240 gr Sierra Match King - 300 blk

[pdsmith505]

While I was out shooting today I figured I'd do a little recording to give an example of just how quiet a 300 blk AR can be with the right ammo, even with a freeze-plug solvent trap can.

Shooting hand-loads with 240 gr Sierra Match Kings at between 1000 and 1080 fps.

https://youtu.be/8ltTEMe6b1Y

https://youtu.be/r6HaRl3dhH8

 

[Elkins45]

How long is that can? Did you cone the freeze plugs or just insert them flat? How many plugs? That's a pretty quiet can.

 

[pdsmith505]

6 coned plugs, 1.625 OD, 8" long. Weighs in at exactly 1 lb before the accumulation of fouling.

 

[Gtscotty]

How do you cone them without changing the OD and messing up your fit in the tube?

 

[pdsmith505]

Several ways to do it...

Cheapest involves drilling out a pilot hole in the center, setting it over the biggest socket you can fit in the plug and using a vice to push a series of torx sockets into the pilot hole, thereby expanding the hole and forming a cone.

Or, on the other end of the freeze plug scale, you can buy one of these fancy jigs and use an arbor or hydraulic press.


Some places will sell you plugs that have already been formed into cones... just need to drill the hole.