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TX, USA
Posted: 8/15/2025 10:27:37 PM EDT
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So, been thinking on playing with some Rate of Fire enhancements, but ... My much loved AR9 is a Forward Charging Foxtrot Mike upper built on a Poverty Pony fed by Endomag. I determined to solve bolt bounce before I made it a problem. Maxim Defense to the rescue. So, I pulled the weight from the FM bolt to make room for the Maxim Defense guide rod, installed the Roller Delayed Buffer System and proceeded to attempt a dry function check. I achieved exactly zero charges. The FM charging rod simply disintegrated before the roller delay was defeated. To be fair, I braced it on a door frame trying get the leverage required. But, I suspect Forward Charging will lose to Maxim Defense RDB again. Now to get FM parts and a new upper so I can continue the build. |
| So in my rear charger with Maxim buffer - on my archery pull scale I get 25lbs to charge rifle. The buffer has super slight preload. It a matter of too loose or just a minimal preload. I do not want play between bolt and buffer so a slight preload it is! Maxim needs to supply shims to get a perfect fit. |
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TX, USA
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Originally Posted By dredeagle: Now to get FM parts and a new upper so I can continue the build. Good news x2: Foxtrot Mike has already requested and received pictures of the damaged charge rod. A response that quick is highly appreciated. And, PSA's website sold me a second 9mm traditional charging upper for Roller Delay Games. So, time to reinstall the FM bolt weight and see if the broken rod is robust enough to charge against a standard flatwire springy dingy. Edit to Add: FM works email on Sundays - color me impressed. After receiving a picture of my damaged charging rod, they have offered a factory replacement, and suggested their available upgrade. I accepted the offer of a replacement, plus I ordered the upgrade just 'cause. |
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TX, USA
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I am definitely happy with Foxtrot Mike's customer focus. Both the n/c replacement charging rod and the purchased Paratrooper upgrade arrived today. And, surprise. The Paratrooper charging rod is, in fact, all aluminum construction. The factory replacement rod is polymer and aluminum construction just like the one I overburdened. I am surprised, because as they are pictured online, they look identical. Although the Paratrooper description claims all aluminum, I expected they were referencing the handle as all aluminum based on appearance. Life is good when "all aluminum" actually means all aluminum. |
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I also get about 30lbs. non-preloaded. I cut out a round shim from the lid of a clear plastic produce clamshell container (blueberries) for the rear of the tube to make it a perfect fit. Aluminum soda can shims should work as well. Glad FM took care of you! |
Blowback9.com - 9mm AR info and troubleshooting that actually works. 9mm buffer selector, and 4 steps to get almost any 9mm AR running 100%.
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I have a PSA ARV 9mm, the felt recoil was bad slowing follow-up shots. So I got the Maxim roller delayed buffer. Doh! I ordered the cqb one by mistake. So I had to shorten my buffer tube (quarters). I took out the buffer weight. It wouldn't run to begin with, extraction issues. Solution: I installed the bolt upgrade with the stiffer extractor spring. Now it wouldn't run at all. I ordered a new extractor and spring combo and installed it. The ARV runs great and is roller delayed. Now the only problem is that it flings brass rear ward. But because it runs so well I'm going to leave as is. |
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TN, USA
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Could you benefit from more weight/less spring? I'm attempting to extrapolate from Step 3 of Blowback 9's 4-step guide to make (almost) any AR9 run 100%, which reads: 3. Use a standard 5.56 carbine recoil spring and any normal carbine (or pistol) length buffer tube. NO .308 springs. NO "XP" springs. NO "Red" springs. NO short/compact/micro/PDW buffer tubes. NO complex recoil systems. NO captured spring/buffers (most are VERY underweight). This solves or prevents a pretty big number of reliability, feed, and trigger reset issues. OPTIONAL: A carbine flatwire spring provides additional advantages at a slight cost increase. These are also the preferred spring option for the Gentle Recoil System. They tend to be a little stronger, but are not strong enough to cause problems, and are the quietest option if you don't like spring noise. Examples: Tubb Lightweight, Tubb AR15, or Spinta. More information: The case against .308 recoil springs in a 9mm AR SB HBPDW 9mm buffer weight Vltor A5 parts and 9mm blowback Captured spring systems a bad idea for PCC? The Strike Industries short buffer tube on 9mm blowback? I know that you're using a roller delayed system, not a straight blowback, but perhaps there's wisdom there? |
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