Click but no bang

[UWone77]

Don't forget the part about the 20+ year gunsmith teaching me things along the way...I ask a lot of questions.

I'm still amused

[Thompson]

...I ask a lot of questions.

This is true haha

[Ordnance]

I would run a different brand of ammo first before jumping into swapping out parts. Also, who manufactured the barrel?

[alamo5000]

I'm still amused

Should I do my Good fellas Joe Pesci routine? LoL

[alamo5000]

This is true haha

Yup. Its a blessing and a vice both at the same time.

[tcoz]

I would run a different brand of ammo first before jumping into swapping out parts. Also, who manufactured the barrel?

Barrel is MAS Defense 16" carbine gas.

[UWone77]

I assume you attempted to try different magazines?

[tcoz]

20 rd Lancers and 30 rd Pmags

[UWone77]

20 rd Lancers and 30 rd Pmags

And you were able to try out another BCG as well?

[tcoz]

At the present time I don't have access to another brand of BCG, but I was considering buying either a BCM or Fail Zero to dedicate to this upper rather than swapping my current PSA back and forth.

Because the problem only occurred 3 or 4 times out of 30 rounds fired, I was wondering if it's possible that the bolt didn't lock up those times. I've never heard of that occurring, but it seems possible since the bolt has fired at least a thousand rounds through my 5.56 upper. Maybe it needs to "wear in" a bit before it runs smoothly in the 300 BLK upper?

[tcoz]

I cant get back to the range for another week but I plan on being more prepared to diagnose the issue and document exactly what happens. I wound up buying a PSA Premium BCG to dedicate to the 300 BLK upper since I have a feeling that my problem might be due to my 5.56 bolt not always locking to the 300 barrel. Whether or not that's the cause I don't want sit at the range continually lubing and swapping bolts. I also picked up an H buffer since I'm currently running with a carbine buffer. I'll take a few different brands of mags and a few different types of ammo. Now all I have to do is figure out a protocol for testing everything without making it a confusing mess.

[Former11B]

Fiocchi makes quality ammo. It's always possible to get a bad batch but Fiocchi is not a crap brand.

[tcoz]

I know that Fiocchi isn't a crap brand otherwise I wouldn't have used it in a brand new upper. I don't know what the allowable load variation is for commercial ammo but if in fact the problem was caused by the bolt not locking up, is it possible that the few rounds with the lightest loads didn't have enough "steam" and that combined with the light carbine buffer prevented complete lock up? Then I'm not sure how or if that would relate to the bolt not locking back on either of the two mags I went through.

Set me straight if you think I'm barking up the wrong tree with this hypothesis. Although not new to the AR platform, I am brand new to 300 BLK and it seems like there are just so many more variables and potential causes of malfunctions.

[Former11B]

You mentioned it wasn't the best stuff available...I was just indicating it's certainly not the worst. No harm no foul

I have a feeling that my problem might be due to my 5.56 bolt not always locking to the 300 barrel. Whether or not that's the cause I don't want sit at the range continually lubing and swapping bolts

300BO is modified 5.56/.223 brass. It doesn't make a difference that its a 5.56 bolt because that's what is required. The first thing I'd do is swap a whole different BCG into it (simple matter of swapping them out...takes just a few seconds and can be prelubed) and see if the problem persisted ...do you have a buddy that can loan you one? If you were a hair closer I have a Colt F/A BCG you'd be welcome to (I'm near Columbia).



If it keeps happening, I'd check the headspace.

[tcoz]

Thanks for the offer, but I did buy a new BCG so the first thing i'll do is try it out without making any other changes and using the same mags and ammo as before. The point I was making about the 5.56 bolt that I swapped into the new upper is that it has about a thousand rounds on the clock and has conformed to the 5.56 barrel. If the tolerances are just slightly different in the new upper, maybe that could explain the few times that the bolt didn't lock up. If that's the case, it probably would just need to be run, but I decided that I really didn't want to be constantly swapping the bolt back and forth anyway so I bought one. I just wish I didn't live 45 minutes from the range so I could get this sorted out.