Went out the other evening with a couple of my associates and did some awesome night shooting with a full moon and excellent weather.
Wanted to do some mix-n-matching with the Vltor A5 buffers and some of my AR's as well as theirs. As with all info it is best that you test your particular set up to ensure reliability.
AR 1- Colt 6920 barrel with Vltor MUR-1 and a BCM MOD 0 comp. BCG is black ion bonded and has standard components. I have been using the A5 on this since it was built. It was was being run with the -3 buffer and green Springco spring. Thus far it has cycled 100% with the ammo that I shoot- M193/M855 to include clone ammo. Hornady 55/75gr. Steel TAP. PMC Bronze (supply is gone) and some of markm's handloads using 60gr. ballistic tips I scored from Midway.
Last night decided to run it with the -4 buffer and Springco spring. It ran 100% with a variety of rounds. Fired an average of 10-15 rounds each of the various ammo.
1. Magtech M193
2. Hornady 55gr. Steel TAP
3. 60gr. markm handloads (loaded slightly hotter than .223)
4. Federal M193
We know that the Colt 6920 has a proper port size (.063) so it is safe to say it isn't overgassed. It shot exceptionally smooth and no malfunctions were encountered.
AR 2- FNMI 20" rifle barrel with Battle Comp 1.0. BCG is a standard BCG with standard components. This one was also built using the Vltor A5 with a -1 buffer and green Springco spring.
Last night decided to run it with the -3 and -4 buffer and green Springco spring. It ran 100% with a variety of rounds. Fired an average of 10-15 rounds each of the various ammo.
1. Magtech M193
2. Hornady 55gr. Steel TAP
3. 60gr. markm handloads (loaded slightly hotter than .223)
4. Federal M193
Again 100% feed and function. The combination of the Battle Comp with the addition of the -4 made it so incredibly easy to shoot and control is was ridiculous. You could literally fire this one handed and the rifle wouldn't move. This barrel has the standard .093 rifle sized gas port.
AR 3- BCM 12.5" Kino upper with AAC 18T suppressor mount, LMT enhanced carrier, NiB cam pin and BCM bolt. This particular upper has had close to 8,000 rounds through it. The lower was also built from the beginning with the A5. This particular A5 set up came from the factory in Tucson and has been in use for just about 3 years (IIRC). It has always had a green Springco spring and -4 buffer since I primarily shoot it suppressed. Functioned 100% as it has, until I removed the suppressor at which time rounds #2 and #3 wouldn't cycle 100% (short stroked). Port size on this is around .076
1. Magtech M193
2. Hornady 55gr. Steel TAP
3. 60gr. markm handloads (loaded slightly hotter than .223)
4. Federal M193
AR 4- BCM 11.5" BFH upper with AAC 18T suppressor mount, standard BCM BCG with an NiB cam pin. This upper is swapped around with the 12.5" routinely. It has approx. 12,000 rounds through it and has fired 100% with all ammo fired. It's using the same BCM lower with -4 buffer and green Springco spring. Port size on this one is also at .076.
AR 5- This one belonged to my associate. It's a Noveske 14.5" middy with a Battle Comp 1.0. We dropped the upper onto a lower with the -4 and it ran 100% with M193 Magtech and Federal as well as the Steel TAP. I don't believe we tested it with the markm loads.
Based on my previous shootings and observations if you are shooting a properly built and spec'd carbine with proper port sizes then I expect it should cycle 100% if you use the -4 buffer and green Springco spring. My associate remarked that he thought he felt a difference between the Springco and a standard GI rifle spring. I know that when I fired the Noveske middy it was also incredibly smooth and I could feel as if it was cycling slower.


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