Barrel Pin Interference Fit???

.0003 to .001 is what I meant. a .002 press fit on a 3" hole on hardend steel is a tight fit let alone on a little 7mm hole

trying to shove a softer pin into a hardend part with will only distort the pin more than nessacary.

I guarentee that if i take a bit that that drills a hole .0005 smaller than my pin and use it in a mill or any good drill press all the pins will be tight. if there not then then its time to buy better equipment or change your drilling meathod. unless your using a floating reamer holder the equipment is going to still cause run out. I can tink of thousands off applications were a dowel pin is press fit into a hole that is drilled not reamed. take any engine apart and you will see some. a press fit in hardend steel hole that small does not requre any were near .002" . .002 is tight on a 23mm barrel bore let alone a 7mm hole.


personaly I dont want that much metal distortion on the softer barrel above a perscion cut chamber. its the barrel that will compress to allow the pin to go in and and it will aonly induce stress on the barrel and affect accuracy and as well as slightly disort the chamber. the pin need to only stay in securaly


the main thing is the barrel is correctly head spaced before you drill and that the bit is not removing metal from the trunion. any hole in fact if the barrel portion of the hole was .000 the pin is still going to be tight in the original factory drilled or reamed trunion hole. the soft barrel is not what holds the pin in its the trunion. measure a virgine trunion and a new pin if you want a rough Idea of what the factory used as interferance. I come up with aprox .0005" as a average but check it your self. there are industry recomedations for press fits of bearing races and pins for differant metals per bore size find them and you will see nothing that requres a two thousands press fit n a 7mm hardend steel hole.