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Posted: 7/13/2011 1:11:31 PM EDT
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I am a class 3 SOT with a RDIAS as of last week. I have officially quit trying to make it work and I am hoping somebody here might have an idea whats wrong with it or what we are missing. I had Phillip at Innovative Arms work on it 5 hours hours today to no avail.
First the problem and then what we have done to try and fix it. I bought a spikes tactical lower and 10.5" upper. Std buffer and spring with a collapsible stock. Full auto carrier and fire control group....Timing is set. Took it to the range and fires on semi fine all day long. Put it on full auto and fires once, cycles, hammer falls where it is suppose to because timing is right but nothing happens. You have to cycle a round and fire again. Every once in a blue moon it will fire a 3 or 4 round burst. We trouble shot it for 2 hours on Sunday and finally noticed the sear was sitting in the lower about a 1/16th" low in the lower...With that being said we had a LWRC lower at the range so we put my sear and fire control in it and it ran flawless for over 400 rounds. That was fine and dandy except it wasn't my lower. I had to give it back. I came home and found that my PSA lower was a tighter fit than the spikes and looked like it was milled like the LWRC so I tried that....Nothing...Same problem. My buddy gave me his pre-ban bushmaster same thing. I had a customer bring a stag and Mega machine and neither worked. I dont want to spend $424 on a LWRC for it not to be the problem. The bushmaster, LWRC, and PSA all fit the sear the same way. Phillip today tried different stocks, bolts, carriers, buffers, lowers, and uppers and nothing. He finally gave up because he had other work to do. At this point I plan on putting it in the safe for a few days so I can cool off. I dont drink alcohol often but this project has driven me to drink. I am open to any suggestions. |
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Quoted:
Is you sear spring in your Dias to strong? Does the Dias move at all under the lug or it shimmed in place? Might be a out of spec lower.–––––– NEVERMIND––––- How about a new FA FCG? Is the sear tripping in the rdias every time the bolt travels forward? We put a softer and harder spring. No change. No shims will fit under the housing. Not even one. Too tight to close the pivot pin. So I guess it doesnt move. We tried two different carriers today. Yes the sear trips everytime. I am just not understanding how it can work in 1 lower but not 6 others. I thought we had it narrowed down to a lower problem when it worked in the LWRC but now after trying so many others I have no clue. |
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If the hammer is falling on F/A but the round is not going off, It is one of two things: (1)Bolt Bounce or (2)premature sear release. (1) is solved by using a heavier buffer. (2) is solved by shiimming the DIAS forward in the lower. Also make sure the DIAS is snug around the rear lug and there is no play. |
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+1 on Bolt Bounce.
You stated it was timed correct and firing on semi-auto well. Try a heavier buffer (either H1 H2) to get the bolt to stay closed just long enough for the hammer fall. Seems like the bolt is bouncing slightly open jst as the hammer falls in full-auto setting. Once you delay the bolt from bouncing, the gun will run :) |
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You guys are awesome!!! after hearing what you guys said about bolt bounce I decided to give something a try. I just borrowed a full length fixed stock and buffer and fired 400 rounds without a hitch. It was bolt bounce!!! Now I just have to buy a heavy buffer so It will work. If it works with a fixed stock buffer what weight should I buy for the collapsible stock? As always....Thanks Guys
I still have no clue why it would work in the LWRC but not anything else...Either way. I am happy as a pig in slop. |
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People love to use the bolt bounce excuse far too much!
Stop thinking about bolt bounce and first see if the hammer is being caught by the sear trip surface. If the hammer is jumping past the sear trip, that could be your problem. Hand cycle will NOT show this problem. Under a hand cycle the hammer is not moving with enough force to test the problem correctly. When the hammer goes back under the force of a fire, the hammer will hit the sear with great force. if the surface area of the sear catch does not engage the surface area of the hammer catch, the hammer will jump past the sear and the sear will fail to catch the hammer. The fix could most likely be having a new trip made. I went through this first hand and everyone said bolt bounce. Well it wasnt bolt bonce. It was my sear trip not having enough contact area to catch the hammer correctly. Another problem is if the DIAS fits poorly and moves to the point where it also causes the hammer to jump past the sear. The key to look for is to make sure your hammer is always caught by the sear trip. If it jumps past, your hammer will follow the carrier home and fail to fire in auto. |
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Quoted:
People love to use the bolt bounce excuse far too much! Stop thinking about bolt bounce and first see if the hammer is being caught by the sear trip surface. If the hammer is jumping past the sear trip, that could be your problem. Hand cycle will NOT show this problem. Under a hand cycle the hammer is not moving with enough force to test the problem correctly. When the hammer goes back under the force of a fire, the hammer will hit the sear with great force. if the surface area of the sear catch does not engage the surface area of the hammer catch, the hammer will jump past the sear and the sear will fail to catch the hammer. The fix could most likely be having a new trip made. I went through this first hand and everyone said bolt bounce. Well it wasnt bolt bonce. It was my sear trip not having enough contact area to catch the hammer correctly. Another problem is if the DIAS fits poorly and moves to the point where it also causes the hammer to jump past the sear. The key to look for is to make sure your hammer is always caught by the sear trip. If it jumps past, your hammer will follow the carrier home and fail to fire in auto. All good info but if you read his last post he tried a full length stock and had no issu |
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Quoted:
You guys are awesome!!! after hearing what you guys said about bolt bounce I decided to give something a try. I just borrowed a full length fixed stock and buffer and fired 400 rounds without a hitch. It was bolt bounce!!! Now I just have to buy a heavy buffer so It will work. If it works with a fixed stock buffer what weight should I buy for the collapsible stock? As always....Thanks Guys I still have no clue why it would work in the LWRC but not anything else...Either way. I am happy as a pig in slop. LWRC ships with H2's. Or at least the ones I've gotten(which were all SBR's) came with H2 buffers. 
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Quoted: Quoted: You guys are awesome!!! after hearing what you guys said about bolt bounce I decided to give something a try. I just borrowed a full length fixed stock and buffer and fired 400 rounds without a hitch. It was bolt bounce!!! Now I just have to buy a heavy buffer so It will work. If it works with a fixed stock buffer what weight should I buy for the collapsible stock? As always....Thanks Guys I still have no clue why it would work in the LWRC but not anything else...Either way. I am happy as a pig in slop. LWRC ships with H2's. Or at least the ones I've gotten(which were all SBR's) came with H2 buffers. My LWRC M6A2 came with a H2 buffer. That was about 2 yrs ago. |
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Quoted:
You guys are awesome!!! after hearing what you guys said about bolt bounce I decided to give something a try. I just borrowed a full length fixed stock and buffer and fired 400 rounds without a hitch. It was bolt bounce!!! Now I just have to buy a heavy buffer so It will work. If it works with a fixed stock buffer what weight should I buy for the collapsible stock? As always....Thanks Guys I still have no clue why it would work in the LWRC but not anything else...Either way. I am happy as a pig in slop. Forget all those buffers and just get the Vltor A5 stock
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| Well I guess the A5 stock is a must. I really wanted to keep the collapsible stock so I called Clint at heavybuffers.com last week and told him what was going on. He immediately said I needed the XH 8.5oz buffer and Wolfe XP extra Power spring. $149 later I went to the range today to test fire and nope...Same thing as before. I called Clint and he told me to shake the buffer. He said if the weight didn't move inside to take out the butt plug and cut 1/4" off the rubber and put it back in and try it. What is your thoughts? Is this going to matter? |
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http://i997.photobucket.com/albums/af100/mk1hhb4/DSC06470.jpg
Thought I would share my toy. It currently has a fixed stock on it. |
The A5 stock from Vltor. 7 position. All the advantages of a collapsible stock with the reliability of the fixed A1 and A2. They offer heavy buffers for it too. But I have yet to hear of anyone needing them. This runs with my 10.5 suppressed upper , 14.5 SOCOM ( the one in this PIC ) and the 20" and looks good with them all.
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