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Posted: 2/2/2009 7:32:43 AM EDT
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After nearly 6 months and two Form 4 transfers I took possession of my RLL (my first NFA) last Friday. Wohoo!
Here's my setup: - Host lower is a Bushmaster with carbine stock, H buffer, M16 burst FCG modded (for select fire), and KNS Protector. - 9mm upper is an LG Armory (Oly type) A2 with 10" barrel and M60Joe profiled bolt carrier. - .223 upper is Bushmaster A4 with 14" heavy profile barrel and Colt SP1 bolt carrier. 9mm upper runs great. However, my .223 upper would stop (fail to fire) every 8-10 rounds. The rounds feed and eject fine. However, it stops with unfired rounds in the chamber that have light primer strikes. What could cause this and what do you suggest? Thank you! |
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After nearly 6 months and two Form 4 transfers I took possession of my RLL (my first NFA) last Friday. Wohoo! Here's my setup: - Host lower is a Bushmaster with carbine stock, H buffer, M16 burst FCG modded (for select fire), and KNS Protector. - 9mm upper is an LG Armory (Oly type) A2 with 10" barrel and M60Joe profiled bolt carrier. - .223 upper is Bushmaster A4 with 14" heavy profile barrel and Colt SP1 bolt carrier. 9mm upper runs great. However, my .223 upper would stop (fail to fire) every 8-10 rounds. The rounds feed and eject fine. However, it stops with unfired rounds in the chamber that have light primer strikes. What could cause this and what do you suggest? Thank you! Bolt Bounce. Try a heavier buffer. I use an MGI buffer and it works with all my calibers (5.56, 7.62x39, .45ACP, 9mm, 6.8). |
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Another lesser-known fact of the RLL system is that pistol calibers are HARD on the link and paddle. You've got the link covered with the KNS protector, but I would suggest you get a paddle for each upper, and keep that paddle with that upper when you switch the link around. Swapping uppers changes the wear points on the paddle, and reduces the paddle life, not to mention subtly reshaping it each time it goes from one upper/carrier combo to the next, which will introduce metal fatigue.
If a fresh paddle, used only with the .223 upper, doesn't solve the issue, then I'd second the earlier recommendation to get a heavier buffer. If you need paddles, I've still got a bunch on hand, and I believe M60Joe makes and sells them, as well. |
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Thanks for the suggestions gents. bullyforyou, the hammer is down on unfired chambered round. circuits, sent you an IM for paddles. Thank you! try running it without the protector. the protector adds "thickness" to the lightning link. this will [sometimes] bind in action on the underside of the takedown lug. if it runs without it, you may have to file a little material off the underside of the takedown lug on the upper reciever before it will run with the protector. if it still does the same thing with the protector off, you are probably experiencing bolt bounce. |
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Thanks for the suggestions gents. bullyforyou, the hammer is down on unfired chambered round. circuits, sent you an IM for paddles. Thank you! try running it without the protector. the protector adds "thickness" to the lightning link. this will [sometimes] bind in action on the underside of the takedown lug. if it runs without it, you may have to file a little material off the underside of the takedown lug on the upper reciever before it will run with the protector. if it still does the same thing with the protector off, you are probably experiencing bolt bounce. Thanks again bullyforyou. I did file the lug as you suggested (sorry I should have mentioned that) but maybe I didn't take off enough so I'll run it without the protector to check. |
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I would suggest that you start with a basic RLL function test as described below.
With the link in the rifle, hold the trigger back and cock the action, then slowly ride the cocking handle all the way forward/closed. The hammer should not release. Then while still holding the trigger back, pull the cocking handle back 1/2", then release and let the carrier slam forward. The hammer should be released. I like to run my timing as late as possible and still get reliable operation. Do not guess at timing perform this test to check operation. Check your clearances make sure the rear upper hold down lug has had metal removed so as not to bind the link with KNS re-enforcer. I made a block that is the correct thickness and put it in the receiver and adjust a new upper until it will close. If the link clearance is ok and if function checks ok I would say it’s bolt bounce, it could be something else but I would start with the basics and test with one upper *223* until I get it running. Good luck and let us know how it’s working. |
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I would suggest that you start with a basic RLL function test as described below. With the link in the rifle, hold the trigger back and cock the action, then slowly ride the cocking handle all the way forward/closed. The hammer should not release. Then while still holding the trigger back, pull the cocking handle back 1/2", then release and let the carrier slam forward. The hammer should be released. I like to run my timing as late as possible and still get reliable operation. Do not guess at timing perform this test to check operation. Check your clearances make sure the rear upper hold down lug has had metal removed so as not to bind the link with KNS re-enforcer. I made a block that is the correct thickness and put it in the receiver and adjust a new upper until it will close. If the link clearance is ok and if function checks ok I would say it’s bolt bounce, it could be something else but I would start with the basics and test with one upper *223* until I get it running. Good luck and let us know how it’s working. Thanks Belchfire! I did that test and both uppers passed. Looks like more and more like bolt bounce. Would a H2 buffer fix it or do I need something heavier? |
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I would suggest that you start with a basic RLL function test as described below. With the link in the rifle, hold the trigger back and cock the action, then slowly ride the cocking handle all the way forward/closed. The hammer should not release. Then while still holding the trigger back, pull the cocking handle back 1/2", then release and let the carrier slam forward. The hammer should be released. I like to run my timing as late as possible and still get reliable operation. Do not guess at timing perform this test to check operation. Check your clearances make sure the rear upper hold down lug has had metal removed so as not to bind the link with KNS re-enforcer. I made a block that is the correct thickness and put it in the receiver and adjust a new upper until it will close. If the link clearance is ok and if function checks ok I would say it’s bolt bounce, it could be something else but I would start with the basics and test with one upper *223* until I get it running. Good luck and let us know how it’s working. Thanks Belchfire! I did that test and both uppers passed. Looks like more and more like bolt bounce. Would a H2 buffer fix it or do I need something heavier? I run a H2 with an 11.5" upper no problems I do not have a 9mm; I think you need a 9mm buffer |
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The first thing I would do is measure the gap between the carrier and the rear lug on every upper you plan on using. Then get in touch with someone and have some paddles made. The second thing is to get a Endine hydraulic buffer. If you may have a buddy with one... Try it out in your MG and you'll see a huge, huge difference.
For your 9mm. if you get the endine, remove your bolt weight. I sheared the pin that was holding the weight in the bolt and it's never getting repaired as it is so much smoother without it. my .02 |
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The first thing I would do is measure the gap between the carrier and the rear lug on every upper you plan on using. Then get in touch with someone and have some paddles made. The second thing is to get a Endine hydraulic buffer. If you may have a buddy with one... Try it out in your MG and you'll see a huge, huge difference. For your 9mm. if you get the endine, remove your bolt weight. I sheared the pin that was holding the weight in the bolt and it's never getting repaired as it is so much smoother without it. my .02 Thanks Magoo! Working on the paddles, my uppers both gap at .021". What thickness paddle would you recommend? And I will look into the Endine, it sounds awesome. |
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The first thing I would do is measure the gap between the carrier and the rear lug on every upper you plan on using. Then get in touch with someone and have some paddles made. The second thing is to get a Endine hydraulic buffer. If you may have a buddy with one... Try it out in your MG and you'll see a huge, huge difference. For your 9mm. if you get the endine, remove your bolt weight. I sheared the pin that was holding the weight in the bolt and it's never getting repaired as it is so much smoother without it. my .02 Thanks Magoo! Working on the paddles, my uppers both gap at .021". What thickness paddle would you recommend? And I will look into the Endine, it sounds awesome. .022". Needs to be a little thicker to pull the disconnector. |
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The first thing I would do is measure the gap between the carrier and the rear lug on every upper you plan on using. Then get in touch with someone and have some paddles made. The second thing is to get a Endine hydraulic buffer. If you may have a buddy with one... Try it out in your MG and you'll see a huge, huge difference. For your 9mm. if you get the endine, remove your bolt weight. I sheared the pin that was holding the weight in the bolt and it's never getting repaired as it is so much smoother without it. my .02 Thanks Magoo! Working on the paddles, my uppers both gap at .021". What thickness paddle would you recommend? And I will look into the Endine, it sounds awesome. .022". Needs to be a little thicker to pull the disconnector. he said above that the hammer is down on the unfired round. that would indicate that the disco is getting pulled too early (paddle too thick or gap too small) if it isn't bolt bounce... |
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he said above that the hammer is down on the unfired round. that would indicate that the disco is getting pulled too early (paddle too thick or gap too small) if it isn't bolt bounce... Yep, the hammer is down on unfired dimpled primer round. The gaps in both uppers measure .021" but they both pass the timing test with the paddle that came with the RLL. I believe it's the standard .032" paddle but I'll check when I get home tonight. I've also got a line on an H2 buffer so I'll give that a try while saving for an MGI or Enindine buffer. Thanks again! |
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The first thing I would do is measure the gap between the carrier and the rear lug on every upper you plan on using. Then get in touch with someone and have some paddles made. The second thing is to get a Endine hydraulic buffer. If you may have a buddy with one... Try it out in your MG and you'll see a huge, huge difference. For your 9mm. if you get the endine, remove your bolt weight. I sheared the pin that was holding the weight in the bolt and it's never getting repaired as it is so much smoother without it. my .02 Thanks Magoo! Working on the paddles, my uppers both gap at .021". What thickness paddle would you recommend? And I will look into the Endine, it sounds awesome. .022". Needs to be a little thicker to pull the disconnector. he said above that the hammer is down on the unfired round. that would indicate that the disco is getting pulled too early (paddle too thick or gap too small) if it isn't bolt bounce... If it passes the timing test and still is hammer down with dimple in round it is bolt bounce. My above answer was to his last question. M60Joe says to go slightly larger than the gap as to minimize bending of the paddles. |
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If it passes the timing test and still is hammer down with dimple in round it is bolt bounce. My above answer was to his last question. M60Joe says to go slightly larger than the gap as to minimize bending of the paddles. Thanks nugentle. Hope the H2 is enough buffer to stop the bolt bounce. I'll be able to test it this weekend. I'll keep you guys posted. |
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If it passes the timing test and still is hammer down with dimple in round it is bolt bounce. My above answer was to his last question. M60Joe says to go slightly larger than the gap as to minimize bending of the paddles. Thanks nugentle. Hope the H2 is enough buffer to stop the bolt bounce. I'll be able to test it this weekend. I'll keep you guys posted. Oops, I meant to answer that one as well. The only buffer that *I* have personally used that has stopped bolt bounce 100% is the MGI buffer. I have tried the H, H2, 9mm, and Enidine. 9mm came the closest to stopping the bolt bounce and the Enidine made my weapons less reliable. YMMV. |
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Oops, I meant to answer that one as well. The only buffer that *I* have personally used that has stopped bolt bounce 100% is the MGI buffer. I have tried the H, H2, 9mm, and Enidine. 9mm came the closest to stopping the bolt bounce and the Enidine made my weapons less reliable. YMMV. No problem, I found a CMT H2 here local for $25, thought it was worth a try. Thanks again. |
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What do you do if you want to avoid bolt bounce but want to use the RLL with a Colt AR15 SP1 (standard 20" barrel) to achieve the same rate of fire as a factory M16?
It seems like the MGI buffer would drop the ROF down to about 600 rounds per minute, which is pretty low. |
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What do you do if you want to avoid bolt bounce but want to use the RLL with a Colt AR15 SP1 (standard 20" barrel) to achieve the same rate of fire as a factory M16? It seems like the MGI buffer would drop the ROF down to about 600 rounds per minute, which is pretty low. You won't need to do anything. The only difference in your SP1 + RLL and a factory M16 is the difference in weight of the BGC, which is minimal. I may be incorrect, but I believe the maximum allowable ROF on a M16 is 1000 RPM. Your setup should be right around there. |
Udate! Replaced the H with the H2 buffer and went to my desert range. Wohoo, she ran like a sewing machine––got an M-16 baby! So it looks like it was bolt bounce. Also, the paddle measures .030" thick so it appears it can be more than .001 - .002" thicker than the lug/carrier gap to function properly. I still want to get a MGI or Enidine buffer to slow the rpm. But as it is it's very controllable with both uppers. Thanks again for everyone's input, you guys rock. 
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That’s great to hear, like I mentioned in my first post I use the function test to get the best paddle combination. Obviously if you ride the carrier closed and the hammer drops your way too advanced *too thick* of paddle and never run the gun in that condition.
I like to run it as thin as can be and still get reliable performance; that way the rof is slower and the paddle will last a long time. I’ve got a paddle with over 3000 rounds and no sign of damage. I have 3 complete guns that I could run the same paddle with; but with how easy it is to change I have one for each gun. I mark them with the thickness “28…32…34” black marker so it’s quick and simple. 
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That’s great to hear,http://img167.imageshack.us/img167/2633/thumbmv2.gif like I mentioned in my first post I use the function test to get the best paddle combination. Obviously if you ride the carrier closed and the hammer drops your way too advanced *too thick* of paddle and never run the gun in that condition.http://img170.imageshack.us/img170/982/scaredzf9.gif I like to run it as thin as can be and still get reliable performance; that way the rof is slower and the paddle will last a long time. I’ve got a paddle with over 3000 rounds and no sign of damage. I have 3 complete guns that I could run the same paddle with; but with how easy it is to change I have one for each gun. I mark them with the thickness “28…32…34” black marker so it’s quick and simple. http://img477.imageshack.us/img477/7645/17007bh0.gif Video +1, the thinner the better as they will last much longer. I had M60Joe make me a shit load of paddles so I should be good for many years to come. Once you go MGI, you never go back 
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That’s great to hear,http://img167.imageshack.us/img167/2633/thumbmv2.gif like I mentioned in my first post I use the function test to get the best paddle combination. Obviously if you ride the carrier closed and the hammer drops your way too advanced *too thick* of paddle and never run the gun in that condition.http://img170.imageshack.us/img170/982/scaredzf9.gif I like to run it as thin as can be and still get reliable performance; that way the rof is slower and the paddle will last a long time. I’ve got a paddle with over 3000 rounds and no sign of damage. I have 3 complete guns that I could run the same paddle with; but with how easy it is to change I have one for each gun. I mark them with the thickness “28…32…34” black marker so it’s quick and simple. http://img477.imageshack.us/img477/7645/17007bh0.gif Video +1, the thinner the better as they will last much longer. I had M60Joe make me a shit load of paddles so I should be good for many years to come. Once you go MGI, you never go back
Thanks guys. But I have a decision to make. Have M60Joe make some .023" thick paddles or mill my carriers to increase the gap and use paddles in the .030 + range. I'm thinking the .023" paddle might be to thin for durability/reliability but I really don't want to mill the carriers because if I change uppers in the future the tolerance stack could go in the opposite direction and end up with too large a gap. Your thoughts would be greatly appreciated. |
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What I’ve found is that it’s not the carrier that makes the difference on my set-ups; m60joe has done all carriers but 1 and they are all at .380 see pic below.
The uppers are what make the difference, a loose-fitting of the carrier or the back side of the rear lug. That’s why I stress that the function test be performed. I have found some rear lugs are not flat and one had a bump or ridge that needed filed down. I have not and will not use any carrier that has not been properly milled for the RLL. I don’t think .023 is to thin if it bends get a hammer and flatten it back out. All my guns are setup and run I just move the link. 
Shot with FinePix S602 ZOOM 
Shot with FinePix S602 ZOOM |
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What I’ve found is that it’s not the carrier that makes the difference on my set-ups; m60joe has done all carriers but 1 and they are all at .380 see pic below. The uppers are what make the difference, a loose-fitting of the carrier or the back side of the rear lug. That’s why I stress that the function test be performed. I have found some rear lugs are not flat and one had a bump or ridge that needed filed down. I have not and will not use any carrier that has not been properly milled for the RLL. I don’t think .023 is to thin if it bends get a hammer and flatten it back out. All my guns are setup and run I just move the link. http://img509.imageshack.us/img509/8718/linkmodhy2.jpg Shot with FinePix S602 ZOOM http://img509.imageshack.us/img509/7983/dpmsmodsyg8.jpg Shot with FinePix S602 ZOOM Both my carriers measure .380" also. Ok, you got me off the fence. I'm going to order a .023" paddle from M60Joe and see how that works out. Thanks for the added info and pics. |
| I don’t have a sp1 carrier so can’t say. I don’t think a few thousands are going to make much of a difference but being consistent would. The main concern is you have a square back cut. Go to this site for a very good explanation Quarterbore or Quarterbore Main |
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