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Posted: 1/30/2024 11:39:24 AM EDT
Alright,
So add my build comes together, I have an issue. My barrel from Solo300 came in, and holy shit it’s so unbelievably difficult to even get it started in the Lantac upper. I will probably go out and buy a heat gun to try and heat the upper a little bit first. I’ve also seen some recommend that I also freeze the barrel. But I seem to recall Randall from ar 15barrels.com saying to not bother freezing the barrel because of the thickness of the steel it can’t really shrink that much and it actually cools down the upper too quickly when you try to insert it. Thoughts? I’m wondering if it might be easier sending it out to ADCO or finding a reputable local armorer? |
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Posted: 1/30/2024 11:58:41 AM EDT
[#1]
Heat the upper to 400 degrees
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AL, USA
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Posted: 1/30/2024 12:03:53 PM EDT
[Last Edit: BhamAR]
[#2]
Small torch it & quickly slide the barrel in.
It’s a feature, not a bug. |
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Posted: 1/30/2024 12:09:13 PM EDT
[#3]
 The Secret of Thermo-Fit™ |
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Posted: 1/30/2024 12:09:59 PM EDT
[#4]
Yeah, all of my others have been more or less cheap-ish blaster type uppers where a barrel just slides right in.
This is my first time building on a somewhat boutique, billet upper. I gotta say, though, it is a really freaking nice upper. |
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Posted: 1/30/2024 12:21:27 PM EDT
[Last Edit: FoxValleyTacDriver]
[#5]
I like to use bcm uppers which are all thermal fit.
You can't even start putting it in prior to heat. After a little love with a torch it slides right in. Gotta be quick though. I put the barrel in the vice, and slide the upper on after heating it with the torch. Once it cools it locks back down on the barrel. Leaving a super tight fit that will not come apart without heat again. I'll vouch the freezer comment. Even I do it sometimes, but steel really can't contract much at the temps in your freezer. Not cold enough. I would reccomend buying a 1/2 in. wooden dowel and have a mallet handy. If you miss the pin and it gets stuck you'll want to smack it off while it's still hot. Put the dowel in the upper to the chamber. Smack it with a mallet to get the barrel back out. Try again. |
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OR, USA
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Posted: 1/30/2024 3:24:50 PM EDT
[#6]
I put my bcm uppers face down on my stove burner for 30-60 secs to get the barrels in
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Posted: 1/30/2024 3:32:22 PM EDT
[#7]
I've thermo fit a few. We had a Thermotron at work, and I could get the barrel down to -60F if I let it soak overnight.
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Posted: 1/30/2024 3:35:27 PM EDT
[Last Edit: Capt_Destro]
[#8]
Chill the barrel in the freezer, right before you Install heat up the upper.
Cold shrinks, heat expands. I feel like this gives you a few thousandths. Sometimes it's just enough to tap it in |
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MT, USA
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Posted: 1/30/2024 5:22:34 PM EDT
[Last Edit: spyderboy03]
[#9]
Quote HistoryOriginally Posted By AS556: I put my bcm uppers face down on my stove burner for 30-60 secs to get the barrels in |
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Posted: 1/30/2024 7:13:27 PM EDT
[#10]
I called Lantac today. They were cool as shit. Actually spoke with the head tech guy who specs out/designs their stuff. He recommended to not do the thermal fit. He said they ARE tight but to apply Aeroshell, spin on a crap FH, make sure the index pin is lined up, and use a mallet and wood block to pound it in. He said that’s how they do it in the shop and he recommended against using heat.
I still might do the heat thing though. So like the JP vid posted earlier, a torch is better than a heat gun? |
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Posted: 1/31/2024 12:58:05 AM EDT
[#11]
Quote HistoryOriginally Posted By Capt_Destro: Chill the barrel in the freezer, right before you Install heat up the upper. Cold shrinks, heat expands. I feel like this gives you a few thousandths. Sometimes it's just enough to tap it in There is an old guy from the YouTube that freezes barrels and measure the extension before and after. Zero change. I only use BCM, JP, and SOLGW uppers. Just a little heat from mommas crème brûlée torch and in it goes. |
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Posted: 1/31/2024 7:32:49 AM EDT
[#12]
Quote HistoryOriginally Posted By AS556: I put my bcm uppers face down on my stove burner for 30-60 secs to get the barrels in Clearly not induction or electric
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Posted: 1/31/2024 7:54:12 AM EDT
[#13]
Have you measured the components to confirm that they are in spec?
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Posted: 1/31/2024 7:23:12 PM EDT
[#14]
Centurion arms method good too? Or is
 Thermal fit upper barrel install -Centurion Arms |
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Posted: 1/31/2024 10:16:13 PM EDT
[#15]
Quote HistoryOriginally Posted By doc_Zox: Heat the upper to 400 degrees You do you. But 200f is my max. |
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GA, USA
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Posted: 1/31/2024 10:23:04 PM EDT
[Last Edit: OTDR]
[#16]
Quote HistoryOriginally Posted By alpha0815: There is an old guy from the YouTube that freezes barrels and measure the extension before and after. Zero change. . lol, its funny being referred to as old, but yeah thats me. I once froze a barrel for 24 hours at -9'F and there was no noticeable change on barrel ext both before and after using a Mitutoyo Micrometer that goes down to .00005 |
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CA, USA
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Posted: 2/1/2024 1:17:34 AM EDT
[#17]
The linear coefficient of expansion for alluminum is about twice that of steel 21 to 24 vs 10.8 to 12.5.
I'd be careful heating an aluminum upper and then only as much heat as is necessary. Sneak up on it, you can always apply more heat later. I've seen and had to repair shafts where a bearing race cooled and locked itself on before being seated where it needed to be; usually needing to be machined off in a lathe and sometimes even leaving an indentation in the steel shaft. Another possibility is having the upper split out because of the stress. The one "good" thing about that is; once the upper or bearing race cracks and splits-- with the tension gone, they're easier to get apart. |
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Posted: 2/2/2024 4:25:29 AM EDT
[#18]
Quote HistoryOriginally Posted By gatlingguns: The linear coefficient of expansion for alluminum is about twice that of steel 21 to 24 vs 10.8 to 12.5. I'd be careful heating an aluminum upper and then only as much heat as is necessary. Sneak up on it, you can always apply more heat later. I've seen and had to repair shafts where a bearing race cooled and locked itself on before being seated where it needed to be; usually needing to be machined off in a lathe and sometimes even leaving an indentation in the steel shaft. Another possibility is having the upper split out because of the stress. The one "good" thing about that is; once the upper or bearing race cracks and splits-- with the tension gone, they're easier to get apart. You recommend "only as much as necessary". I agree. And there is a metric for that. You can look back in a jillion threads and very rarely see anyone talk about a temp, or how to derive it. So I can sleep at night at least having tried, I recommend a laser thermometer and 200F. If someone looses an eye, it won't be because I kept a secret. |
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AZ, USA
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Posted: 2/2/2024 4:27:52 AM EDT
[#19]
Its a thermal fit. Those r those only uppers I buy now.
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Posted: 2/5/2024 3:20:32 PM EDT
[#20]
Just did the JP method posted above. Gave it 8 "spins" in the flame. Worked like a charm!
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Posted: 2/5/2024 8:10:08 PM EDT
[#21]
Quote HistoryOriginally Posted By Trumpet: Just did the JP method posted above. Gave it 8 "spins" in the flame. Worked like a charm! What temp did it reach? |
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Posted: 2/5/2024 9:55:59 PM EDT
[#22]
Quote HistoryOriginally Posted By xciapup: What temp did it reach? Enough? |
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CA, USA
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Posted: 2/6/2024 2:21:45 AM EDT
[#23]
Quote HistoryOriginally Posted By xciapup: You recommend "only as much as necessary". I agree. And there is a metric for that. You can look back in a jillion threads and very rarely see anyone talk about a temp, or how to derive it. So I can sleep at night at least having tried, I recommend a laser thermometer and 200F. If someone looses an eye, it won't be because I kept a secret. This is the primary reason I don't buy anyone else's home assembled firearm part or parts. Rarely built to spec or with proper technique |
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Posted: 2/6/2024 8:34:14 AM EDT
[Last Edit: Trumpet]
[#24]
Quote HistoryOriginally Posted By bravo_677: This is the primary reason I don't buy anyone else's home assembled firearm part or parts. Rarely built to spec or with proper technique As a counterpoint, do you think JP or Centruion are really using a laser thermometer for every upper they assemble? |
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Posted: 2/6/2024 12:41:16 PM EDT
[#25]
Whats the temp of a blue flame?
3000 degrees? 6-8 seconds and ram it in till it seats seems like the method |
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CA, USA
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Posted: 2/6/2024 12:49:44 PM EDT
[#26]
Quote HistoryOriginally Posted By Trumpet: As a counterpoint, do you think JP or Centruion are really using a laser thermometer for every upper they assemble? Home built, not factory or manufacturer assembled. Where would the accountability be if something were to go wrong? |
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Posted: 2/6/2024 1:17:37 PM EDT
[#27]
What like with the 1999 Y2K Bushmasters with the FSB over torqued left, due to someone gorilla cranking on the barrel nut?
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Posted: 2/6/2024 9:55:00 PM EDT
[#28]
Quote HistoryOriginally Posted By bravo_677: This is the primary reason I don't buy anyone else's home assembled firearm part or parts. Rarely built to spec or with proper technique Quote HistoryOriginally Posted By bravo_677: Originally Posted By xciapup: You recommend "only as much as necessary". I agree. And there is a metric for that. You can look back in a jillion threads and very rarely see anyone talk about a temp, or how to derive it. So I can sleep at night at least having tried, I recommend a laser thermometer and 200F. If someone looses an eye, it won't be because I kept a secret. This is the primary reason I don't buy anyone else's home assembled firearm part or parts. Rarely built to spec or with proper technique Laser thermometers are about $30 from Amazon. That is a lot cheaper than a scanning electron microscope to check for changed crystalline structure. |
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IA, USA
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Posted: 2/6/2024 11:22:17 PM EDT
[#29]
Quote HistoryOriginally Posted By FoxValleyTacDriver: ... I would reccomend buying a 1/2 in. wooden dowel and have a mallet handy. If you miss the pin and it gets stuck you'll want to smack it off while it's still hot. Put the dowel in the upper to the chamber. Smack it with a mallet to get the barrel back out. Try again. btdt make damn sure the dowel isn't wedging itself into the chamber. might want a bigger diameter dowel. still cleaning out the 5.56 barrel I took off the Aero Precision upper. |
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Posted: 2/7/2024 11:05:20 PM EDT
[#30]
Quote HistoryOriginally Posted By azmp5: Its a thermal fit. Those r those only uppers I buy now. @azmp5 What rails do you find that fit the Lantac Billet uppers? |
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AZ, USA
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Posted: 2/8/2024 7:51:50 PM EDT
[#31]
When it comes to billet stuff, it's good to just Google (or search on here) for what rail other companies use on their billet uppers. For the most part most rails for forged uppers should be fine for billet as well.
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USA
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Posted: 2/15/2024 11:46:05 AM EDT
[#32]
Just use a common propane torch like the ones plumbers use or those little ones for cooking.
Personally I dont like thermofit uppers as its a deviation from the original spec. People start jacking with the spec and they wonder why stuff doesnt work. Granted this is not a moving part but I would rather not have to use a torch to get it on/off. Witness all the boutique 1911's that have tons of problems because they tightened everything up from the original spec. |
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