Chad, Thanks for taking the time to do this! I want to note, I did not stake or torque the castle nut in fear the lower ended up being total trash.....LOL. I didnt want to put the sauce to the end plate until we confirmed the lower to be usuable after encountering the blatant issues. This seemingly was the correct choice haha! Again, thank you! Always enjoy a solid learning experience! J
So what was the ending to this.. and due to the pins being oversized for the trigger can you or is there something to fix the issue at hand so it does not become dangerous in the long run.
@@SchooloftheAmericanRifle Hi, I have a lower that the bolt catch "channel" is out of spec. It is too wide and the bolt catch is loose. It doesn't hold the bolt back on last round anything I can do like fill it in with jb weld or something similar? It is a 17design lower and they're out of business now... I think I know why
I'll never buy a cosmetic blem again. I purchased a blem "matched" receiver set from a well respected company and the holes were so out of spec that I never used them. QC rejects with a scratch should not be sold as cosmetic blems but they regularly are. $300 in the toilet.
I have had great luck with bcm, and aero precision blems. In most cases its a tiny nick or scratch. But I agree if its out of spec than it should have been scrapped
@@aramirez8427 bins and racks of shame are somewhat extensive. Some of my own rifles are included. I won't fix certain things so I can show students how to find problems band what results from not fixing it.
The fact KAC charges people $300+ on a stripped lower while having stuff like this pass QC is inexcusable, guess this one just got tossed into the "blem" pile instead of the "trash" pile 🤷.
This channel is criminally underrated! I have enjoyed these videos tremendously! School of the American 🇺🇸 Rifle should be a mandatory class for high school students. Thank you for sharing your thoughts and knowledge in such a fantastic way. The camera angles are very good to show the viewer exactly what they need to see.
I recently found this channel and all I have to say is this is this guy is the Yoda of the modern rifle. As a former machinist turned USAF jet engine mechanic I can greatly appreciate every aspect of these videos. Insightful, articulate, educational.... keep it up! In fact, I think you should write a book! You could call it "The mechanics of the American rifle....learn it you must"
@@davidschaadt5929 ya, over sized trigger pin holes or tight magwell ect are one thing; but the holes for the bolt catch being so big that it won't take the role pins is another. I expect scratches or some things to be slightly out of spec with blems, but still fully functional
@@muddyhotdog4103 Slop in the safety selector is an even bigger issue. You could assemble an inherently unsafe rifle with that, bolt catch is a convenience feature.
This is my continued experience with KAC. I have had multiple sr15s and sr16 components that have been all over the map with tolerances and finishing details. Definitely paying for the roll mark.
Why are you buying these crap guns? A Smith and Wesson M&P has better QC than these warmonger, anti- 2A contract companies. God forbid they sell guns to people that aren’t committing murder in random countries.
Be careful about buying during a panic buying period. QC gets rushed, machinery isn't shutdown for proper maintenance, and tooling gets run longer than recommended life cycles. Also increase in staff to fill orders means less experienced labor.
In all the years watching gun channels and guys that claim to know their way around ARs this is the ONLY channel that actually shows his knowledge and process. It’s obvious that others are at best unknowingly shills and at worst complete shills. There are great brands but when guys act like good brands don’t fail it’s a lie. Thank you for what you do.
Really appreciate these videos. I don't think I've ever watched one and not learnt something new. You are doing your fellow Patriots a great service. I have an upper I'd love for you to go over. How would I do something like that?
Wow! I understand this is a sample size of one but a “blem” is a blemished item, a scratch or wrong color, poor anodizing and other cosmetic issues, not every single hole being oversized. KAC should be ashamed. This lower should’ve been melted and made into one of proper dimensions.
Right? Sample size of one, but still left a really bad taste in my mouth that that lower ever made it out the door. I wonder if they have the machinist tolerance check only every 5 or more lowers? Every CNC job I've had, we very rarely checked every part, just systematically every 3, 5, 10, ect., parts made.
I have several of these KAC lowers, and honestly I have PSA lowers that are nicer. I sent one back and got a replacement from KAC because it would barely accept and drop a whole handful of mags. Super disappointing receiver given the manufacturer. Mine were also NOT marketed as blems.
Having worked at an aluminum extruder for several years, and aerospace machine shop for several more, i can tell you with relieve certainty that the reason for the holes all being oversize is with the anodizer. First step in anodizing is a caustic stripping which removes about .001 per surface which makes holes get bigger, but the anodizing makes the surface 'grow' which puts everything close back to where it started, in a perfect scenario. If the caustic solution is brand new or if someone didn't follow the 'recipe' right, or if there was a problem with some parts that need to be striped and re anodized your hole sizes can get blown wide open in a hurry. The mag well being undersized is a completely different issue.
Then the tolerancing should be taking place after that procedure as well, or have the parts toleranced prior with that change in mind if they aren't willing to check twice
I used to work as a QE for an anodizing and plating company. While it is true that over etching or over anodizing can change dimensions, you'll usually see that all over the component. If all the other lower features are still in spec, it's likely that these specific holes were machinded out of spec or at the very bottom of the spec limit. Regardless, KAC should be verifying these AFTER anodizing - they should not have shipped this part.
I always thought the term "blem" meant a cosmetic imperfection,which is what l have read on web pages.An out of spec hole shouldnt be considered a blem.That would be a deal breaker for me.Kinda misleading.
I know this is an old video but just wanted to say I learned a lot from this video about the tolerance values for a lower receiver thanks to you! Thank you for showing all this valuable information!
@@KI.765 yes. Fingers crossed but I do want the truth even if it costs me money. No mercy just because I love KE Arms and In Range. I’m guessing it will absolutely pass and definitely be a solid win, but reality is a motherf$&ker!
I would be very interested in seeing that. I think probably it would pass, but a plastic lower is a real different beast from an aluminum one, there's got to be things one needs to pay attention to with that.
Yes, curious about how it would hold up. Mine appears to have a larger than normal gap between the upper and lower where the bolt meets the buffer tube, but not reliability issues at 700 rounds (BCM blem upper, Aero BCG, BA Hanson barrel). Would love to see him open one up.
I love this channel. It just makes me more aware and cognizant of the details when building. thank you for your effort in putting out quality presentations.
What an incredibly educational video sheesh. I've just completed acquiring parts for a complete home build and I swear I learned more from watching this than everything I've read leading up to this lol. Great content and great camera work by the Mrs!
I learn so much from these videos. And this goes to show even the best which is kac, hodge, lmt, bcm etc... can be out of spec. Although rare, it happens. But learning the signs and symptoms helps the average owner a ton. Thanks sir
I want to thank you for putting out these videos... they are a wealth of knowledge that no one else is producing at even close to the same level.. I have a knights ambi lower with a tight mag well, love the gun but the mag well not dropping most mags freely is aggravating to say the least
I came across this channel a few weeks back. After watching the video suggested by youtube then, I subscribed without hesitation. This video is just as awesome as the past one. I love how in depth the explanations go. Keep up the good work.
I love these videos. It goes to show that ALL manufacturers make mistakes, have various degrees of QC issues, and that we the end user are responsible for the purchases we make. What makes a company great isn't so much the mistakes or lack thereof, its how they remedy it and treat the customer.
I can't believe the amount of slop that was built into a top tier lower. It should be replaced with a new one. It's funny that a friend of mine brought me his friends AR from a home build with a loose castle nut and buffer tube not timed right. Had to replace the keeper and spring and then you put this video out. Keep up the good work learning more everyday.
I had a buddy that bought one of these lowers, and he encountered the exact same issues with the roll pin and magazine well issues. The Pmags we had would drop free, but the USGI aluminum mags we had on hand wouldn't. It was such a weird issue. He contacted KAC about it. They did send him a new lower but it took about a month for them to respond.
Chad, thanks for putting me onto Vibratite VC-3, I use it on my red dots on my pistols, have had them mounted for about a year with no movement, previously I'd need to remount them every 6-9 months with locktite, VC-3 works fantastically!
You are a great gunsmith and teacher I use Anderson lowers and some PSA the Anderson usually has never give me much trouble and mostly everything fits pretty good you have taught me a lot these high-dollar companies nowadays seems like just markup the money for the name they're not putting time in building the rifles undoubtedly are they have unexperienced workers
Love your videos, knowledge and advice, this lower could be replaced for less money than your costs to repair. But, yes, there are many ways you show to fix problems for these issues. Great to see this for fixes for SHTF type scenarios, otherwise this lower just needs to be replaced for longevity and increased functionality.
Let the buyer beware , but as the host explained in the video , there are over sized pins available to make a fix . Which leads me to believe this is more common than you might believe .
very informative video for me I'm no gunsmith by any means I learn what to look for and have some insite on possible way to fix it or leave it or use a professional gunsmith ...I would not have thought about the safety not working properly and that's golden knowledge to have .
Ironically I just had a similar issue with a Griffin Armament blem lower I put together for my brother in law. The take-down pin detent spring hole wasn't drilled out. It was sold as a "cosmetic" blem, not a defective blem. I didn't realize it till I began assembling it and the spring wouldn't go beyond a quarter in the hole. Luckily it wasn't a big deal for me to bore it out with a simple hand drill; but most people who have no experience would have been screwed, or terrified to drill into the lower... It was a christmas gift for him, so there was no time to send it back to Griffin and frankly, the prospect of them doing anything was nill, since as Rainier told her, "you ordered a blem lower and they are sold as is"... which is true; but this wasn't a "cosmetic" blem; but rather an actual defect...
@@KI.765 it makes assembly / disassembly of the bolt catch SO much easier (especially if you’re a klutz like me). No banging in roll pins, no risk of scratching your lower. Aero also threads the takedown pin detent hole so you don’t have springs flying out if you remove the end plate.
@@KI.765 They have a threaded hole for the bolt catch. The most pain in the ass part of putting a lower parts kit into a lower is the roll pin for the bolt catch. You just screw in a threaded pin instead of using a long punch and hammer to drive it in. If the punch comes off the pin you most likely will put a big scratch down your lower if you don't put enough tape for insurance. Just makes life a little easier. Plus the M4e1 lower and M4e1 enhanced upper looks really nice. Has a billet look but still a forged receiver.
Always great videos. For a gunsmith to fix properly costly for the customer, as you stated the company can assist or reject 🤔. Customer has to think about what is the best course of action.
Could you do a lower forge plant tour? On how these are born at the forge birth place? Like their has to be good and bad places that make these. But thank you for putting this on yt and enjoy just listening to the knowledge y’all provide.!! Have a safe Christmas during this trying times.!
FYI: a small string also is good for pulling levers if you don't have a plastic tool. Loop it around and pull. Tip is used by guitar and electronics techs to pull stubborn, and often rare knobs without causing damage..
Removing the selector arm properly is a testament to your knowledge, experience, skill, and most important, patience. It's learned, not taught. Hat's off to you.
I bought a block and hold because you gave a discription of yours. Fantastic tool. Also JP has a really nice upper vice block - two piece. Check it out. I like mine way better than a reaction rod. Thank you for sharing your skills with us.
For a company that really doesn’t offer much commercial it seems the commercial stuff they do roll out gets a ton of complaints. Makes me feel like I won the lottery with the upper I received. Also for 200 plus dollars. What a freaking rip off
Lol i'm not a just as gooder i'm CHEAP! I personally couldn't bare the thought that "my" $350 lower could possibly have more machining inconsistencies than a $30 lower. I understand quality of manufacturing materials is a thing. I am not ignorant I am cheap. Don't let my personal thoughts offend anybody. Just voicing my opinion on a vastly educational video.
For all the 80% guy's out there , you opened my eyes with this video. Receiving inspection will be done before I make a gun that is maybe bad and I have to take a hammer too because it's a gun and can't be shipped back.
Class III technical difficulties. :) Thanks for the information. Peaning the holes may give the lower added life. Not a great solution, but better than oversized.
I use a lot of automotive plastic panel removers. I have some flat ones and some that have a nice bend for moments like that selector. I use them on cars first and when they get beat up I shape them and use them on smaller stuff like this. 🤙🏾
I'm sure KAC would make good on replacing this lower receiver. I would have at least contacted them, in a civil manner, to see what they had to say. Crap happens. I'd even settle for another "Blem", but with in spec safety switch holes this time, please. Love the videos. Doing great work here, SOTAR.
Hi Chad. I hope you read this. I have had oversizing issues with my KAC lower as well. Mine is a non-ambi like this one except it was most certainly not sold as a blem. I have my suspicions that the company KAC has outsourced these lowers to are doing a very poor job, so I do not blame KAC in any way directly. However, I will try to bring this to their attention and my case as well.
These are absolutely _fascinating_ videos just to watch! Sadly firearms are heavily restricted in my country, but thankfully looking at them is not (yet)!!!
I have a 20-year-old Rock River lower that has a tight magwell, but it's a cool one because they did it on purpose so that GI mags wouldn't rattle around in the reciever. I can't use gen one p mags and gen 3 mags can sometimes require a shake to come free. Everything else is perfectly in spec though and the upper to lower lockup is solid.
I had this exact same problem with a non-ambi SR-15 lower last year purchased in the fall. Mine was not as severe as this case. I contacted knights they sent me a brand new lower with no hassle. It was not a blem lower but they treated me very well. Just my .02
This might have been the blems that was offered a few weeks ago on gundeals. I don't recall the vendor, but I remember the disclaimer was possible cosmetic issues , enlarge holes and undersize magazine wells.
I had the buffer retaiing pin on my palmetto ar-9 pretty much in EXACTLY the same condition...it came loose when i took it to the range putting my weapon down for the day, completely mangled the spring too. Had to mortar it to eject the last 9mm round and clear the weapon for transport..such a simple mistake and something i now know to look for.
A lot of people will take the opportunity to crap on KAC, because they are expensive, or they can't afford it, so they will say their AERO or PSA is just as good as a KAC rifle, when they are not. The example used in the video was not good enough to make it on a factory rifle, which means their QC is on point, so just buy a factory gun, and you wont experience this. KAC produces a top 2 or 3 rifle. 'Small Arms Solutions' has great videos explaning why they are top 2 in the ARs, and the innovation that went into the design.
I bought my SR-15 non-ambit lower in 2019 brand new and have the exact same issues. I use Geissele triggers and during dry fire you can see the trigger pins rotate inside the hole. They haven't come out yet surprisingly. The takedown pin holes are also big, same as in the video. Have to use a wedge in the rear to get it even close to snug. Magazines also usually do not drop free; only use Pmag M2/3 & Okay stanags. I have buddies that have the ambi lowers and they have the same issues with the magazines dropping. I can't imagine with the sample size and anecdotes that these are blems, they're just bad quality pawned off to civilians looking for a roll mark. That being said, the SR-15 uppers are incredible. Just the lowers are beyond pathetic.
I did not see in the comments nor did he mention but ALSO by having oversized trigger control group holes and an oversized selector hole you can be on semi and actually fire a burst if slowly pulling the trigger... the hammer will be riding the bolt home to accomplish this (usually 2-3 rounds before short stroking and not a good situation even if it sounds cool)
This makes me feel lucky with the "blem" receivers I've built so far, but after watching this video I don't think the savings is worth needing this much extra attention. Let's hope this is an extreme example.
I want all your gauges, damn!! I didn’t know they even made all of these, also didn’t know the class 1, 2, 3, thread thing! I guess it pays off to insist on mil spec parts or you could build an unsafe rifle. I really enjoyed learning these things for future reference in trouble shooting lower parts. Thanks for making this video.
