Any Subsonic loads for a 200gr SMK?
 

I've looked at the Sierra data, and their slowest listing is for 1100FPS with the 200 gr SMK, and a statment "Loads less than minimum charges shown are not recommended".

Got a couple boxes of the 200 gr SMK's left over from a 300RUM project, thought I could us them with the 300/221. Kind of ironic, trying to find a subsonic use for bullets I was trying to drive as quickly as humanly possible. With the RUM, I discovered that I really didn't enjoy recoil all that much.

Try 6.8-7.0 grains of aa#5. I use this with 208 gr amax out of a BOLT GUN and it is super quiet and accurate.

I have had good luck with AA 1680 with both 220gr bullets and 150gr bullets. As an added plus it cycles the action on my AR.

Ive been playing with H4227 and H322 for 200gr subsonics and both work really well as they cycle an AR reliably.

I to use mostly 1680, and also the 4227 both cycle fine

I have settled on W296 as the best powder with H4227 as a backup. These powders seem to be the most reliable with a wide operating range.

I've got 296 and H4227 - where are you subsonic with the 200gr sierra? The sierra data has 10.6gr of W296 going 1100 fps, how low are you going with it?

What is your range with the H4227? I haven't seen much data on it....and I happen to own a pound of it.

subsonic load development
 

When you develop subsonic loads you absolutely need a chronograh. You should start with the minimum loads listed in the manual and decrease the loads by 0.2-to-0.5gr until your loads drop to 1050-1080 fps.

In some cases, you might find that in your gun the load listed at 1100 fps might be right a 1050 fps in your gun. So without out a chronograph you have no idea what your loads are doing.

I hope this helps
320pf

I chrono'd 9.2gr of H4227 at 846 fps. This load fills the case roughly 65% and cycles my 10" Whisper reliably. I plan to try 10.0gr to see what velocity that gives me.

9.9gr of W296 gave 983 fps and filled the case 55%.

H322 is also worth experimenting with. I found that 13.6gr gave 996 fps with 85% load density.

H110
 

9gr of H110

Mark K