During dry fire practice (just now) I noticed that taking up the initial slack of the trigger moves the whole slide assembly slightly. The muzzle end rises what I'd guess is a tad under a millimeter which makes the back end dip as well. Of course for quickly firing under stress it wouldn't be noticed, and I seriously doubt would throw a shot badly enough to matter. However, I can see it causing me to second guess myself if I'm trying to be precise at the range. I'd imagine this would be more problematic firing one handed, which is always part of my practice sessions - limited and far between as they are.

Anyone else experience this?
Thanks

They all do this. The easiest way to minimize this is a hard grip and prepping the trigger helps.

Was hoping that was the case. Is it due to the modular trigger group design then?

It is caused by the sear pulling the striker “foot” downward as it lowers during trigger press. It does not affect accuracy, and will decrease some with wear. I’ve got an X-Carry and M18 that fo not exhibit it; but every other one I’ve seen does this. Keeping that contact point lubed will help.

You're talking about the vertical motion of the slide as the trigger is moved; It's mechanical play in the pistol, and they all do it.

Bruce Gray commented once about the design of the pistol, that it rides on the bottom of the rails not the top.

It seems counterintuitive when you first think about it, but he's right.

When you depress the trigger, and the striker is drawn back slightly, the slide is pulled down gently and released; the appearance is that the front sight dips, or the rear sight rises.

Before the trigger pull began, the slight was pressed upward, against the underside of the rails; the motion you're seeing as the sear releases the striker is the slide drawn down very slightly then released up to it's natural position again, on pressed on the underside of the rails.

Press down on the slide of your P320. Notice it as play pressing down. None if you lift up; it's already pressed against the underside of the rail. Remove the magazine. Still the same. It's preloaded in that direction.

The barrel lockup hasn't changed during the interval when the slide is lowered, and the front sight, if the grip is correct, doesn't move. If you prep the take up to the trigger and have a firm master grip with your support hand wrapped around, thumbs forward and heels of both hands together, and the pistol pressed out, it's naturally locked into the grip, and a deliberate press of the trigger makes the slide motion all but disappear.

If the trigger is pressed slowly from zero to break, the slide motion appears more pronounced. I don't know why...but someone here does.

This message has been edited. Last edited by: sns3guppy,

yes it does move and yes it does piss me off

I have seen some people with 80% builds where there is very little to no movement at all. And I have seen some with lots of slop and movement. With 80% builds, part of the finishing is completing the rails so one could spend more time "fitting" the rails to their slide. I guess with a homebuild, one might not be too worried about messing with the rails, but has anyone considered tinkering with the rails on their serialized FCU? The question is does the slop affect accuracy and if so, how much slop must be present to affect it.

Ick

quote:

Originally posted by paperchasin:
I have seen some people with 80% builds where there is very little to no movement at all. And I have seen some with lots of slop and movement. With 80% builds, part of the finishing is completing the rails so one could spend more time "fitting" the rails to their slide. I guess with a homebuild, one might not be too worried about messing with the rails, but has anyone considered tinkering with the rails on their serialized FCU? The question is does the slop affect accuracy and if so, how much slop must be present to affect it.

Bruce Gray commented here once regarding the design of the P320, the slide riding on the underside of the rail, and the engineering that went into the rail angles, including the fact that the rail cut in the slide isn't at 90 degrees.

He pointed out that considerable time, engineering, and effort went into the design that is the P320. Not one to reverse-engineer those efforts, I'd leave well enough alone until I was sure I knew more than the engineers. In my case, I'm happy to go with the factory parts as designed, because I know they work.

Put a magazine in, it will stop

Exactly, a magazine pretty much makes this quirk go away. I'm flattered that y'all remembered my previous comments about this. In any event, this is generally innocuous.

-Bruce

quote:

Originally posted by fbmg:
Put a magazine in, it will stop

Well how about that? A loaded mag does indeed make the aforementioned movement cease.
Once again I am glad to feel stupid here.
Thanks

Every striker pistol I have does this - yes even Glocks. As the sear falls, the slide is pulled downward by friction between the sear and striker. The amount is a function of the amound of vertical play between the slide and rails. And yes a loaded magazine minimizes this, but an empty one helps too.