Gun sluggish/problems chambering in "cold"

[RetreatHell]

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?

[scottryan]

What brands of parts are you using?

[RetreatHell]

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!:D

BTW mags were PMAGs.

[RetreatHell]

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.

[dpaqu]

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

[mini4m3]

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

Yah but 40-50 degrees Fahrenheit?

[Jay Cunningham]

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.

[RetreatHell]

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

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

[Clint]

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.

[Heavy Metal]

Measure your free spring length.

[orionz06]

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.

[markm]

14.5 middy upper BCM as well.

Sluggish is inherent in that config.

[Littlelebowski]

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

[subzero]

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.

[Jack-O]

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.

[orionz06]

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.

Doubtful.

[ST911]

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.

[RetreatHell]

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.

[careboy]

Thank you. I thought I was the only one.
http://www.primeaffiliate.com/track/images/22.gif

[decodeddiesel]

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.

[Jay Cunningham]

While I don't claim to know precisely what is occurring when this happens, for me it's been when the weather is extremely humid (freezing rain) and the temperature transitions from the 40s into the 30s.

[mini4m3]

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.

I shoot outside right through the winter. Here in Michigan it usually gets around 0-35F (sometimes colder) this time of year and never have had personally, seen, or heard of the issue the OP presented being caused by 40-50F degree weather whilst using SLIP 2000 (the same lubrication I and many use up here). This isn't to say lubricants don't become affected by the cold. They'll thicken up for sure but to cause the OP's problem I'm not sure that's a major part of it.

I wouldn't think twice about a 14.5'' midlength especially due to moderately cold to cool weather.

[RetreatHell]

I wanna clear things up here a bit and make sure it's known I HAVE NOT had any problems with the gun actually running, cold weather or hot as hell. I'm ONLY talking about manually clambering a round via a speed reload, when the bolt is locked to the rear via the bolt catch/release or using the CH to release the bolt. OR when doing an initial Administrative load when the bolt is forward on an empty chamber.

Once the round actually gets chambered, the pressure and force generated from the gun firing a round is plenty enough to fully eject the spent brass and load the next round in the magazine.

Something that just donned on me though is that the only other gun I've had this same issue with was last year with one of my 11.5 guns, and the one thing they all have in common is I've run them all suppressed before the problem occurred. So maybe it's just a combo of the extra thick layer of soot from running suppressed beforehand, using the thicker EWL lube, and the slightly cooler temp that's causing it?

For those of you who run suppressors often, do you typically run your gun several thousand rounds without any sort of wipe down? Or do you make sure to clean it/wipe it down quickly more often than that?


ETA: Whenever it happened with my SBR last year I wound up swapping the buffer spring and saw that the one I was using was close to 2" shorter than a new one, which instantly solved the problem (But I don't remember the condition of the gun at the time). So that of course led me to believe that was the problem with that one. But as I said in my OP, this gun's spring wasn't that bad, and the other one gun my friend was shooting which also had the issue, though not as bad, had a mostly new sping in it.



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.

[thopkins22]

I think this happens to be the answer...especially given the circumstances Jay describes when he experiences it. 30-50 degrees and humid? Sounds like us.

Lubing the buffer and spring would also jive with what it "feels" like the gun needs. All that suppressed shooting and what not....

See you soon!


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.

While I don't claim to know precisely what is occurring when this happens, for me it's been when the weather is extremely humid (freezing rain) and the temperature transitions from the 40s into the 30s.

[orionz06]

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.

What would I do if a 6920 (stock and NIB), Noveske N4 with an H2, and a 11.5" Daniel Defense were all exhibiting slower cycle rates at the ~40 degree mark? Send all the guns back because they are broken?

[yhmspecter]

I have been experiencing the same malfunction, except it happend during firing Both range days it was in the 20s, the first day the gun was dry... So I applied some Slip EWL, which was rather thick but once it worked into the weapon it was malfunction free.. The second day at the range the gun was doing the same..The only difference being I started with a clean and lubed weapon..

I will be headed back to the range in a few days , I am going to take Jay's suggestion and lube the buffer spring, hopefully that makes a difference

[Smuckatelli]

I wanna clear things up here a bit and make sure it's known I HAVE NOT had any problems with the gun actually running, cold weather or hot as hell.

Paul,

Before you start wearing the same underwear on the range....me thinks it could be the dope behind the weapon and not the dope on the weapon. :)

The rifle runs fine once the round is chambered....IMO, it's gotta be you brother.

The temperature drop has more of an effect on you than it does the weapon. Your reactions are probably slower, I think you might be inadvertently riding the charging handle & slowly finger banging the bolt catch. I saw this problem in 3/2 when we were doing the work up for Norway and again in 2/1 in smallboats, the Marines were cold, their reactions were slower...they had issues getting the rifles into condition 1.

S/F

Paul

[ST911]

What would I do if a 6920 (stock and NIB), Noveske N4 with an H2, and a 11.5" Daniel Defense were all exhibiting slower cycle rates at the ~40 degree mark? Send all the guns back because they are broken?

How much slower? Is the difference palpable, and/or producing a real change in functional threshold at that temperature? I'd wonder about the gun.

The 6920, certainly. An H2-buffered mid-length like the N4? I would expect that gun to be closer to threshold by virtue of component combo alone, so I'll defer on that one. No experience with a DD 11.5.

Meteorologicals can be considerations, but still, at 40 degrees? Doesn't wash with my experiences.

[orionz06]

The difference was noticeable. If you are the type that accessorizes your firearm to the edge of reliability it is enough to make them not work. Now this refers to firing the gun of course.

[markm]

Switch to this buffer!!! :jester:

http://i106.photobucket.com/albums/m264/19283938/S8000226.jpg

[orionz06]

Switch to this buffer!!! :jester:

http://i106.photobucket.com/albums/m264/19283938/S8000226.jpg

Oh no, not more of this shit.:shout::shout::shout:

[markm]

I just saw this on a full retard site that rhymes with silencertalk.com.

This... Plum crazy lowers.... Welding Silencers to short barrels.... My God there's a lot of ****ing retards in this world!!!

[SteadyUp]

Oh no, not more of this shit.:shout::shout::shout:

I'll second that. No more buffer circle jerking, please.

[markm]

I hadn't seen this douchebaggery.... :p

Sorry, guys!

[RetreatHell]

Paul,

Before you start wearing the same underwear on the range....me thinks it could be the dope behind the weapon and not the dope on the weapon. :)

The rifle runs fine once the round is chambered....IMO, it's gotta be you brother.

The temperature drop has more of an effect on you than it does the weapon. Your reactions are probably slower, I think you might be inadvertently riding the charging handle & slowly finger banging the bolt catch. I saw this problem in 3/2 when we were doing the work up for Norway and again in 2/1 in smallboats, the Marines were cold, their reactions were slower...they had issues getting the rifles into condition 1.

S/F

Paul

Well 3/2 is known for being pretty weak...

I kid, I kid!!;)

I know what you're saying, I once almost dropped my rifle in boot camp during Inspection Arms because my numb left hand (from standing at Parade Rest for 1 hour in the cold) barely caught the buttstock at the beginning. Then it took me two tries to lock the damn bolt to the rear and I damn near made my lips bleed trying not to laugh because I thought it was so funny that my hands were so numb and stiff I couldn't do the one thing we did a million times before. The inspecting officer didn't think it was too funny though... For some reason they take things SO serious in Marine Corps boot camp:D

But in this case I can guarantee you it ain't me, bro. For one, it's not that cold. I was also wearing my Oakley gloves the last time. Besides, hitting the bolt release in any way if the bolt carrier is locked fully rearward should do the trick no matter what.

I already proved my manhood and then some on and after April 12, 2003, so I'm all about admitting I'm wrong or acting like a woman. But this isn't one of those times... at least not yet proven, anyways:p

[RetreatHell]

I hadn't seen this douchebaggery.... :p

Sorry, guys!

Jesus, guys are really taking that shit to the extreme now!:rolleyes:

[Smuckatelli]

Paul,

Quick question, does it happen when you don't have the gloves on?

I feel the need to clarify my cold weather dohickey. I'm not talking about bone numbing cold, just a drop in temperature. In April 03 when you were playing in the sandbox...the temps were mid 80's in the day and dropped down to mid fifties at night, not a big difference yet it seemed really cold at night.

Common sense tells me that it shouldn't matter 'how' you engage the bolt catch....my girlie instinct tells me that if the catch doesn't have a fast clean break, just maybe it could slow the BCG down enough to have loading problems. I'll try to create this with some snap caps later on today or tomorrow.

I'm stuck with what you reported; basically the weapon works fine as long as the only human intervention is pulling the trigger.

BTW, when I was in three who....they were weak. I checked in 2 years after Rother died....they still had five formations each day before 07:30 when in garrison...it sucked goat turds!

S/F

Paul

[Magic_Salad0892]

Use a more oil like lube, instead of a more grease like one.

Here up in Oregon I've had that problem. Once.

Changed lube.

Problem solved. Flawless results. Rain or shine, cold or dry.

Jay has a good answer though. I lube my receiver extension every 3k rounds.

[Magic_Salad0892]

While I don't claim to know precisely what is occurring when this happens, for me it's been when the weather is extremely humid (freezing rain) and the temperature transitions from the 40s into the 30s.

These are the conditions I am referring to in my post.

Heavy rain conditions ranging from 45 degrees to about 34.

[rob_s]

Interesting that this comes up as I just had a similar issue yesterday. 16" ML, Vltor A5, ASYM 55 grain ammo, Lancer AWM. In ~60 rounds I had multiple failures to feed on each mag, from chambering the first round to feed issues while shooting. Had just put 168 trouble-free rounds through the gun the day before in the 70s vs 50s the day of the troubles. I would not expect the temp to be an issue but the only other thing different from one day to the next was that on day one it started with 0 rounds on it and on day two it started with 68 rounds on it.

[Robb Jensen]

Paul how much wear do you have on your buffer springs?
What do they measure out to?
Also of you just install your bolt carrier in your upper receiver without a bolt in it do you feel any resistance as the carrier key closes on the gas tube?

I have a VLTOR A5 on my BCM 14.5" Midlength. With 5.56mm NATO ammo it runs all day trouble free with a 5oz standard A5 buffer. With most .223Rem pressure I have to make the buffer 3.8oz by replacing one of its tungsten weights with a steel one.

[StrikerFired]

Just put my rifle out in the garage for a quick test myself. Outside air temp: 16 Degrees. I'll let it get good and cold for a few hours and then head out to the range.

[ST911]

Of those experiencing these issues, is the mid-length a common variable? And if it is, what buffers are running those guns?

I still don't suspect a temp effect, but if the guns are close enough to threshold, anything is possible.

We need a meteorology-type to weigh in on the effects of air temp, density, and pressure.

[rob_s]

Mine's a ML 16" with a 0.080" gas port (measured with pin gauge) and a Vltor A5 with the standard buffer (whichever one comes with it) and the spring that comes with it. I'll get a weight on the buffer shortly. BCG is BCM, if that matters. Lube is (was?) Slip 2000 EWL 30wt. Thinking of just lubing it up with standard EWL vs. the 30 wt.

Rounds for me hung up on the way into the chamber. tip would stop anywhere from the base of the feedramp to just past the top. I was able to slightly retract the CH (enough to get some momentum but not so much as to potentially cause a doublefeed) and seat the round every time it happened. Happened 8 times out of three, 28-round, magazines. Mags were Lancer AWM. Ammo was ASYM 55 grain.

Air temp was mid-50s, unsure on humidity.

[308sako]

Is it always the same magazine that causes this FltFd?

Since you mention speed reload, is it possible the magazine is being inserted just a little bit too high into it's normal position and thereby robbing the BCG of it forward momentum while stripping the round?

The rifle apparently runs fine when fired, and it's lubed and the parts will almost surely be within their respective specs (except the magazine catch position) so it falls back upon the operator or this settling of the magazine into it's proper place after the rifle cycles normally.

[StrikerFired]

Rifle is good and cold now, air temp: 20 degrees. Will leave it for one more hour before heading to range.

[Artiz]

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.

X2. Up here our AR-15's run just fine down to -20°F.

[Magic_Salad0892]

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.

regardless of my reply. I still think you might be more right.

[StrikerFired]

Just got back from the range. Cold as hell and the AR didn't have any feed problems. I used 28 rounds in Pmags ( loaded with 62 gr PMC Xtac ammo), and couldn't duplicate the misfeed. Just before the test the rifle had been cleaned and re lubed with Slip EWL

[Ratfink]

i had issues in much colder climates but you never know so here goes

completly degrese the weapon some people will hate this but wipe off all oil and grease then use brake cleaner and it will get everything off when the temp drops really low i didnt run any lube in my ar when i lived in alaska but were talking super cold and it would cause the firing pin enough drag to make rifle not fire

in your area of the world after a complete degreasing i would put new lube like frog lube or slip2000 in it

or ignore what i said since you have no idea who i am

[ST911]

Rob, it occurred to me that this thread dovetails nicely with your other one on individual carbine configurations. Good reference document to flip back and forth on.

[Heavy Metal]

i had issues in much colder climates but you never know so here goes

completly degrese the weapon some people will hate this but wipe off all oil and grease then use brake cleaner and it will get everything off when the temp drops really low i didnt run any lube in my ar when i lived in alaska but were talking super cold and it would cause the firing pin enough drag to make rifle not fire

in your area of the world after a complete degreasing i would put new lube like frog lube or slip2000 in it

or ignore what i said since you have no idea who i am

Texas isn't Alaska and the gun should run fine well-lubed. Hell, it gets colder where I live than Texas and I don't have any issues with conventional lubes even shooting all day in the teens.

The cold issue is a chimera, therre is some underlying problem that needs addressed.

Even in arctic temps there are specialty lubes that allow one to use the gun wet and cold.

It might be worthwhile for him to strip his BCG, Upper and Buffer Tube with degreaser to ensure there is not some cross-contamination issued caused by mixing different lubes but the gun should still be relubed sloppin' wet when he finishes.

[Jay Cunningham]

Just put my rifle out in the garage for a quick test myself. Outside air temp: 16 Degrees. I'll let it get good and cold for a few hours and then head out to the range.

The OP did not mention that it was a problem in 16 degree weather.

[Jay Cunningham]

Of those experiencing these issues, is the mid-length a common variable? And if it is, what buffers are running those guns?

I still don't suspect a temp effect, but if the guns are close enough to threshold, anything is possible.

We need a meteorology-type to weigh in on the effects of air temp, density, and pressure.

The OP clearly stated that the issue occurred during initial load or reload - the type of gas system is moot.

[Jay Cunningham]

i had issues in much colder climates but you never know so here goes

completly degrese the weapon some people will hate this but wipe off all oil and grease then use brake cleaner and it will get everything off when the temp drops really low i didnt run any lube in my ar when i lived in alaska but were talking super cold and it would cause the firing pin enough drag to make rifle not fire

in your area of the world after a complete degreasing i would put new lube like frog lube or slip2000 in it

or ignore what i said since you have no idea who i am

Running the AR bone dry is not a good idea.

[Jay Cunningham]

Texas isn't Alaska and the gun should run fine well-lubed. Hell, it gets colder where I live than Texas and I don't have any issues with conventional lubes even shooting all day in the teens.

The cold issue is a chimera, therre is some underlying problem that needs addressed.

Even in arctic temps there are specialty lubes that allow one to use the gun wet and cold.

It might be worthwhile for him to strip his BCG, Upper and Buffer Tube with degreaser to ensure there is not some cross-contamination issued caused by mixing different lubes but the gun should still be relubed sloppin' wet when he finishes.

It's not a "cold" issue, it's a temperatures transitioning just barely into the 32 degrees Fahrenheit range with high humidity issue.

[StrikerFired]

[QUOTE=Jay_Cunningham;1198448]The OP did not mention that it was a problem in 16 degree weather.[/QUOTE

And you just decided to point that out? I was just trying to see if it was a repeatable problem, but it colder up here. I don't have control of that

[Jay Cunningham]

You are addressing an "issue" that never was brought up as an issue. It never was about absolute cold temperature, it was about a temperature that perhaps topped out in the low 50s and hovered near freezing at the other end - with very high humidity.

There are a bunch of people posting in this thread that are just randomly throwing stuff against the wall to see if anything will stick.

[Clint]

Something related from
http://www.chuckhawks.com/firearms_cold_weather.htm
take it for what it's worth.



Natural and synthetic lubricants are designed to resist extreme amounts of heat so as to not break down through the fast, repetitive cycling of modern firearms, especially automatic ones. Yet few are capable of retaining their viscosity when exposed to sub-zero temperatures. In the freezing weather, lubricants begin to bind and set, becoming gummy.

For the majority, there is only one reasonable solution. This is simply to clean the action of all fluids and lubricants. There is little risk of damage from friction, as the extreme temperatures will moderate heat within the firearm. Also, the amount of wear incurred by the lack of lubrication over shorter time spans is generally negligible, and easily managed by action smoothing by a qualified gunsmith. The important thing to remember here is that every trace of lubricant and the cleaner used to remove it must be completely gone before the weapon is exposed to the environment.

But lubricants are not the only liquid in a gun's action. Air contains moisture. As that air is cooled, it can no longer hold moisture and so it collects on surfaces. Think of the way condensation collects on the side of a water glass. The same thing happens to a cold rifle brought into a warm room. Moisture will begin almost immediately on every surface of the rifle, inside and out. By itself, this is not inherently bad. The risk comes as that now damp rifle is brought back out into the cold. The condensation will begin very quickly to freeze on all those surfaces. This can cause the weapon to lock, not firing, or to fire, creating high stress on the internal structures.

[Jay Cunningham]

But lubricants are not the only liquid in a gun's action. Air contains moisture. As that air is cooled, it can no longer hold moisture and so it collects on surfaces. Think of the way condensation collects on the side of a water glass. The same thing happens to a cold rifle brought into a warm room. Moisture will begin almost immediately on every surface of the rifle, inside and out. By itself, this is not inherently bad. The risk comes as that now damp rifle is brought back out into the cold. The condensation will begin very quickly to freeze on all those surfaces. This can cause the weapon to lock, not firing, or to fire, creating high stress on the internal structures.

I think this may be on the right track. It's not moving the gun in and out of a warm vehicle or clubhouse, though (I know better than to do that, and I warn my students about it). I think it might have to do with a hot cheek on a cold receiver extension and some kind of water forming and then freezing inside the extension.

Or something.

[Heavy Metal]

I think this may be on the right track. It's not moving the gun in and out of a warm vehicle or clubhouse, though (I know better than to do that, and I warn my students about it). I think it might have to do with a hot cheek on a cold receiver extension and some kind of water forming and then freezing inside the extension.

Or something.

...yeah but water condenses on cold surfaces, heat drives it away.

[Jay Cunningham]

:big_boss:

[RetreatHell]

Paul how much wear do you have on your buffer springs?
What do they measure out to?
Also of you just install your bolt carrier in your upper receiver without a bolt in it do you feel any resistance as the carrier key closes on the gas tube?

I have a VLTOR A5 on my BCM 14.5" Midlength. With 5.56mm NATO ammo it runs all day trouble free with a 5oz standard A5 buffer. With most .223Rem pressure I have to make the buffer 3.8oz by replacing one of its tungsten weights with a steel one.

Damn notification emails didn't work properly, just saw all these posts.

My BCM spring that came out of the gun was replaced by a new BCM carbine buffer spring, and the old one (which actually had just OVER 4,000 rounds, not under, as I originally said) is just barely under 1" shorter. I wouldn't think that would be bad enough to cause issues, but I suppose it could.

And Yes, I just now checked and verified that the carrier sans bolt slides perfectly over the gas tube. However it is all spick and span now after I cleaned the gun.


ETA: Running a standard H buffer from BCM.

[RetreatHell]

Is it always the same magazine that causes this FltFd?

Since you mention speed reload, is it possible the magazine is being inserted just a little bit too high into it's normal position and thereby robbing the BCG of it forward momentum while stripping the round?

The rifle apparently runs fine when fired, and it's lubed and the parts will almost surely be within their respective specs (except the magazine catch position) so it falls back upon the operator or this settling of the magazine into it's proper place after the rifle cycles normally.

Nope. Multiple magazines, all loaded to 28 rounds.

Not just speed reloads. Initial admin loading as well.

[RetreatHell]

So now that my shooting buddy (thopkins22) finally got his shit together (;)), we should be hitting the range this Wednesday afternoon, evening and into the night.

Low will be 43F, with 74% humidity.... I didn't realize we had that high humidity on cooler evenings, and I'm coming up on 6 years living here now! So conditions will be perfect for evaluation.

[ST911]

The OP clearly stated that the issue occurred during initial load or reload - the type of gas system is moot.

Quite right, thanks for the check.

My brain was thinking of larger possibilities in differential function, not necessarily the OP's problem.

[R.P.]

I too, have had this issue during my last two trips to the range. I tend to believe that my issue is buffer/spring related. The reason I believe this is I recently swapped uppers/lowers on two different guns.
Gun #1 (the one with this issue) is a BCM 14.5" midlength on an M&P lower. I believe the buffer in this lower is a carbine buffer.

Gun #2 is a BCM 16" midlength on an Armalite lower with an H Buffer.

I never had this issue before I changed out lowers so my next task at hand is to swap out buffers to see if this fixes the problem.

Like the OP, the only time I have this issue is during a speed reload using the bolt release to load the round. If I use the CH to load the round I do not have this problem.

ETA, the temp was in the 40's my last two range trips but I can't see this being the main issue in my case.

[ST911]

I was curious enough about the OPs problems that I conducted the following deliberate exercise.

Rifles

Colt LE6920, OEM configuration, H buffer
Colt AR6720, OEM configuration, H buffer
Colt AR6520, OEM configuration, H buffer
LMT lower, 6520 upper, OEM configuration, carbine buffer
LT Stealth lower w/ CMT LPK, LT Stealth upper (16/11), carbine buffer

All carbines were in various states of fouling. A couple were filthy. They were all generously lubricated with Slip 2000 or EWL. Lubrication included buffer and spring, as is my norm. All have various round counts on them, with springs passing length specs. All are of proven function and reliability.

Magazines

Tango Down ARC, 30rd
Magpul PMag, 30rd
Colt (NHMTG) USGI, 30rd

Ammunition

Various FMJ

Test Design

All rifles were placed into secure cold storage in ambient temperatures in the low to high teens. Humidity was about 50%.

Five each of the three types of magazines were loaded to 28 rounds, and placed into storage where they reached the same temperature as the rifles.

Each rifle was removed from the storage location, and one magazine of each of the three types was inserted into the mag well of each rifle under an open bolt. The bolt was then released via a palm strike to the mag catch. Any failure to fully feed into the chamber and lock, or any discernable hesitation in doing so, was deemed a failure. After chambering, the round was extracted and ejected, and the bolt locked open again. The process was then repeated for a total of 15 feed attempts per magazine, 45 feed attempts total per rifle.

Results

225 successful feeds out of 225 attempts.

Discussion

The three mag types were chosen as they are the most prolific in circulation. They are different enough from one another that if a magazine type-specific variable was in play, there would likely be at least an indication of it.

Only 15/28 rounds were attempted. 15 was thought likely to produce the problem if it was to occur, without consuming unnecessary time.

I did not vary lube type, quantity, or application location, as those are my norms regardless of prevailing weather conditions. The test wasn’t intended to be a diagnostic or differential measure of all possible variables but rather a proof of concept/validation of technique that I knew worked.

I couldn’t assess or control the effects of humidity, but duplication of the test in a different humidity environment could be done by someone else.

Best success: Lube generously, operate vigorously.

If I get ambitious, I’ll strip the lube off the buffers and springs and repeat. I suppose I could also switch up the ammo type. However, based on past experience of these guns, specific units and by model, in my hands and those of the LCDs, I don’t expect different results.

[StrikerFired]

Nice Post,

I tried the same thing, but was "corrected" by someone else who stated the OP did not say it was a problem at colder temps then what he listed.

[thopkins22]

I'm sure RetreatHell will chime in later tonight or tomorrow, but I witnessed the issue crop up tonight as temperatures dipped as well.

When dropping the bolt on a new magazine, the round would catch halfway into the chamber. It didn't matter if he racked it or pressed the bolt catch. It wasn't 100% repeatable...but enough that it was noticeable.

Also the weapon was well lubricated with a new spring from BCM that was also lubricated. Shooting was suppressed, but the lube still appeared to be there.

[GrumpyM4]

I've used marine wheel bearing grease on my action spring for years now with no issue such as the one described in the OP and I live in an area that goes to extremes. We can get 110 plus degrees in summer and right now as I speak it's 28 degrees and dropping.

I recently switched to fully synthetic Amsoil grease due to it's temperature range and added protectants that are similar to the protectants in marine wheel bearing grease which is a must up here in the northwet to keep parts from rusting.

So far it has kept my guns running like a raped ape regardless of the temp, suppressed or unsuppressed, clean and dirty alike.

I'm liking this Amsoil, even if it's made by the amway people.

[thopkins22]

I've used marine wheel bearing grease on my action spring for years now with no issue such as the one described in the OP and I live in an area that goes to extremes. We can get 110 plus degrees in summer and right now as I speak it's 28 degrees and dropping.

I recently switched to fully synthetic Amsoil grease due to it's temperature range and added protectants that are similar to the protectants in marine wheel bearing grease which is a must up here in the northwet to keep parts from rusting.

So far it has kept my guns running like a raped ape regardless of the temp, suppressed or unsuppressed, clean and dirty alike.

I'm liking this Amsoil, even if it's made by the amway people.

Did you read the thread? It's not an issue of the gun "running." The gun runs well as in once it's loaded it shoots to empty. It's an issue with the first cartridge being stripped off of a new magazine.

[Jay Cunningham]

Why let something as bothersome as the actual point of the original post get in the way of people with the overwhelming urge to type random things?

[Heavy Metal]

Did you read the thread? It's not an issue of the gun "running." The gun runs well as in once it's loaded it shoots to empty. It's an issue with the first cartridge being stripped off of a new magazine.

That would suggest a couple of things to me. Either an insufficient action spring or a sharp barrel extension where the edges of the 5 and 7 O'Clock locking recesses are 'biting' the jacket of the bullet and/or possibly a rough feed ramp. just enough of a problem when the bolt is released from the bolt catch but not enough to stop it when released from full compression.

I wll say this much, on every barrel I mount, I break the edges on these recesses with some small diamond dust files and then dremel-polish the shit out of the feed ramps and the edges of the 5 and 7 O'Clock recesses.

[GrumpyM4]

Did you read the thread? It's not an issue of the gun "running." The gun runs well as in once it's loaded it shoots to empty. It's an issue with the first cartridge being stripped off of a new magazine.

Yes I read the thread. The OP was concerned about his choice of lube and the temps of his area.

Therefore I mentioned that the lube I use has proven itself across a variety of temps and my guns do not have the same issue that his does regardless of the temp. In other words, I was giving him another option of lube that may help prevent the issues he is experiencing.

Clear enough for you or do I need to break out the crayons and construction paper?

[thopkins22]

Yes I read the thread. The OP was concerned about his choice of lube and the temps of his area.

Therefore I mentioned that the lube I use has proven itself across a variety of temps and my guns do not have the same issue that his does regardless of the temp. In other words, I was giving him another option of lube that may help prevent the issues he is experiencing.

Clear enough for you or do I need to break out the crayons and construction paper?

I shoot side by side with him, using the exact same lubricant. Albeit not suppressed nearly as much. No issues, in fact last night his gun was lubricated with the lighter Slip 2k instead of the EWL(which should still be fine WAY colder than we're experiencing.)

The crayons would have been helpful the first go-round when your post was easily interpreted as meaning that the issue reared up when firing the gun...not now.

[GrumpyM4]

I shoot side by side with him, using the exact same lubricant. Albeit not suppressed nearly as much. No issues, in fact last night his gun was lubricated with the lighter Slip 2k instead of the EWL(which should still be fine WAY colder than we're experiencing.)

The crayons would have been helpful the first go-round when your post was easily interpreted as meaning that the issue reared up when firing the gun...not now.

Is cool. I happen to like crayons and construction paper. Reminds me of better days.

To be honest, you're right, his choice of lubricant *should* work fine in the given temps he's talked about.

That being said, this leads me to believe that the issue is one with the gun as others have pointed out and the temps are just the proverbial straw that broke the camels back.

Let me put it this way...... One time, for shits and giggles, I tried a grease in my M4 that is used on the missile tube hatches of boomers. It was a very thick and extremely tacky (sticks to everything and super hard to clean off), but was super slick (when the parts in question was moving slowly). It was designed to keep a system lubed at low temperatures, in corrosive environments, and under extreme pressure (under the ice caps, salt water, and in the depths of the oceans).

When I tried this grease, it was at a winter shoot where the tems were in the 20s and it was snowing. Cold, the gun ran slooooooooow. I mean you could watch the bolt schloop forward and strip the round off of the magazine (Pmags) as if in slow motion when the bolt was dropped manually for the first time. When the rifle was fired, it ran clunky until it warmed up and then it ran normally.

Point being is that it still ran. Even cold and, for lack of a better term, "goopy". Meaning that a gun that is running up to spec and has all parts within specified operating perameters will still work properly even with thickened lube.

All said and done, I hope RetreatHell gets this figured out satisfactorily.

[RetreatHell]

Alright, so here are a couple pics from my and thopkins22's range trip the other night.


This was the first time it happened that night, and it was after firing around 250+ rounds suppressed. It didn't happen while running my painted BCM lower (at least not that I remember) for the previous hour or so. We actually took a break and I swapped lowers to a Larue billet lower. But I'm pretty positive it would have soon because it was beginning to load REALLY slowly. But it did continue feeding when manually chambering. I just wanted to swap to another lower which had not yet been shot with a suppressed upper installed to see if the "fresh" lower would also start off great and quickly begin slowing down. And it did. I expect to have to reapply lube when running suppressed every 4-500 rounds, but the upper components don't seem to be the problem here (although I'm not saying something can't be wrong).

This is a Larue lower and it was nice and clean and felt great at first. But after a few mags (maybe 3?) I could tell it was going to start having issues very soon, and it did. Note that I also reapplied lube generously to the upper's inside and CH and BCG before swapping lowers, as the Slip 2000 lube had burned off almost all the inside of the upper and the part of the bolt that is visible.

http://i685.photobucket.com/albums/vv219/RetreatHell/b7e35a33.jpg

http://i685.photobucket.com/albums/vv219/RetreatHell/6fe6ae52.jpg


And here are 3 videos linked below. Now you'll all be able to see what I'm actually talking about here.

Video 1:
http://youtu.be/OD_i8Jvf810

Video 2:
http://youtu.be/UQ1nkDr5aWQ


Here in video 3 you'll see something that I'm friggin' clueless as to how the hell it happens! I've only seen this happen a few times. The round gets chambered but is loose in the chamber and the bolt never grabs a hold of it. WTF?!

Video 3:
http://youtu.be/QLKuvQgBw7M


So there you are... If you read the complete original post AND have also followed this thread AND also are in the know AND also have an idea as to what's going on and how to (possibly) remedy it, please do feel free to fill my ass in. Thanks!


****And BTW Thomas, if I'm not remembering something correctly or I said something wrong about the sequence of events, or you remember shit differently, please feel free to correct me. My memory sucks.

[Iraqgunz]

I have tried to follow with this thread as I was curious as well as to what was going on. I cannot for the life of me figure out what is causing this- internet diagnosis and all.

Video 3 was interesting in that it seems as if there may be too much tension on the extractor which is why it wouldn't grab the rim.

If you don' mind, do a little recap for me.

1. How many rounds through this AR total (SWAG)?

2. What exactly is your extractor set up? Colt, BCM, ?? O-ring or no O-ring?

3. This is only happening in cold weather and not when it's warmer?

4. I will also agree with a few others here. The temps you are experiencing aren't "cold" per se and I know that I have experienced similar conditions in Arizona and overseas.

5. Have you noticed any change in the accuracy of the weapon from when you first started shooting it?

6. Can you see any abnormal or odd wear in the chamber extension or the bolt lugs?


I have some possible suspicions, but I am going to hold them to myself for the moment.

[eternal24k]

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).


I cannot see how the gas system would affect the function of chambering the first round from a mag :confused:


As mentioned, check the spring length. EWL should be good-to-go for those temps, I use it all winter, and we actually have winter here :p

Buffer springs are one of the things I used to cheap out on, but have learned that it is one of the areas where quality really shines. I buy my springs from SAW, Colt OEM only

[Iraqgunz]

Correct- it shouldn't matter at all.

I believe that he just put a brand new spring in there. Colt isn't the be all end all in springs. I have purchased new ones that weren't far off from being at the failure point.

I would be tempted to use a Springco spring (I have a secret compact with them and get kick backs for purchases).

There is something else happening and I can't put my finger on it, just yet.


I cannot see how the gas system would affect the function of chambering the first round from a mag :confused:


As mentioned, check the spring length. EWL should be good-to-go for those temps, I use it all winter, and we actually have winter here :p

Buffer springs are one of the things I used to cheap out on, but have learned that it is one of the areas where quality really shines. I buy my springs from SAW, Colt OEM only

[eternal24k]

this definitely seems like a place where the A5 with the rifle spring would shine.

Retreat,
have you tried different lowers and/or examined this lower for oddities? I would look at the bolt catch for odd wear marks or anything out of the ordinary.

[RetreatHell]

Alright, collected some more data for you here.


1. I made a mistake with my initial round count a mentioned. As of the other night, this gun has 4,720 rounds through it.

2. BCM BCG with the black insert AND the O-Ring. I've been told it isn't quite necessary for mid-length systems, but went ahead and installed it on this particular one. Here's a pic I just snapped of the bolt/extractor setup just after taking it out for the very first time:
http://i685.photobucket.com/albums/vv219/RetreatHell/917d55ad.jpg

Do you think using the O-ring could be an issue here?

3. Correct, only when it gets down to around 55-40 degrees (or colder I assume, but it doesn't usually get colder than that, and if it does I'm likely not shooting)

Please also note that this also ONLY happens while running the gun SUPPRESSED.

4. Yes I know it ain't actually "cold," as I was always used to much colder winters in Oklahoma before moving here. I never shot guns there though:(

5. No degradation of accuracy noted. In my most previous class (McNamara TAPS) I won a little "contest" shooting from 200-25 yards using his 6" rifle bulls. In same class the next day I shot 10" steel squares with ease out to 350 yards.

However, I guess that's not to say there couldn't still be some. I would assume not though, and I haven't seen anything crazy with it while shooting (albeit all close range since class).

6. Just stared at those components and nothing stands out, looks good as far as I can tell.


Any of that help you out to make any sort of plausible determination(s)?



I have tried to follow with this thread as I was curious as well as to what was going on. I cannot for the life of me figure out what is causing this- internet diagnosis and all.

Video 3 was interesting in that it seems as if there may be too much tension on the extractor which is why it wouldn't grab the rim.

If you don' mind, do a little recap for me.

1. How many rounds through this AR total (SWAG)?

2. What exactly is your extractor set up? Colt, BCM, ?? O-ring or no O-ring?

3. This is only happening in cold weather and not when it's warmer?

4. I will also agree with a few others here. The temps you are experiencing aren't "cold" per se and I know that I have experienced similar conditions in Arizona and overseas.

5. Have you noticed any change in the accuracy of the weapon from when you first started shooting it?

6. Can you see any abnormal or odd wear in the chamber extension or the bolt lugs?


I have some possible suspicions, but I am going to hold them to myself for the moment.

[RetreatHell]

this definitely seems like a place where the A5 with the rifle spring would shine.

Retreat,
have you tried different lowers and/or examined this lower for oddities? I would look at the bolt catch for odd wear marks or anything out of the ordinary.

I messed around with a couple A5 systems and got tired of trying to make everything perfect for every gun, and went back to standard carbine REs/Springs/buffers to keep things simple. Been doing that with a lot of aftermarket upgrades and such lately, actually. (although for my 18" SPR I'm still running an A5 on that one with great success)

Yes I've used 2 different lowers now. You'll notice in the pics/videos on the previous page that the lower is a black Larue billet lower, while the upper is painted. I'd swapped lowers just before to see if a "fresh" lower would have issues as well (obviously it did).

[Iraqgunz]

Paul,

I would encourage you to toss that O-ring in the trash. Then tell us what happens. You absolutely do not need it with a midlength or most other AR's.

I haveseen them cause numerous FTF issues.

[RetreatHell]

Paul,

I would encourage you to toss that O-ring in the trash. Then tell us what happens. You absolutely do not need it with a midlength or most other AR's.

I haveseen them cause numerous FTF issues.

Roger. Done.

I assume in this case "FTF" means Failure To Feed, not Fire, correct? Just wanna make completely sure I'm tracking everything here;)

I said in my OP that I wouldn't be surprised if its something simple/stupid that's the issue. And an O-ring certainly fits the bill for that. Guess I'll just have to wait and see next range trip.

Will be going to the range again early next week sometime and will once again shoot well into the night. I'll update immediately afterward. I hope shit gets squared away because I've got a low-light class on the 30-31 this month. Be nice to have a gun that loads properly.

[Iraqgunz]

Failure to Feed.


Roger. Done.

I assume in this case "FTF" means Failure To Feed, not Fire, correct? Just wanna make completely sure I'm tracking everything here;)

I said in my OP that I wouldn't be surprised if its something simple/stupid that's the issue. And an O-ring certainly fits the bill for that. Guess I'll just have to wait and see next range trip.

Will be going to the range again early next week sometime and will once again shoot well into the night. I'll update immediately afterward. I hope shit gets squared away because I've got a low-light class on the 30-31 this month. Be nice to have a gun that loads properly.

[5pins]

I had the same exact problem that you had in your first two vids. It was with an Armalite carbine upper on a Colt match target rifle lower. Both times it happened the temp was in the low 30’s or high 20’s. It happened after about 100 or so rounds. The action would start slowing down becoming sluggish and then it would not feed from a full mag when using the bolt catch. I had no problem when using the Colt upper. I didn’t keep the upper for very long so I don’t know what was causing the problem. I was not shooting suppressed and the upper was clean and well lubed.

[GrumpyM4]

I might be pulling this out of my ass, but do me a favor and thoroughly clean that upper (do not re-oil), then, with the BCG removed, take a real close look inside the upper where the bolt cam pin rides against the inside of the receiver.

The first place lube gets burned off in the upper is right around that area which coincides with the end of the gas tube and is the immediate area surrounding the gas tube/carrier key mate-up. This is the place that gets the most fouling when the carrier key and gas tube seperate during the cycle and all excess pressure and carbon in the system vent.

If there is a burr of some sort or an indent that has developed on the inside of the upper where the cam pin rides that cooresponds with the area where the bolt comes into contact with the top round of the magazine and the cam pin is actually put under pressure against the inside of the receiver as the bolt tries to collapse into the carrier by the force of stripping the top round off of the top of the magazine, this might cause the issue that you're experiencing especially if you have some sort of indent in that location and are running dirty.

Then for shits and giggles, look at the exact opposite side of the same area in the inside of the upper where the carrier would be forced the opposite way and the carrier key would be placing opposite pressure.

Lastly, take a good long look at your gas tube and see if it's slightly bent enough that even though it allows a mateup between the carrier key and gas tube, perhaps it is adding enough friction to add to the issue.

Perhaps the system works fine with enough lube and running cleaner (unsuppressed), but when you add the extra fouling it allows the issues to stack up. When you pull the BCG all the way to the rear and fully compress the action spring, it may have enough power to overcome all of this, but when you manually drop the BCG using the bolt catch, it just doesn't have the "oomph" to bypass whatever is causing the extra friction.

Something along the same lines as why some folks advocate slingshotting the slide of a piston on reload instead of using the slide catch to drop the slide.

Like I said, perhaps i'm talking out of my ass, straying out of my lane, etc., but it's something to look at I suppose. Can't hurt.

[ursus.peracto]

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.

This. ^^^

It's the buffer spring.

I shoot sub-freezing temps frequently & have shot at around 0 degrees with no issues (2 different rifles).

Reason?

Less people at the range. Only hardcores. :)

[Robb Jensen]

I've seen the O-rings cause this issue. They are only needed on pistol length and CAR length gas guns. Helps with many piston ARs too.

[threeheadeddog]

There was reciently a thread on TOS about cold weather and 0-ring use. It was causing problems as well and was also a BCM BCG. After seeing this issue I noticed that AAC is using a "new" green o-ring in there uppers that RSilvers stated was supposed to have been tested down to -60.

Not sure that is the problem, and I am in no way an ARsmith. Just passing on some hopefully relevant info.