SR25 + RC2 & Double Feeds, Lube thoughts?

Detroit_1

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Minuteman
Apr 17, 2006
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So I have 16" APC and and RC2 and shoot exclusively hot 175s. For some time now I have been using the KAC buffer (21057 4.5 OZ) and a Tubb flat wire. Now I am not saying my lube regime is correct - in fact, I am pretty sure it is a part of the problem, but I just slather some white grease on the worn areas of the BCG & bolt. Now it seems like I get @ 40 - 80 rounds before I get a one of those fun stoppages - fresh round is caught under the ejected round and it is all caught in the port and the fresh round usually is junked.

Now for the longest time I thought to myself if I just had a magic buffer and spring combo this fat pig could just keep chugging along without creating that bird's nest of shit in the port. I procured a 5.5 oz CAR buffer from Slash plus his spring; a new Tubb spring and no name H2 buffer; the 21057 + KAC spring. So I started out with my grease & the 21057 + Tubb. I think I made it @ 40 rounds or so before the first stoppage. I then left the gun dirty (maybe 60 rounds or so at this point) and started swapping out buffer and spring combos. To me the best was the no name H2 (which is perceptively heavier than the 21057) and the Tubb. None of them were 100%. Total stoppages with all combos and over @ 220 rounds was probably 8 or so. The 21057 & spring were not better than the 21057 + Tubb. The combo from Slash is interesting, the spring is the shortest of the 3 and feels about as stiff as the KAC spring. When shot it seems to exacerbate the feeling of a big freekin BCG sloshing around - like a brief delay before unlock, rapid coiling, a more noticeable secondary impulse over the Tubb, and then rapid uncoiling and bolt lock. The H2 + Tubb chugged along pretty good but was smoother throughout the impulse cycle. Gun runs great with no suppressor even when dirty.

How do you all lube? Is there a point where your large frame chokes?

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Thank you all. I'll work on my lube game. I have gotten away with grease on 5.56 guns for a long time now, but they do not respond quite like the large frame. The volume of gas and particulates must be (exponentially?) higher.

FWIW - I had a 20" at one time and used a rifle length buffer from Slash w/ the KAC spring I had - worked like a charm. The body of his CAR10 (5.5 oz) buffer is too wide to fit the inside diameter of the Tubb spring - otherwise I do wonder about that combo. On his site, Slash advises that flat wire springs are not recommended for any application.

I think there are several ways to skin a cat, and a flat wire spring 'feels' like it smooths out the impulses a touch. However, I personally don't claim to know if it is the correct thing to use or not, but if Sinister says thumbs up - that is a very strong rec in my book.

Again, thank you all.
 
No grease. Consider moving to a KAC PRG suppressor on your APC. They are widely available and cheap nowadays. If you go this route then you can put the OE KAC spring and buffer back in like the gun was designed to run and all problems disappear. Added bonus of a much nicer mounting solution than the RC2. Also, your BCG won't look like something out of a Mad Max movie after a few rounds.
I have an APC and a PRG can and have never had a malfunction. Yet.
 
Consider moving to a KAC PRG suppressor on your APC. They are widely available and cheap nowadays. If you go this route then you can put the OE KAC spring and buffer back in like the gun was designed to run and all problems disappear.
This is the most correct answer. RC2 is overgassing the SR25. Addressing that from the backend is a bandaid at best, addressing it from the front end is ideal.