Originally Posted By: billt460
Originally Posted By: JRoDDz
Guns do not require extreme lubrication. They require very minimal lube. The less the better.
Not true with AR-15's.
I've found that light application of lube is best for low-volume shooting (
Part of the reliability situation with the M4 type rifle is the "springing" and the geometry of the weapon cycling.
With the M4 type rifle, the BCG only has about 3/4" of momentum-room before it strips a round from the magazine. The cam-pin track is also much "sharper" than other designs, which means that more friction occurs during the lock-up process.
The two ways to overcome this are more spring, and more mass. Spring equates to pressure and velocity, and mass equates to adding some momentum to that.
I have gone to the Vltor A5 system, and run a 5.2oz buffer (standard for that system), along with a Sprinco "Green" spring.
Before I transitioned to the "Green" spring from Sprinco, I would get intermittant failures to chamber when using the bolt-release. I have experienced this using the Carbine RE and mil-spec carbine springs, as well, so it's not a "Vltor" thing, and I have experienced that on multiple M4 types. When a Sprinco White (supposedly the same as the mil-spec compression rate/strength) was subbed, the failures were cut in half. Going to the Sprinco Blue eliminated them. The same was seen when I went with the Sprinco "Green" in the Vltor system.
When adding mass and spring to the system, you also create unintended consequences, the main one being that the weapon won't cycle "weak" ammo as well, and that you get more "muzzle dip" when the carrier returns to battery. The Vltor A5 system has mitigated both of these in my experience. With a Sprinco Blue and H2 buffer, I was getting significant muzzle-dip With the Vltor A5 and "Green" spring and 5.2oz A5 buffer, I get virtually none. The more coils in the spring allow it to more effectively accept, store, and release energy. The rifle runs un-suppressed with Tula, and suppressed with MK262 and 70gr "Browntip" (the hottest stuff I've ever shot, 70gr @2900fps from my 16.1" rifle, suppressed) just fine. The A5 system "broadens" the performance envelope, if you will.
The next thing I did, was change over to a QPQ'ed bolt-carrier group. It is very smooth/slick, and the contact points don't get much carbon build-up, as you can see. I have found that over time, when it gets dirty and dry, it still keeps running, as the slick and polished contact points don't slow things down too bad. (see photos).
Long story short, lube will reduce friction by suspending fouling, which is what causes friction. The metal-on-metal in the M4 causes VERY LITTLE friction. Add fouling, though, and it gets gritty. The best performing lubes are the ones that "stay wet" the best, and suspend fouling for the longest. If they break the fouling down a bit, all the better.
This is where the "lube science" and all that jazz comes in. I have noticed HUGE differences in rifle function with a weapon that is running mil-spec components, when varying the lube used. Set the gun up like I have mine set up, and about the only thing you notice is how easy it is to clean, or not. However, there is a massive difference in products I have used, regarding this.
Here is my rifle's after a 1500+ round course (lubed lightly initially with MPRO7 LPX, and not lubed or cleaned during the course), shooting Wolf Polyformance suppressed about 98% of the time. It still functioned un-suppressed, near the end of day 3 (final day). A correctly set up gun will run very well, even dirty...
