Hi Gun Forum, Have a question about my AR15. For some reason my bolt will not remain in the open postion after I fire my last round. Any ideas how I can correct this problem ? Thanks Steve

Without having more info,I would say it is a magazine problem.

Yup......

X3

Was going to say magazine but wanted to look at mine to see how the follower engages the bolt catch. Might be a bent pin under the receiver?

Easiest thing is to try a different mag and see if the problem persists.

Magazine would be the first thing to check as its the most likely.
If not:
Check your bolt release for damage/wear.
What ammunition are you using? Are you having any problems with the action shortstroking? Have you tried different ammo?
Was the upper assembled at a factory?

Try a different mag.

I have tried different magazines and the problem still occurrs, also there seems to be an occassional problem when the action cycles put the firing pin will not strike the primer on the follow up shot. Regards Steve
ps ammo is south afrikan 55gr.

south african ammo there your proplem buy good ammo

Something sounds really screwy here.
Try different ammo first- SA ammo will be on the hot side if anything.
If the firing pin isn't striking, it might be because the bolt isn't locking all the way- either you have a dirty chamber, a headspace problem (not likely but possible) or the ammo is out of spec.

Who or what company assembled your upper?

i would take a mag apart and stretch the spring a little bit and try that
could be the ammo too
had a problem with my model 1 sales upper too
turned out i just needed to stretch the spring out in my 5 round mag
now she works like a charm