.308 AR Wont Chamber in Cold Weather?


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griff383
November 15, 2010, 09:17 AM
I had a problem last weekend while deer hunting. This is the first year I decided to reload for hunting. I tested several loads and found one that was accurate and took it with me to deer camp. Got out the first morning and saw a good eatin doe within an hour. Took aim, held steady, pulled trigger, click..... Took some serious muscle on the charging handle but cleared the round and chambered another. Didnt see another deer the rest of the morning. Went in for lunch and tried to clear my weapon, same thing. I had to rest the butt of the rifle on the bumper and put both arms into the charging handle and about gave myself a stroke getting the round out. It looked like the neck was what was sticking / rubbing.

I live in Texas and hunt in Minnesota, temp while shooting here was in the high 60's low 70's and temp while hunting was low 40's. Is it just the temp change that caused this? Is there a way to prevent it from happening?

I would really like to know how this happened so I can fix it. Any ideas or information would be really appreciated.

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243winxb
November 15, 2010, 09:37 AM
This is the first year I decided to reload for hunting. A common problem is not Full length resizing fully. Give the die that extra 1/8 turn down after the die makes contact with the shell holder. Or you may need small base dies. As for the temerature change, will the rounds now shoot/chamber at home where its warmer?? The click..... could be because the action was not fully closed. In very cold weather, freezing, thick oil can slow the firing pin, but this i dont think is your problem at 40 degrees. Check how you size your brass. Or could the bullet be seated out to far?? Make sure the crimper in the seating die is not over crimping and puting a bulge in the neck or shoulder also.

griff383
November 15, 2010, 10:30 AM
I dont have the rifle with me at the moment so wont be able to test those reloads for a while. But I had zero problems using the same materials and process before hand.

The click was definitely from the bolt not being fully forward. I use very little oil when hunting as it can gum up pretty quick in cold weather, ask me how I know....

The bullet is seated so that it will fit into the magazine and chamber without problems.

Im almost positive it was the way the brass was sized / round was produced, the only problem is I dont know when I will be able to recreate this problem to test for the solution. Is there a way or method to check and measure the problem loads so that I have a reference of what the wrong size / procedure is?

jem375
November 15, 2010, 10:43 AM
We had the same problem years ago when I was using WD40, this stuff is not to be used in cold weather, gums up too much....

MrOldLude
November 15, 2010, 11:04 AM
We had the same problem years ago when I was using WD40, this stuff is not to be used in cold weather, gums up too much....
Another reason why WD40 is a terrible lubricant. Too thin when hot, (apparently) gummy when cold, and horrible at rust protection. I keep it in my garage as a penetrant. Nothing more.

243winxb
November 15, 2010, 11:22 AM
Is there a way or method to check and measure the problem loads so that I have a reference of what the wrong size / procedure is? Take measurement of the loaded rounds. Look here for the maximum diameters for your caliber. http://www.stevespages.com/page8d.htm RC will tell you to use a black marker all over the round, see where it gets rubbed off when chambering it.

MEHavey
November 15, 2010, 02:08 PM
Cold weather should increase clearances between a steel chamber and a brass casing due to differential strinkage between the metals.

I believe the problem was less the temperature effect on the cartridge than something else that might have changed. My bets are same as yours: sizing and/or lubrication

Sizing:
Question: Had you fired any of this reloaded batch before w/o problem?
Question: Have you checked the case length (of the dud rounds)
Question: Are you using a using a small base die?

Lube:
Is the bolt absolutely dry, all oils/lubes wiped off as best you can of everything -- particularly the gas chamber/internals of the bolt carrier and the firing pin channel AND the cam pin. (A sticky cam pin will produce excactly what you describe as slow lock up rotation.)

If you are truly Full-Length resizing, my bet is on lube/crud/residue in the bolt.

rcmodel
November 15, 2010, 02:16 PM
Took some serious muscle on the charging handle but cleared the round and chambered another. I don't think it had anything to do with 40 degree weather causing expansion, or gumming up any kind of oil.

I think your problem is as 243winxb suggested in post #2.
Make sure the crimper in the seating die is not over crimping and putting a bulge in the neck or shoulder also.

When a crimp bulges a case shoulder, it is usually so slight you cannot see it, but it will do exactly as you described in an AR.

It will not fully chamber to shoot it, and you can't get it out with the charge handle.

Check your die adjustment and make sure it isn't crimping long cases unintentionally.

rc

MEHavey
November 15, 2010, 02:37 PM
Good point. That problem should show up in measuring the shoulder area/dia of an empty-but-fully-resized case (that will chamber) as compared to (a) the duds; (b) the rest of that loading batch.

BTW.... are you in fact crimping?

rcmodel
November 15, 2010, 02:49 PM
A good way to find out, if you still have one of the stuck / sticky rounds?

"Color" it with a magic-marker or dry-erase marker and try to chamber it.

Where the "color" rubs off is what is getting stuck where.

rc

griff383
November 15, 2010, 04:54 PM
I do use a crimp die, but, very very light pressure is applied when using it. I did over crimp a few rounds when I first used it and have since adjusted it so that I am not forcing the round into the crimp die in any way. But then again I could see how that could affect the chambering.

I have been using the same settings for all my load testing, only changing the seating depth via adjustment on top of die to accomodate different bullets. Do you think that had something to do with it? Its the only thing that I can think of that changed, like I said, I had zero problems while shooting here in TX.

rcmodel
November 15, 2010, 05:01 PM
Are all your cases trimmed to the exact same length?

If not, any that are longer then average are getting more then a "very light crimp" in the seating die, and may very well be buckling the shoulder imperceptably.

Also, if you seat a different bullet shape too long, it may be jamming into rifling and getting stuck.

Did you try the "coloring" test I posted in #10?

rc

griff383
November 15, 2010, 05:59 PM
I wont have access to the rifle until friday, its still in MN, but I can try then and see how it comes out. I will bring my caliper with and measure what I can and compare to the factory ammo I used in lieu of my handloads which I had no problems with.

MEHavey
November 15, 2010, 07:00 PM
FWIW#1: It does begin to sound like a bulged shoulder/crimp problem.

FWIW#2: I never crimp any rifle bullet short of a warm load in my, 300WinMag, or any load in my 375H&H and/or hot 45-70/458Win -- and I then crimp in a separate/final operation after trimming all cases in that batch to even length.

IN MY EXPERIENCE (cough, cough), I've never had backed-out/jammed-in bullet movement in my 30-06 and below (Garand/M1-A) or bolt actions. That means I seat at least 90% of a caliber into the case -- and don't go after game that can kill me.

And when I do want a crimp on the big guys, I alays try to use canalured bullet.

Kernel
November 15, 2010, 09:13 PM
It’s always a good idea to cycle test handloads, to make sure they freely chamber and extract, prior to going into the field. Perhaps your ruined hunt could have been avoided, had you done so.

If you had access to a chest freezer, you could experiment with the effects of temperature on your rifle/cartridge combination. If nothing else, it would let you rule out if temp had anything to do with the malfunction.

Since an AR action easily breaks down into a upper and lower, I fairly small freezer (or even a frige) would work. Just be sure to take appropriate action to project your rifle from condensation, which would likely form not just on the outer surfaces, but the inner ones as well.

griff383
November 16, 2010, 09:08 AM
Kernal, thats a good idea, I do have a large upright deep freeze that I could test in, and at the moment its empty so plenty of space for it.

While I should have checked my loads before heading out, I had no problems a week before I left, which is why I am confused that they didnt work

griff383
November 29, 2010, 10:12 PM
Finally got down to the nitty gritty and checked everything out (in the nice 70 degree weather).

First I loaded a factory federal round to ensure it would chamber, it did

Then I put in the exact same round that wouldnt chamber in the colder weather, chambered just fine although a little extra pull needed to clear the weapon.

So... I thought that the brass might be a little bigger than spec and I was right. Although it was only .002" bigger than the factory federal round it still chambered.

All I can get out of this is that the cold affected the rifle just enough to be a PITA and make me miss an opportunity to get a doe on opening morning.

Any suggestions on how to check loads so that this doesnt happen again?

243winxb
November 29, 2010, 10:16 PM
I would buy a small base FL die http://www.midwayusa.com/viewproduct/?productnumber=681255 & a Wilson case gauge. http://www.midwayusa.com/viewProduct/?productNumber=880646

SlamFire1
November 29, 2010, 10:28 PM
As mentioned, small base die and cartridge headspace gage.

Size to gage minimum for gas guns.


http://img.photobucket.com/albums/v479/SlamFire/Reloading/ReducedWilsongagemeasuringnew308bra.jpg

http://img.photobucket.com/albums/v479/SlamFire/Reloading/CartridgeHeadspacegagelinedrawing.jpg


I wrote this post about how standard sizing dies may not size the brass sufficiently and general advice on reloading for a M1a.

http://www.thehighroad.org/showpost.php?p=6734894&postcount=4

GW Staar
November 30, 2010, 01:54 AM
I didn't see any mention of what "AR" .308 you have. If its chambered to commercial .308 specs rather than Military specs, the chamber may be tighter. DPMS .308 chambers are noted for having tight chambers. My Remington R25 (made by DPMS) is chambered for commercial .308 and it is tight. I bought a box of cheap "blue box" Federals when ammo was scarce and found that though it would chamber and go into battery upon release of the bolt, upon firing, the next round would cycle, but stop a half inch short of going into battery, yet a box of Remington factory Core-Lok worked just fine. Being that the rifle is that sensitive, I bought an RCBS small-base die, set it to bump the shoulder properly, and my reloads worked as well as the Remington factory loads. I'm offering this experience as food for thought only...having no idea what gun you are shooting.

BTW, my Remington DPMS will not chamber and cycle cheap stuff like Wolf Ammo, worth a damn. A military chamber definately works better for that stuff.

griff383
November 30, 2010, 09:50 AM
oops, I should have mentioned that. It is a DPMS LR308 TAC 20 which is chambered for 7.62x51. I also just ordered the RCBS small base die yesterday but didnt think to order the gauge.

Im headed to Cabelas for lunch today so maybe they will have one in stock.

GW Staar
November 30, 2010, 11:06 AM
Hmmm. Maybe they mismarked it as a military chamber. If not, it appears DPMS's reputation for minimum sized chambers includes their military chambers as well.

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