SWMP and Mark 7 Mechanical Powder Measure

[d3ydx3]

I have an automated Apex 10 with the newer (post 2019) mechanical powder measure. I have mostly loaded AA7 & 3N38 with it and never really had an issue until now. Bought some SWMP a few months ago after exhausting my supply of AA7. With SWMP my charges vary +/- 0.5-1gr. Seems that it will run the same charge for several cycles, but eventually throws out something off for a few cycles only to start throwing consistently correct again. Had an instance this morning where it was repeatedly dropping my target of 10.1gr consistently, and then I come back a few hours later only to find it is dropping a 4ish gr charge now. My lot is 115 which was very clumpy out of the jug. I've used dryer sheets and wipe down the internals of the powder measure with no success. I see no powder sticking on the sides of the funnel, so I don't think the issue is static electricity. 

 

Anyone else using SWMP reliably on their Mark 7? 

Edited March 21, 2022 by pealandco

[d3ydx3]

Was finally able to get consistent drops tonight. The trick seems to be to hand snug the lock nut on the plunger assembly vs using a wrench to tighten it. I’ve always used a wrench to tighten and never had any issues until SWMP. Usually, when I’m adjusting the power measure I’ll hand tighten, do 10 drops, weigh and repeat as necessary. When everything is dialed in then I use the wrench to tighten and it usually lessens the charge by 0.1-0.2gr, which I account for with other powders.

 

With SWMP whenever I tighten down the wrench the initial drops are a 1.0-2.0 gr light and work up with more drops, but it is always inconsistent and never near what I’m going for. Guess I’ll just keep it hand snug going forward since the drops across 300 rounds were all consistent.