How to make a proper dummy round

[powdergun]

For a precision rifle build the gunsmith requires a proper dummy round.

1) Is virgin brass preferable ?
2) Should the new brass be run through a full length sizer die ?
3) Do you need to fill the case with silicone ?

Any and all advice greatly appreciated

 

[Alpheus]

Why does he need a dummy round? The smith should have go/no go gauges to set the headspace.
If he needs it for the throat, just use new brass and seat the bullet to how long you want to load for it. Don't worry about filling it or anything else.

 

[guntech]

A dummy round really isn't required other than to possibly custom throat longer.

If you are making a dummy round for a custom chamber it is best to use full length sized virgin brass. Next to that would be fired full length sized (with lots of lube). You do not want any diameters of the brass to bind in the chamber at all...

 

[gunpro]

depending on the action being used or other mods, proper feeding and extraction from the magazine. for example, AI mags often need the feed lips adjusted, so a dummy round will help test this better than head space gauges. remembering there is more to a precision rifle build than the fit of the round in the chamber and headspace.

 

[hunter5425]

When I make one I put some red locktite on it so it won't change depth when shipped or handled.

 

[guntech]

I guess the title should be "dummy rounds"... definitely more than one is needed to check feeding.

 

[AikiNut]

I used to keep a few dummy rounds and scatter them in with the live stuff to check that my trigger control was good.

 

[bearhunter]

I have dummy rounds made up for several different cartridges.

I drill holes into the case walls for quick ID and fill the primer pocket with hard rubber so it can be used as a snap cap. I've tried epoxy but it's to hard and deforms permanently.

As mentioned, you should have more than one.

OP, I'm a bit surprised that the smith asked for a dummy round to do the build on the precision rifle build you're commissioning. Most smiths already have match grade reamers on hand and about the only thing they will be concerned about would be throat diameter and depth. Usually, they just cut the chamber with what they have on hand.

The only thing I can think of is that the smith is going to send off the dummy round to the reamer manufacturer and have a special reamer made up. By doing this, the smith can keep tolerances as tight as possible.

If you're planning on hunting with this rifle, take extreme care when making up your hunting ammo.