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Posted: 8/9/2025 7:25:50 PM EDT
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Radical Firearms 7.5" MHR Upper has fired approximately 100 rounds flawlessly between function testing and sighting since first installed. It has been suppressed since round #1, and I was running it with the factory included non-adjustable gas block. Recently, after the 17th round of perfect functioning one day, it would only fire one round, then chamber the next round and cock the trigger, but would not fire that round, there is a clear, audible click which I assume is the hammer falling, but it never fires the round. If I pull the charging handle and eject the loaded round and let the bolt close, it chambers the next round and fires it - it does this 100% of the time. Gun has been thoroughly cleaned and properly lubricated after a thorough check of all components, nothing is broken or missing that I can find. The trigger "click" is very clear, and the safety will not rotate to safe position after the trigger is pulled and a round does not fire. My first assumption was that it was likely overgassed, and maybe there was bolt-bounce, so I purchased/added/properly aligned an adjustable gas block, went to the range and no change. I adjusted the gas all the way closed, and it does as it should, does not eject the round. I opened it one click at a time until it would lock the action open and then would pick up the next round with a loaded mag - still functions exactly the same. Eventually tested every gas block setting until fully open with no change. Removed the suppressor, still functions 100% the same, adjusted gas block from open to closed without suppressor - still the same. Tried 4 different factory ammunition options from 53 to 77 grains, still functions the exactly the same. Tested it after replacing firing pin, tested it after replacing complete bolt, nothing I've tried will get it to fire a 2nd round. What am I missing? |
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So, gun fires, cycles, you attempt to fire and only get a click as the hammer fails. Correct? Is the bolt fully closing? Look at the primer on the attempted round. Light Firing pin strike? Have you disassembled your FCG? ie removed the hammer and hammer spring? Is the hammer spring installed correctly? Get a chamber brush and scrub your chamber, locking lug area and inside the Bolt Carrier. Thoroughly cleaned doesn't describe the details of cleaning. Scrub that chamber as something is bleeding your firing pin energy. Also check your gas tube and gas key for obstructions. Last year I had a gas key get clogged. Correct description on after hammer fails, the gun is uncocked and cannot be placed it on safe. Attached File |
De Oppresso Liber
Iraq: 91,03,04,05,06,08,09,15,16,22,23,24&25'
Afghanistan: 09,10,11,14,17,18,19,20&21'
Iraq: 91,03,04,05,06,08,09,15,16,22,23,24&25'
Afghanistan: 09,10,11,14,17,18,19,20&21'
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Just throwing some randomness to see if anything sticks to the wall here. Is it possible that when the gun was functioning fine you were using it in a manner different than when it was malfunctioning? I.e. using sandbags the first time, then switching to resting the rifle on a bench on its magazine? I'm wondering if the magazine lips are scrubbing the bottom of the carrier as the BCG travels forward to chamber a new round, but it can't fire because it's minutely out of battery. Then, when you pick the rifle up to recharge it, you release pressure from the magazine, you chamber a new round, set it back down on the magazine, it fires, then you get another click on the next try. When you were getting clicks, did you try using the forward assist to check for in/out of battery? |
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Thank you for suggestions. I am fairly certain it is my Rise Armament RAVE 140 trigger. I've found several reports of them failing and the symptoms are exactly what I am experiencing. I looked it over thoroughly, cleaned and lubed it, and I am unable to see any kind of defect, but it is a cassette-style, drop-in trigger, and the YT videos showing symptoms similar to my own, also do not show any defect. It has a lifetime warranty, and even though this is not an EDC gun, I do want it to function 100%, so not sure what I will do with a replacement trigger. Impossible to predict when you'll need to count on the gun nearest to you. The RAVE 140 seems to have a good reputation overall, and was even praised and suggested here as a good drop in trigger option. I'll contact Rise tomorrow and hopefully they will allow me to pay an upgrade fee to replace it with one of their higher tier products. |
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OP, I've got a gi style hammer/trigger assembly I'll give you, free of charge, if you want it. They're good pieces that are fully functional that were replaced by a Geiselle SSA-E. IM me your address and I'll drop it in the mail. |
Drugs kicked in now, need sleep, radiation tastes funny at 7 am every day... a bit like victory. - Ginger
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Originally Posted By Bumblebee_Bob: OP, I've got a gi style hammer/trigger assembly I'll give you, free of charge, if you want it. They're good pieces that are fully functional that were replaced by a Geiselle SSA-E. IM me your address and I'll drop it in the mail. Originally Posted By Bumblebee_Bob: OP, I've got a gi style hammer/trigger assembly I'll give you, free of charge, if you want it. They're good pieces that are fully functional that were replaced by a Geiselle SSA-E. IM me your address and I'll drop it in the mail. Thank you! That's a very generous and appreciated offer. There are great people here. You will definitely make somebody's day, but I'm in good shape with triggers. The only reason for searching out an alternative is I'm a bit frustrated and disappointed that this one failed in 100 rounds, and I am sure I would be uncomfortable replacing it with an identical model. Time and logistics mean I won't be able to get to the range this week, so no point in swapping out this trigger immediately. I can wait for a replacement, and I may order something different in case Rise Armament is only willing to replace it with the identical model. Having extra triggers around is never a bad thing, in fact, you may want to hang on to that "just in case." Thank you again for the offer, nice to see people step up to help others. Make sure the hammer spring is installed correctly. This is a cassette-style trigger, so the springs are all self-contained. It still looks fully intact and it ran perfectly for nearly 100 rounds before acting up, and it does fire when the bolt is manually charged, so the springs should still be functioning. The online reports about the RAVE 140 failures seem to point to a problem with the disconnect not properly allowing the trigger to reset. That's exactly my experience. |
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If reloads, then did not check ammo with ammo gauge, since may have over bullet crimped, to cause problems in the case shoulder, and the case is not longer fully sized correctly, will bind up as it being fully loaded into the chamber. Or, could be problem with bolt bounce, and the gas tube is no longer indexed correctly with the carrier key, and when the carrier bounces back, the gas tube not aligned with key is not allowing the carrier to move all the way back forward to be flush against the face of the barrel extension when hammer comes down. The last one, pull the bolt out of the carrier, instead firing pin all the way into back of bolt tail, and messure the protrusion of the tip of the FP out the bolt face (should be .028"~.032". If protrusion is short, then can use sand paper on the tail of the bolt on your thumb to get a few more thousands, or if way short, then replacement FP. Grants that FCG could have weak hammer spring, or some binding in it to slow the hammer fall down to not have enough energy to ignite the primer on clean strike, but most of the time short of that, carrier is not tight against face of barrel extension, and the hammer coming down to push the carrier forward to correct position to allow correct protrusion of FP, is what causes the light strike/FP to not ignite. Note to understand the FP block on the AR, flip the B/C over in hand, and pull the bolt forward in the carrier. The back of the bolt tail is not out the back side of the carrier, so FP can move forward to back of carrier, but until bolt is locked up all the way and back, its tail does not protrude out out the back of the carrier to allow protrusion out of the bolt face. As for checking gas tube alignment, pull bolt off carrier, the insert just carrier with key into the upper. The gas tube will enter the key when front off key is about 1" off barrel extension, should not be binding as you push the carrier all the way forward, and muzzle up, and slight tap of upper, should have carrier coming back down under it own weight. If gas tube needs to be tweaked to correctly, gas tube is bent at middle of barrel, not the section that is protruding out into the upper receiver instead. Also, double check the barrel nut, since tube should pass through upper void or channel without touching the sides. Hence if barrel nut is coming loose, then it going to push the gas tube again ejection side of the upper receiver gas tube channel, to cause binding as well. The last one, which suppressor, since it not a low blow back type, then tons of crap is going to be coming back from supressor as bolt is unlocking, and this extra debries/fouling, means that your going to have to keep the BC on the wet side (in and out), to help combat the extra fouling that is going to be going on. Also to point out, such does cause the bolt to unlock faster that normal, meaning more crap coming back as well, so problem could be as simple at over function on the bolt, and may need to run heaver buffer to slow the unlock back down to normal, to help reduce the amount of blow back as the bolt opens up as well. |
Posted By PlaymoreMinds:
'Twas not the <cough> sweet and innocent <cough> PlaymoreMinds...
<---skips away in frilly skirts to Candyland, leaving gutters and snorkels FAR behind.
'Twas not the <cough> sweet and innocent <cough> PlaymoreMinds...
<---skips away in frilly skirts to Candyland, leaving gutters and snorkels FAR behind.
| When charging the first round, are you locking the BCG back and releasing with the bolt release or are you slingshoting it withthe charging handle? IF using the charging handle, try locking the BCG then releasing - doesn't sound like its completely locking up. I have a Rise trigger and haven't had any issues with it... jus say'in... |
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