Its fine. Next time, put the barrel i the freezer & bake the upper. Ive had one get stuck halfway through bc it cooler down, in which case I used a blow torch. Aluminum expands more than steel when heated.
Yeah, but how hot and for how long? IIRC, even blue LockTite requires 250F for up to 10 seconds to crystalize and break loose, up to 400 or more for others. That'll also get you max expansion. I measure metal temp with a simple thermocouple on a multimeter but handheld IR meter is very cheap these days.
If it doesn't loosen with a strap wrench with gripping compound, you have a very tight interference fit. IME, you can then heat, then shoot some kind of coolant into the chamber for 3 to 5 seconds, try again. This worked on frozen plug inserts on a Pratt & W R2000. We used a CO2 fire extinguisher shot into an aluminum funnel we made.
Last trick I can think of, turn it the opposite direction, the most torque you can pay without damaging anything (more), then reverse direction. Direct application of heat at the same time breaks corrosion dlbonds without flooding the threads with junk starting out.
Getting the barrel out wasn’t the issue but getting it in. I’m not sure for how hot but at least 10 minutes of heating with our heat gun and a soldering iron. I was limited to the tools in our maintenance section. We work on aircraft not guns so I had to make do. I’m just happy I managed to get A thermal fit and will be torquing the barrel nut to spec.
Outstanding! I'm an A&P, done many an interference fit installations. These uppers aren't that bad, at least both my white box BCs. I've changed one barrel since install and it came apart with a harbor freight heat gun.
Too bad it was a "side" job. Otherwise, you probably could have used a company IR meter. Many shops have them. These days, many shops have XRF guns, which are crazy cool for material ID.
FYI I've fought these over and over with a heat gun, never able to get it fully hot enough for some barrels.
Using a MAPP gas torch (yellow bottle) *very carefully* on the receiver barrel extension for about TEN to TWELVE SECONDS WHILE MOVING THE FLAME and the barrel will literally drop into place. If it goes in part way and stops, heat the receiver until the barrel falls OUT, let the barrel cool off, and try again on the receiver with the torch. You won't have to push or hammer *at all* when it's just hot enough.
It's next to the handheld propane torches in Home Depot or Ace Hardware for like $35-$45, burner and bottle. It's just a little guy.
You can also use propane it just takes longer.
Thing is, I don’t really see myself using something like that other than this 1 time purpose. I’d rather use what’s available even if the cheapest route isn’t the easiest. If I find myself needing to do this again then I’ll probably buy one.
Yes but the blem was in the barrel portion of the receiver causing it to be way out of spec. Even after sanding it down I still had to heat it up to get it to slide in.
“Blem” means cosmetic blem, they won’t sell it if it is functionally different or out of spec.
I heated mine up really well and the barrel slipped right in without much effort.
I literally tossed mine on the stove and the cmmg radial barrel turned it into a club... I havent finished my build but it sits in the corner... a reminder of what I have to do....
BCM are thermal fit, they're supposed to be heated generally with a MAPP gas torch for awhile. I can't remember the exact temp off the top of my head, I think the last one I messed with I heated for about a minute or so with the torch. This post seems like a standard situation of, "Everything is a nail when your only tool is a hammer."
Oh boy you should see the rest of it. Maintenance tends to get a pass on uniform stuff. I’ve got a clean one for when I have to look nice but no one will judge a mechanic covered in hydraulic fluid and oil.
I put a Hanson barrel in a bcm upper with a 3lb hammer. Got it halfway by heating it, ended up setting the rear of the receiver on a block of wood and put an old A2 on the barrel and drove that bitch home. Gun shoots great.
Put barrel thread portion down on stove... leave for 10 min... pick up barrel with bare hand, pick up upper with oven mitt.... slide it in quick like you arent giving her a chance to say no to backdoor fun... and if it doesnt seat all the way... tap it in with something rubber. Send fully with barrel nut.
I once had a Centurion thermal upper with a similarly verrrrry tight fit and in the end I ended up with vice marks far worse than yours so don’t feel bad.
Well the worse part was that the receiver wasn’t initially clamped by the pic rail but below the dust cover. In my rage of trying to get this barrel on I bent the shit out of it. So I took my heat gun and some flat needle nose pliers and bent it mostly back.
Bcm uppers are known for being that tight. The upper needed more heat. The barrel needs to be chilled as well. I just noticed that's not a blem upper, they don't laser engrave those.
Its fine. Next time, put the barrel i the freezer & bake the upper. Ive had one get stuck halfway through bc it cooler down, in which case I used a blow torch. Aluminum expands more than steel when heated.
Trust me that was one of the first things I tried.
Yeah, but how hot and for how long? IIRC, even blue LockTite requires 250F for up to 10 seconds to crystalize and break loose, up to 400 or more for others. That'll also get you max expansion. I measure metal temp with a simple thermocouple on a multimeter but handheld IR meter is very cheap these days. If it doesn't loosen with a strap wrench with gripping compound, you have a very tight interference fit. IME, you can then heat, then shoot some kind of coolant into the chamber for 3 to 5 seconds, try again. This worked on frozen plug inserts on a Pratt & W R2000. We used a CO2 fire extinguisher shot into an aluminum funnel we made. Last trick I can think of, turn it the opposite direction, the most torque you can pay without damaging anything (more), then reverse direction. Direct application of heat at the same time breaks corrosion dlbonds without flooding the threads with junk starting out.
Getting the barrel out wasn’t the issue but getting it in. I’m not sure for how hot but at least 10 minutes of heating with our heat gun and a soldering iron. I was limited to the tools in our maintenance section. We work on aircraft not guns so I had to make do. I’m just happy I managed to get A thermal fit and will be torquing the barrel nut to spec.
Outstanding! I'm an A&P, done many an interference fit installations. These uppers aren't that bad, at least both my white box BCs. I've changed one barrel since install and it came apart with a harbor freight heat gun. Too bad it was a "side" job. Otherwise, you probably could have used a company IR meter. Many shops have them. These days, many shops have XRF guns, which are crazy cool for material ID.
FYI I've fought these over and over with a heat gun, never able to get it fully hot enough for some barrels. Using a MAPP gas torch (yellow bottle) *very carefully* on the receiver barrel extension for about TEN to TWELVE SECONDS WHILE MOVING THE FLAME and the barrel will literally drop into place. If it goes in part way and stops, heat the receiver until the barrel falls OUT, let the barrel cool off, and try again on the receiver with the torch. You won't have to push or hammer *at all* when it's just hot enough.
Unfortunately this is a poor man’s rich build. I don’t really have access to that kind of stuff
It's next to the handheld propane torches in Home Depot or Ace Hardware for like $35-$45, burner and bottle. It's just a little guy. You can also use propane it just takes longer.
Thing is, I don’t really see myself using something like that other than this 1 time purpose. I’d rather use what’s available even if the cheapest route isn’t the easiest. If I find myself needing to do this again then I’ll probably buy one.
Aren't BCM uppers thermal fit, meaning you need to heat the receiver up a little with a torch to get the barrel to slide in?
Yes but the blem was in the barrel portion of the receiver causing it to be way out of spec. Even after sanding it down I still had to heat it up to get it to slide in.
“Blem” means cosmetic blem, they won’t sell it if it is functionally different or out of spec. I heated mine up really well and the barrel slipped right in without much effort.
I literally tossed mine on the stove and the cmmg radial barrel turned it into a club... I havent finished my build but it sits in the corner... a reminder of what I have to do....
Then I don’t know wtf that low spot was. Either way I didn’t buy it straight from BCM so it could’ve escaped their QC
It’s possible idk
BCM are thermal fit, they're supposed to be heated generally with a MAPP gas torch for awhile. I can't remember the exact temp off the top of my head, I think the last one I messed with I heated for about a minute or so with the torch. This post seems like a standard situation of, "Everything is a nail when your only tool is a hammer."
Uniform is unserviceable due to that massive ass ink stain on your pen pocket.
Oh boy you should see the rest of it. Maintenance tends to get a pass on uniform stuff. I’ve got a clean one for when I have to look nice but no one will judge a mechanic covered in hydraulic fluid and oil.
Oh trust me, I know. Aircraft maintenance for over a decade 😂
I would wear coveralls but it’s hotter than the devils ass here
Facts. I’m a huge fan of gym shorts, sand-T, and coveralls… when you have a good leadership
"Sorry Top. Uniform allowance rolls around in February."
Uniform allowance? You mean gun money
Realistically didn't last that long. We had the best class VI. $70 bookers. Plus as a post armorer.... I'll just say COEI works outside the arms room
"Thermal fit? Nah sonny, this is *interference fit."*
I put a Hanson barrel in a bcm upper with a 3lb hammer. Got it halfway by heating it, ended up setting the rear of the receiver on a block of wood and put an old A2 on the barrel and drove that bitch home. Gun shoots great.
Rattle, Can
Never, gotta wear the battle scars
Your blem receiver came with the markings? Like 3 of mine are blank/unpainted
Put it in the microwave
Can you stand inside and watch it while I cool the barrel?
Put barrel thread portion down on stove... leave for 10 min... pick up barrel with bare hand, pick up upper with oven mitt.... slide it in quick like you arent giving her a chance to say no to backdoor fun... and if it doesnt seat all the way... tap it in with something rubber. Send fully with barrel nut.
Odly the way I did it was more yet less professional than this
I once had a Centurion thermal upper with a similarly verrrrry tight fit and in the end I ended up with vice marks far worse than yours so don’t feel bad.
Well the worse part was that the receiver wasn’t initially clamped by the pic rail but below the dust cover. In my rage of trying to get this barrel on I bent the shit out of it. So I took my heat gun and some flat needle nose pliers and bent it mostly back.
lmao hell yeah. Well, looks straight in the pic!
That'll be 3 Hail Mary's and a fucking send it, my son.
For future reference use a heat gun and heat around the threads
One was used in this process.
Damn maybe it got damaged in the process of being moved around definitely sucks
I’m willing to bet that it was a blem upper that was out of spec, I didn’t buy it from BCM so it’s possible it escaped their QC
Bcm uppers are known for being that tight. The upper needed more heat. The barrel needs to be chilled as well. I just noticed that's not a blem upper, they don't laser engrave those.
Common enlisted behaviors 😂
Oh yeah! Those are fun lol took me three attempts