The Marlin 780 dosent use a clip, it uses a magazine. You can get these from
aimsurplus.com
The Ranger 22 was built by Marlin firearms, try a clip that fits the folowing Marlin Rifles. 50-50E, 80C, 780. You are looking for something that was built in the 1930s.
ableammo.com has them for $13
With the serial number that you have supplied,your Marlin model 780 was made in the year 1978.
I can say that the marlin 780 series of .22cal rifles were discontinued in 1988.Maybe the marlin firearms company wb site may be more helpful?
1986
1985.
50-125 USD
Call Marlin Customer Service 800-544-8892. Place orders there. Part # 504046. Glenfield 20 is same as Marlin Model 780, except for the wood.
Contact Marlin
Your Marlin model 780 was produced in the year 1977.
Your Marlin model 780 was made in the year 1987.
Try e-gunparts.com