300 BLK pistol build... possible?

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  • DaemonAssassin

    Why should we Free BSD?
    Jun 14, 2012
    23,970
    Political refugee in WV
    No vice, no work bench, and the gas block/tube looks confusing. Does the barrel have to be dimpled? But I think I will buy the parts and take my time with it. I’ll be back as questions come up. May take awhile before I assemble the parts. Thanks everyone for all the advice and offers of help.

    Like I said up thread. Other members have all the tools. You show up at their place and a few hours later you walk out with a shiny black toy.

    Ask the member named "Conundrum" how it went down. I assembled his 300BLK AR pistol for him.

    Another one is "firefighter_21701". I assembled his AR in 300BLK and his other one in 556. Once his stamp is approved, I'll be assembling a short barreled upper for him.
     

    outrider58

    Eats Bacon Raw
    MDS Supporter
    Jul 29, 2014
    49,818
    No vice, no work bench, and the gas block/tube looks confusing. Does the barrel have to be dimpled? But I think I will buy the parts and take my time with it. I’ll be back as questions come up. May take awhile before I assemble the parts. Thanks everyone for all the advice and offers of help.
    Yeah, lower receivers are pretty straight forward(as long as you don't put the hammer spring in backwards), but uppers not only require a few specialty tools, they also require a bit of familiarity with the process. Otherwise, your next thread might be titled "AR won't cycle". ;)
     

    Shore88

    Active Member
    Dec 20, 2020
    206
    Eastern Shore
    Yeah, lower receivers are pretty straight forward(as long as you don't put the hammer spring in backwards), but uppers not only require a few specialty tools, they also require a bit of familiarity with the process. Otherwise, your next thread might be titled "AR won't cycle". ;)
    Lol. You read my mind.
     

    Shore88

    Active Member
    Dec 20, 2020
    206
    Eastern Shore
    Like I said up thread. Other members have all the tools. You show up at their place and a few hours later you walk out with a shiny black toy.

    Ask the member named "Conundrum" how it went down. I assembled his 300BLK AR pistol for him.

    Another one is "firefighter_21701". I assembled his AR in 300BLK and his other one in 556. Once his stamp is approved, I'll be assembling a short barreled upper for him.
    Thanks DA. Honestly I’m sort of an independent sort. Wife says stubborn. But I do appreciate the help and maybe once I get the parts I’ll get stuck and send a PM or two asking for help. I’ll keep you updated. Thanks again. Don’t have a garage or work shop but I’m seriously thinking of building a work table in the home office. We’ll see.
     
    Last edited:

    DaemonAssassin

    Why should we Free BSD?
    Jun 14, 2012
    23,970
    Political refugee in WV
    Thanks DA. Honestly I’m sort of an independent sort. Wife says stubborn. But I do appreciate the help and maybe once I get the parts I’ll get stuck and send a PM or two asking for help. I’ll keep you updated. Thanks again. Don’t have a garage or work shop but I’m seriously thinking of building a work table in the home office. We’ll see.
     

    Bountied

    Ultimate Member
    Apr 6, 2012
    6,903
    Pasadena
    No vice, no work bench, and the gas block/tube looks confusing. Does the barrel have to be dimpled? But I think I will buy the parts and take my time with it. I’ll be back as questions come up. May take awhile before I assemble the parts. Thanks everyone for all the advice and offers of help.

    The trickiest part about the tube is getting the barrel nut timed correctly so the gas tube will line up with the upper receiver and the barrel nut. You put the gas tube in the gas block using a roll pin. Most gas blocks use set screws so the dimples aren't really necessary but can be helpful for lining things up. You'll need a credit card to space the gas block off where the delta ring would go. I'm assuming that you want a free float upper? Anyway its pretty simple and if you mess up the gas tube or the block the gun won't function correctly and then you just fix it. I had a friend that did a build, his gas block came loose and the gun would not cycle. I identified the problem we torqued it down with a little blue Loctite and problem solved. The biggest issue you could have is headspace for which you will need go/no-go gauges in 556 or 233 I have both sets.
     

    Shore88

    Active Member
    Dec 20, 2020
    206
    Eastern Shore
    The trickiest part about the tube is getting the barrel nut timed correctly so the gas tube will line up with the upper receiver and the barrel nut. You put the gas tube in the gas block using a roll pin. Most gas blocks use set screws so the dimples aren't really necessary but can be helpful for lining things up. You'll need a credit card to space the gas block off where the delta ring would go. I'm assuming that you want a free float upper? Anyway its pretty simple and if you mess up the gas tube or the block the gun won't function correctly and then you just fix it. I had a friend that did a build, his gas block came loose and the gun would not cycle. I identified the problem we torqued it down with a little blue Loctite and problem solved. The biggest issue you could have is headspace for which you will need go/no-go gauges in 556 or 233 I have both sets.
    Good info. Thanks! Sounds like I’m going to have to watch a few more videos. Bear with me, I’m switching gears again. Found a 10.5” complete upper 300 BO for the pistol. Ordered it. So I’m going to build a 16” BO upper like I originally planned. Now I can take my time and I’ll still have a gun to shoot in the meantime. I guess a pistol length gas tube would still be best if I want to cycle super and subs? Sorry if I hijacked this thread with a ‘How to’ class.
     

    DaemonAssassin

    Why should we Free BSD?
    Jun 14, 2012
    23,970
    Political refugee in WV
    Good info. Thanks! Sounds like I’m going to have to watch a few more videos. Bear with me, I’m switching gears again. Found a 10.5” complete upper 300 BO for the pistol. Ordered it. So I’m going to build a 16” BO upper like I originally planned. Now I can take my time and I’ll still have a gun to shoot in the meantime. I guess a pistol length gas tube would still be best if I want to cycle super and subs? Sorry if I hijacked this thread with a ‘How to’ class.
    Pistol length has is the only way to fly on a 300BLK. Beat in mind that you'll have to shoot supers and subs out of each upper to verify that they will chuckle both and be able to lock the bolt back.

    As for the upper you plan on building, I'd highly recommend getting a SLR Sentry 7 adjustable clamp on gas block. When the time comes you'll understand why you have a adjustable gas block.
     

    Shore88

    Active Member
    Dec 20, 2020
    206
    Eastern Shore
    Pistol length has is the only way to fly on a 300BLK. Beat in mind that you'll have to shoot supers and subs out of each upper to verify that they will chuckle both and be able to lock the bolt back.

    As for the upper you plan on building, I'd highly recommend getting a SLR Sentry 7 adjustable clamp on gas block. When the time comes you'll understand why you have a adjustable gas block.
    Thanks. I was going to become familiar with the 10.5 with both supers and subs before I even buy the 16”, for the reasons you stated. With pistol length gas is the blowback and/or recoil going to be greater when shooting supers or subs? And I assume that’s the reason for the adjustable gas block, not only so it will cycle but to cut down on it being over gassed?
     

    DaemonAssassin

    Why should we Free BSD?
    Jun 14, 2012
    23,970
    Political refugee in WV
    Thanks. I was going to become familiar with the 10.5 with both supers and subs before I even buy the 16”, for the reasons you stated. With pistol length gas is the blowback and/or recoil going to be greater when shooting supers or subs? And I assume that’s the reason for the adjustable gas block, not only so it will cycle but to cut down on it being over gassed?

    Recoil is a matter of perception.

    It allows you to tune the gas for what you are shooting. If you are shooting suppressed, you dial the gas down a bit. If shooting unsuppressed, you open it up a bit.

    It will also allow you to regulate the gas, so you can have enough gas to cycle, but not short stroke or be over gassed.
     

    Shore88

    Active Member
    Dec 20, 2020
    206
    Eastern Shore
    Picked up my stripped lower today, finally, with the 77R and 4473 all went smoothly. Until, I mentioned to my FFL that I might build a pistol. I was told I had to have an HQL if I built it as a pistol. Doesn’t rhyme with everything I’ve learned on here. Should I go back and tell them they’re wrong or just let it slide and use another FFL next time? I made sure to check the block ‘other‘ just so they wouldn’t do otherwise.
     

    outrider58

    Eats Bacon Raw
    MDS Supporter
    Jul 29, 2014
    49,818
    Picked up my stripped lower today, finally, with the 77R and 4473 all went smoothly. Until, I mentioned to my FFL that I might build a pistol. I was told I had to have an HQL if I built it as a pistol. Doesn’t rhyme with everything I’ve learned on here. Should I go back and tell them they’re wrong or just let it slide and use another FFL next time? I made sure to check the block ‘other‘ just so they wouldn’t do otherwise.

    You have got to be kidding! Is the lower classified as "other"? If yes, then it doesn't matter whether you have an HQL or not. Find an FFL with a brain and buy from them. Look at Medusa Joe in SMd. Your guy is an ijit.
     

    Shore88

    Active Member
    Dec 20, 2020
    206
    Eastern Shore
    You have got to be kidding! Is the lower classified as "other"? If yes, then it doesn't matter whether you have an HQL or not. Find an FFL with a brain and buy from them. Look at Medusa Joe in SMd. Your guy is an ijit.
    Switching FFL’s was kind of my plan. Section C where you check the block for handgun, long gun or other was supposed to be completed by the FFL before transfer but they just had me fill out my section, sign it and hand over the transfer fee. I made sure to check other before I left. I don’t think they really care what I do they just didn’t want to take the time to complete the form then and there. Customers were waiting. I won’t be going back. I have proof of what I purchased and where it was shipped to should they screw up the form.
     

    Bountied

    Ultimate Member
    Apr 6, 2012
    6,903
    Pasadena
    Switching FFL’s was kind of my plan. Section C where you check the block for handgun, long gun or other was supposed to be completed by the FFL before transfer but they just had me fill out my section, sign it and hand over the transfer fee. I made sure to check other before I left. I don’t think they really care what I do they just didn’t want to take the time to complete the form then and there. Customers were waiting. I won’t be going back. I have proof of what I purchased and where it was shipped to should they screw up the form.

    Just go back and say you are going to build a rifle? Seems stupid to me. They wouldn't give it to you because you said you intended to build a pistol? Say what you need to say to get the lower, the paper work won't reflect your intentions.
     

    Shore88

    Active Member
    Dec 20, 2020
    206
    Eastern Shore
    Just go back and say you are going to build a rifle? Seems stupid to me. They wouldn't give it to you because you said you intended to build a pistol? Say what you need to say to get the lower, the paper work won't reflect your intentions.
    They gave me the lower. No problem there. I guess I didn’t make that clear. Sorry. I would have liked the FFL to complete their part of the form before I left. I was really hoping to get a copy. Maybe they were just trying to make it faster for me to get in and out. It was when I was leaving they told me I needed a HQL should I eventually decide to build a pistol.
     

    dblas

    Past President, MSI
    MDS Supporter
    Apr 6, 2011
    13,087
    Picked up my stripped lower today, finally, with the 77R and 4473 all went smoothly. Until, I mentioned to my FFL that I might build a pistol. I was told I had to have an HQL if I built it as a pistol. Doesn’t rhyme with everything I’ve learned on here. Should I go back and tell them they’re wrong or just let it slide and use another FFL next time? I made sure to check the block ‘other‘ just so they wouldn’t do otherwise.

    1. - Find another FFL for your next purchase.

    2. - Name the idiot here so he doesn't get business.
     

    Bountied

    Ultimate Member
    Apr 6, 2012
    6,903
    Pasadena
    They gave me the lower. No problem there. I guess I didn’t make that clear. Sorry. I would have liked the FFL to complete their part of the form before I left. I was really hoping to get a copy. Maybe they were just trying to make it faster for me to get in and out. It was when I was leaving they told me I needed a HQL should I eventually decide to build a pistol.

    That's not true but whatever
     

    Shore88

    Active Member
    Dec 20, 2020
    206
    Eastern Shore
    1. - Find another FFL for your next purchase.

    2. - Name the idiot here so he doesn't get business.
    I’m not going to smear them on the internet over that one person’s opinion. It’s a small shop and they’ll know exactly where it came from when it got back to them. Which I’m sure it would. The person that I dealt with was not the owner to my knowledge but a cashier. If I go back that way I might just set them straight because they do provide a service to a lot of people. And they were courteous and I got my part. I mainly made the post to verify that I did everything right.
     

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