I have a smith and wesson sport I attempted to instal a cmc drop in trigger and the trigger pins won't fit. Do I need to buy the 15-22 trigger pins or? I thought I needed to if it was only a 15-22 should they fit?

Are the trigger pins you're trying to install the original ones or ones that came with the trigger assembly? SFAIK, the Sport has the same lower as any other AR.

Since you appear to have all your trigger parts out, try the pins in the receiver without the trigger assembly in place and see if they fit. If they do with the trigger assembly out, but won't with the trigger assembly in, return the trigger assembly and get your money back.

WHATEVER YOU DO, DON'T MESS WITH THE TRIGGER GROUP HOLES IN THE RECEIVER!!!!!!!!!!!!!!!!!!!!!!!!!!! DON'T FORCE TRIGGER PINS INTO THE RECEIVER!

Good for you, when something didn't fit, you didn't get a hammer out. Instead, you stopped and tried to understand the problem.

Whats the part number for the trigger you tried to use?

You might have bought one made for a Colt AR (manufactured from 1990 to 2009) that uses 0.169 inch pins, whereas the standard pin dimension is 0.155 inches.

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M&P15 sport II, Retired Army

What is meant by "don't fit"? Are they too long? too short? too fat?

While folks are trying to help, it's like calling up a mechanic and saying "My car is broke".