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Posted: 2/24/2026 1:16:03 PM EDT
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Because of Chase and being a big fan of 300 blk and a roller lock fan I built a 53 in 300blk years ago from a flat and a 33 kit. I did buy a proper 53 cocking tube but used the 33 bolt carrier. For those who dont know the 53 bolt carrier has a much shorter nose and a different recoil spring. Well me being a cheap skate I did not want to buy a 53 carrier so I did the math and made a sleeve that fit inside the 33 carrier and put the recoil spring front end at the correct point. In my first test firings it would not cycle correctly, it would not eject and I figured that the recoil spring was too strong, I did use the correct locking piece. So I started cutting down the recoil spring, several cuts later it still would not function properly and I just stopped messing with it. Well I have gotten on the folding stock thing and wanted a spear lt, but could not decide if I wanted 5.56 or 300. I decided to get the spear in 5.56 and try to figure out the 53. So I bought a new recoil spring for it and it was a serviceable one, not the surplus 53 spring that I had bought. Due to how they make the serviceable one I tried it in the carrier. It had a screw on the end not the rivited in cap of the surplus, I checked to make sure it moved in the carrier. It did not the head of the screw as a little bigger. So I measured the head and ran a drill bit down the sleeve I made to give more clearance. I took it to the range this weekend and tested it out, with the new 30 cal form 1 can I built. Well 60 rounds of 110 grain saber aac 300 blk ammo I had full function no issues. I thought it might have been the added back pressure from the can and took the can off and it still ran great. I dont know if it was the spring, or the sleeve was too tight but it works. Now to get a welder friend to clean up my crappy welds and get it painted. Sorry no pics, its too ugly right now but still worth posting that I got it working. Now I need some real 33 mags and just keep the promags I have a spares. |
"I am gonna laugh my ass off looking out the air vent of the box car watching some of you shot in the head in a ditch when you finally realize it's time to resist." stolen from RR_broccoli
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Originally Posted By StaccatoC2: Because of Chase and being a big fan of 300 blk and a roller lock fan I built a 53 in 300blk years ago from a flat and a 33 kit. I did buy a proper 53 cocking tube but used the 33 bolt carrier. For those who dont know the 53 bolt carrier has a much shorter nose and a different recoil spring. Well me being a cheap skate I did not want to buy a 53 carrier so I did the math and made a sleeve that fit inside the 33 carrier and put the recoil spring front end at the correct point. In my first test firings it would not cycle correctly, it would not eject and I figured that the recoil spring was too strong, I did use the correct locking piece. So I started cutting down the recoil spring, several cuts later it still would not function properly and I just stopped messing with it. Well I have gotten on the folding stock thing and wanted a spear lt, but could not decide if I wanted 5.56 or 300. I decided to get the spear in 5.56 and try to figure out the 53. So I bought a new recoil spring for it and it was a serviceable one, not the surplus 53 spring that I had bought. Due to how they make the serviceable one I tried it in the carrier. It had a screw on the end not the rivited in cap of the surplus, I checked to make sure it moved in the carrier. It did not the head of the screw as a little bigger. So I measured the head and ran a drill bit down the sleeve I made to give more clearance. I took it to the range this weekend and tested it out, with the new 30 cal form 1 can I built. Well 60 rounds of 110 grain saber aac 300 blk ammo I had full function no issues. I thought it might have been the added back pressure from the can and took the can off and it still ran great. I dont know if it was the spring, or the sleeve was too tight but it works. Now to get a welder friend to clean up my crappy welds and get it painted. Sorry no pics, it’s too ugly right now but still worth posting that I got it working. Now I need some real 33 mags and just keep the promags I have a spares. Sweet! |
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Sorry I try and stay away from this section as it usually costs me money. Good luck finishing it out The largest problem I had with mine is being stubborn and trying to make certain bullets work It really needs long pointy bullets 110 tac tx has always been perfect. Tipped heavy grain stuff My obsession was getting it to work with some heavy lead bullets. I put it down for awhile and picked it back up recently Seems a NOE 225 RN bullet works good for it Heres a video for inspiration to finish it out. Ignore the misses as I was battling some accuracy problems I since solved with said lead bullets(.309" vs .311" makes all the difference)  HK53 in 300 blackout |
Battle Of West Appalachia Survivor
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What locking piece are y’all using? I was considering 300 BLK 12.7” barrel to convert my V93 to a V33k in 300 BLK, but Ghillie (and being broke) talked me out of it. Told me it needs (I believe this is correct) a 110*, and no one makes one for thag bolt head? |
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Originally Posted By lilMAC25: What locking piece are y’all using? I was considering 300 BLK 12.7” barrel to convert my V93 to a V33k in 300 BLK, but Ghillie (and being broke) talked me out of it. Told me it needs (I believe this is correct) a 110*, and no one makes one for thag bolt head? I used the RCM 300 one and as far as I know its the only out there. |
"I am gonna laugh my ass off looking out the air vent of the box car watching some of you shot in the head in a ditch when you finally realize it's time to resist." stolen from RR_broccoli
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Originally Posted By lilMAC25: What locking piece are y’all using? I was considering 300 BLK 12.7” barrel to convert my V93 to a V33k in 300 BLK, but Ghillie (and being broke) talked me out of it. Told me it needs (I believe this is correct) a 110*, and no one makes one for thag bolt head? Im not sure what degree it is but I used the rcm one as well I played a bit with the magazine seat angle by modifying the mag catch area a little. Sits slightly lower in the rear. I also gave the barrel face a very slight ramp Pointy bullets are the key. If they are too stumpy they'll bang the front lip of the magazine |
Battle Of West Appalachia Survivor
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Originally Posted By chase45: Im not sure what degree it is but I used the rcm one as well I played a bit with the magazine seat angle by modifying the mag catch area a little. Sits slightly lower in the rear. I also gave the barrel face a very slight ramp Pointy bullets are the key. If they are too stumpy they'll bang the front lip of the magazine I found adapters to put on AR mags, I printed one it actually allows the mag to lock up. I posted in the 53 SBR thread, I really need to get out and try out one of the adapters. Be fun if it allowed the 300 to work with AR mags. Link to file and pics others took page 3 of the thread. |
"I am gonna laugh my ass off looking out the air vent of the box car watching some of you shot in the head in a ditch when you finally realize it's time to resist." stolen from RR_broccoli
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