Thank you all for your input. I appreciate it.

Kevin

quote:

Originally posted by Crom:
If you focus on the "muzzle dip" or "muzzle flip" you can probably see subtle differences and start thinking it makes a difference.

But if you focus on the bullet exit" (or smoke ejections, which must follow bullet exit) I think you will notice the amazing thing that the bullet has left the muzzle loooong (relatively) before the pistol has a chance to move detectibly at all.
So shooting accuracy is entirely grip/trigger/flinch control. The pistol reaction is an interesting after-phenomenon. There are other, better, hi-speed videos on the net to demonstrate this phenomenon. That's why people are generally more accurate when they are "surpised" by the shot. Anything you consciously try to do to "compensate" for muzzle dip of flip can only disrupt the targeting accuracy.
Here's a great one:
https://youtu.be/7y9apnbI6GA?t=3

Recoil springs are there to return the slide to battery. They do not remove energy from the system. So if you use a strong recoil spring the recoil that is supposed to go into the frame at the rearmost point of slide travel just gets stored in the spring and ends up being dumped into the frame and take down latch, where it wasn't designed to be absorbed. This causes wear and makes the muzzle dip. It also increases the slide velocity during feeding, which can reduce feeding reliability.

A higher bore axis is going to have more tendency to rock back with muzzle rise and rock forward at chambering. So it shouldn't be surprising that a Glock isn't much affected by spring weight in dip.

The ideal "dip" is where the force of the slide chambering brings the muzzle back down to firing level - which is probably why many guns with highish bore axis shoot quickly - they are "self correcting" for muzzle rise.

Dropping the recoil spring strength is effectively going to make the muzzle rise more and the muzzle dip less, ending up in a better spot for firing. The downside is now your slide is hitting the frame at the rear harder than it was designed for (which can be okay), and that the available spring energy available for feeding is now decreased. This is a concern in striker fired weapons that "cock on close" because the recoil spring is opposing the striker spring. (See RSA test for Glock).

Weapons that are designed well have recoil springs optimized for feeding from the magazine, and everything else (like slide mass) is selected to work with that. That's why all Glock's use 17 lbs recoil springs regardless of caliber - it is the right spring for feeding.

Some guns - especially polymer guns with higher bore heights - are going to suffer from some muzzle dip when the ideal recoil spring is used. There just isn't enough mass in the frame to make up for the high bore axis to not make the gun move around.

I'd be interested to see what the equivalent P250 uses for a recoil spring strength since it doesn't have a striker to fight.

Late to this discussion but if "the Bullet has left the barrel.before recoil happens," why do heavier bullets tend to impact the target higher than light bullets?

Because they don't. It's just something people say. lol Heavy bullets have a longer dwell time, which makes them (usually) hit higher.


Some people have muzzle dip (pre/during ignition, a downward flinch, not the post shot muzzle dip caused by the slide) and in an attempt to fight recoil they "follow through" with a second dip. Add into that a mechanical slide related dip and you've really got something.

Personally, other than on my "race guns" I don't give a hoot about muzzle dip.

Odd on the 34, because for me with 13 lb spring it tracks much flatter and did reduce front end bounce.

quote:

Originally posted by Sigholic:
Late to this discussion but if "the Bullet has left the barrel.before recoil happens," why do heavier bullets tend to impact the target higher than light bullets?

There is still some effect in terms of recoil that can't be controled by any amount of engineering, and this is one of them. In a semi auto unless you have a much lighter or heavier powder charge, there isn't a practical difference in POA/POI with different bullet weights. I've played around with this with the 115/124/149 grain 9mm commercial loadings, and practical accuracy out to 25 yards is pretty much the same.

Where I did get a difference is in 38/357 loadings. At 25 yards 38 Special wadcutters will impact around 5" lower than 357 Magnum does out of revolver.

quote:

Originally posted by SgtGold:

quote:

Originally posted by gentleone:
I did the same test with my G34 gen4. What I discovered was not expected: There was no discernable difference in muzzle dip between the 13 lbf reduced power spring and the 17 lbf factory spring. This puzzled me. I had read from other Glock users that a lighter recoil spring would reduce muzzle dip; and I can FEEL a difference in the recoil impulse. But i did not see any measurable difference in muzzle dip. What's the deal?

The Glock has a lower bore axis and in my experience had less flip and dip than a P series Sig does. It just might be that since there is less to deal with these is less of a difference when you change springs.

Simple mechanics (physics) would suggest that the lower the bore axis the less "flip" or "dip" you should see. The relative mass and length of the slide will also come into play of course.

In simplest terms, the rotational inertia is determined mostly by the distance from the pivot point (bore axis) and the mass involved (mass of slide in this case). Again.... this is a simplification, but in general think about tightening a nut. The longer your wrench, the easier it is. A force applied at the end of a long wrench exerts much more torque than that same tiny force exerted closer to the pivot point.

I try not to overthink it. No need for the spring to slam the slide home so hard. That makes sense to me. But .40 for example has some slide velocity that needs to be absorbed so i don't drop too low on the g35. I've had success with the following configs:

p320 9mm - 14 lb
g35 - 15 lb
g34 - 11 lb

I do have lighter striker springs in the glocks so no issues with that 11lb spring being too light.