Retrieved: 12/06/2013

Note that on some firearms, the difference between "extractor" and "ejector" is blurry... for this note, I'm considering "ejector" to mean "that which throws the case out of the breech and clear of the firearm" as opposed to "yanks the case out of the chamber, then to be shaken out or fall free."

There are two basic types of ejector: the fixed anvil and the spring-loaded plunger.

The anvil is the earliest type, appearing on bolt action rifles. As the bolt reaches its rearmost travel, the case a stop in the receiver that kicks it out. These can be fixed blades like a 1911, hinged blades like an Arisaka, a screw in the side like an SMLE, and probably various other designs.

The anvil is very positive, and depending on how vigorously the operator works the bolt, the cartidge might just lie in the breech to be picked out with the fingers (handy for $10-each exotic brass) or kicked far from the gun. Downside: with some designs, short-stroking the bolt can cause a smokestack jam or double feed.

The later type is the spring-loaded plunger in the bolt face. The most common examples of this are the M-16 and later Savage bolt action rifles, though it was first used much earlier.

With an anvil, the cartridge doesn't eject until it encounters the anvil, so you can design the action for clearance between the bullet nose and the breech opening. With the plunger, the cartridge flips out as soon as the bullet or case mouth clears the opening. Also, the spring in the plunger adds to the closing force of the bolt (in designs like the Auto Mag, this is an issue), and finally, the plunger forces the case to one side of the chamber when the breech is closed. Originally this was thought to be a problem; later, shooters realized it was very consistent, and accuracy was generally better than anvil designs.

Corrosion or crud can jam the plunger, causing weak or no ejection. Also, if you want the bolt face to surround the case head, the recess has to be much deeper, to accomodate the travel of the plunger.

I've been sketching a dangerous game rifle, going down the decision tree for features. I've always liked the anvil setup; it's probably the most reliable, and I like not automatically throwing expensive brass into the dirt to be stepped on. However, I've come to the conclusion that the plunger ejector is the correct decision for a dangerous game rifle; it either works or it doesn't, no operator technique is involved. For this purpose, we can expect proper maintenance as a given. The decision tree for a DGR is a bit different than for an ordinary hunting rifle.

raven007
August 23, 2013

Also some very cheap semi autos use the firing pin as the ejector. Im pretty sure my Jimenez 25 is like that.

TRX
August 23, 2013

Arragh! I meant to include that. Thanks!

Several of Browning's early small-caliber designs used the firing pin as an ejector.

Ejecting a live round that way to clear the weapon gives me the creeps.

barnbwt
August 23, 2013

The SIG STGW57 uses a "wiping" motion of the extractor claw arm to sweep the case head off the bolt face and out the ejection port. A ramped camming surface on the receiver shell actuates the extractor arm.

raven007
August 23, 2013

firing pin ejectors dont bother me a whole lot because the slide has to be near fully retracted before it comes into action. I dont slam it back anyway though. :)

TRX
August 23, 2013

Quote from: barnbwt
The SIG STGW57 uses a "wiping" motion of the extractor claw arm

If you have a good picture of that you could post or link to, I'd sure appreciate it.

barnbwt
August 23, 2013

www.forgottenweapons.com/rifles/sig-stgw-57/

Really good rundown of the operation and how much better than the g3 it is