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Posted: 5/4/2023 10:08:23 PM EDT
I have a MAX-11/15 inbound for my M11/9. It's the version that uses the M16 buffer & spring, so I thought I'd ask here. I'm hoping to tune it for a smooth, slow-ish rate of fire. I'm thinking somewhere around 600-650 RPM. I have seen reference to flat buffer springs, hydraulic buffers, etc. but I haven't paid that much attention previously, as all of my full-auto shooting to date has been with subguns.
So any suggestions for what I should be looking for? I've got an old AAC rate reducing buffer, which I'll try out. But I'm sure something else has come along in the 20 years since I bought that. |
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FL, USA
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Posted: 5/5/2023 1:48:06 PM EDT
[Last Edit: amphibian]
[#1]
Originally Posted By GarrettJ: I have a MAX-11/15 inbound for my M11/9. It's the version that uses the M16 buffer & spring, so I thought I'd ask here. I'm hoping to tune it for a smooth, slow-ish rate of fire. I'm thinking somewhere around 600-650 RPM. I have seen reference to flat buffer springs, hydraulic buffers, etc. but I haven't paid that much attention previously, as all of my full-auto shooting to date has been with subguns. So any suggestions for what I should be looking for? I've got an old AAC rate reducing buffer, which I'll try out. But I'm sure something else has come along in the 20 years since I bought that. Some points that come to mind.
 Also, since you mentioned LMG here are some pics of some testing I did, note that I'm getting great results even with a collapsible stock with this buffer and spring combo.  Same upper with a typical buffer / tube and spring you would find on an M4....very fast.  My favorite 5.56 upper is a 12.5 Mid. Super smooth and great cyclic rate.  |
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MI, USA
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Posted: 5/5/2023 4:06:29 PM EDT
[#2]
Originally Posted By GarrettJ: I have a MAX-11/15 inbound for my M11/9. It's the version that uses the M16 buffer & spring, so I thought I'd ask here. I'm hoping to tune it for a smooth, slow-ish rate of fire. I'm thinking somewhere around 600-650 RPM. I have seen reference to flat buffer springs, hydraulic buffers, etc. but I haven't paid that much attention previously, as all of my full-auto shooting to date has been with subguns. So any suggestions for what I should be looking for? I've got an old AAC rate reducing buffer, which I'll try out. But I'm sure something else has come along in the 20 years since I bought that. Keep in mind your non-IRM MAX-11/15, being, IIRC, piston operated, open bolt firing, has a somewhat different operating system than an M16 (D.I., closed bolt). Also, I don't believe that there were very many non-IRM MAX-11/15 uppers sold (and it appears to have been discontinued). As such, there does not appear to be much information about how to "tune" such an arrangement beyond adjusting the piston gas modulation. While some general facets of M16 tuning will undoubtedly transfer (the laws of chemistry and physics still apply), what works best or close to best may require some experimentation (with the concomitant cost in time and money). I might be wrong, but I think that being an open bolt operating system, bolt bounce should not be a concern. Disclaimer: I have no affiliation with or financial interest in any vendor or manufacturer. I am not a competitive shooter or a blogger who receives any form of compensation or sponsorship for endorsements, or favorable public or private comments. I do not have a website, podcasts, webinars, or online videos; or books/magazine articles. Use of vendor and/or product brand names, if any, is for informational purposes only; and products or services were purchased by me from regular commercial sources. Best of luck. MHO, YMMV, etc. Be well. |
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Posted: 5/5/2023 11:18:47 PM EDT
[#3]
@amphibian, thanks for the info. Your insight is always appreciated.
Quote HistoryOriginally Posted By SecondAmend: Keep in mind your non-IRM MAX-11/15, being, IIRC, piston operated, open bolt firing, has a somewhat different operating system than an M16 (D.I., closed bolt). Quote HistoryOriginally Posted By SecondAmend: Keep in mind your non-IRM MAX-11/15, being, IIRC, piston operated, open bolt firing, has a somewhat different operating system than an M16 (D.I., closed bolt). Very true. But it’s the closest system that I’m aware of, so it at least gives me a starting point. Originally Posted By SecondAmend:Also, I don't believe that there were very many non-IRM MAX-11/15 uppers sold (and it appears to have been discontinued). As such, there does not appear to be much information about how to "tune" such an arrangement beyond adjusting the piston gas modulation. You’re likely right on the small number manufactured. While it has been removed from the website, I was still able to order one. Jackie tells me they have enough parts to build a few more. I figured since I had drilled the hole in my M11/9 receiver 20 years ago I might as well use it. The adjustable gas block in addition to allowing for changes in buffers & springs should provide a bit more flexibility in how it can be tuned. I’ll report back what I’m able to come up with. |
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CT, USA
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Posted: 5/6/2023 6:57:15 AM EDT
[#4]
Are you going to be running a full-length buffer tube (fixed stock) or the shorter collapsible stock one? With a full-length buffer tube it's easier to get the cyclic rate down due to the extra room available and the old AAC rate reducer worked really well in my experiments. Even better was the original LMG hydraulic buffer. They're hard to find these days, but still work well.
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Posted: 5/6/2023 8:02:45 AM EDT
[#5]
I’m planning to use a collapsible stock if I can get the ROF I want with it.
I used to run an A1 stock with the TASK setup on the M11/9. But since the distance from the grip to the rear of the receiver is longer than on an M16, the rifle stock makes for a really long LOP. I’ve got the AAC buffer for both rifle and CAR length buffer tubes, so I can try both out. |
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Posted: 5/19/2023 8:02:56 PM EDT
[Last Edit: GarrettJ]
[#6]
Ok, some info. MAX-11/15 upper arrived yesterday. I was able to try out the supplied M4 buffer and spring as well as the AAC rate reducing buffer and spring.
The M4 spring feels pretty stiff, which would usually increase the ROF. Alternately, the AAC spring was so soft/weak, that I was getting failures to fire with it. It’s probably just great with an M16 where it just has to strip a round and feed it into the chamber. With the Lage open bolt system, it needs to slam forward hard enough for the firing pin to set off the primer. Shooting 55 gr. Wolf Military Classic, the standard M4 buffer ran at 762 RPM. The AAC buffer and spring ran at a sedate 550 RPM, but I had a handful of light primer strike failures. I tried the AAC buffer with the stiff M4 spring and got 677 RPM. I bought a Kynshot RB5007 and the Tubb flat wire spring, but I still need to get an A5 buffer tube for them. The AAC buffer would not fit in the Tubb spring. I may also check some of my other M4 length springs and see if I have a weaker one. As noted, the spring that came with the upper feels extra stiff. It might be an extra power spring, to ensure good ignition. Something else to play with. |
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Posted: 5/24/2023 9:17:38 PM EDT
[Last Edit: GarrettJ]
[#7]
Wednesday update: the A5 buffer tube arrived today. So I swapped tubes, installed the Kynshot RB5007 and Tubb flat wire spring and headed off to the range.
I did not bring the timer, so I didn’t get a chance to check ROF. Set up this way, the gun felt pretty good and the ROF felt like it was in the right place. However, I had a number of failures to fire. I was shooting Fed 5.56 and some of my reloads using Rem 7-1/2 primers. All of the failed rounds but one fired when I tried again in an AR15. But none would fire if tried a second time in the MAX11/15. The problem is this system needs to slam the bolt carrier forward with more force than an AR15 or M16 does. The MAX11/15 uses a modified AR15 firing pin. It won’t protrude from the bolt face until the bolt rotates into the locked position. So in addition to stripping and chambering the round like an AR15/M16, the bolt also has to retain enough energy to reliably ignite the firing pin, just as the bolt locks. Looking at the Tubb website, the flat wire spring reportedly uses less energy to close the bolt, reducing the amount of forward “lurch” felt as the bolt carrier cycles forward. This is counter to what the MAX11/15 needs. Eta: the above was not correct. The Kynshot buffer does work with a standard spring. It’s the AAC buffer that won’t fit on the flat wire spring. |
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FL, USA
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Posted: 5/25/2023 5:58:21 AM EDT
[#8]
Quote HistoryOriginally Posted By GarrettJ: Wednesday update: the A5 buffer tube arrived today. So I swapped tubes, installed the Kynshot RB5007 and Tubb flat wire spring and headed off to the range. I did not bring the timer, so I didn't get a chance to check ROF. Set up this way, the gun felt pretty good and the ROF felt like it was in the right place. However, I had a number of failures to fire. I was shooting Fed 5.56 and some of my reloads using Rem 7-1/2 primers. All of the failed rounds but one fired when I tried again in an AR15. But none would fire if tried a second time in the MAX11/15. The problem is this system needs to slam the bolt carrier forward with more force than an AR15 or M16 does. The MAX11/15 uses a modified AR15 firing pin. It won't protrude from the bolt face until the bolt rotates into the locked position. So in addition to stripping and chambering the round like an AR15/M16, the bolt also has to retain enough energy to reliably ignite the firing pin, just as the bolt locks. Looking at the Tubb website, the flat wire spring reportedly uses less energy to close the bolt, reducing the amount of forward "lurch" felt as the bolt carrier cycles forward. This is counter to what the MAX11/15 needs. Quote HistoryOriginally Posted By GarrettJ: Wednesday update: the A5 buffer tube arrived today. So I swapped tubes, installed the Kynshot RB5007 and Tubb flat wire spring and headed off to the range. I did not bring the timer, so I didn't get a chance to check ROF. Set up this way, the gun felt pretty good and the ROF felt like it was in the right place. However, I had a number of failures to fire. I was shooting Fed 5.56 and some of my reloads using Rem 7-1/2 primers. All of the failed rounds but one fired when I tried again in an AR15. But none would fire if tried a second time in the MAX11/15. The problem is this system needs to slam the bolt carrier forward with more force than an AR15 or M16 does. The MAX11/15 uses a modified AR15 firing pin. It won't protrude from the bolt face until the bolt rotates into the locked position. So in addition to stripping and chambering the round like an AR15/M16, the bolt also has to retain enough energy to reliably ignite the firing pin, just as the bolt locks. Looking at the Tubb website, the flat wire spring reportedly uses less energy to close the bolt, reducing the amount of forward "lurch" felt as the bolt carrier cycles forward. This is counter to what the MAX11/15 needs. The Kynshot buffer doesn't seem to fit in a standard buffer spring. Anyone know what other springs work with it? It doesn't appear that he has the .308 Tubb spring. That is their strongest. I would suggest trying that with the RB5007. I have to use that spring in my full auto 7.62x39 setups to have enough force to strip rounds off the rough comm block feed lips of AK mags/drums. I also use it with my Shrike to strip rounds from the belt. |
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Posted: 5/25/2023 10:39:46 AM EDT
[Last Edit: GarrettJ]
[#9]
Thanks for the additional info.
Looking at the video on Tubb’s website, they state the AR15 spring works in both carbine and rifle buffer tubes, but the longer AR10 spring is only for rifle tubes. Worst case, I could get one and clip coils. Also, looking at springs it appears the spring supplied from Lage is an extra power buffer spring. Pulling springs from a couple AR15s to compare, the Lage-supplied spring is longer, has wider spacing between coils, and feels stiffer than the standard M4 buffer springs. I imagine this was to ensure adequate force to ignite the primer. I’ll have to bring a pile of buffers and springs to the range and do some more testing to see what I can get to run. |
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FL, USA
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Posted: 5/25/2023 11:39:41 AM EDT
[#10]
Quote HistoryOriginally Posted By GarrettJ: Thanks for the additional info. Looking at the video on Tubb's website, they state the AR15 spring works in both carbine and rifle buffer tubes, but the longer AR10 spring is only for rifle tubes. Worst case, I could get one and clip coils. Also, looking at springs it appears the spring supplied from Lage is an extra power buffer spring. Pulling springs from a couple AR15s to compare, the Lage-supplied spring is longer, has wider spacing between coils, and feels stiffer than the standard M4 buffer springs. I imagine this was to ensure adequate force to ignite the primer. I'll have to bring a pile of buffets and springs to the range and do some more testing to see what I can get to run. |
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Posted: 5/26/2023 10:56:55 PM EDT
[Last Edit: GarrettJ]
[#11]
More shooting today:
I was shooting reloads using a 55 gr. FMJ over 26.5 gr. of WC-846. I haven't shot it over the chronograph from the Lage upper, but from a 10.5" rifle these produced 2740 fps. All shooting was done with the A5 buffer tube. I found I do have enough travel in the bolt carrier group that I can run a standard carbine buffer and not crash anything I'm not supposed to. So that should give me a little more flexibility. I ended up swapping around between the Kynshot buffer, AAC buffer, Lage supplied extra power spring, and a standard "milspec" carbine spring. The gas port was opened to 7 clicks for all tests. Here's what I came up with: Buffer: Kynshot RB5007 (6.1 oz) Spring: "milspec" carbine ROF: 658 Buffer: Kynshot RB5007 (6.1 oz) Spring: extra power carbine ROF: 727 Buffer: AAC (5.4 oz) Spring: extra power carbine ROF: 686 And just for fun, I threw a silencer on there. The only "full auto rated" rifle silencer I have is a Triple-X Warrior that was built probably 20+ years ago. The thing is a tank. It's also as heavy as a tank. But it has a relatively large aperture through the baffles (I shoot .30 caliber through it), so I figured the back pressure shouldn't be too excessive. But the roughly 150 RPM increase was a little more than I had expected. I could probably turn the gas block down a few clicks and slow it back down. Buffer: AAC (5.4 oz) Spring: extra power carbine Silencer: Triple-X Warrior ROF: 842  |
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Posted: 5/26/2023 11:06:02 PM EDT
[#12]
Both the standard "milspec" carbine spring and the extra power spring reliably stripped and fired rounds. No light strikes today.
I apparently missed testing the milspec spring with the AAC buffer. Based on what I'm seeing, that one should be a bit slower. Probably due to the combination of the softer spring and the longer travel from the buffer being shorter. Even though the Kynshot buffer / milspec spring gave the slowest results, I thought the AAC buffer / extra power spring felt a little smoother. I was also thinking about trying a standard 9mm buffer. But the one I weighed was the same 5.4 oz as the AAC buffer. I know the M16 gets "bouncy" when the weight gets too heavy, without going to some sort of hydraulic or sliding weight buffer. I wonder if the open bolt setup has that same issue, though. No bolt bounce issues to worry about, since it slam fires just as the bolt locks. |
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FL, USA
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Posted: 5/27/2023 6:05:42 AM EDT
[#13]
Great info. Note that Droppoint's website does mention that he didn't like the hydraulic buffers unless they were used with the flat wire spring. Would be curious how a .308 Tubb spring would function with your setup.
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Posted: 7/14/2023 8:52:46 PM EDT
[#14]
I had some stuff I was ordering from Midway so I added a Tubb .308 spring. When I received it, I compressed it over the Kynshot RB5007 buffer and confirmed the buffer would bottom out before the spring goes solid.
Up to this point I’ve settled on the AAC buffer and the extra power spring that came with the upper. Recall that gave 686 RPM. I installed the .308 spring and Kynshot upper in the gun and headed to the range. I also brought the AAC buffer & Lage spring so I could compare how they felt. Unfortunately, I failed to bring the M16 wrench and couldn’t loosen the castle nut from the buffer tube to remove the stock adapter. Oh well, maybe next time. I’m happy to report the new setup felt fairly smooth, and had a ROF of 679. Better yet, when I screwed on the Triple-X silencer, the ROF only increased to 727 RPM. I only ran around 90 rounds today, but had zero failures to fire, shooting both singles and bursts. I’ll have to put more rounds through this setup, but so far it’s looking promising. While I do like how the AAC buffer feels, I had one of those break once. AAC replaced it free, but I believe those buffers have been out of stock for years now. And AAC today is not the same company it was then. So getting similar results with something that can be replaced is a good thing. |
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FL, USA
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Posted: 7/18/2023 7:55:58 AM EDT
[#15]
Quote HistoryOriginally Posted By GarrettJ: I had some stuff I was ordering from Midway so I added a Tubb .308 spring. When I received it, I compressed it over the Kynshot RB5007 buffer and confirmed the buffer would bottom out before the spring goes solid. Up to this point I've settled on the AAC buffer and the extra power spring that came with the upper. Recall that gave 686 RPM. I installed the .308 spring and Kynshot upper in the gun and headed to the range. I also brought the AAC buffer & Lage spring so I could compare how they felt. Unfortunately, I failed to bring the M16 wrench and couldn't loosen the castle nut from the buffer tube to remove the stock adapter. Oh well, maybe next time. I'm happy to report the new setup felt fairly smooth, and had a ROF of 679. Better yet, when I screwed on the Triple-X silencer, the ROF only increased to 727 RPM. I only ran around 90 rounds today, but had zero failures to fire, shooting both singles and bursts. I'll have to put more rounds through this setup, but so far it's looking promising. While I do like how the AAC buffer feels, I had one of those break once. AAC replaced it free, but I believe those buffers have been out of stock for years now. And AAC today is not the same company it was then. So getting similar results with something that can be replaced is a good thing. That is great to hear. Now I have had the head of (3) RB5007 buffers fall off and each time they were replaced I was told they have made improvements to fix and could see small changes on how it was secured. I have to have another one fail but I also may not have shot as much either. I personally believe the benefits outweigh any reliability concerns. |
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Posted: 7/19/2023 12:08:54 PM EDT
[#16]
since you’re kinda on same topic as i have a question for - i have the max11/15 and the included BCG spring is getting wonky and bent up.
anyone know what type or have a link for me to buy replacement springs? was thinking mcmaster carr would have em but so many options and i don’t have a caliper. thanks in advance, not trying to pay 3x price from lage. |
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MI, USA
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Posted: 7/19/2023 1:36:09 PM EDT
[#17]
Quote HistoryOriginally Posted By swolliepop: i don’t have a caliper. . I believe that a digital caliper suitable for such measurements can be had for about $25 or less. Best of luck with your endeavors. MHO, YMMV, etc. Be well. |
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Posted: 7/19/2023 8:34:36 PM EDT
[#18]
Quote HistoryOriginally Posted By SecondAmend: I believe that a digital caliper suitable for such measurements can be had for about $25 or less. Best of luck with your endeavors. MHO, YMMV, etc. Be well. lol, thanks....I shall find my local friends that has one to measure for me. God knows I'd somehow fuck it up! |
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NH, USA
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Posted: 9/17/2023 10:55:50 PM EDT
[#19]
Garrett, have you been playing with the gas adjustment screw on the gas block? Certainly, the gas needs to be enough to get a full stroke, but not so much to have the buffer strike the back of the receiver extension with any force. The volume of gas would certainly be another variable along with the spring rate and buffer mass.
With the additional mass of the sear catch/fixed firing pin attached to the bolt carrier, along with the required extra energy to push the firing pin into the primer, might change the mass requirements for the buffer. If I was going to buy a Max-11/15 I would go the route you are going. I think with some time and tuning, I think that you will have a great 5.56X45 open bolt machinegun. Good luck with the tuning. Scott |
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USA
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Posted: 1/12/2024 10:07:29 AM EDT
[#20]
This follow up question sort of fits here, rather than starting a new thread...
Paging @amphibian I've switched my MCR/Shrike over to Amphibian's recommended A5/308 Tubb/RB5007 setup. The recoil impulse has smoothed out drastically and I'm running .09 sec spits in auto (~666 rpm) using M193. Much less jumpy and easier to keep on target than before. I love it. However, I've lost some reliability in stripping the rounds out of the links. They seem to get hung up frequently, especially after I get one or two good bursts in and things start getting hot/dirty. I did not used to have this issue. I'm considering a buffer/spring change to address this, but I don't want to get too far away from Amphibian's set up given I like the RoF and smoothness. @Amphibian - have you found in your testing that the Kynshot buffers make more of a difference or do the Tubb springs make more of a difference for RoF and feel? In other words, in this system with multiple components, which component is the most important to achieving the end result? I may try and change whichever is the less critical component (back to the Ares spring or back to the heavier MGI buffer) to see if my feeding improves. |
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FL, USA
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Posted: 1/12/2024 11:36:04 AM EDT
[#21]
Quote HistoryOriginally Posted By TyrannyOfTheMinority: This follow up question sort of fits here, rather than starting a new thread... Paging @amphibian I've switched my MCR/Shrike over to Amphibian's recommended A5/308 Tubb/RB5007 setup. The recoil impulse has smoothed out drastically and I'm running .09 sec spits in auto (~666 rpm) using M193. Much less jumpy and easier to keep on target than before. I love it. However, I've lost some reliability in stripping the rounds out of the links. They seem to get hung up frequently, especially after I get one or two good bursts in and things start getting hot/dirty. I did not used to have this issue. I'm considering a buffer/spring change to address this, but I don't want to get too far away from Amphibian's set up given I like the RoF and smoothness. @Amphibian - have you found in your testing that the Kynshot buffers make more of a difference or do the Tubb springs make more of a difference for RoF and feel? In other words, in this system with multiple components, which component is the most important to achieving the end result? I may try and change whichever is the less critical component (back to the Ares spring or back to the heavier MGI buffer) to see if my feeding improves. You will have issues if you do NOT run domestic brass cased ammo. I suspect if you did stretch and / or lube links you could get more reliability. If you don't want to do either then maybe consider using the Ares / Fightlite spring in conjunction with the RB5007 |
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USA
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Posted: 1/12/2024 10:43:42 PM EDT
[#22]
Quote HistoryOriginally Posted By amphibian: I've posted before that I do NOT stretch my links....nor do I lube them. I also mentioned that I use the .308 Tubb flat spring for more power to strip the links not the standard 556 Tubb spring (we should probably be discussing in the other Shrike / MCR specific thread). You will have issues if you do NOT run domestic brass cased ammo. I suspect if you did stretch and / or lube links you could get more reliability. If you don't want to do either then maybe consider using the Ares / Fightlite spring in conjunction with the RB5007 Yep- tracking you do not stretch your links. I’m of the same mind. If I have to resort to that level, it’s a nonstarter for me given the quantity of links I have. I run exclusively quality brass cased stuff, most often M855. I am running the 308 Tubb as you suggested. If you think the lesser of the evils is swapping springs vs swapping back to the heavier buffer, I may try the Ares spring with the Kynshot and see what detriment there is to the RoF and smoothness. Lubing the links may be an option too- I’ve been noodling on that some but have not tried it out. In a perfect world, I’d like to not to have to give the ammo any special treatment. |
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CT, USA
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Posted: 1/13/2024 7:18:05 AM EDT
[#23]
FWIW, do your links have holes in them? Way back when the Shrike was new there was discussion about a specific batch of links that were intended for the HK 23E and had more tension on the ammo than standard US links. They were identified by having a round hole in the body of the link. Checking your links and setting any such aside might help with your reliability.
Like Amphibian, I do not stretch, lube or even clean links. I just knock any loose dirt off them, relink the ammo and go shoot. I mostly use Tula or Wolf steel-cased stuff and the old Shrike eats it up just fine. |
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USA
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Posted: 1/13/2024 11:07:53 AM EDT
[#24]
Quote HistoryOriginally Posted By Silverbear_51: FWIW, do your links have holes in them? Way back when the Shrike was new there was discussion about a specific batch of links that were intended for the HK 23E and had more tension on the ammo than standard US links. They were identified by having a round hole in the body of the link. Checking your links and setting any such aside might help with your reliability. Like Amphibian, I do not stretch, lube or even clean links. I just knock any loose dirt off them, relink the ammo and go shoot. I mostly use Tula or Wolf steel-cased stuff and the old Shrike eats it up just fine. Nope, no holes in my links. Standard M27 links. FWIW, like yours my MCR has always done fine- no real issues stripping or feeding rounds historically, and I’ve had it running in auto for about 6 years with other buffers. It’s only with my recent buffer/spring change to @Amphibian ‘s recommendation that I’m now sacrificing feeding reliability in order to gain a nice RoF and recoil. I’m trying to have my cake and eat it too I suppose- reliability AND smooth action. : ) |
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FL, USA
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Posted: 1/13/2024 11:38:07 AM EDT
[#25]
Someone posted before that they didn't like the term 'stretching' the links and said it should be called 'conditioning'.
I think a case can be made for that considering if you are using used links, they could be stepped on and what not. I use a magnet on a stick and have been re-using the same links for a long time. I can feel some are tighter than others but don't care. I'm sure the cyclic rate does slow down when hitting the tighter links. I would think if did want a consistent rate, you really should use consistent links like others mentioned.... I personally never cared that much to do it as it is just a toy but I would think if are really serious about consistency it should be considered. Not everyone runs brand new never fired links w/ LC M8155. |
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CT, USA
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Posted: 1/13/2024 1:49:27 PM EDT
[#26]
Could we get a little more specific about the rounds getting "hung up"? What do things look like when the gun stops functioning? Are you using a bullet guide in the top cover?
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USA
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Posted: 1/15/2024 11:37:43 AM EDT
[#27]
Quote HistoryOriginally Posted By Silverbear_51: Could we get a little more specific about the rounds getting "hung up"? What do things look like when the gun stops functioning? Are you using a bullet guide in the top cover? I am not using a bullet guide in the top cover, though I'm considering trying one just to see if it controls the round into the chamber a little more smoothly. But I have not yet. The cartridge gets about half or 2/3 of the way out of the links, nose dives into the chamber, with the ass end (still through the first ring on the link) sticking up through the slot in the feed tray. I am NOT getting tips of bullets impacting on the top of the chamber/barrel/receiver area (nor have I ever). Next time I'm fooling with it, I'll snap a pic if you like. Again, the gun has historically fed from links fine but for my change to the new buffer setup. So the cause of the problem is not a mystery. Just exploring options that might help improve the feeding issue I've caused with the change so I can still keep the buffer config - as @Amphibian has said in many threads, it is niiiiiiiice. But I'm not going down the stretching link route. I'll change the buffer back before I do that. |
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CT, USA
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Posted: 1/16/2024 9:04:26 AM EDT
[#28]
Did you change the buttstock also when you changed the buffer and spring?
Have you taken a look inside the top cover? You have been running the upper for a while and it's possible that one of the small parts/springs controlling the cartridge as it gets pushed forward into the chamber has worn or broken. |
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USA
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Posted: 1/18/2024 1:15:09 PM EDT
[#29]
I did not change the stock itself (though I'm legitimately curious why you thought that might be a factor), but did change to an A5 length buffer tube per Amphibian's set up (A5/308 Tubb spring/Kynshot RB5007).
Looking at the feed pawls and mechanisms inside the top cover everything seems to be in working order. I had a thought last night and put the supplied spacer from fightlite (for the carbine buffer tube) in there with the new configuration thinking restricting the space that 1/8" might give the spring just enough oomph do get the job done. Seems to work when hand cycling. That was not always the case before I put it in there. A live fire test will tell the tale. |
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CT, USA
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Posted: 1/19/2024 7:50:39 AM EDT
[#30]
My apologies- I should have said "buffer tube" or "receiver extension" instead of buttstock. Since the A5 buffer tube is a different length than the regular carbine-type buffer tube, is can effect the travel of the buffer and bolt carrier assembly back and forth. The AR15 system doesn't allow for a lot of extra travel as the BCA goes to the rear. A little too much and your carrier is banging into the "loop" on your lower receiver. Too little and the bolt doesn't properly pick up the back end of the cartridge and feed it into the chamber. You want as much travel to the rear as possible so the bolt has a little running start before it starts pushing the cartridge forward. This is good when feeding rounds from a magazine and even better when pushing rounds out of a link.
When I am trying out a new buffer or a new buffer tube, I drop the buffer in without the spring, then push the BCA in to see how far it will go (with the buffer compressed if you're using a hydraulic or spring-loaded one). I then add spacers (usually quarters) so I have about 1/8" of clearance between the BCA and the loop on the receiver. Depending on how they are threaded, buffer tubes can vary in length a bit when they are installed and it's good to be sure you are set up for the proper distance to get maximum movement out of the system without endangering your precious lower receiver. |
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USA
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Posted: 1/19/2024 4:21:24 PM EDT
[#31]
Yep, tracking on all that. The A5 tube having more space, in conjunction with the new (appropriate length for the A5) buffer and big ass 308 spring, is what @Amphibian rightly deduced helps bring the rate of fire down/smooths things out.
The MCR/Shrike DOES INDEED have a very narrow operation window like you say. My bolt carrier travel (when having done the same test you described above) fits in that small window. I initially left the spacer out with the same line of thinking: give it max rear travel to have a running start. Since my feeding was compromised in that config, I figured I'd try it adding the buffer. Line of thinking being the spring is ever so slightly more compressed, so it might be ever so slightly extra spring-y to push the cartridge out of the links. Not being a spring expert, I don't know if that theory holds water or not but figured it's worth a try. It would certainly be a minor difference if at all, so we shall see. Without the spacer, I don't get contact on the rear of the receiver but the gap I have is minuscule. We'll see if adding the spacer helps my feeding issues or not, but a little extra gap is good insurance as you point out. |
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CT, USA
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Posted: 1/19/2024 5:45:03 PM EDT
[#32]
Crap- I'm rapidly running out of ideas. Good luck is all I can offer right now.
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USA
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Posted: 1/19/2024 9:26:35 PM EDT
[#33]
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TX, USA
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Posted: 3/17/2024 9:34:13 PM EDT
[#34]
Maybe try the Geissele Super 42 spring? Ever since I started using it my MCR has no problems stripping round from the links. It's tight on the inside; I had a VLTOR stainless steel A5 buffer turned down a few thousandths so it would fit inside the spring, but any aluminum buffer I tried fit just fine.
I had zero luck with either of Tubb's 5.56 or 308 springs in the MCR. I even hate moving them between lowers because those flat edges hang up on the buffer retaining pin. Not sure if I'll ever find a use for those PITA. The linked CBC ammo I've been using has really tight links so that's what prompted the switch for me, but overall reliability has improved with used links as well. I'm using a heavy SS A5H4 buffer since I pretty much always shoot suppressed and I can't say that it's the smoothest shooting but it's not too bad and the ROF is somewhere between 600-700 based on the split times for ten round bursts. I can't really go with the mad scientists on this quest for the ultimate slow and smooth MG since I'm not an SOT or machinist so I'm stuck with whatever parts the market deigns to provide us, but I wish them the best of luck. |
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TX, USA
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Posted: 3/17/2024 9:41:14 PM EDT
[#35]
Quote HistoryOriginally Posted By TyrannyOfTheMinority: Without the spacer, I don't get contact on the rear of the receiver but the gap I have is minuscule. We'll see if adding the spacer helps my feeding issues or not, but a little extra gap is good insurance as you point out. That minuscule gap disappears when you fire the thing. The buffer bumper doesn't seem to have any give but it do. I have a receiver with the scars to prove it. It probably doesn't help the bolt carrier either. Fortunately this was before I got my M16 and really turned on the battering ram. |
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MI, USA
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Posted: 3/17/2024 9:53:59 PM EDT
[#36]
Quote HistoryOriginally Posted By TheBrandonEntity: ... I had zero luck with either of Tubb's 5.56 or 308 springs in the MCR. I even hate moving them between lowers because those flat edges hang up on the buffer retaining pin. Not sure if I'll ever find a use for those PITA. .... FWIF, KAK Industry sells ($4.95) or you can 3D print for free (well, the cost of the resin) using the file linked on their website a tool to assist the installation and removal of AR flat wire recoil springs. I don't care for flat wire AR recoil springs, so I can't say how well the tool works. The tool is in the Accessories, Gunsmithing Tools section. Good luck. MHO, YMMV, etc. |
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