Baffle stack vs monocore/solid weld design

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  • JohnnyE

    Ultimate Member
    MDS Supporter
    Jan 18, 2013
    9,466
    MoCo
    Ok - you are telling me that anti-seize compounds like (e.g.) Special 18002 Aluminum Anti-Seize will eat up aluminum?? Great! I use that on my AR upper receivers. :sad20:

    [EDIT] Manufacturer claims you can use on spark plugs for aluminum block engines. (?)

    I don't know the composition of that particular formulation. It's that detail that makes the difference.

    If you look at the table below, it tells us that the substances at the bottom are the most nobel, meaning they are the things that tend not to corrode, whereas the substances higher up the table are the things that get eaten up when in electrical contact with something lower down on the table and an electrolyte is present. That's why we put zinc sacrificial anodes on saltwater boats, to protect the bronze hardware below the waterline. We put magnesium sacrificial anodes on freshwater to protect aluminum outdrives.

    Aluminum is near the top, and carbon (graphite) is at the very bottom. Put them in contact with each other, add an electrolyte like water, and the aluminum gets corroded. On an anodized AR upper or lower, I'm not as worried about graphite because I keep things really dry. As my own rule, however, I don't use graphite when aluminum is involved. In most cases any problems may only be cosmetic, but when clearances are tight, that's another story.

    In my situation, the long aluminum monocore slides into the 3/4 inch diameter steel tube. The clearance is very tight and the core is about 10 inches long, which makes for a lot of contact area. I had a devil of a time getting the core out even though I never added any anti-seize. The carbon that really encouraged the corrosion came from the burning powder, as did the moisture (the electrolyte), and no doubt some sulphur or another source of acidity to really make the electrolyte conductive.

    I neglected to mention upthread that when I wrestled the monocore out of the tube it looked like an old piece of aluminum that had been left in the bay for a while. Not just the parts of the core in contact with the steel tube, mind you, but all over the entire surface of the core. It was covered in a fine layer of corrosion. I had to get out some very fine sandpaper to knock it off, then grabbed a rag and some polishing compound to shine it up.

    While a graphite-based anti-seize may work without problems because the grease it's mixed with will exclude water, in a suppressor I was concerned that the heat and pressures may cook off the grease or blow it out from the tight space between the core and tube such that water could get in there. I decided to skip the whole issue and use a metal-free anti-seize.
     

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    outrider58

    Eats Bacon Raw
    MDS Supporter
    Jul 29, 2014
    49,818
    Ok - you are telling me that anti-seize compounds like (e.g.) Special 18002 Aluminum Anti-Seize will eat up aluminum?? Great! I use that on my AR upper receivers. :sad20:

    [EDIT] Manufacturer claims you can use on spark plugs for aluminum block engines. (?)
    You should be using Aeroshell 33 for that. Also, be careful using brake fluids on suppressor parts. Great on cups and cores. Terrible in threaded attaching points. They tend to want to continuously work loose.

    Nothing worse than shooting you can down range...
     

    calicojack

    American Sporting Rifle
    MDS Supporter
    May 29, 2018
    5,348
    Cuba on the Chesapeake
    Johnnye Glad your bought this up because it forced me to think about how I lube the threads of my Uppers. Thanks for the detailed description :)

    Outrider, reading some of the other forums, yeah a lot of folks say the same; that a moly grease compound is way to go (Aero 33 is a synthetic I think, probably even better). Some still argue for the anti-seize compound, or lithium grease. I have not seen anyone that thinks an anti-seize compound is detrimental, just that the molly grease is BEST suited for putting barrels on AR uppers. Course places like Brownells want to sell you their ant-seize compound. And some guys say they use nothing :shrug: Found some pretty heated discussion threads.

    Anyways - I am ordering Aero 33 or similar.
     

    teratos

    My hair is amazing
    MDS Supporter
    Patriot Picket
    Jan 22, 2009
    59,775
    Bel Air
    Johnnye Glad your bought this up because it forced me to think about how I lube the threads of my Uppers. Thanks for the detailed description :)

    Outrider, reading some of the other forums, yeah a lot of folks say the same; that a moly grease compound is way to go (Aero 33 is a synthetic I think, probably even better). Some still argue for the anti-seize compound, or lithium grease. I have not seen anyone that thinks an anti-seize compound is detrimental, just that the molly grease is BEST suited for putting barrels on AR uppers. Course places like Brownells want to sell you their ant-seize compound. And some guys say they use nothing :shrug: Found some pretty heated discussion threads.

    Anyways - I am ordering Aero 33 or similar.

    Aero 33 is recommended for barrel installs in the AR. Moly grease would be my second choice.
     

    JohnnyE

    Ultimate Member
    MDS Supporter
    Jan 18, 2013
    9,466
    MoCo
    Johnnye Glad your bought this up because it forced me to think about how I lube the threads of my Uppers. Thanks for the detailed description :)

    Outrider, reading some of the other forums, yeah a lot of folks say the same; that a moly grease compound is way to go (Aero 33 is a synthetic I think, probably even better). Some still argue for the anti-seize compound, or lithium grease. I have not seen anyone that thinks an anti-seize compound is detrimental, just that the molly grease is BEST suited for putting barrels on AR uppers. Course places like Brownells want to sell you their ant-seize compound. And some guys say they use nothing :shrug: Found some pretty heated discussion threads.

    Anyways - I am ordering Aero 33 or similar.
    Thanks CJ, I really started learning about this in the 90's following some bad experiences involving boats in saltwater.

    Once I used stainless steel screws to secure an aluminum panel to an aluminum cabinet. A few years later I attempted to remove the screws and found that the threaded aluminum holes they were screwed in to had turned to powdered aluminum oxide. It was a mess. The screws though were just fine. I rethreaded the holes one size larger and secured the panel using aluminum screws. Ah, now everything was aluminum, achieving full galvanic compatibility. Problem solved. Unless you learn in a hurry, it can cost a lot of money!

    Another thing to keep in mind is there are anti-seize lubes that contain different metals or non-metallic substances as their effective ingredient. The most common is graphite, which is ok for dry environments or metals that are close together on the galvanic table, like a steel nut on a steel bolt (but never my fav with aluminum). Others contain copper, like the anti-seize Glock uses, and others contain nickel, which is noted for doing well in high-heat environments. I decided against nickel in my suppressor because it's worse than copper from a galvanic standpoint.

    Molybdenum disulphide, while not a metal, still reacts in a galvanic cell as though it were. While an AR barrel nut uses moly-based Aeroshell 33, the grease carrier won't get cooked off or blown out, and water isn't much of an issue, so it should be fine. Millions of AR's can't be wrong!

    Aero 33 is recommended for barrel installs in the AR. Moly grease would be my second choice.

    Yup, see immediately above.

    Any other lube recommendations, Doc? :innocent0
     

    teratos

    My hair is amazing
    MDS Supporter
    Patriot Picket
    Jan 22, 2009
    59,775
    Bel Air
    Not as of yet, but I'm certain I have that walk of shame in my future...:o

    Did it with my Gemtech Multimount. Launched about 15 meters. Buddy didn’t fully seat the 3 lug mount. Luckily no damage. Big pucker factor going to pick it up, though.
     

    rsideout

    Senior Member
    MDS Supporter
    Dec 11, 2009
    6,709
    MD - Capital Region
    Did it with my Gemtech Multimount. Launched about 15 meters. Buddy didn’t fully seat the 3 lug mount. Luckily no damage. Big pucker factor going to pick it up, though.

    I once watched an integral 7.62x51 Barrel/Suppressor get detached and launched about the same distance down range. The projectile never came out of the can. It was destroyed. The rifle & can were owned by the 07 SOT, so not a big loss......but embarrassing for him.
     

    teratos

    My hair is amazing
    MDS Supporter
    Patriot Picket
    Jan 22, 2009
    59,775
    Bel Air
    I once watched an integral 7.62x51 Barrel/Suppressor get detached and launched about the same distance down range. The projectile never came out of the can. It was destroyed. The rifle & can were owned by the 07 SOT, so not a big loss......but embarrassing for him.

    Yikes. That is an embarrassment. Hope he didn’t have any customers with the same experience....
     

    Sundazes

    My brain hurts
    MDS Supporter
    Nov 13, 2006
    21,304
    Arkham
    Did it with my Gemtech Multimount. Launched about 15 meters. Buddy didn’t fully seat the 3 lug mount. Luckily no damage. Big pucker factor going to pick it up, though.

    I had a Specwar almost make the 50 yard berm at BCGF when my son didn't tighten the ASR mount all the way. Baffle strike and end cap had a big strike. I sent it to SiCo fully expecting to pay for repairs. They covered it under warranty. We were the only ones there... But HPF was high.
     

    teratos

    My hair is amazing
    MDS Supporter
    Patriot Picket
    Jan 22, 2009
    59,775
    Bel Air
    I had a Specwar almost make the 50 yard berm at BCGF when my son didn't tighten the ASR mount all the way. Baffle strike and end cap had a big strike. I sent it to SiCo fully expecting to pay for repairs. They covered it under warranty. We were the only ones there... But HPF was high.

    Glad they covered it!
     

    teratos

    My hair is amazing
    MDS Supporter
    Patriot Picket
    Jan 22, 2009
    59,775
    Bel Air
    I had that when I fired a 9mm luger round by accident once through a .40 glock with a can attached! Fortunately, it flew true and didn't hit any baffles.

    My Colt 6920 didn’t fare quite as well firing a .300 BLK round. I had to put a new barrel on and replace the bolt. Carrier and upper were fine. I had to machine a bending jig, but the lower is back in spec (SOTAR confirmed).
     

    rsideout

    Senior Member
    MDS Supporter
    Dec 11, 2009
    6,709
    MD - Capital Region
    My Colt 6920 didn’t fare quite as well firing a .300 BLK round. I had to put a new barrel on and replace the bolt. Carrier and upper were fine. I had to machine a bending jig, but the lower is back in spec (SOTAR confirmed).

    So .300 BLK doesn’t fit through a .223 barrel? Learn something new every day! :)
     

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