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Posted: 5/27/2020 3:52:00 PM EDT
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I would guess that most of us know that the bolt bounce on these rifles is shockingly large, but we've been lead to believe that's just the nature of the 22lr AR platform. I've been working on this project for a long time now (just about 6 months) and it took everything I had not to let it slip out by mistake too early! Rather than try to explain it all with a bunch of photos and text (TLDR and all that) I produced a video to let the high frame rate footage explain what words can't:  Eliminating 22lr AR bolt bounce using the BoreBuddy weight kit Spoiler: the bolt bounce is gone by the end of the video. I'm crunching the numbers on the reduction in bolt velocity and should have a summary tonight, which I'll post up. Direct video link: https://www.youtube.com/watch?v=EmYgZrUQpxQ |
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Quoted: Cool!! Accuracy should improve; maybe a lot.. I am going to test that thoroughly next time I go to the range, actually, since this particular rifle usually gives about 1.5" at 50 yds with Armscor, and the one group I shot was Armscor and was 0.75" at 50 yds...I'm going to do a video on accuracy and chronograph data soon. I'm thinking it might bump velocity a tad as well, since it's keeping the breech closed much longer. |
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I didn't watch the vid, link doesn't work for me, but I bought the bounce kit from CMMG which has a stiffer spring and a counter weight. Combined with a ST-T2 spikes buffer, I got my kit to blast through stacks of BDM mags with an Echo II trigger (also with a modified spring installed). I guess the buffer doesn't do anything, but it was needed for 5.56, so that is what is in there. I also put a quarter between the buffer and the bolt for the rimfire conversion. |
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Quoted: I didn't watch the vid, link doesn't work for me, but I bought the bounce kit from CMMG which has a stiffer spring and a counter weight. Combined with a ST-T2 spikes buffer, I got my kit to blast through stacks of BDM mags with an Echo II trigger (also with a modified spring installed). Direct link: https://www.youtube.com/watch?v=EmYgZrUQpxQ |
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Here is a link to the CMMG counterweight, which also comes with a sear trip for full auto or for the Fostech Echo II kit. I think the tabs need to be ground off to work with the kit. I don't recall where I found this, maybe Fostech told me about it. They also have info on the springs.
CMMG link CMMG kit:  $40
Bore buddy with insert weights: 
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Quoted: No, it hasn't -- I don't have access to a FA lower, unfortunately. I need to find someone who has one and make a trip out to them with my camera and a bucket of parts to test! Pictured below are some of my anti-bounce weights. Left to right, Ciener, Spikes, custom SS that broke from a lot of FA and one that hasn't broken yet. I like how your design is 'connected' on both sides which should make it stronger. I'm wondering how well the brass is going to hold up from a lot of full auto and I'm also curious what cyclic rate you are getting. I also have two timers that measure cyclic rate I could use to get some actual numbers.  |
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Quoted: Regarding the HD version. I’m not seeing how to preorder one. I also have a collection of broken CMMG weights from running in auto. You can add me to the preorder list. Thanks There should be a dropdown menu on this page: https://borebuddy.com/product/22lr-bolt-weight/ Select "Heavy Duty (Stainless Steel)" to pre-order. |
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Quoted: Interesting video and information. It looks like it works great for taming bolt bounce. I am definitely interested. I would like to see the same test done with standard velocity ammunition. I'll see if I can get my hands on some for the next round of filming when I have the chrono set up. Either weight should run just fine with the ~1000 fps SV. I know that the CCI quiet that runs at about 700 does not cycle the AR in the stock configuration. |
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Order placed for the HD stainless. I think this may help if not cure my occasional light strike issue. Only happens when I shoot fast. I think the hammer is moving forward as the bolt is bouncing killing hammer energy when they meet or the bolt is still slightly out of battery from bouncing as the hammer strikes... |
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Quoted: I'll see if I can get my hands on some for the next round of filming when I have the chrono set up. Either weight should run just fine with the ~1000 fps SV. I know that the CCI quiet that runs at about 700 does not cycle the AR in the stock configuration. So far the only thing I have bought and used from Bore Buddy has been the charging handle insert and it works great with both my CMMG and my Chiappa bolt. I'm glad to see you guys making stuff for AR22's. Keep up the good work. |
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Very cool, Renaissance! You are on fire, sir. With the extra weight theoretically keeping the bolt shut longer, is the rifle any quieter with the weight? Also, I might just be really stupid, but what’s the weight on the HD unit? I’m very interested and still love my pressure plug. Thanks! |
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Quoted: Interested to see how it works with the Franklin Binary. Put in an order for the brass with weights. I am thinking it will run cleaner/quieter with less debris blowing back into the action. I will know very soon and can let you how it goes for me. Believe me it was hard to remember to not mention this to anyone as well as I had a heads up about him working on this weight. I'm looking forward to putting one through it's paces with the Franklin BFS3. |
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Very cool. I've been running the CMMG weight and auto trip kit for years in my dedicated .22lr upper on an RR M16 lower in FA. Guess I was one of the lucky ones who didn't have issues out of the box. Now I want to weigh the CMMG weight and see if yours is heavier. Thinking a heavier weight would keep the action closed a fraction of a second longer and help keep the action and FCG a little cleaner. ETA: any plans for an adjustable stainless weight? Not sure I want to run a brass weight in an FA set up. Usually do 300-700rds each range trip with it and thinking that might chew it up pretty quickly. |
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Quoted: Believe me it was hard to remember to not mention this to anyone as well as I had a heads up about him working on this weight. I'm looking forward to putting one through it's paces with the Franklin BFS3. I've been talking with people to try to find a machinist to make something like this economically for over two years. I'm giddy that this has been produced. |
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I've been in communication with the OP and plan on doing some testing in full auto. I will also be updating a webpage with any new info as I get it. For now, I posted up just some pictures of the weights I have on hand now: http://www.c3junkie.com/?page_id=712 It's been a while since I bothered to clock the cyclic rate on any of my 22kits...I never did a great job saving that information. I have at least 4 different 22LR uppers of various lengths. Next time I go out, I'll clock the Ciener and maybe my custom SS to see what I get. In some configurations the heavy may be too heavy to cycle reliably so it is nice that he is making his design adjustable.   Note that this is the same design as the one I broke above.    |
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I shoot standard velocity CCI in my match .22, so I'd be curious if it'll run with that kind of ammo. 85$ is a lot to spend on a BCG that already cost $170. I did not know the bolt was bouncing on these builds. Also, what is the big deal about dry-firing 22s? I shoot highpower and dry-firing during prep or even during the match is common. When I started shooting rimfire matches, I continued with the practice. It would be impractical to install a dry-firing device because of time limitations during matches. |
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Quoted: I shoot standard velocity CCI in my match .22, so I'd be curious if it'll run with that kind of ammo. 85$ is a lot to spend on a BCG that already cost $170. I did not know the bolt was bouncing on these builds. Also, what is the big deal about dry-firing 22s? I shoot highpower and dry-firing during prep or even during the match is common. When I started shooting rimfire matches, I continued with the practice. It would be impractical to install a dry-firing device because of time limitations during matches. Rimfire firing pin strikes outside of chamber face and damages firing pin. Peening is also an issue. I don't dry fire rimfire without an empty case or some kind of protection for the firing pin. |
| I will assign you a new project Renaissance man. I need a last round hold open that will work with the Black Dog 50 round drums. I have dreamed up a couple things in the past. But none were really feasible.. Maybe not a big enough audience for ample sales. But it would be nice to have something. |
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ETA: any plans for an adjustable stainless weight? Not sure I want to run a brass weight in an FA set up. Usually do 300-700rds each range trip with it and thinking that might chew it up pretty quickly. Yes, this is the next project. I've got a design that needs to be implemented that will integrate the wear point into the back plate so it will be replaceable at a low cost without having to replace a complex machined part. I imagine this is going to be a mid-summer release. The brass parts are a beta prototype of sorts and I do not have very many of them on hand. We decided to release them to judge interest before committing to a costly production run, and we'll be honoring warranty on the brass parts and replacing with stainess version should they wear out. |
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Quoted: Details on the cameras and settings? The camera is a Sony RX-100 Mark 7 and it's set to 960 frames per second at 1080P resolution. Each little clip spans about 1 second in real time and the files are about 1GB each (!!). The footage is then slowed down 40x to 24 frames per second. |
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Quoted: I always shoot suppressed 22LR. To that end, I use subsonic or called standard velocity ammo. Will it work with that? I saw you used high or hyper velocity ammo in the video. This is the same with me. All my malfunctions are for two reasons: 1) Defective ammo - Good dent on the rim but no bang. Most times, another fire attempt on a different part of the rim, the round fires. A few times, no joy at all. Using good ammunition instead of Remington Golden bullets or Winchester rounds makes this a very rare occurrence anymore. 2) Gun goes *click*. Bolt is slightly out of battery. This happens more often than I like, but it is fairly rare and annoying as hell. After watching the slo mo video, I think that these stoppages might be from similar bolt bounce. Not sure this is true given suppressed subsonic (Gemtech Subsonic) ammo creates the same bolt bounce as shown in the video. What do you think? |
| I think "full power" 40gr standard velocity at ~1000fps should work fine. That armscor ammo used in the video is only about 1150 from my upper, and it's a 10% lighter bullet. I'll run some CCI SV next trip out and get some footage -- I'm guessing SV will cycle with the 1.6oz weight no problem. We'll add weight to the adjustable one up as high as we can to see if we can stop the cycling. |
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Quoted: I think "full power" 40gr standard velocity at ~1000fps should work fine. That armscor ammo used in the video is only about 1150 from my upper, and it's a 10% lighter bullet. I'll run some CCI SV next trip out and get some footage -- I'm guessing SV will cycle with the 1.6oz weight no problem. We'll add weight to the adjustable one up as high as we can to see if we can stop the cycling. I'll be interested in seeing a video of the CCI SV as that is what I have found works best with my Ceiner/CMMG 4" suppressed setup running the Franklin BFS. I do experience an occasional out of battery ignition that catches my attention so I am hoping that problem will be eliminated while running cleaner/quieter. Then, I expect I'll find that I can reliably run a larger variety of ammo just by adjusting weights. I'm pretty excited about the potential here. |
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Quoted: What’s the benefit to the average basement dweller? I have 2 cmmg kits, a 4.5 and 9.2 or whatever and only run them suppressed. Noise reduction? Extractor wear? Reduced extractor wear and a bit quieter for suppressed due due to increased mass holding the bolt closed longer and the weight and buffer eliminating metal on metal impact at the rear of the bolt travel. I'm going to be testing accuracy and velocity the same day I do some SV testing, but my (very) preliminary tests indicated great potential. It seems to reduce vertical stringing and tighten groups up pretty nicely: 
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Quoted: I didn't watch the vid, link doesn't work for me, but I bought the bounce kit from CMMG which has a stiffer spring and a counter weight. Combined with a ST-T2 spikes buffer, I got my kit to blast through stacks of BDM mags with an Echo II trigger (also with a modified spring installed). I guess the buffer doesn't do anything, but it was needed for 5.56, so that is what is in there. I also put a quarter between the buffer and the bolt for the rimfire conversion. Whats the quarter do? I dont have a buffer tube in my ar22. |
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