Shimming/Bedding the Barrel on an M4E1 Enhanced upper

GrendelCurious

Private
Minuteman
Aug 26, 2021
8
1
USA
I'm in the process of putting together the parts for a precision oriented 6.5 Grendel rifle.

I've never done a precision build before, and it seems to be widely recommended to shim and/or bed the barrel into the upper with shim stock and loctite 620.

I'm using an M4E1 enhanced upper, and the I think that handguard mounting ring might make it difficult to remove excess loctite around the rim once I slide the barrel in place, and similarly awkward to keep the shim stock in place during the install.

I thought about spreading the loctite around the receiver itself instead of on the barrel extension, but I'm worried that the excess might get pushed into the upper and get into the teeth of the barrel extension, which would be similarly difficult to remove.

Has anyone bedded a barrel into one of these uppers before? If so, how did you go about doing it?

And before anyone recommends that I buy a BCM/VLTOR/etc. upper instead, I've already got the aero upper/handguard on hand. If I find myself with another receiver just lying around, I'll wind up needing to build another rifle, which is how I got into this situation in the first place. I don't think my wallet can handle that.
 

SupressYourself

Hillbilly Intellectual
Full Member
Minuteman
Mar 26, 2017
525
445
Eastern ND
The loctite doesn't dry immediately, so in either case, I think you could just wipe up any excess, just like you would with a "normal" receiver. q-tips are good for that. It doesn't take much loctite.
 

FishinGuns

Doesn’t fish well with others
Full Member
Minuteman
Jun 29, 2017
357
413
USA
I’ve 620 loctite bedded barrels into Seekins IRMT-R uppers. Same deal. Explained perfectly above me. Rifles shoot well, I don’t think it can hurt.
 

The38Super

Sergeant of the Hide
Full Member
Minuteman
May 10, 2020
242
206
I used 620 to bed the barrel on my pseudo precision 556 build and it worked well. .7 MOA at 200 yards all day using a Faxon barrel (on which the bore disintegrated after ~900 rounds of 4 round strings).
 

The38Super

Sergeant of the Hide
Full Member
Minuteman
May 10, 2020
242
206
Yes, please. Always looking for more reasons to not buy Faxon
By the time I'm done, there will be two brands you won't want to buy. In the beginning because of an evil enabling colleague, I discovered how easy it was to build AR's. My second build wound up as my cheap 556 bench rest-esque gun. In its ultimate configuration, it was basically Aero upper and lower, Faxon 18" fluted barrel, SSA-E trigger, Bushnell Forge 4.5x27 (parent company is based in KC and my rifle club gets a discount at the factory store) etc. Life was good as I sat and fired 4 round strings at paper 200 yards away, regularly holding .7 MOA, with an occasional .45 MOA group thrown in. Then, one day, after ~900 round down the pipe, my <MOA gun became a 6 MOA gun. Long story short, the bore looked like this.

Faxon day after.jpg


Faxon said they'd send a replacement, although they didn't have an ETA on when they'd run 18" non gunner profile barrels again. That was 2 months ago. In the meantime, other poor choices were made and I wound up buying a Ballistic Advantage fluted 18" barrel to stick in the gun. Because BA didn't want to be outdone, here's what the brand new barrel looked like out of the packaging on the day it hit my doorstep.

BA 18 inch 21 Aug 2021.jpg


And because BA can't be bothered with even substandard customer service, they're requiring me to return this boat anchor for inspection before they send a replacement. Dimwit I spoke to started babbling about a third party seller, storage conditions....I came close to ripping his head off and pointed out their warranty says nothing about point of purchase.

There's my story. I know Faxon isn't well liked here, but at least they're not morons and saw their barrel was toast. On the other hand, Ballistic Advantage puts out crap and does its best to further inconvenience you. I'd say 'The End', but I still have two garbage barrels in my possession and zero good ones.
 

BCP

Lt. Colonel
Full Member
Minuteman
  • Dec 4, 2008
    6,623
    1,740
    121
    CA
    Was that straight from them or from some reseller? I bought a couple awhile ago that were advertised as "blems" 129$ for an 18" SPR OPS contour. One shot great, other was not so great. Sent it back and they mailed me a new one a couple weeks later.
     

    msgriff

    Sergeant of the Hide
    Full Member
    Minuteman
    Feb 10, 2021
    177
    162
    Rogue Valley OR
    I have not done a Aero Enhanced, but I could tell that it would be a pain. Have you test fit yet? Sometimes it's pretty tight to begin with, almost thermal on some barrels. I would probably shim, but measuring the barrel hub diameter for shim thickness would be hard. I doubt shim stock over 0.001" would be needed.
     

    The38Super

    Sergeant of the Hide
    Full Member
    Minuteman
    May 10, 2020
    242
    206
    Bought from a reseller. Maybe I'm an ass, but I think BA should take care of it. Not my job to play 'who's the responsible party' on a brand new barrel.

    Faxon fit nicely, although not overly tight. BA is already in the gun and it's a super tight fit.
     

    BCP

    Lt. Colonel
    Full Member
    Minuteman
  • Dec 4, 2008
    6,623
    1,740
    121
    CA
    Bought from a reseller. Maybe I'm an ass, but I think BA should take care of it. Not my job to play 'who's the responsible party' on a brand new barrel.

    Faxon fit nicely, although not overly tight. BA is already in the gun and it's a super tight fit.

    Send it back and they will give you another one. Not hard.
     

    The38Super

    Sergeant of the Hide
    Full Member
    Minuteman
    May 10, 2020
    242
    206
    Send it back and they will give you another one. Not hard.
    This thing is so blatantly bad and I don't have a return label, three days after I contacted them. I may be a dick, but every other product issue I've had in recent memory (shooting and other products) has been handled much more quickly. Taking care of your customer; not hard.
     

    JS8588

    Ballistic Hipster
    Full Member
    Minuteman
    Apr 7, 2020
    282
    203
    NEPA
    By the time I'm done, there will be two brands you won't want to buy. In the beginning because of an evil enabling colleague, I discovered how easy it was to build AR's. My second build wound up as my cheap 556 bench rest-esque gun. In its ultimate configuration, it was basically Aero upper and lower, Faxon 18" fluted barrel, SSA-E trigger, Bushnell Forge 4.5x27 (parent company is based in KC and my rifle club gets a discount at the factory store) etc. Life was good as I sat and fired 4 round strings at paper 200 yards away, regularly holding .7 MOA, with an occasional .45 MOA group thrown in. Then, one day, after ~900 round down the pipe, my <MOA gun became a 6 MOA gun. Long story short, the bore looked like this.

    View attachment 7691892

    Faxon said they'd send a replacement, although they didn't have an ETA on when they'd run 18" non gunner profile barrels again. That was 2 months ago. In the meantime, other poor choices were made and I wound up buying a Ballistic Advantage fluted 18" barrel to stick in the gun. Because BA didn't want to be outdone, here's what the brand new barrel looked like out of the packaging on the day it hit my doorstep.

    View attachment 7691895

    And because BA can't be bothered with even substandard customer service, they're requiring me to return this boat anchor for inspection before they send a replacement. Dimwit I spoke to started babbling about a third party seller, storage conditions....I came close to ripping his head off and pointed out their warranty says nothing about point of purchase.

    There's my story. I know Faxon isn't well liked here, but at least they're not morons and saw their barrel was toast. On the other hand, Ballistic Advantage puts out crap and does its best to further inconvenience you. I'd say 'The End', but I still have two garbage barrels in my possession and zero good ones.

    Aero/BA were already on my "friends don't let friends buy" list along with Faxon. I just always enjoy more documentation to support my biases.
     

    clcustom1911

    "Cartman 1-2, come in"
    Supporter
    Full Member
    Minuteman
    Supporter+
  • Oct 23, 2017
    7,985
    19,001
    The River in Arizona
    OP, do a test fit of the barrel I to the upper,, to may find it's a good fit as is without having to deal with bedding/shimming. I have a Faxon 16" pencil profile mid-gas in my Aero M4E1 build. Upper was a nice, tight,, rubber mallet fit onto the barrel extension. Couple thousand rounds through it, including several bump-fire mag dumps for reliability as it was my first ever build...and still does 2-4moa with anything I put through it. It's a lightweight plinker, so I'm only going for the good ol' IPSC steel plates out to 400-500 and does those without issue at all. YMMV

    Screenshot_20210827-131445_Gallery.jpg
     

    clcustom1911

    "Cartman 1-2, come in"
    Supporter
    Full Member
    Minuteman
    Supporter+
  • Oct 23, 2017
    7,985
    19,001
    The River in Arizona
    By the time I'm done, there will be two brands you won't want to buy. In the beginning because of an evil enabling colleague, I discovered how easy it was to build AR's. My second build wound up as my cheap 556 bench rest-esque gun. In its ultimate configuration, it was basically Aero upper and lower, Faxon 18" fluted barrel, SSA-E trigger, Bushnell Forge 4.5x27 (parent company is based in KC and my rifle club gets a discount at the factory store) etc. Life was good as I sat and fired 4 round strings at paper 200 yards away, regularly holding .7 MOA, with an occasional .45 MOA group thrown in. Then, one day, after ~900 round down the pipe, my <MOA gun became a 6 MOA gun. Long story short, the bore looked like this.

    View attachment 7691892

    Faxon said they'd send a replacement, although they didn't have an ETA on when they'd run 18" non gunner profile barrels again. That was 2 months ago. In the meantime, other poor choices were made and I wound up buying a Ballistic Advantage fluted 18" barrel to stick in the gun. Because BA didn't want to be outdone, here's what the brand new barrel looked like out of the packaging on the day it hit my doorstep.

    View attachment 7691895

    And because BA can't be bothered with even substandard customer service, they're requiring me to return this boat anchor for inspection before they send a replacement. Dimwit I spoke to started babbling about a third party seller, storage conditions....I came close to ripping his head off and pointed out their warranty says nothing about point of purchase.

    There's my story. I know Faxon isn't well liked here, but at least they're not morons and saw their barrel was toast. On the other hand, Ballistic Advantage puts out crap and does its best to further inconvenience you. I'd say 'The End', but I still have two garbage barrels in my possession and zero good ones.
    Have any before pics of the Faxon barrel? Or, did you do what most people do with bore scopes, and only buy one after an issue popped up to inspect for an issue with no actual baseline comparison?
     

    The38Super

    Sergeant of the Hide
    Full Member
    Minuteman
    May 10, 2020
    242
    206
    My delicate feelings may be hurt at the suggestion I only bought my scope after an issue arose. I purchased it when any adult male would - because I saw it and thought it was cool.

    Here's the Faxon about mid way through its short life.
    Faxon approx 300 rds.jpg


    After the accuracy went to hell - immediately following a range trip. Doesn't look bad, which confused the heck out of me.
    6-24 preclean 1.jpg


    However, the next day, it looked like this
    Faxon day after.jpg


    As you can see, it's begun to corrode, along with some other interesting reactions.

    Here's a video (taken contemporaneously with the above pic) showing how the bore surface degraded.

    Faxon Barrel
     

    clcustom1911

    "Cartman 1-2, come in"
    Supporter
    Full Member
    Minuteman
    Supporter+
  • Oct 23, 2017
    7,985
    19,001
    The River in Arizona
    My delicate feelings may be hurt at the suggestion I only bought my scope after an issue arose. I purchased it when any adult male would - because I saw it and thought it was cool.

    Here's the Faxon about mid way through its short life.
    View attachment 7692247

    After the accuracy went to hell - immediately following a range trip. Doesn't look bad, which confused the heck out of me.
    View attachment 7692249

    However, the next day, it looked like this
    View attachment 7692251

    As you can see, it's begun to corrode, along with some other interesting reactions.

    Here's a video (taken contemporaneously with the above pic) showing how the bore surface degraded.

    Faxon Barrel
    Excellent. I'm glad you're not most people.
     
    • Like
    Reactions: BCP

    Odysseus1911

    Piled higher and Deeper
    Full Member
    Minuteman
    Feb 14, 2019
    580
    1,207
    Arkansas
    I used green loctite to bed a Craddock/Bartlein into an Aero M4e1 last fall. It was already a tight fit, but I figured it couldn't hurt. Wiped off the excess, torqued the nut, let cure 48 hrs. Shoots great, but it probably would have without the loctite. I say go for it.
     

    clcustom1911

    "Cartman 1-2, come in"
    Supporter
    Full Member
    Minuteman
    Supporter+
  • Oct 23, 2017
    7,985
    19,001
    The River in Arizona
    My delicate feelings may be hurt at the suggestion I only bought my scope after an issue arose. I purchased it when any adult male would - because I saw it and thought it was cool.

    Here's the Faxon about mid way through its short life.
    View attachment 7692247

    After the accuracy went to hell - immediately following a range trip. Doesn't look bad, which confused the heck out of me.
    View attachment 7692249

    However, the next day, it looked like this
    View attachment 7692251

    As you can see, it's begun to corrode, along with some other interesting reactions.

    Here's a video (taken contemporaneously with the above pic) showing how the bore surface degraded.

    Faxon Barrel
    Thinking about this.... maybe just fuck ton of copper fouling? Maybe could been corrected with several rounds of Sweets762 or other specific de-coppering agent.
     

    BCP

    Lt. Colonel
    Full Member
    Minuteman
  • Dec 4, 2008
    6,623
    1,740
    121
    CA
    I used green loctite to bed a Craddock/Bartlein into an Aero M4e1 last fall. It was already a tight fit, but I figured it couldn't hurt. Wiped off the excess, torqued the nut, let cure 48 hrs. Shoots great, but it probably would have without the loctite. I say go for it.

    I'm always hesitant to do that because I've had expensive barrels be "bad" and when it's all loctited in there they can be a motherfucker to get out.
     
    • Like
    Reactions: MR.Abrams

    roostercogburn98

    Crawling America, one mall at a time
    Supporter
    Full Member
    Minuteman
    Supporter+
    Nov 3, 2010
    5,824
    11,048
    Last barrel I installed did not need any loctite. It took a few days in the feeezer and some heat on the mega receiver to fit. Even then it still required some help. Barrel fit was exceptional and will see how it shoots soon again I hope.
    47A6C78F-5FD3-4FAC-885A-0D0D22613E52.jpeg
     

    The38Super

    Sergeant of the Hide
    Full Member
    Minuteman
    May 10, 2020
    242
    206
    Thinking about this.... maybe just fuck ton of copper fouling? Maybe could been corrected with several rounds of Sweets762 or other specific de-coppering agent.
    Ran a full course of Bore Tech Eliminator through the barrel, in the hopes the rust was confined to the surface. A) it's not and B) there was a bit of blue on one of the patches, but that's it. Broke in my Bergara BMP earlier this week and that had a fuck ton of copper, with tons of blue patches coming out of the barrel. It's definitely rust.
     

    GrendelCurious

    Private
    Minuteman
    Aug 26, 2021
    8
    1
    USA
    OP, do a test fit of the barrel I to the upper,, to may find it's a good fit as is without having to deal with bedding/shimming. I have a Faxon 16" pencil profile mid-gas in my Aero M4E1 build. Upper was a nice, tight,, rubber mallet fit onto the barrel extension. Couple thousand rounds through it, including several bump-fire mag dumps for reliability as it was my first ever build...and still does 2-4moa with anything I put through it.
    I'm hoping for something a bit better than 2-4 MOA.
     

    Odysseus1911

    Piled higher and Deeper
    Full Member
    Minuteman
    Feb 14, 2019
    580
    1,207
    Arkansas
    What barrel are you using?

    You can put a Bartlein/Krieger/Proof/Satern cut-rifled barrel in the cheapest receiver on the market, and you'll still have a sub-MOA hammer. You can put a BA/Faxon in the most expensive, top-of-the-line receiver, and you'll still have a 2-4 MOA dog. Spend the coin on a good barrel.
     
    Last edited:

    BCP

    Lt. Colonel
    Full Member
    Minuteman
  • Dec 4, 2008
    6,623
    1,740
    121
    CA
    Got an 18" odin works heavy profile barrel.

    Did you buy one of the packages where you get their barrel, bolt and gas block? The hard part will be handloading for it since components are scarce right now.
     

    GrendelCurious

    Private
    Minuteman
    Aug 26, 2021
    8
    1
    USA
    Yeah, it came with the BCG, bolt, block and gas tube. I was originally going to order a longer criterion barrel from Precision firearms, but their lead times were 6-9 months, and I got a really good deal on the odin package, so I just went that route instead.
     

    Ravenworks

    Zebco Pro Staffer
    Full Member
    Minuteman
  • Feb 8, 2019
    4,011
    7,844
    Somewhere
    By the time I'm done, there will be two brands you won't want to buy. In the beginning because of an evil enabling colleague, I discovered how easy it was to build AR's. My second build wound up as my cheap 556 bench rest-esque gun. In its ultimate configuration, it was basically Aero upper and lower, Faxon 18" fluted barrel, SSA-E trigger, Bushnell Forge 4.5x27 (parent company is based in KC and my rifle club gets a discount at the factory store) etc. Life was good as I sat and fired 4 round strings at paper 200 yards away, regularly holding .7 MOA, with an occasional .45 MOA group thrown in. Then, one day, after ~900 round down the pipe, my <MOA gun became a 6 MOA gun. Long story short, the bore looked like this.

    View attachment 7691892

    Faxon said they'd send a replacement, although they didn't have an ETA on when they'd run 18" non gunner profile barrels again. That was 2 months ago. In the meantime, other poor choices were made and I wound up buying a Ballistic Advantage fluted 18" barrel to stick in the gun. Because BA didn't want to be outdone, here's what the brand new barrel looked like out of the packaging on the day it hit my doorstep.

    View attachment 7691895

    And because BA can't be bothered with even substandard customer service, they're requiring me to return this boat anchor for inspection before they send a replacement. Dimwit I spoke to started babbling about a third party seller, storage conditions....I came close to ripping his head off and pointed out their warranty says nothing about point of purchase.

    There's my story. I know Faxon isn't well liked here, but at least they're not morons and saw their barrel was toast. On the other hand, Ballistic Advantage puts out crap and does its best to further inconvenience you. I'd say 'The End', but I still have two garbage barrels in my possession and zero good ones.
    Well to be honest neither are quality barrels.
    I have several BA barrels on beater builds that will probably never see a brush or a patch And expect them to shoot accordingly.


    OP, you need to stop and regroup.
    Putting Loctite all over the place is not going to magically make things great.
    Do you plan on cutting the face of the receiver to true it ?
    If so you'll need to buy the lapping tool to do it.

    Why not try putting the gun together and seeing how it shoots?
    That's how it's been done since Hector was a pup.