Today I ran some throw consistency tests for 700-X with my Uniflow.
Here is the series of 10 consecutive tests, 10 throws each:
37.5, 37.0, 37.3, 36.8, 37.1, 36.9, 37.4, 37.6, 37.3, 37.0 grains
The max spread was 0.8gr per 10 loads = 0.08gr/load. This is almost 0.1gr spread/load. My limited experience does not allow me to make a judgement if such variation will be of any importance; I'd welcome some comments about that from the more experienced forum members.
Since my loads are far away from the max (4.2gr), I'm not concerned with such load variations at this point.
Mr Sas -
With such a wide spread, we must assume (I hope you're sitting down) that there is some type of "operator error".
True some powders just don't like to meter well, but if the powder in question is not a stick powder, then you should have better results. With the Uniflow there are several tricks that can be used to really bring down the weight deviations...
• Powder baffle. You always want to fill your hopper at least 1/3 full
and use a baffle placed at the bottom. When I get home I'll post a link to plans for "make your own baffle" for all you cheap, do-it-yourself types.
• The first shall be last. You never want to deal with the first 10 drops from any powder measure. What you want is correct weight
, but what a PM dispenses is volume
. Therefore, the key to accurate powder drops is consistent density
. The powder in the PM needs to "settle in", so the first 10+ drops need to stay unused and be poured right back into the top of the hopper.
• Knock-Knock. Vibration helps settle the powder to a consistent density. It also helps fight any powder stuck up inside the PM. So when you raise your operating handle "knock" it against the end-of-throw twice. and when you lower the operation lever bang it against the stop twice again. So operating the PM sounds like: Knock, knock.....knock, knock. This take some practice.
• Static. Wipe the plastic parts with an anti-static clothes dryer cloth. Static is more of an issue on all-plastic Lee PMs, but can affect anyone during colder months.
• Smooth operator. Obviously you want to operate the PM handle the same way each time for over-all consistency. Practice makes perfect.
• Setup adjustment. Use a drop averaging method when making the initial adjustments. If you want 3.9gr of powder, then dial-in your PM in by dropping 10 loads and looking for a weight of 39.0gr. So you may get some drops at 3.95gr and some at 3.85gr, but the average drop will be closer to 3.90gr than adjustment by using single drops.
• Lubrication. PMs get their lubrication from the gray graphite coating on the powder itself. If your PM is sticky you can best lubricate it by applying some graphite powder. Never use oil or grease on the parts that touch the powder.
Hope this helps !