Geissele Super 42 Receiver Damage

[Iraqgunz]

You need to change the title of this thread, since you actually have no idea if your changes caused the issue. You should also contact Geissele as well.

[Benito]

Sorry for the basic question but isn't the cam cutout in the upper there simply to make room for the cam pin to rotate while moving forwards with the bolt carrier? The cutout isn't supposed to contact the cam pin, is it?

If so, this sounds like a tolerance/spec issue. Please correct me if I am wrong.

[panzerr]

You need to change the title of this thread, since you actually have no idea if your changes caused the issue. You should also contact Geissele as well.

When you have a system that works perfectly and you change one thing and the system no longer works perfectly you can logically assume that the thing you changed (the Super 42) is the cause of the issue so the title stands as is.

I did contact Geissele (as I eluded to in an earlier post) and they essentially shrugged their shoulders and said I should put a heavier buffer in. The question is why switching from a standard H2 buffer and spring to the Geissele H2 buffer and spring caused bolt bounce and associated receiver damage. For lack of any other explanation so far I can assume that the Geissele spring and buffer are not up to spec. Or am I completely wrong?

[panzerr]

So I can't sleep and the kids are down so it's time to get some empirical evidence.

Here is the original H2 from my Mk18




Here is the S42 buffer in what is supposed to be H2 configuration



That's a full one ounce difference. No effing wonder why my receiver was getting banged up. On closer inspection is easy to see how this happened. The Super 42 ships in H1 configuration. That is one tungsten weight and two steel weights. To convert it to H2 configuration you buy a tungsten weight and replace one of the steel weights. When I pulled the weights out individually it's easy to see what happened.











On my S42 buffer the included tungsten weight was shiny and the two steel weights were blued. The replacement weight I received from Geissele to convert the S42 to an H2 buffer came in a zip lock bag with instructions and was shiny, just like the one tungsten weight I already had -except it wasn't tungsten. Apparently whoever packaged the weight slipped in a shiny steel weight instead of a tungsten weight and I, in a rush to get shit done as usual, didn't notice the difference nor would I have reason to think I would be provided the wrong product. So instead of running a 4.6 ounce H2 buffer I was running a 3.7 ounce buffer. It's no wonder why my receiver was damaged.

[georgeib]

That really is interesting that they shipped the wrong weight. But I'm really dubious that 0.9 oz variation in buffer weight is enough to make that significant of a difference.

As far as the damage to the upper goes, are you sure that it isn't normal?

[panzerr]

That really is interesting that they shipped the wrong weight. But I'm really dubious that 0.9 oz variation in buffer weight is enough to make that significant of a difference.

As far as the damage to the upper goes, are you sure that it isn't normal?

Indeed, although I can see how someone could have mistaken the shiny steel weight for a tungsten weight since the other steel weights are blued.

I wouldn't call this damage normal at all. It wasn't there before swapping to the S42 and now it's there.

[themonk]

What did Geissele say about the mistaken weight?

[556BlackRifle]

Interesting about the weights. Can you post a pic of the cam pin from a few different angles? I'd like to see the contact points but I'm also interested in seeing the firing pin pass through from both sides.

[tom12.7]

Maybe, a better question could be posted as to what factors contribute to more or less wear in that location.
We could discuss this further as a group, I'm short on time myself with my own issues. If the discussion leads off later, I could chime in later.

[Clint]

Maybe, a better question could be posted as to what factors contribute to more or less wear in that location.
We could discuss this further as a group...

That's where I'm at.

What forces cause this?

Unlocking during high chamber pressure pushes the bolt back faster than the carrier?