You're not having the best luck with nailers!

I'll see if I can help, or at least get you closer to resolving the problem. I don't (admittedly) have a ton of experience with these metal connector nailers ("MCN"-style) but I gleaned some information from my factory rep that I think is useful.

I cannot speak for the Senco nails as I am not too familiar with their Metal Connector nails, but in general all Senco Paper tape 30 – 34 Degree common framing nails should work in this tool.

Perhaps they MC nails may be designed/collated differently, but I do not know. I doubt it.

It is not impossible that a severely worn driver can cause the nails to tumble, but it would not be my first thought in this situation. I doubt it is the magazine either.

Keep in mind that the very short 1-1/2" nail is shorter than what is normally used in these tools. The shortest framing nail is 2", so admittedly we stretch the parameters a bit on the application.

When the 1-1/2" nail is sheared from the collation in the magazine, it must travel quite a way in the nose until it engages the MCN guide tip. The shorter the nail, the more likely a nail will tumble.

Of course we have parts in play to control that, but it can still happen from time to time. If it is happening consistently, then I expect there is a problem in the Metal Connector tip itself (sold as MCN-KIT3):

www.mastertoolrepair.com/kit-metal-conne...n-kit3-p-403212.html

There are two parts in this assembly to control nail kickback, on the breakdown below see items 5 and 6; the Pendulum, and Pendulum Spring.

Inspect these to make sure they are even there, or is the Spring or Pendulum broken or worn.

Part numbers:

158456 – Pendulum
158457 – Pendulum Spring

If needed:

160016 – Pivot Pin
854004 – Retainer grommet

Also, if the back side of the trip housing is damaged it would affect its ability to control the nail tumble. This would require a complete assembly replacement: MCN-KIT3.

It is important to correct this as continued jamming can damage the nose!

- MTR

Great, let me know if have any luck with your diagnoses this weekend and if you have any more info to add. I'll continue to do some research on this and reply shortly, hopefully with a possible solution!

- MTR

Sorry, but I did miss another possibility as I was focused on the MCN tip itself due to the application, but your description leads me to believe I may have been in the wrong area.

Bostitch does indeed have a mechanism in place to help keep shorter nails from kicking back when the driver strikes them. In fact this is worse with the Paper tape collated MCN nails because they are collated with more rigid tape because the nails are spaced vs. tight together on standard framing nails.

On the left side of the nose there is a “Kickback” pawl that keeps the tip of the nail in the driver channel. As noted, it is the natural tendency with “spaced” nails for the nails to tumble. The driver strikes the front half of the head, which naturally pulls the tip back. Most prominent with the shorter nails.

See pictures of the nails and a picture of the kickback pawl on a tool for location.

It is not impossible that the pawl is chipped or broken on the inside facing the nails.

There is a pawl, a spring, and pivot pin with a retainer. 43, 44, 45, 46.

- MTR