That's how I ended up with one. Figured at that price I couldn't lose. It absolutely required a frozen barrel and heated receiver to make the magic happen.
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Who Makes Thermal Fit Stripped Uppers?
- Thread starter JS8588
- Start date
Very much a thermal fit upper.
BKF M4 MOD-0 Stripped Upper Receiver - Black (Light T-Marks)
BKF M4 MOD-0 Stripped Upper Receiver - Black (Light T-Marks)bkingsfirearms.com
Very much thermal and priced right. Ordered one for a friend based on your opinion and it took heat and ice. Appreciate it
Glad it did the trick. The one I have happens to be a laser. Not saying it's the receiver, but it can't be hurting.
Good to hear!
This is a hunting and range set up for his son. 20” WC 6.5 Grendel barrel. Know soon I’m sure, it’s all together now.
I’d use another for a quality felt lightweight thermal upper though
Yeah I've got 4 or 5 of those now (I think from your recommendation here IIRC), they've all been a strong thermal fit and shoot really well when matched with good barrels.
To clarify for anyone buying these though, their standard uppers are not thermal fit, but the "Mod 0" are. It's in their descriptions on the website too, for reference.
Always happy to help other people spend their money!
Negative Ghost Rider....
JP Thermo Fit Receivers are under sized, and thier small frame barrel extensions are standard .98 IIRC..
You can deal with this one of three ways, you can order receivers that are undersized, have a custom barrel made with a oversized barrel extension or you can go hillbilly Locktite..
My current .223 that I just finished utilizes the JP Thermo fit Receiver, and the the White Oak Competition Barrel exstenion.. she's definitely the most ridged upper I've ever built.
My current .223 that I just finished utilizes the JP Thermo fit Receiver, and the the White Oak Competition Barrel exstenion.. she's definitely the most ridged upper I've ever built.
It's. 998... if someone is making .98 on purpose I want to know. That would NOT be a thermal fit. It would be a broken receiver with any standard barrel.
The spec is -
BARREL- 0.998 TO 0.9995
Reviever- 0.999 to 1.000
The spec is -
BARREL- 0.998 TO 0.9995
Reviever- 0.999 to 1.000
The socket on the upper is intentionally undersized, that's the intent of a thermal fit. An example is linked in post #103:
"The Inside Diameter for the barrel extension is slightly undersized for a tighter fit to the barrel and will produce a more accurate rifle. Please note: you may need to use a heat gun or hair dryer to warm up threaded bore of receiver and freeze your barrel if your barrel extension is too tight."
bought a couple BCM uppers for the 'extra' Proof stainless barrel I'd forgotten ordering
Better to have one too many than one too few since VA's legislature is mostly leftist gun-grabbing morons now
M
Better to have one too many than one too few since VA's legislature is mostly leftist gun-grabbing morons now
M
Yes. But it's a big difference between a .002 thermal fit and a .020 broken upper. That is so far out of a forced fit it's not possible. Numbers matter. Multiple people claimed a .98 receiver. It would be .998.
The -0.0005 difference between the receiver ID and the barrel OD is the thermal fit.
In prespective a FN5 forced fit would have 0.0033" MAX interference.
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JP is an interesting situation for thermofit all the higher end JP stripped uppers are Thermo.
If you buy a JP-15™ Stripped Forged Upper Receiver it's not thermofit.
If you buy a JP-15 assembled upper or rifle it is thermofit. I believe they have a different upper they sell at retail that is not used for the builds.
That may be something WOA used to do but not anymore. I recently emailed them asking this question and Jane replied by telling me they are all mil-spec and they do not offer alternate sizing.
The last couple of BCM uppers I bought (retail) were not exactly thermofit.
The barrel extension goes about 2/3 - 3/4 the way in before it starts to get snug and with a little effort I can push it all the way in.
Not real happy with their uppers anymore.
Not as bad as the Aero Precision AR-10 upper I have.
Needs 0.001 shim to make it tight. Almost like a hot dog down a hallway without shims.
The barrel extension goes about 2/3 - 3/4 the way in before it starts to get snug and with a little effort I can push it all the way in.
Not real happy with their uppers anymore.
Not as bad as the Aero Precision AR-10 upper I have.
Needs 0.001 shim to make it tight. Almost like a hot dog down a hallway without shims.
I've been using B. King's thermofit uppers lately with great results.
I just built my 6 ARC upper with a BCM demo upper and had to heat it up to go in also just like all the ones before it.
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I just built out a B. Kings M5 Mod-0 large frame upper. Extension is -.004 under an Aero. Fits their M5 Mod - 0 lower like a glove.
Forgot to point out in this earlier comment - B Kings sells both mil-spec and thermofit "Mod-0" uppers. Gotta look at the description to understand what you're getting.
