no one else is crazy enough to go in such weather so I have the places to myself).

Perhaps a 14.5" carbine would be better suited for the colder climates as it is less sensitive to the pressure variations stemming from lower powder temps?

An interesting side note, I have fired my 10.5" LMT upper in as cold as -22F weather before, and have fired Colt M4s in extreme cold as well using LSA as a lube and never had any issues.