Light Polishing Of M1A Chamber--Crazy?

[YankeeFlyr]

Rough Chamber

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]

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]

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.

 

[Slamfire]

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_5.7×28mm

FN's 5.7×28mm 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]

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.

 

[Slamfire]

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.





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/37...Videos+&+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]

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

 

[Slamfire]

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]

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]

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]

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]

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]

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.