toothandnail 275 Posted October 21, 2013 Report Share Posted October 21, 2013 We received a BR-99 Friday, so we immediately tore it down to see how it compares to the MKA. First off it appears that there have been a few improvements over the MKA's forend design. The BR-99 has a much sturdier one piece forend as well as the obvious bonus of a picatinny rail on top. Another improvement would be the folding feed ramps. This allows the user to remove the bolt without the need to remove the lower. Pictures of both feed ramps up and down as well as a top view. After tear-down we began comparing parts from the BR-99 and both versions of the MKA. The bolt and bolt carrier from the BR-99 are from the Pre-XN MKA. The pre-XN gun had an offset on the bolt carrier just the same as the BR-99 Bolt Carrier shown below. The drive block from the BR-99 is an exact copy of the Pre-XN drive block with the exception of the slot milled in the top side. I assume this was done to try to avoid the fractures that were common on the Pre-XN model guns. The gas block location was also a shock. The BR-99 gas block location is the same as the Pre-XN barrel. Below, from top to bottom: Pre-XN, BR-99, then XN. The bolt handle is identical to the pre-XN bolt handle as well. Below, front to back: XN bolt handle, BR-99, then the Pre-XN. The butt pads are different on the stocks, both in construction and mounting. While the BR-99 looks like it would have a better recoil pad due to its size, it is actually harder than the MKA pads. The majority of the BR-99 butt pad is actually a hollow construction over-molded in rubber giving the illusion of a thicker pad. 1 Quote Link to post Share on other sites
toothandnail 275 Posted October 21, 2013 Author Report Share Posted October 21, 2013 Thankfully BR-99 does not use the pre-XN trigger group. The triggers themselves are not much different between the XN and BR-99. The biggest difference would be the thickness of the dis-connector and profile of the hammer. BR-99 Dis-connector: 0.137” XN Dis-connector: 0.117” The hammer profile differs where the hammer contacts the bolt carrier as well as having a smooth radius on the lower portion of the hammer. Pictures below of the Pre-XN hammer, BR-99, then XN hammer. Then the lower portion of the BR-99 and XN hammer. I am sure I left something out. If you want any pictures of anything else let me know. As of now most all of the MKA parts will interchange with the BR-99. Exception being grip adapter and stock adapter. Sadly, there is and prolly will never be a cheap way to install an aftermarket stock and grip. We currently are not really impressed by the "improvements" made. Obviously stock for stock the BR-99 has a slight advantage. As soon as you break into the modifications, the MKA takes it hands down. 1 Quote Link to post Share on other sites
bofor 7 Posted October 21, 2013 Report Share Posted October 21, 2013 Well done Matt, this is just what I was looking for, especially the stock part about not being able to change it to aftermarket. The best bit looks like the feed ramp. Quote Link to post Share on other sites
Flatland Shooter 22 Posted October 21, 2013 Report Share Posted October 21, 2013 The best bit looks like the feed ramp. With a little luck, maybe we will see someone offering this as an aftermarket upgrade. As long as it doe NOT adversely affect reliability, I would like it on my MKA 1919. Quote Link to post Share on other sites
ShadowFire 220 Posted October 21, 2013 Report Share Posted October 21, 2013 Well done Matt, this is just what I was looking for, especially the stock part about not being able to change it to aftermarket. The best bit looks like the feed ramp. Well from the topic I read on here you can but the tolerances/allowances are tighter and you need to take better care of your measurements before you make the cut. I would likely error on the plus side of the median measurement. It's like I tell the newer students at the school when they get out in the shop, you can take it off better than you can put the material back on. Quote Link to post Share on other sites
Rebel Katt 6 Posted October 21, 2013 Report Share Posted October 21, 2013 Old news... Anubis covered all this about a month ago... R K Quote Link to post Share on other sites
AR-12 Shotgun 16 Posted October 21, 2013 Report Share Posted October 21, 2013 Thanks Matt. Best side-by-side comparison so far. Quote Link to post Share on other sites
JeremyT 15 Posted October 21, 2013 Report Share Posted October 21, 2013 Old news... Anubis covered all this about a month ago... R K Insert suckling sounds here................ Quote Link to post Share on other sites
Rebel Katt 6 Posted October 21, 2013 Report Share Posted October 21, 2013 Bwahaha! Quote Link to post Share on other sites
bofor 7 Posted October 21, 2013 Report Share Posted October 21, 2013 Old news... Anubis covered all this about a month ago... R K Your turn to suckle now, what goes around comes around. 1 Quote Link to post Share on other sites
Brett248Vista 5 Posted October 21, 2013 Report Share Posted October 21, 2013 Matt, Thanks for the comparo. The ability to turn the feed lips down is "neat" but also not needed, if you know how to take your MKA apart, breaking the lips would be a non issue. I've had mine apart a bunch of times already with no issues. Competition is a good thing though, and it's nice that consumers have some choices. This market is still really untapped..There is room for lots more magazine fed Semi Auto Shotguns! Quote Link to post Share on other sites
Rebel Katt 6 Posted October 21, 2013 Report Share Posted October 21, 2013 Old news...Anubis covered all this about a month ago...R KYour turn to suckle now, what goes around comes around. I leave that all to you Lapdogs. RK Quote Link to post Share on other sites
toothandnail 275 Posted October 21, 2013 Author Report Share Posted October 21, 2013 Matt, Thanks for the comparo. The ability to turn the feed lips down is "neat" but also not needed, if you know how to take your MKA apart, breaking the lips would be a non issue. I've had mine apart a bunch of times already with no issues. Competition is a good thing though, and it's nice that consumers have some choices. This market is still really untapped..There is room for lots more magazine fed Semi Auto Shotguns! I agree, I wonder how long till we get " I had the feed ramp partially up, slammed the bolt closed and damaged them" questions. Until I see something different, I'll still be recommending the MKA over the BR, now if you want to keep a basically stock gun, the BR MAY be as good, we will be doing a Side-By-Side shooting comparison later today. Starting with 1300PFS and working down to 1145's. The BR has already had a few rounds down the pipe as it is a customers gun, he shot it a few times before sending it in. Quote Link to post Share on other sites
toothandnail 275 Posted October 21, 2013 Author Report Share Posted October 21, 2013 I knew I was forgetting something, The BR safety is the same as the Pre-XN, UN-captured spring and ball, no big deal, it does operate somewhat harder. and you must be more careful with dis-assembly as to not lose the spring, ball, or set screw. 3 small parts to keep track of. It can be easily changed out for a captured one, and smoother operation. Quote Link to post Share on other sites
toothandnail 275 Posted October 21, 2013 Author Report Share Posted October 21, 2013 Test firing is done, here was the process and why. Originally we were going to start with 1300FPS, but the MKA XN , will run those about 99.8% right out of the box. And since the BR is advertised as having an IMPROVED gas system, we figured start them both on 1200FPS. Shells the NEW Winchester Universal 1200 FPS bulk pack from Walmart. Firing 5 rounds each from factory mags, switching mags after every 5 rounds, to eliminate any mag related problems. This test was performed with the 2 guns we had here in the shop. Each gun is slightly different and your results may vary. Results MKA 1919XN; (NIB) We fired 25 rds total 1st Mag: 1 Failure to Feed, 1 Failure to Lock Back 2nd Mag: 1 Failure to Feed 3rd Mag: 1 Failure to Feed 4th Mag: 100% 5th Mag: 100% All failure to feeds were on the first rd of each mag. BR-99; (Roughly 5 rds previously fired from owner) We fired 50 rds total 1st Mag: 5 Failures to Feed, 1 Failure to Lock Back 2nd Mag: 5 Failures to Feed, 1 Failure to Lock Back 3rd Mag: 4 Failures to Feed, 1 Failure to Lock Back 4th Mag: 3 Failures to Feed, 1 Failure to Lock Back 5th Mag: 1 Failure to Feed, 1 Failure to Lock Back 6th Mag: 3 Failures to Feed, 1 Failure to Lock Back 7th Mag: 2 Failures to Feed, 1 Failure to Lock Back 8th Mag: 3 Failures to Feed, 1 Failure to Lock Back 9th Mag: 2 Failures to Feed, 1 Failure to Lock Back 10th Mag: 1 Failure to Lock Back The BR-99 gas system has been improved from the Pre-XN MKA but it still takes a much longer break-in period than the newer XN model MKA. The XN MKA is the obvious choice for out of the box reliability. Quote Link to post Share on other sites
Rebel Katt 6 Posted October 22, 2013 Report Share Posted October 22, 2013 And...Cue sycophants... Quote Link to post Share on other sites
Brett248Vista 5 Posted October 22, 2013 Report Share Posted October 22, 2013 My personal experiance with my 1919XN this weekend shooting Federal Super X 2 3/4 Foster Slugs Out of all four magazines (all the new model mags that do not designate 2 3/4 or 3") the first four rounds out of each magazine fed properly. On each magazine the last round would stand up and stove pipe. Not sure what is causing the last round to stand up so much. When I load the mags I tap the backside of the mag to seat all the rounds. None of this was done "Rapidly" this was all done in normal shooting fashion Quote Link to post Share on other sites
toothandnail 275 Posted October 22, 2013 Author Report Share Posted October 22, 2013 Your nose up jam is caused by the shell not being presented high enough for the bolt to pick up the rd. The bolt passes over the rd, the friction between the bolt and the rd strips it off the magazine. The nose of the shell hits the feed ramp and travels upwards like it should. Since the rear part of the shell is not being pushed by the bolt it is pushed downward and swings forward as the bolt closes on the nose of the shell. Tweak the rearmost part of your feed lips outward. This will present the shell higher and stop your nose up jams. Just do a little at a time. A tiny adjustment to each side makes a huge difference to the height the shell is presented. Quote Link to post Share on other sites
Brett248Vista 5 Posted October 22, 2013 Report Share Posted October 22, 2013 Matt, Noted! I am going to run a bit more varying types of ammo through her first to make sure it's fully broken in. If I continue to have issues I will adjust the feed lips per your suggestion. Even with the last round hiccup, what a blast this thing is! I had a cut down version of the A2 sight that I put on (came with my S&W 15-22) and the thing cracked in half.. Guess it wasn't MKA Rated Quote Link to post Share on other sites
ShadowFire 220 Posted October 22, 2013 Report Share Posted October 22, 2013 Matt, Noted! I am going to run a bit more varying types of ammo through her first to make sure it's fully broken in. If I continue to have issues I will adjust the feed lips per your suggestion. Even with the last round hiccup, what a blast this thing is! I had a cut down version of the A2 sight that I put on (came with my S&W 15-22) and the thing cracked in half.. Guess it wasn't MKA Rated Standalone A2 right? (No carry handle) For a Standalone I recommend the DPMS version, it's what I have on my gas piston 7.62x39 AR and I redialed it in for closer ranges and that rifle is surprisingly accurate and it does not crap where it eats, I love that rifle almost as much as my AKs. lol But for a shotty I'd just stick a flip on it (Which is what I plan to do with my MKA before it's all said and done.). Quote Link to post Share on other sites
Brett248Vista 5 Posted October 22, 2013 Report Share Posted October 22, 2013 (edited) Matt, Noted! I am going to run a bit more varying types of ammo through her first to make sure it's fully broken in. If I continue to have issues I will adjust the feed lips per your suggestion. Even with the last round hiccup, what a blast this thing is! I had a cut down version of the A2 sight that I put on (came with my S&W 15-22) and the thing cracked in half.. Guess it wasn't MKA Rated Standalone A2 right? (No carry handle) For a Standalone I recommend the DPMS version, it's what I have on my gas piston 7.62x39 AR and I redialed it in for closer ranges and that rifle is surprisingly accurate and it does not crap where it eats, I love that rifle almost as much as my AKs. lol But for a shotty I'd just stick a flip on it (Which is what I plan to do with my MKA before it's all said and done.). Yep Stand Alone A2. I just tried it because I had it laying around. I have a Trijicon RX30 due in some time this week Edited October 22, 2013 by Brett248Vista Quote Link to post Share on other sites
toothandnail 275 Posted October 22, 2013 Author Report Share Posted October 22, 2013 two other things I forgot, 1 plus , 1 minus Guess I got it wrong, my son said the new MKA mags have the krinkle finish, we didn't get mags sent with the BR, SO MKA mags are VERY tight in the BR magwell, don't know if the BR mags will drop free. The finish on the BR mags seems alot better, kind of a krinkle finish, (for lack of a better word) As many of you know the MKA mag finish is marginal at best, since I'm sure all the mags come from the same place, maybe MKA mags will get better. ALL the mags will have a better finish On the minus side, the BR magwell is VERY tight, no way a mag will drop free, not even a fully loaded 10 rounder. Quote Link to post Share on other sites
ShadowFire 220 Posted November 12, 2013 Report Share Posted November 12, 2013 (edited) two other things I forgot, 1 plus , 1 minus Guess I got it wrong, my son said the new MKA mags have the krinkle finish, we didn't get mags sent with the BR, SO MKA mags are VERY tight in the BR magwell, don't know if the BR mags will drop free. The finish on the BR mags seems alot better, kind of a krinkle finish, (for lack of a better word) As many of you know the MKA mag finish is marginal at best, since I'm sure all the mags come from the same place, maybe MKA mags will get better. ALL the mags will have a better finish On the minus side, the BR magwell is VERY tight, no way a mag will drop free, not even a fully loaded 10 rounder. Keep the in general shape and shave a few .001" off at a time with a Wire EDM machine (What they use in factories to cut AR magwells.) and you should find a sweet spot for the magwell size. Find the difference between the two mag sizes with a micrometer (You can make a set of calipers say anything.) and that should be a starting point. Bare in mind that temperature will effect your tolerances, warm = material expansion on a molecular level and cold=material compression as molecules get closer together. Edited November 12, 2013 by ShadowFire Quote Link to post Share on other sites
Brett248Vista 5 Posted November 12, 2013 Report Share Posted November 12, 2013 Keep the in general shape and shave a few .001" off at a time with a Wire EDM machine (What they use in factories to cut AR magwells.) and you should find a sweet spot for the magwell size. Find the difference between the two mag sizes with a micrometer (You can make a set of calipers say anything.) and that should be a starting point. Bare in mind that temperature will effect your tolerances, warm = material expansion on a molecular level and cold=material compression as molecules get closer together. Not trying to be a smart-ass so I hope it doesn't come across that way. Most production AR15 lower mag-wells (not including billets) are Broached to final shape. http://www.youtube.com/watch?v=erO7RMP_GzE And you can't wire EDM plastic, it's not conductive. Quote Link to post Share on other sites
ShadowFire 220 Posted November 13, 2013 Report Share Posted November 13, 2013 Ehh true about the plastic, forgot about that. You can mill it with a cnc instead then. You can also mill it with a standard vertical mill but it's not as accurate, you'll need to watch that. As for the broaching of forged lowers, as far as I was told, they use a Wire EDM, so you still might be right. The broaches I've seen are basically a different kind of reamer. This would get you the final radius you see on the four rounded corners on the inside of the magwell. Again I'm a machining student so I'm still learning. Just trying to hopefully give him something he might be able to work with to solve the problem. Quote Link to post Share on other sites
Brett248Vista 5 Posted November 13, 2013 Report Share Posted November 13, 2013 Ehh true about the plastic, forgot about that. You can mill it with a cnc instead then. You can also mill it with a standard vertical mill but it's not as accurate, you'll need to watch that. As for the broaching of forged lowers, as far as I was told, they use a Wire EDM, so you still might be right. The broaches I've seen are basically a different kind of reamer. This would get you the final radius you see on the four rounded corners on the inside of the magwell. Again I'm a machining student so I'm still learning. Just trying to hopefully give him something he might be able to work with to solve the problem. Yeah they still have to do some different type of "machine process" to get the general mag-well hole punched out, you don't go from a solid 0% lower to a broached mag-well in one step. They may wire EDM they may use a CNC Vertical, it all depends on what is fastest and most cost effective for a particular shop to do. Either process would work fine to get the majority of the material out, and I suppose they could CNC Wire EDM to final shape because wire EDM is very precise. I'm not sure how fast it is, we didn't have a wire EDM when I went to machinist school just a regular Ram EDM. Like I said above, I hope I didn't come off as an ass, that certainly was not my intention! Quote Link to post Share on other sites
cad_man 4 Posted November 13, 2013 Report Share Posted November 13, 2013 Plunge rough the magwell in less than 30 seconds on a VMC or HMC, follow with a single contour pass at 4 or 5 doc, then either wire or broach. Wire EDM is slow and expensive, so you want to finish in one pass if possible. Broaches are more sensitive to the size of the initial form they have to go into, but a faster operation. At the last shop I worked at they would get quotes to wire AR magwells, but would never get any of the jobs because the process is too expensive. This would include hole pop the start hole, then 2 passes (rough & finish). You are looking at $40-$60 per magwell. Quote Link to post Share on other sites
Brett248Vista 5 Posted November 13, 2013 Report Share Posted November 13, 2013 CadMan, Yeah I didn't think Wire EDM would be cost prohibitive. I know it's a necessity on hard materials where you have no other choice, but for AR lowers they have been broaching them since the beginning of time! Quote Link to post Share on other sites
cad_man 4 Posted November 13, 2013 Report Share Posted November 13, 2013 Yep. If it ain't broken..... The other issue with the wire EDM process is the finish. The recast layer from wire EDM doesn't have any functional affect on an AR magwell, but the finish is not that great and can be slightly abrasive, especially after anodize. A broached finish is far superior. The cost of a broach is not cheap either, and you need a broaching machine too, but for production you can't touch it. Quote Link to post Share on other sites
Brett248Vista 5 Posted November 13, 2013 Report Share Posted November 13, 2013 Initial set up cost would be expensive either way, but I'm just taking a guess here, in T6 Alloy that broach will last for tens of thousands of broachings, where as with that wire EDM it's always chewing up wire as a consumable. I wish I would have got to play with a CNC Wire EDM in school. I had the "Old School" Teacher who believed that we needed a solid foundation in manual machining skills. I never got to delve into CNC in school but I play with CAD at home, so at tax time I think I am finally adding a CNC Mill to my tool collection. It will be a small table top, probably the Horrible Freight Micro Mini Mill that I can use to do manual stuff (80% lowers) and then "tinker" with CNC Quote Link to post Share on other sites
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