Best Case Trimmer?

[Ipscshooters]

I went to my LGS who had an RCBS Brass Boss and the Lee 8-32 adapter in stock. Absolutely killer setup since I have case length guages for all my cals. I might add the Lee 3 jaw chuck if I can find mine, in a cheap toolless drill chuck you can buy at any hardware store to make it easier on my hands doing large batches.

Golf balls work great too!!!!

 

[adamg]

What's more conducive to accuracy, consistent case overall length or consistent case neck length?

If neck length varies by a few thou, how much will this change chamber pressure and vertical at distance?

Is it best to gauge from the shoulder or case base when trimming?

I think the key situation where the case mouth position affects the overall shot consistency, is how the mouth interacts with the carbon ring that accumulates immediately in front of the case mouth. That is to say, if you have a perfect clean barrel (chamber) every shot, I don't think case length (position of the case mouth) matters at all.

However, if you shoot a round (or 50) at a case mouth position X, then you load up a longer case that puts the mouth ahead of X by say 0.010", now that case mouth is being constricted by the carbon ring. This drastically changes the bullet release from the case, which changes pressure, impact location, and speed. And since we don't do a perfect clean every shot, it does make a difference if we can keep that case mouth at exactly X every round: it never interacts with the carbon ring that is building in front of it.

Now, is it better to index the trim off the base or the shoulder? Given the above theory, and if we assume that the case sets back or is pushed backwards hard against the bolt face throughout the ignition process and bullet release, then the mouth is ultimately indexed off the case head rather than the case shoulder. Conversely, if the case is pushed forward against the shoulder (say, by the ejection plunger), then its the shoulder-mouth distance that determines the mouth position.

 

[sard]

I'm surprised no one has mentioned L.E. Wilson. It's been the best I've used electric or otherwise and is faster than I thought it would be because of the shell holder. As an added bonus the shell holder works for that cartridge family I.e. the same one does 30-06, 270, 25-06, 35 Whelen etc.

 

[Terrible Tim]

I sold my Giraud, I did not like the cookie cutter sharp case mouths. I upgraded to the L.E. Wilson. It is very consistent.

 

[thump_rrr]

I'm surprised no one has mentioned L.E. Wilson. It's been the best I've used electric or otherwise and is faster than I thought it would be because of the shell holder. As an added bonus the shell holder works for that cartridge family I.e. the same one does 30-06, 270, 25-06, 35 Whelen etc.

I have the Sinclair/L.E. Wilson Ultimate Trimmer.
It isn’t anywhere near as fast as a Giraud since you still have to chamfer and deburr with the Wilson.