How to make a powder measure baffle

Baffles of the type sold by RCBS for their Uniflow powder measure are simple to design and fabricate.  The advantage from making your own baffles is cost, and the flexibility to experiment with your own ideas about regulating the flow of powder through the baffle.  I suppose in the extreme case, a person could create custom baffles for use with particular gunpowder types, i.e., one baffle for long extruded powders, another for ball powders, still another for flake powders, and so on.  These baffles can be combined with circular washer type baffles to regulate the passage way from the powder reservoir to the measuring drum.

The purpose of a powder measure baffle is to improve the uniformity of the charge weight dispensed by a drum type measure.  Baffles accomplish this by regulating the  supply of powder to the drum chamber over the broadest possible volume of powder held in the reservoir by supporting the weight of the powder column above the entrance to the measure’s drum, and forcing the powder to flow into the chamber via an indirect route.

Several materials may be used for a baffle.  I’ve used 0.020 inch thick aircraft aluminum from my scrap box.  Aluminum flashing from the hardware store is a candidate, although a slightly heavier gage is prefered.  A good grade of heavy card stock or light cardboard could be used, and made more durable and stiff by soaking with CA cement, thin epoxy, fingernail polish, or other plastics.  A beer can or a sheet of thin brass from the hobby store will also give up the stock material, as well as other common materials.

The baffle laid out in this article is an elliptical shape, the same as obtained by cutting a cylinder on an angle 45 degrees to its centerline, hence the description, “45 degree ellipse”.  The basic shape of the ellipse can be had by four or five methods, but only one will be described in detail here – make a copy of the sketch below, measure the inner diameter of the powder measure reservoir, then scale the template for the baffle up (or down) on a photocopy machine so the minor axis (the narrow dimension across the template) is the same length as the inner diameter of the measure.

Other methods -
If you are so lucky to own a 45 degree ellipse template with the same minor axis as the inner diameter of your powder measure, the correct ellipse can be drawn directly on the stock material for the baffle.  (I recommend drawing a minor axis to serve as the bend line.)
Coordinates for the ellipse can be calculated from the equation for an ellipse, then used to plot points from which to draw the ellipse using a French curve to fair the outline.
Computer aided drafting.
Layout of the major and minor axes and the foci of the ellipse, then drawing the outline using the constant length string method.  This requires a means of holding the pencil dead normal to the surface (“square to the world”) of the drawing for an accurate shape.

Use the first ellipse made to serve as the master template for all future baffles.  Glue the paper template to a durable material that will hold up to tracing many times; a thin piece of aluminum or brass sheet is perfect, or a piece of stiff plastic, say from the lid of a container.  Carefully cut the master template out, file the edge to match the outline on the paper template, and deburr the edge.  Add a tiny notch on each edge at the ends of the line for the minor axis; this is the bend line for forming the baffles and the notches help locate this line on each baffle drawn with this master.  Once this work is complete, mark the master with something like, “Master, DO NOT BEND”, although the notches will serve that function, too.  Peel the paper off if desired.

Trace the outline of the template on the stock you want to use for your baffle.  Mark the ends of the minor axis.  Cut the baffle out, file or sand and deburr the edges of the blank, then add the cutout shape  you want to try where the gunpowder passes through.  Adding the cutouts now are a little simpler than after the blank is bent, but they can be added or modified afterwards, too.

Now bend the legs of the blank to form a 90 degree angle.  Several methods can be used to make the bend if the stock is metal.  The simplest is to clamp the blank in a vice with the bend line (the minor axis) aligned parallel to the vice jaws and about one thickness above the jaws.  Bend the blank until it forms the 90 degree angle.  Lay a wood block on the bend and hammer to form the baffle down hard against the vice to firm up the bend line and shape.

Your new custom powder baffle is ready to use.

Fabrication hint:  If you want to cut the blank out of metal with sheet metal shears, first cut outside the outline by about 1/8th of an inch, then cut close to the outline.  This will keep the edge fairly smooth and free of little bends and notches that ruin the template.


The template:




Examples of cutouts to try; use your own ideas, too:




This thread is linked through the Gateway thread at the top of page 1 in the Reloading Forum.

I wrote that and made the drawings months ago.  I decided to clean up the writeup a little and get it posted, since I've been slacking off here and all.

So, here's your chance; I started a tutorial about how to make a poor man's shotgun loading rig.  All I need is a slick method for priming that doesn't require machining or blacksmithing and gets the shell pointed away from the loader while the primer is seated.  Machining limited to drilling, hacksawing, and filing is okay, it has to be a tool anyone can make with tools on hand.  I have an idea for a tool similar to the ones that were sold with old time loading sets, where the shell slips into a ring in the middle of the handle on pliers, but either made from scrap aluminum or a couple of wood handles hinged at one end.

I have a handful of fender washers I found that fit the inside of an RCBS measure perfectly.  The measure on my bench has the screw on bottle conversion from Sinclair.  That adapter has a conical inside shape that helps uniform powder throws.  I think a combination of a fender washer and 45 degree baffle might be a good combination on an unmodified measure.

Bump for the comedians weekenders that didn't see the article.

"Look nicer" is secondary.  This is like rifles; only accurate powder measures are interesting.

This thread inspired me to make a baffle for my Redding PM, I have a store bought baffle in my Hornady PM, and it works well.



Made mine out of a piece of copper I had.

Here is the whole thread on how I made mine.

The holes could be anywhere, I happen to prefer front/back as my preference. Just "looks right" to my eye.