PCC cycling issues.....need advice

[sch2046]

I have built 4 9mm pcc's now. My new one, using Aero, upper, lower and bolt carrier. I have a 6.5 oz buffer, with a 308 carbine spring. Milspec trigger. I keep getting 2 round bursts out of it. Almost like the bolt won't go back far enough to reset the trigger. I have used 3 different bolts now, new buffer.....my only thought is the 308 spring is too springy.....Have any of you guys had this issue and how did you fix it.
Thanks
Sean

 

[91Eunozs]

What trigger?

Not on my PCC which has a single stage Geissele, but I recently went through a similar experience with a couple of my 2-stage Geissele triggers. Sent them in and Geissele assured me they’re still gtg, but did get new springs.

Pretty sure it was me being too light on the trigger pull, and with such a short reset was inducing the ‘malfunction’ myself. Have switched all but a couple lowers over to single stage triggers now.

 

[TonyTheTiger]

I've had two mil spec triggers over the years that doubled right out of the box. I'd swap that quick and see what happens.

 

[sch2046]

I will throw a Geissele in and see what happens. I have not had this happen......could be me. I used a mil spec trigger thinking "how can I go wrong with a heavy trigger, it has to work......"

 

[bfoosh006]

Make sure your Mil-Spec hammer has a true USGI profile at the very top. Like an ALG hammer.
Sometimes, the ramp portion on a 9MM PCC carrier can be to long, and the tip of the hammer profile, does not allow full cocking of the hammer with anything less then a USGI hammer profile.
If the ramped area on the carrier bottom is to long, the hammer sometimes isn't allowed enough depression to fully / properly cock, given the short travel of the 9MM PCC bolt.... and it doesn't take much more ramp to mess up cocking.

That USGI profile hammer profile sometimes helps with complete cocking, given that situation.

Pics of the hammer profile and ramp section on the carrier ?

And a few more details on your build, please. Extended 9MM PCC buffer ? What brand 308 carbine recoil spring ?

What specific ammo used ?
Also, it might need a little more break-in. To allow some of the parts to loosen up.

Pic showing hammer profiles and what I mean.

 

[SalomonQST99]

LaRue triggers works well with my Aero PCC build if you want to try something fairly cheep but good.

 

[CK1.0]

Have you tried a regular carbine spring? I once got some unwanted burst behavior (almost too easy to bump fire, etc) when running a 6.5oz buffer with an orange Sprinco spring (.308) and a carbine spring (and 3-4 quarters as spacers in the back of the tube) fixed it.