View Full Version : Cracked lower repair?
I'm pretty new to ARs, so I wasn't aware that you're not supposed to let the hammer drop on a lower receiver when it's separated from the upper receiver. I had a Geissele trigger which has a stronger hammer spring and a cutout so that it contacts the receiver instead of the bolt catch. I let it drop a few times and I have a crack on my lower receiver now. I'm pretty bummed about this and since this is a Noveske lower, I want to know if it's salvageable. Since it's forged 7075 aluminum, I don't think it's weldable. Alternately, I wonder if something like epoxy would do the trick.
Got any pics of the damage?
It's hard to capture on camera but on the forward wall of the receiver where the fire control group cutout is, there is a hairline crack near the left corner.
I'm pretty new to ARs, so I wasn't aware that you're not supposed to let the hammer drop on a lower receiver when it's separated from the upper receiver. I had a Geissele trigger which has a stronger hammer spring and a cutout so that it contacts the receiver instead of the bolt catch. I let it drop a few times and I have a crack on my lower receiver now. I'm pretty bummed about this and since this is a Noveske lower, I want to know if it's salvageable. Since it's forged 7075 aluminum, I don't think it's weldable. Alternately, I wonder if something like epoxy would do the trick.7075 is not considered a weldable alloy . . .
Pics? It may just be a "don't do it again" kind'a thing.
Does the bolt catch still move freely?
Does the bolt catch still move freely?
Bolt catch still moves freely.
Running my fingernails along the front wall I can notice it. Currently the lower seems to function fine.
Also, before this accident, I had this lower cerakoted, so I’m not sure if the crack is even longer and the cerakote is obscuring it.
Since it's not weldable, I would probably try and clean it real good and try and press some JB weld into. Keep and eye on it. Seems worth a try, it's that or toss it.
Of course there may be some better options I'm not aware of.
If it's functioning correctly I'd not do it again, use the lower as intended and keep an eye on it for signs of change.
I was considering JB weld or some kind of epoxy with aluminum powder, but the crack is quite fine and I‘m not sure if I can get the compound in there. It's a Noveske lower, and I had it cerakoted too, so I rather not have to throw it away.
Does that area of the lower receiver normally see a lot of stress?
You can weld lowers, John Norrell used to weld saw cut demilled M16A1's back together and I have also heard of cloner's having mag wells welded on 80% back ends to get the markings. But unless it's a really special lower it would be cheaper to just replace it.
Here's a link to a Norrell Hydra-Matic By GM Corp. M16A1 weld that sold for $20.5 k in 2020.
http://www.sturmgewehr.com/forums/index.php?/topic/19577-wts-m16a1-hydra-matic-norrell-reweld-20500/
You can weld lowers, John Norrell used to weld saw cut demilled M16A1's back together and I have also heard of cloner's having mag wells welded on 80% back ends to get the markings. But unless it's a really special lower it would be cheaper to just replace it.
Here's a link to a Norrell Hydra-Matic By GM Corp. M16A1 weld that sold for $20.5 k in 2020.
http://www.sturmgewehr.com/forums/index.php?/topic/19577-wts-m16a1-hydra-matic-norrell-reweld-20500/
https://blog.blackadvtech.com/why-is-welding-7075-aluminum-impossible
Does that area of the lower receiver normally see a lot of stress?
Yes and no, the pressure is all in the chamber, where there might be stress is with fully loaded magazines, but I doubt it will be an issue.
Some manufacturers have made lowers out of polymer, so a hairline crack that doesn't run the length of the receiver should be safe to shoot, but just keep an eye on it.
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It can be welded, the technology has been available for a couple years. Finding a welder in your local area who does it, and uses the correct materials to do it might be a bit harder.
Friction stir welding (FSW) is one method which touts the ability to weld 7075. Nanoparticle-enhanced aluminum 7075 wire welding appears to my ignorant knowledge base to be a slightly better option, though it probably lies somewhere between preparation and temperatures used with the NPE wire.
I was considering JB weld or some kind of epoxy with aluminum powder, but the crack is quite fine and I‘m not sure if I can get the compound in there. It's a Noveske lower, and I had it cerakoted too, so I rather not have to throw it away.
Does that area of the lower receiver normally see a lot of stress?
No, it does not.
No, it does not.
It does for this guy. :jester:
jackblack73
05-25-22, 18:03
What are the odds it’s an actual crack in the aluminum as opposed to just the cerakote or anodizing? If I remember correctly someone on the other site dropped the hammer on a 6061 80% lower hundreds of times before seeing any damage. I would think 7075 could handle a few strikes just fine.
What are the odds it’s an actual crack in the aluminum as opposed to just the cerakote or anodizing? If I remember correctly someone on the other site dropped the hammer on a 6061 80% lower hundreds of times before seeing any damage. I would think 7075 could handle a few strikes just fine.
True that 7075 is stronger than 6061, but it's also harder and more brittle, so maybe it's more prone to cracking?
The cerakote is actually a bit of a concern, because cerakote doesn't seem to be as hard or brittle as anodized aluminum, and I'm wondering if the crack underneath the cerakote is more extensive that what it shows on the surface.
I'm pretty new to ARs, so I wasn't aware that you're not supposed to let the hammer drop on a lower receiver when it's separated from the upper receiver. I had a Geissele trigger which has a stronger hammer spring and a cutout so that it contacts the receiver instead of the bolt catch. I let it drop a few times and I have a crack on my lower receiver now. I'm pretty bummed about this and since this is a Noveske lower, I want to know if it's salvageable. Since it's forged 7075 aluminum, I don't think it's weldable. Alternately, I wonder if something like epoxy would do the trick.
Absolutely no offense or insult intended, but why?
This isn't a registered MG receiver, just get a new one and move on lesson learned. If this is a "save my life" firearm, you really want to trust it to epoxy? I'd even be willing to bet Noveske might cover it under warranty, give them a call and find out. If not having them replace the receiver can't be too damn expensive.
to do a proper JB Weld repair you need to open up the area of the crack. Remove enough material so that you can fill in with the mix. I would remove all of the crack from both sides. Leave the ground out portion rough so the weld will have better grip. JB Weld is very strong and can be a very effective repair. Good luck!
Evil Black Rifle
05-26-22, 17:27
Shoot it. It will either be fine, or get worse.
I strongly suggest that if you try any half-arsed JB weld repairs, it will make a useless mess.
I shot it again and it functioned fine. Hopefully it was just a crack in the cerakote then. Geissele triggers have a really strong hammer spring, and the surface crack on the lower receiver had me really worried.
I'd even be willing to bet Noveske might cover it under warranty, give them a call and find out. If not having them replace the receiver can't be too damn expensive.
Can a manufacturer replace a receiver and use the same serial number, or does it have to be transferred as a new firearm?
Can a manufacturer replace a receiver and use the same serial number, or does it have to be transferred as a new firearm?
No.
They would have to replace the receiver with a new "firearm."
Just curious, since cerakote doesn't seem to be as hard as anodizing or 7075-T6 aluminum, would the finish conceal cracks underneath?
Just curious, since cerakote doesn't seem to be as hard as anodizing or 7075-T6 aluminum, would the finish conceal cracks underneath?
Stop worrying and continue shooting.
Stop worrying and continue shooting.
^
This X 10!
Same Idea, may not be a stressed area
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