What brand of barrel has a loose chamber? I am looking for a bit loose for a steel case only build I'm doing. I just don't want to have to have polymer/stuff buildup be an issue if I decide to go a few hundred rounds (or more) without having to worry about cleaning/stuck in chamber issues. If no factory loose chamber possibly opening one up a few hundred thousandths with polishing compound?

Why in God's name would you want to take a chamber out of spec just to avoid cleaning your rifle??

there is NO polymer buildup. the problem with steel case is that the steel case doesn't expand as much as brass case, causing a carbon buildup in the thin empty space between the now expanded(but not completely expanded) case wall, and the chamber, where as brass expands completely forming a perfect seal with the chamber.


if you are ONLY shooting steel case, you will have no problem, the only problem is when a brass case is shot after steel, the carbon in the chamber caused a fully expanded brass shell to become glued to teh chamber.


also, "loose" chamber is something you never ever, ever want, thats cracked cases, and all sorts of other issues.

so to recap, if you are only shooting steel, you are fine, and if you want to shoot steel and brass, you just need to clean the carbon in the chamber between switching.

Sounds like a recipe for , only a lot faster.

No, just no.

Brass expands to the size of the chamber.

An oversized chamber means the brass will expand farther than designed.

This can lead to case ruptures and a large problem.

The polymer on the exterior of the steel cases shouldn't be a problem in a quality barrel and a properly tuned gas system.

I have shot thousands of rounds of both polymer and regular steel through my BHW barrels with no issues when switching back to brass.

guess what a loose chamber means the steel will not seal as well= more carbon blowby= more stuck cases



 

You do NOT want a loose chamber. Personally I would be more concerned about gas systems and tuning the rifle for steel.

Next time, if you can't think of another way to put it, stay in GD - Eric802

One: polymer coatings on steel cases cannot "build up" in a chamber.  Neither, for that matter can lacquer.  Technically, the "lacquer" used on rifle cases has been a synthetic polymer rather than an organic lacquer for many decades.  Do an experiment: get a few spent steel cases (AK cases will do), and include a few poly cases and a few lacquered cases.  Without burning yourself, hold one of each in a flame and watch what happens.  Neither will "soften," "drip off," or otherwise leave any sort of residue.  Both will eventually burn with little ash or smoke.  The temperature needed to burn off the coatings is higher than the ignition point of most powders, so if you don't get a gun hot enough to cook off rounds, you are not going to have coatings leave gunk in your chamber.  See Two and Three below...

Two: the issue with steel cased ammunition in ARs is that steel is not as springy as brass, and with the small diameter of the .223/5.56mm neck, the case doesn't seal the chamber as well as brass cases do when fired.  

Three: the above leads to leakage of powder gases into the forward part of the chamber, which, if allowed to build up, will (not just "can") cause problems with stuck cases.  NOT coatings, NOT a Commie conspiracy, just powder residue that doesn't get cleaned away.

Four: if you're intending to put together a "steel-only" AR, invest in some quality bore and chamber brushes, and practice cleaning the chamber and barrel.  A clean rifle will have fewer stoppages of any kind, for any reason, and especially will handle steel cases better than a filthy gun.

Five: the reason you don't hear about AKs having stuck case problems with steel cased ammunition is two-fold.  First, the 7.62x39 (and the 5.45x39, for that matter) were designed with a significantly tapered case to facilitate both feeding and extraction.  Second, AKs almost always have chrome lined chambers and bores, which reduces the stickiness of the crap that will inevitably build up in the gun.

Advice: if you really want a "this gun can eat the crappiest ammo I can feed it" build, start looking at Melonited barrels.  Melonite makes surfaces substantially slicker than chrome plating, which will make cleaning easier and reduce stoppages even in a badly neglected gun.  You'll also have to decide if you want to run truly crappy ammo, such as TulAmmo, and make allowances for varying gas pressure levels; you may need to buy multiple buffers to tune the rifle for good, poor, and bad ammo.

Good luck.

Thank you
This is the kind of info I need. I have been going on some false info. Yes I have run plenty of steel case through both current ars without issue but am looking for a steel case only build. And this is the kind of misinformation that is out there.
Might have to look at melon ire.
Thanks again!

5.56 already is "looser" than .223 Rem.

Avoid an overtly loose chamber, go for definitely a 5.56 chamber.  Being a military chamber, a 5.56 barrel will have a larger chamber that's still safely within specs.  Nothing wrong with shooting steel through ARs, you'll just be changing your barrels a little sooner.  It's been referenced to death, but I think the very scientific and thorough luckygunner study on steel v. brass put that shit to bed a long time ago.

Russ and Mr.2ndAmendment have the right sort of idea, but their details are kind of fuzzy.

YES, go with a 5.56 NATO chamber.  The cartridge portion of the basic SAAMI .223 Remington and the basic 5.56 NATO chamber are essentially identical.  Howeveer, the portion forward of the case neck, called the "leade" is longer and more gradual in the 5.56 chamber, which is what allows such chambers to handle higher-pressure loads than the .223 chamber.

Details: The leade is essentially two parts.  First is "freebore," the section of the bore that is cut to the barrel's groove diameter.  This is followed by the "leade" proper, which is a tapered section that transitions from groove diameter to lands and grooves; it's where the rifling actually begins.  In the .223 SAAMI chamber, these sections are quite short, which is what a bolt gun used wants.  The NATO chamber, on the other hand, has longer freebore and leade areas, so the bullet engraves into the rifling more gradually.

This is important for a SHTF rifle because in such situations, you may have to shoot whatever there is around, and not limit yourself to commercial-grade .223 loads.