Light Polishing Of M1A Chamber--Crazy?


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Cosmoline
April 30, 2012, 06:45 PM
After resolving the failure to feed issues on my M1A scout, I ran into another problem last weekend. After about 100 rounds, the rifle started to fail to extract spent brass. I'd have to reset the extractor over the rim and then use the range table for leverage to knock the brass out. Nothing was wrong with the brass, and it was not overpressure. I looked a the chamber and it's ringed with ridges. I understand SOME roughness in these chambers is intentional to the design. And I understand that if you shoot it enough the failures to extract stop happening as the chamber breaks in. And I also understand that polishing a chamber much is a no-no.

But I'd like to accelerate the break-in and get rid of this annoying feature. My crazy idea is simple. Coat the sides (not shoulders) of 20 rounds of NATO standard with a little flitz, then cycle them through (not shooting) followed by a good cleaning of the chamber. I'm also thinking of mixing in some dummy once-fired rounds in there as well. I'm thinking that light abrasive will smooth the chamber a tad in the bad spots, improve reliability and at the same time not give me the mirror-polish chamber of death I'd like to avoid. Grippy, but not too grippy is what I'm after here. I'm very much leery of using any kind of drill or automatic polisher. I want the brass to do the work it wants to do.

What do you think? Be brutally honest :D

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ApacheCoTodd
April 30, 2012, 07:55 PM
Back when a particular manufacturer was putting out some absolute pooh quality barrels - in finishing the chamber, execution of the gas port and muzzle crown - one of the things I had great success with (which will no doubt elicit cries of dismay from the fringe) was installing a brand new GI chamber brush on a section of flex rod and chucking that up in a variable speed drill.

Normally, I would end with lapping compound. This alone would remedy nearly all the failure to extract issues which weren't caused by the horrendous burrs found in some of the worst chambers.

Oops, forgot to address your question... I'm thinking the concept is not ridiculous but the fact that the form you'll be using (the brass) is so much softer than the chamber that your efforts will render little if any results.

Edarnold
May 1, 2012, 01:43 AM
"I looked at the chamber and it's ringed with ridges. I understand SOME roughness in these chambers is intentional to the design." Not on my M1A, or any other semi-auto weapon I've owned. You have a bad chamber, period.

Why aren't you going back to the manufacturer to fix what is obviously a quality-control problem? Since you are not having problems chambering rounds, the chamber dimensions are apparently at least minimum. Any polishing is going to make the chamber larger, depending on the depth of the ridges this could leave you with a seriously oversize chamber by the time you're done, and after you've tinkered with it the manufacturer has every right to refuse any responsibility for fixing what was originally their problem.

Doubting Thomas
May 1, 2012, 01:54 AM
As I recall, in fitting up two Criterion barrels to M1s the last step after getting the headspace right (as per Kulek's book) was to polish the chamber with fine steel wool on a brass brush driven by a variable speed drill. But then I had been using my own finish reamer very carefully up till then, too.

If the mfr did a really lousy job in the first place I 'd see if I could embarrass them into replacing the barrel with one properly done. There really is no excuse for letting something like that out the door.

Cosmoline
May 1, 2012, 02:47 AM
The ridges aren't *that* deep. They're only visible when I use a tactical light shone in from the breech.

I've attached a photo showing the marks. Do you think that's just crappy finishing? If so then it's back to Springfield.

madcratebuilder
May 1, 2012, 06:14 AM
Your photo does show what appears to be some nasty tooling marks. I would call SAI, they well talk to you about this and if needed send you a shipping box and UPS label to return the rifle for service. They have a good turn around time, I sent one rifle in for a new bolt (recall), had a trigger job done while they had it and it was about two weeks total.

I've polished rough chambers before the same way your thinking. I've gone as far as screwing a brass rod into a primer pocket and using fine grinding compound on a case in a rough Brit .303 chamber.

You may want to post this question at m14firingline. Some of the best M14 smiths in the country post there every day.

Personally I would send it back to SAI, use the life time warranty.

boricua9mm
May 1, 2012, 08:30 AM
That chamber certainly looks to be on the rough side. I'm not sure any polishing will resolve that, but....

Are you using, with any regularity, the M14 ratcheting chamber brush? Remember, these are not chrome lined barrels (where nothing really sticks), so a little more attentative cleaning is needed. If I neglect the chamber scrubbing I notice a lot of carbon stuck on the case necks of extracted brass. In one case the carbon buildup was the sole cause of the FTE; the extractor jumped the rim and the case was frozen in place. When I finally removed it there was a heavy carbon buildup on the neck. Have you noticed any thick carbon on the extracted casings?

SlamFire1
May 1, 2012, 09:06 AM
You will find that shooting actually polishes the chamber.

I don't think a little polishing will hurt anything. Just don't be aggressive and get into the throat or oval the chamber.

Till then, lubricate your ammunition. That will reduce the friction between case and chamber and improve the function of your rifle.

Andrew Wyatt
May 1, 2012, 10:59 AM
I'd send it back to Springfield. The time you spend monkeying with it is time you can spend going shooting or drinking, or strangling caribou with your bare hands.

ApacheCoTodd
May 1, 2012, 12:00 PM
Yup, lookin' at the photos - no way I'd tolerate it or take on correcting it myself. Those grooves will never go away without significant metal being removed and the best you'll get is the ridges (if any to go along with the grooves) will smooth some.

I'm wondering, is the chamber tight? It certainly presents as a bad/encrusted reamer in a chamber that has in fact not been finish reamed.

I'm confident SA would want it back to correct it rather than have it out there representing the company. Just looks like another "oops" in manufacturing followed by a flawed inspection... it happens.

I'd also like to see a fired case in a good photo.

Robert101
May 1, 2012, 12:10 PM
I've polished chambers with red (fine) jeweler's rouge on a felt wheel in a hand drill. Great results. I am in agreement with the other posters that those marks are too deep to polish out. I would call SA, send them the pictures, and get their opinion. That chamber is to rough for me.

Cosmoline
May 1, 2012, 02:10 PM
I contacted Springfield and they're going to take a look at it. Very excellent customer service! I received a response within two minutes of email.

ApacheCoTodd
May 1, 2012, 03:08 PM
Outstanding! That's just what a fella wants to hear from a good company - hell, any company.

Robert101
May 1, 2012, 04:36 PM
that is great news. I am partical to Springfield Armory for that reason. If they made AR's that would be my source.

rcmodel
May 1, 2012, 04:38 PM
I understand SOME roughness in these chambers is intentional to the design.No, it actually isn't.

A M1/M14/M1A chamber should be smoother then a babys bottom.

rc

Cosmoline
May 1, 2012, 04:56 PM
I thought too much polishing creates undue pressure on the bolt face.

The rep I spoke with at Springfield said they don't put a high polish on the chambers, and that it's not unusual to see those kind of marks.

Looking at the M1A forums on this issue, it appears to be pretty common for Springfield barrels to have rings left in them particularly past the lower half. Whether or not this is done on purpose I don't know. But they do appear to have caused problems with some, but not for others.

GBExpat
May 2, 2012, 07:55 AM
FWIW, if I purchased an expensive (especially) brand new rifle and found that the chamber looks like yours, I would immediately contact them about sending it back for barrel repair/replacement. As rcmodel indicated, the chamber walls should be mirror-smooth.

O'course, I would have discovered its condition prior to firing since I completely disassemble, inspect and reassemble prior to firing any new acquisition ... milsurps got me into THAT good habit. ;)

One thing to check after getting it back: make sure that they have not simply polished the chamber into a grossly out-of-spec condition rather than replacing the barrel.

Good Luck!

Cosmoline
May 2, 2012, 12:45 PM
Rifle is heading out today, so hopefully they'll be able to fix it.

30Cal
May 2, 2012, 06:25 PM
Do you see rings on the spent brass? Either way, I think your extractor is the issue; not the chamber.

If the rims were being torn off, then I'd suspect the chamber.

Art Eatman
May 2, 2012, 07:19 PM
SlamFire1, I've read for decades and decades that it's an ultimate no-no to ever put lubricant on ammo. That dramatically reduces the uber-brief grip of the chamber wall on the cartridge case at the moment of firing and allows a high force against the bolt face.

SlamFire1
May 2, 2012, 08:57 PM
Art: I put a lot of effort into this question over the years and my answers get longer, perhaps more tedious.

Take a look at this thread, written not that long ago, if you see flaws in the data or arguments, let me know.

http://www.thehighroad.org/showthread.php?t=627365&highlight=case+lubrication

Cosmoline
May 3, 2012, 12:10 AM
I wasn't about to lube the ammo. It's messy and shouldn't be necessary.

It could be the extractor, but keep in mind that while it's not yanking the rims off it's trying pretty hard to. The brass in question had some pretty good dings taken out of the rim. And this is a near new rifle that should not have weak springs. If the extractor were stronger, it might well just tear the rims off. And that's no solution.

Also, and this is the kicker, if it was a weak extractor I'd be having problems from start to finish. Instead the problem starts appearing after I've fired a few mags.

The brass does have striations in it that correspond to the chamber.

I'm pretty sure what's happening is this. As I fire, crud starts to build up in the chamber as normal. What's not normal are the machining marks. These grab bits of crudola and act to wedge it against the brass. A few pieces won't matter, but enough small bits of crud create enough friction to lock the brass pretty solid in there and defeat the extractor. Crud alone is perfectly normal, and in a smooth chamber just drops out with the brass. You never notice it. But crud lodged in a grove can't just fall out with the brass. It's locked in place--the front end fused to the cooling brass and the other end lodged in the crack. This isn't big stuff, but it doesn't have to be.

We'll see what the experts at the labs say about it. In any case I'm strongly inclined to agree that *NO* chamber on a rifle that expensive should be so sloppily finished. It's not kosher at all.

gatorjames85
May 3, 2012, 09:00 AM
Good idea to send it back. That is way too expensive of a rifle to have to deal with failures to extract.

Art Eatman
May 3, 2012, 12:09 PM
SF1, makes sense to me. I've mostly just neck-resized in my pet cartridges, and have accumulated so much brass that for the amount of bolt-action shooting I do, there would be little benefit. The main thing, though, is the absence of hazard from lubing. It appears to be beneficial for the semi-auto folks.

gamestalker
May 4, 2012, 01:57 AM
I'm so glad that our watchful administrator Art, addressed the lube on ammo statement. That is in fact a big a no-no. Ammunition, chambers and barrels should always be dry and free of lube. Lube will prevent the much need case sieze, and ultimately damage the firearm at the very least. I've seen lugs on bolt actions get set back by those who didn't know better. Good job Art!

GS

YankeeFlyr
May 4, 2012, 02:15 AM
I'm not a machinist but I am a mechanical engineer; there is no way in Hell that chamber should look like that.

Send it back. My 2004-production M1A has a chamber as smooth as you like.

Cosmoline
May 4, 2012, 02:25 AM
Am I going to risk my hands and face on the theory that the government engineered a coverup in the 20's blaming soldiers using lube? Nope. Do I care that much about getting a third or fourth reload out of the brass? Again, no. Do I want to dig through hundreds of rounds of nicely packed ammo to get my oily fingers on it? No. Do I want to introduce lube to the chamber, attracting dust, dirt and grit and turning to a sticky black film after a few dozen rounds? No. Do I want gun oil to be superheated and released back in my face as bunch of tiny blobs of extremely hot goo on ejection? No.

Whether or not it actually creates excessive bolt face pressure I'll leave to others to sort out. The bottom line is under no possible set of circumstances should a $1400 near new rifle require me to be make my brass unctuous to function. The brass stays dry.

NWCP
May 4, 2012, 05:26 AM
Don't go messing with your chamber. That's what warranties are for. Contact the manufacturer with your problem and send it back. Let them do it right the first time and get back to enjoying your rifle. I don't play backyard gunsmith with my M1A Super Match. I haven't had any issues to date and don't anticipate any, but should one occur the manufacturer will be doing the work, not me.

SlamFire1
May 4, 2012, 11:54 AM
Am I going to risk my hands and face on the theory that the government engineered a coverup in the 20's blaming soldiers using lube? Nope. Do I care that much about getting a third or fourth reload out of the brass? Again, no. Do I want to dig through hundreds of rounds of nicely packed ammo to get my oily fingers on it? No. Do I want to introduce lube to the chamber, attracting dust, dirt and grit and turning to a sticky black film after a few dozen rounds? No. Do I want gun oil to be superheated and released back in my face as bunch of tiny blobs of extremely hot goo on ejection? No.

Actually the points about dirty fingers and lube attracting dust are valid. Dirt and dust were the reasons oilers were finally designed out of automatic mechanisms in the 40's.

As for gun oil ejecting in your face, I worry more about powder particles and the excessive amount of lube I use on my guns. I use gobs of grease on my M1a's/Garands. My AR's are well coated and I often clean my shooting glasses between relays. For everyone, always wear your shooting glasses, you cannot predict pierced primers or worse.

Still if you are really worried about lubed cases, better not shoot paper hulled shotgun shells. They are soaked for days in wax.

I have a theory that lubricated cases shoot more accurately because there is less binding in the chamber. In a properly designed mechanism loading is symmetrical and friction in the chamber just defeats that. If you are aware, competition shotgunners still use paper hulled shells because they believe they are more accurate. Might be due to the wax.

Better not shoot a 5.7 X 28 mm. The cases are coated in Teflon.

http://en.wikipedia.org/wiki/FN_5.7%C3%9728mm

FN's 5.728mm cartridge cases are covered with a special polymer coating for easier extraction with the PS90 carbine due to the high chamber pressures and lack of case tapering.[32] In addition, this coating ensures proper feeding and function in the magazines.

Don't scrape the telfon off the cases, a 5.7 fan reported injuries when shooters fired reloads with the coating removed or reduced.

Better not shoot .22LR’s. Match LR’s are totally coated in a greasy wax.

Better not shoot commercial ammunition. Many of the cases are coated in wax, a wax so thin it is hard to tell it is on the case. Ammunition manufacturer’s do that because they want those shiny cases to stay shiny on the shelf.

Better not add car wax to your tumbler media.

If anyone is worried about pressure and thrust on your bolt the smartest and safest thing to do is cut your loads. Whatever friction occurs between a case and chamber is insignificant to the pressures created by excessive charges of gunpowder.

Cosmoline
May 4, 2012, 12:26 PM
Wax is not oil. If the makers of the round, whether it's externally lubed.22 LR bullets or GP11 with its special ring around the base of the bullet, have placed wax around the cartridge, then it belongs there. That's a far cry from me rubbing CLP or motor oil onto otherwise dry 7.62 NATO cases. I trust commercial and military makers to have tested the chemical properties of whatever they're putting on the round to ensure it won't have negative side effects. I have not conducted any such testing on the various lubes and oils on the shooting bench. I do know that they're all different--sometimes substantially different--in how they react to various extreme conditions. I'm willing to experiment with lubes outside the chamber, on the rails and in places that need grease or oil. But inside the chamber it gets intense enough to turn brass soft and the pressures are way beyond my bike tires. So I'm staying out of there ;-)

Anyway the rifle should be over at Springfield next week and they'll take a look see. I'm hoping to get a new barrel.

SlamFire1
May 4, 2012, 05:10 PM
Wax is not oil. If the makers of the round, whether it's externally lubed.22 LR bullets or GP11 with its special ring around the base of the bullet, have placed wax around the cartridge, then it belongs there. That's a far cry from me rubbing CLP or motor oil onto otherwise dry 7.62 NATO cases.

Incidentally I have applied motor oil on cases and I have left RCBS water soluble on them too.

Those oilers on Nambu's, schwarzlose, breda light machine guns, it is very unlikely that that anything but straight mineral oil was used in the tanks.

These oiler designs come from LTC Chin's book on Machine guns. I think the top design was used on the Nambu.

http://img.photobucket.com/albums/v479/SlamFire/Reloading/Case%20Lubrication/Oilingcasesonbelt.jpg

http://img.photobucket.com/albums/v479/SlamFire/Reloading/Case%20Lubrication/Oilingcasesinchamber.jpg

As for wax, wax works well, not as good a lubricant as oil, but at least it dries to a hard surface. If you remember, the Pedersen rifle required wax on the cases:had to, it was a delayed blowback.

Wax melts at the temperatures and pressures of combustion. Call it a phase change. So waxes are liquid during the pressure build up. My Garands/M1a's eject hot brass and the wax feels very slippery.

So, for things like rim fires and any cases coated in wax, when they are fired the wax melts which breaks the friction between the case and chamber. And yet, the gun does not blow up (assuming no over pressure loads)

You see, your gun was designed to carry a certain load. Bolt load was based on chamber pressure max and the surface area on the base of the cartridge. The only arguments are where to establish the surface area. You can look in the book Bolt Action by Ottesen and see how he does it. http://www.midwayusa.com/product/379313/bolt-action-rifle-volume-1-and-2-cd-rom-by-stuart-otteson?cm_mmc=Froogle-_-Shooting+-+Books%2c+Magazines%2c+Videos+%26+Software-_-PriceCompListing-_-379313 No load calculations are based assuming any cartridge friction, no bolt is weakened assuming that the cartridge case takes any of the load.

However, exceed standard pressures by overloads, you will exceed the loads the gun was designed for, and that in time will damage your gun.

Cosmoline
May 4, 2012, 06:26 PM
I have no reason to dispute that, and it makes sense. As I understand it, the brass becomes quite fluid anyway during the process and if it were required to bear part of the thrust backwards it would ooze back towards the bolt. Oil would be the least of your problems. Instead it just fire forms in all directions, indicating pressure out from the center not thrusting backwards into the bolt face. In some ways it's a mistake to think of the brass as anything structural. It's more of a thin metal film designed to separate components prior to loading and keep the chamber clean. But it is no more needed to create friction to bear thrust than, as you say, a shotgun hull. Or a combustible paper cartridge for that matter.

But that still won't get me rubbing oil onto .308 rounds LOL

SlamFire1
May 4, 2012, 07:36 PM
But that still won't get me rubbing oil onto .308 rounds LOL

Not a problem, hope you get your chamber issues resolved. Those reamer marks look excessive to me, it is a new rifle, Springfield should make it right.

I still shoot my M1a super match in competition, the M1a is a great action.

Cosmoline
May 20, 2012, 12:34 PM
Just an update on this. I received the rifle back from Springfield last week with a note that they had polished the chamber and put in a new extractor. I tested it yesterday with zero failures in 150 rounds. It's shooting very well. No sign of any problems with the brass, and they no longer have shadows matching stirations. I'm still not sure how a chamber like that made it into circulation, but Springfield made it right very quickly. Great folks to work with, and I would buy from them again. Though next time I'll shine a light in the chamber first ;-)

clem
May 20, 2012, 01:57 PM
The ridges aren't *that* deep. They're only visible when I use a tactical light shone in from the breech.

I've attached a photo showing the marks. Do you think that's just crappy finishing? If so then it's back to Springfield.
That is WRONG! Send it back!

Look's like you did send it back.
Springfield is pretty good about backing thier stuff.

Jason_G
May 20, 2012, 03:04 PM
Just an update on this. I received the rifle back from Springfield last week with a note that they had polished the chamber and put in a new extractor. I tested it yesterday with zero failures in 150 rounds. It's shooting very well. No sign of any problems with the brass, and they no longer have shadows matching stirations. I'm still not sure how a chamber like that made it into circulation, but Springfield made it right very quickly. Great folks to work with, and I would buy from them again. Though next time I'll shine a light in the chamber first ;-)

Good deal. Glad to hear it's running correctly now.


Jason

TurtlePhish
May 20, 2012, 11:09 PM
Just an update on this. I received the rifle back from Springfield last week with a note that they had polished the chamber and put in a new extractor. I tested it yesterday with zero failures in 150 rounds. It's shooting very well. No sign of any problems with the brass, and they no longer have shadows matching stirations. I'm still not sure how a chamber like that made it into circulation, but Springfield made it right very quickly. Great folks to work with, and I would buy from them again. Though next time I'll shine a light in the chamber first ;-)


Think you could post a pic? I'd like to see the before and after. Glad they fixed the problem!

madcratebuilder
May 21, 2012, 08:06 AM
Just an update on this. I received the rifle back from Springfield last week with a note that they had polished the chamber and put in a new extractor. I tested it yesterday with zero failures in 150 rounds. It's shooting very well. No sign of any problems with the brass, and they no longer have shadows matching stirations. I'm still not sure how a chamber like that made it into circulation, but Springfield made it right very quickly. Great folks to work with, and I would buy from them again. Though next time I'll shine a light in the chamber first ;-)
That was very quick turn around time. All manufacturers have stuff slip past quality control, but not all of them deal with it as well as SAI.

That fast turn around tells me SAI is not backed up with warranty work, that's good.

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