Ruger Introduces the New 308 Small-Frame Autoloading Rifle (SFAR)

[georgeib]

What would be the best way to polish the chamber? What tools? I’ve never done it before.

A regular brass 308 chamber brush (one without the star chamber steel bristles) coated in Flitz polish and an electric drill on slow. Reapply polish a few times, and finish up with a used chamber brush wrapped in a 2x2 cloth patch with polish and the drill. After you're done, clean it up carefully, and you're done. The chamber will be in much better condition than anything Ruger will do for you.

[BuzzinSATX]

Not speaking from personal experience here, but from what I read, you don't want any oil in your chamber at all. It can cause over pressure.

Okay. Thanks. Never heard that before but I have no grounds to argue or doubt what you are saying.

However, I’ve typically squirted a bit of CLP in the chamber after each cleaning on any/all guns for years without any issues. But I’ll be sure to wipe it out from now on.


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[Tokarev]

However, I’ve typically squirted a bit of CLP in the chamber after each cleaning on any/all guns for years without any issues.

This might be worth a watch.



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[Disciple]

Okay. Thanks. Never heard that before but I have no grounds to argue or doubt what you are saying.

However, I’ve typically squirted a bit of CLP in the chamber after each cleaning on any/all guns for years without any issues. But I’ll be sure to wipe it out from now on.

As usual lysander has the reference for this.

Thank you, but I will continue to get my engineering advise from actual engineers, with actual degrees.

"Effects of Lubrication and Pressure on Bolt Face Forces", by Michlin, South and Brosseau, Weapons and Materials Research Directorate, Army Research Laboratory, October 2010:

Abstract:
"In this research, the effects that the level of lubrication has on the case mouth pressure and bolt force of a M16 are quantified. The case mouth pressure and resulting bolt force were measured for M855 and M855A1 cartridges as a function of the level of lubrication in a modified M16. The research found that the level of lubrication on the ammunition, and specifically the lubrication between the cartridge and the chamber of the weapon, greatly changes the level of force on the bolt face. The average difference between the conditions of heavy and normal lubrication was found to be 3000 lb. This force is a linear function with the peak pressure of the cartridge case and the peak forces on the bolt occur prior to the unlocking of the bolt and projectile exit. The results of the experiments are presented and the ramifications of the force on the M855 cartridge case are discussed."

For reference, the average normal (measured) force on the bolt at 70 degrees F, with M855 ammunition 2073 pounds, with M855A1, 2560 lbs. At the same temperature, but with a heavily oiled cartridge case, the measured force on the bolt face was 5230 lbs for M855 and 5796 lbs for M855A1

If the ammunition temperature gets to 125 degrees F (which is easy to do if left in direct sunlight for some time) the numbers are:

M855
normal - 2526 lbs
oiled - 5553 lbs

M855A1
normal - 2721 lbs
oiled - 5875 lbs


Outside of the chamber, I will agree that there is no such thing as "too much oil", inside the chamber, things are different.

[Dirty_H]

I have always squirted CLP in the chamber too, I always follow it up with a bore snake, but good info

[georgeib]

As usual lysander has the reference for this.

Thanks for reposting that. Couldn't remember where I'd read that lube in the chamber was bad, but that was it.