Stupid questions about the Shield EZ

[jar]

Adding this again for those who have not seen it yet.

 

[someguy2800]

Hammers-fired designs benefit from greater leverage and mechanical advantage when being cocked than striker-fired designs. The rotational movement involved in cocking a hammer occurs over a substantially greater distance than the tiny, straight movement involved in applying tension to a striker.

In a typical striker fired gun like a Glock you are not overcoming the firing pin spring at all because a striker fired gun cocks on closing. When you pull the slide back the striker is not moving at all. When the slide goes forward the sear catches the striker and the spring is compressed as the side is closed. The striker spring and the recoil spring are actually fighting against each other in opposite directions. If you assemble a striker fired gun with no recoil spring, the striker spring will actually pop the slide open and you need to hold the slide forward. It’s this reason, along with the fact that a hammer fired gun is slowed down by the hammer spring on opening, that the recoil spring has to be stronger in striker fired gun than in a hammer fired gun. For example the recoil spring in a glock 17 is typically about 17 lbs and won’t function if you go too much lighter than that because it will fail to go in battery fighting the striker spring, but a 9mm 1911 or CZ75 will function fine with a 10-12 lb recoil spring. I’ve run as light as 8lbs.

 

[Kleanbore]

Hammers-fired designs benefit from greater leverage and mechanical advantage when being cocked than striker-fired designs. The rotational movement involved in cocking a hammer occurs over a substantially greater distance than the tiny, straight movement involved in applying tension to a striker.

Ahah!

 

[Kleanbore]

In a typical striker fired gun like a Glock you are not overcoming the firing pin spring at all because a striker fired gun cocks on closing.

I never realized that.

 

[gc70]

In a typical striker fired gun like a Glock you are not overcoming the firing pin spring at all because a striker fired gun cocks on closing. When you pull the slide back the striker is not moving at all. When the slide goes forward the sear catches the striker and the spring is compressed as the side is closed. The striker spring and the recoil spring are actually fighting against each other in opposite directions. If you assemble a striker fired gun with no recoil spring, the striker spring will actually pop the slide open and you need to hold the slide forward. It’s this reason, along with the fact that a hammer fired gun is slowed down by the hammer spring on opening, that the recoil spring has to be stronger in striker fired gun than in a hammer fired gun. For example the recoil spring in a glock 17 is typically about 17 lbs and won’t function if you go too much lighter than that because it will fail to go in battery fighting the striker spring, but a 9mm 1911 or CZ75 will function fine with a 10-12 lb recoil spring. I’ve run as light as 8lbs.

You have provided an excellent description of the operation of a striker-fired gun. Excuse me for assuming everyone knew striker-fired guns (except for a couple of exceptions like the Beretta Neos) cock on closing and not detailing that information. And you are correct that standard recoil springs of striker-fired guns are consistently heavier than those of similar size and caliber hammer-fired guns.

The force to cock a hammer-fired gun is applied directly while opening; the force to cock a striker-fired gun is stored in the recoil spring on opening and applied while closing. The timing and direction in which the cocking force is applied does not change the leverage and mechanical advantage of a hammer's longer movement over a striker's much shorter movement.

 

[MAKster]

How can the EZ always have the hemmer cocked?

The EZ models are single-action only. You just cannot see the cocked hammer because it is internal. No way to manually decock other than by pulling trigger on an empty chamber.

 

[Kleanbore]

The EZ models are single-action only. You just cannot see the cocked hammer because it is internal. No way to manually decock other than by pulling trigger on an empty chamber.

Yep.

 

[gc70]

A gentleman with a YouTube channel has posted a video in which he measures the force required to rack several guns. He measured racking force both with the guns cocked and the guns not cocked.

Some of the guns included the hammer-fired Ruger Security-380 (10# cocked, 12# uncocked), hammer-fired S&W Shield EZ 380 (8.5# cocked, 12# uncocked), and striker-fired Sig P365-380 (12.5# cocked, 14# uncocked).

 

[jar]

A gentleman with a YouTube channel has posted a video in which he measures the force required to rack several guns. He measured racking force both with the guns cocked and the guns not cocked.

Some of the guns included the hammer-fired Ruger Security-380 (10# cocked, 12# uncocked), hammer-fired S&W Shield EZ 380 (8.5# cocked, 12# uncocked), and striker-fired Sig P365-380 (12.5# cocked, 14# uncocked).

Interesting. That's not at all what I have found with mine. Maybe I just got lucky with the ones I bought.

 

[gc70]

Interesting. That's not at all what I have found with mine. Maybe I just got lucky with the ones I bought.

I saw your chart at the top of the page (very good work BTW) and wondered how you measured racking force and what device you used. Measuring racking force is not very usual and common standards have not been developed, so I would expect pioneers in the field might get different results using different approaches. Nevertheless, the results in your chart and the video seem to be ordered roughly in the same way.

 

[Spats McGee]

I just never know which thread around here is going to teach me something new. Today, it was this one.

Thanks, everyone.

 

[jar]

I saw your chart at the top of the page (very good work BTW) and wondered how you measured racking force and what device you used. Measuring racking force is not very usual and common standards have not been developed, so I would expect pioneers in the field might get different results using different approaches. Nevertheless, the results in your chart and the video seem to be ordered roughly in the same way.

I used the Lyman Digital gauge I used to test triggers. I did three sets of 5 pulls per pistol with the first pull in each set with the hammer uncocked (for striker fired pistols it doesn't matter since the striker is charged by the slide returning into battery but still followed the same format for consistency) then averaged the average from each set. Where there was room I simply hooked the gauge over the front of the slide but where there was no clearance I put a clamp on the rear edge of the slide and hooked the clamp with the gauge.

It's important to remember that when it's a striker system the striker spring is totally irrelevant so it does not matter if it's uncocked or not. The striker spring is compress as the slide returns into battery, not when the slide is pulled back.