Most likely there is a combination which will work suppressed and unsuppressed. What happens with a USGI spring and the DPMS buffer?
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Most likely there is a combination which will work suppressed and unsuppressed. What happens with a USGI spring and the DPMS buffer?
Mr Silvers, There really never was an "original" buffer on this gun. I substituted a BCM upper on a LWRC lower which originally had their piston upper on it. Since most everything movable had changed, it was necessary to figure out what to put into the receiver extension to make it work correctly. Hence my little excursion into spring/weight "engineering". BTW, by benching the LWRC 16 inch piston upper and going with the 14.5 BCM lightweight profile I saved a measured 1 pound 4 ounces. A "carbine" should be light.
Yep, your right and it has worked for a long time. The milspec will not let you down and is made to be abused by way of lacking PM's in the field. I'm surprised the "why not a heavier BCG" didn't pop up. I also agree with you on the extractor springs...be careful or you end up with extractor bounce and other failures associated with a "to strong" spring. It is good to see so many replies and theories..it keeps us thinking.
Stay safe gents
What CAR spring did you compare them to?
How did you determine end of life?
What was the life of the regular spring and what was the life of the Springco spring?
I determine end of life by removing the lower from the upper, putting the lower onto a digital scale. Zero the scale. I then push down on the buffer until it moves a few millimeters. I then reject the spring if the scale reads below 5.3 lbs.
I actually found one in my collection today that was 4.8 lbs. I bet if someone sent me a box of take-out springs 90% of them would be good (by good, I mean within USGI specifications for a new spring).
Last edited by rsilvers; 09-27-10 at 16:24.
Well, I just pulled it out of the trash. It is 10 3/8 inches long.
My problems with the length method are:
1. The engineering drawing for the spring does not even have a length tolerance - just a reference length. What it has for pass/fail are forces at two compressed lengths.
2. Is it that hard to test with a scale like I did and be sure?
So yes, the length method was (hopefully) presumably designed to never pass a bad spring but to sometimes reject good springs. But since I am not sure they designed it that way, I would rather just test to the drawing and use force.
I have a clear plastic tube that fits a buffer spring. I marked several points for reference at 11.25" and 10.125". If the spring falls below the 10.125" I junk it. I used to use the CAR springs from Bravo and I found those to last around 3k rounds + maybe 500 dry fires before falling below the mark with noticeably less resistance when pulling back the CH(first thing I noticed). My oldest springco blue spring has seen 3k on a .223 carbine and perhaps 2.5 on my 5.45 carbine. So far it falls about 1/4 between my witness marks in my "gauge".
Ill probably run the spring in my 5.45 carbine to failure to see just how long it lasts.
Last edited by vicious_cb; 09-27-10 at 20:11.
My LMT buffer spring dropped to 10 1/8'' and began to give me FTF with just over 2000 rounds. The sprinco has just under 2000 on it so far but it still feels like new I will keep track and see how it holds up.
I do feel that a SS spring would be the ideal choice for a service rifle.
Last edited by Thomas M-4; 09-27-10 at 21:02.
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