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Reduced recoil spring wieght more reliable?


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Old 02-17-2017, 06:45 PM   #11
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Originally Posted by rbbeers View Post
According to the SAAMI Standard (page 17), the lowest 9mm Luger power factor is 120 for the 100 gr x 1,195 fps cartridge... followed by the 96 gr @ 1,330 fps and 105 gr @ 1,200 fps cartridges at 126.

To ensure reliable cycling, given that, for the above cartridges, the G34 is 'sprung accordingly' (17 lbs), I'm at a loss as to how 13 lbs is the 'proper' RSA spring weight for a 130 PF cartridge (147 gr @ 880 fps).

That being said, it's my understanding that RSA spring weight is a multi-faceted compromise (as described here). And, as such, there really is no 'proper' weight... other than the spring weight that best satisfies the 'compromise' most important to the shooter. As the article states...


All the above notwithstanding, I do agree that stock Glocks reliably cycle SAAMI compliant cartridges, as I've run cartridges topped with 90 gr to 147 gr bullets at PFs as low as 110 in all of my 9mm pistols without issue... including 147 gr LFPs @ 750 fps.

Best regards,

Bob
Spot on. Too heavy and the gun may not reliably cycle and you get front sight dip as it goes back into battery. Too light and you get harsh recoil and sight lift. Powder burn rate also has an influence and spring selection. My preference is a fast powder (Titegroup/Bullseye) with a heavy (147gr) bullet. With the stock RSA (17lb) it was about 95% reliable with that load. I experimented with 11-15lb springs and settled at a 13lb. That worked best for my load and grip. May not be best for others. As you stated, many variables.


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Old 02-17-2017, 10:22 PM   #12
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Someone correct me hear if I'm wrong, but I assume more wear on the frame. Three less pounds of resistance against the rearward motion of the slide, basic physics says three more pounds of kinetic energy is getting absorbed by something. Either the frame or perhaps just the user(more perceived recoil?) is eating the extra energy. Food for thought.


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Old 02-17-2017, 10:51 PM   #13
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Someone correct me hear if I'm wrong, but I assume more wear on the frame. Three less pounds of resistance against the rearward motion of the slide, basic physics says three more pounds of kinetic energy is getting absorbed by something. Either the frame or perhaps just the user(more perceived recoil?) is eating the extra energy. Food for thought.
You're correct... sort of.

However, considering that the charge cycle force on the slide lock and frame is proportionally less, the question really becomes 'Is the additional recoil force on the frame a negative, or not?'

In reality, the recoil phase of the slide cycle 'smacks' the frame and the locking block when the slide moves rearward and the return (charge) phase of the slide cycle 'smacks' the slide lock and the frame when the slide moves forward (returns to battery). Accordingly, forces are distributed front-to-back AND back-to-front. Yet, it seems to me that, while the front-to-back 'smack' is typically acknowledged, the back-to-front 'smack' is typically ignored.

Don't forget that the slide moves forward as well as rearward... and the forward impact force is directly proportional to the RSA spring weight as well. There's no such thing as a 'free lunch'.

In my experience, while Silver-Bolt considered both, most shooters tend to focus on the recoil phase of the slide cycle and disregard the charge (return) phase of the slide cycle. (Again, as presented in post #10, refer to the article How Recoil Spring Rate Affects Timing.)

So, what conditions actually cause more wear on the frame? And, more importantly, from a practical perspective, does it really matter?

If, with a given RSA, the pistol life is shortened from 500,000 rounds to 200,000 rounds, but the shooter, in his lifetime, will only shoot 20,000 rounds, who cares?

So, what's 'right'?

More food for thought...

Best regards,

Bob

Last edited by rbbeers; 02-18-2017 at 05:29 AM. Reason: 'Cleaned up' post.
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Old 02-18-2017, 02:02 AM   #14
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You're correct... sort of.

However, considering that the charge cycle force on the slide lock and frame is proportionally less, the question really becomes 'Is the additional recoil force on the frame a negative, or not?'

In reality, the recoil phase of the slide cycle 'smacks' the frame and the locking block when the slide moves rearward and the return (charge) phase of the slide cycle 'smacks' the slide lock and the frame when the slide moves forward (returns to battery). Accordingly, forces are distributed front-to-back AND back-to-front. Yet, it seems to me that, while the front-to-back 'smack' is typically acknowledged, the back-to-front 'smack' is typically ignored.

Don't forget that the slide moves forward as well as rearward... and the forward impact force is directly proportional to the RSA spring weight as well. There's no such thing as a 'free lunch'.

In my experience, although Silver-Bolt did not, most shooters tend to focus on the recoil phase of the slide cycle and disregard the charge (return) phase of the slide cycle. (Again, as presented in post #10, refer to the article How Recoil Spring Rate Affects Timing.)

So, what conditions actually cause more wear on the frame? And, more importantly, from a practical perspective, does it really matter?

If, with a given RSA, the pistol life is shortened from 500,000 rounds to 200,000 rounds, but the shooter, in his lifetime, will only shoot 20,000 rounds, who cares?

So, what's 'right'?

More food for thought...

Best regards,

Bob


While I will certainly concede that I hadn't consciously thought about forward motion, I was more accurately trying to describe a downside to decreasing recoil spring weight. Hadn't thought about if this would cause issue on the "charging" phase of the action. Is there any downside? Again I can imagine an increase in recoil. Would it cause excess frame wear, or increased recoil? Probably not! I don't know.
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Old 02-18-2017, 02:46 AM   #15
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While I will certainly concede that I hadn't consciously thought about forward motion, I was more accurately trying to describe a downside to decreasing recoil spring weight.
I understand... and your perception is typical. However, the effects of 'recoil' spring weight is only half of the cycle. The effects of 'return' spring weight is the other half. And, as you've just illustrated, it's typically overlooked or ignored.

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Hadn't thought about if this would cause issue on the "charging" phase of the action. Is there any downside?
While a 'heavier' spring weight increases the return (charge) slide speed, increases the muzzle dip as the slide/barrel impacts the slide lock and frame, and increases the stress on the slide lock and the frame (just forward of the slide lock), a 'lighter' spring weight reduces the return (charge) slide speed and reduces the force pushing the slide into battery.

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Would it cause excess frame wear, or increased recoil?
Increased recoil 'stress' on the frame?

Yes.

Increased frame 'wear"?

Possibly... I don't know. Increased frame 'stress' doesn't necessarily translate into increased frame 'wear'.

Increased felt recoil?

Maybe... depending on the shooter.

Increased 'jerk'?

Yes, more recoil jerk, but less return jerk. The recoil slide speed is higher. But, the return slide speed is lower.

How will a 'lighter' spring weight affect the shooter?

It depends on the shooter. A shooter with a 'firm' shooting frame may not notice much of a difference. However, a shooter with a 'soft' shooting frame may notice more recoil muzzle flip and/or 'push', but the return muzzle dip will be less.

My point is that, in reality, both halves of the slide cycle should be considered. As Silver-Bolt described here, the spring weight that makes the shooter happy is the 'proper' spring weight. Frame life is but one of many considerations... and, in reality, for some shooters, it may not even be an issue.

Best regards,

Bob

Last edited by rbbeers; 02-18-2017 at 12:48 PM. Reason: 'Cleaned up' post.
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Old 02-18-2017, 03:35 AM   #16
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I mentioned in a post how I reduced my recoil spring(G19/4) from 18# to 15# with impressive results ...
Did you eMail Gaston @ Glock .com? Give him a heads up on that.
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Old 02-19-2017, 11:10 AM   #17
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Did you eMail Gaston @ Glock .com? Give him a heads up on that.
Glock disapproves of any aftermarket part on their firearms, after all it's Glock Perfection and they are all perfect.
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Old 02-24-2017, 03:04 PM   #18
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Default The most notable issue seems to be 'reliability'...

While the article How Recoil Spring Rate Affects Timing is very informative, for me, it's somewhat hard to discern some of the meaningful information 'tucked away' in the data. So, to better understand 'things', I generated the tables found here from values extrapolated from the charts in the article... and I thought I'd share them with the forum.

To me, the notable 'messages' of the numbers are as follows...

The 'Recoil time' shows that the recoil slide speed with the 'light' spring weight is about 7% faster than the speed with the 'standard' spring weight. However, given the robust design of Glock pistols, it seems odd that a 7% slide speed increase would be a 'pistol wear' problem, especially since it seems to be simply equivalent to shooting SAAMI compliant '+P' cartridges (150 PF) instead of SAAMI compliant 'standard pressure' cartridges (140 PF).

The 'Cartridge pickup delay time' surprised me. I had no idea that the delay time was so long... but it makes sense. Adequate delay is necessary to allow the magazine spring time to push the top cartridge into its 'pickup' position. Longer delay times ('lighter' springs) may help reduce 'failure to feed' malfunctions.

Also, keep in mind that the cartridge pickup delay time is shooter dependent. With a 'soft' shooting frame or by 'limp wristing', a shooter can cause the slide to 'short cycle' (not travel 'fully to the rear'), thereby reducing the cartridge pickup delay and inducing 'failure to feed' malfunctions.

The 'Charge time' seems to be a trade-off between reliability and muzzle dip. Faster charge times ('heavier' springs) imply more force pushing the slide into battery, which is absolutely paramount for reliable operation, especially when the pistol is dirty or the slide travel is otherwise impeded... which is very important for those carrying firearms for self-defense. Slower charge times ('lighter' springs) imply less force pushing the slide into battery, which causes less muzzle dip when the barrel lug strikes the slide lock and may be a meaningful consideration for competition shooters.

Bob's bottom line:

It's my perception that...

Relative to 'increased pistol wear', using lighter RSA spring weights with SAAMI compliant cartridges, seems to be a non-issue, at best, and a minor issue, at worst.

The most notable issue seems to be 'reliability'... that is, the cartridge pickup delay time vs. the force pushing the slide into battery. Unfortunately, increasing one reduces the other. It's a 'balancing act' and the 'perfect' balance seems to vary from shooter to shooter and pistol to pistol.

Notes:

'Total cycle time' is the time required for the slide to travel from battery to 'fully to the rear' (when the barrel cutout of the slide contacts the frame), then return to battery.

'Recoil time' is the time required for the slide to travel from battery to 'fully to the rear'.

'Cartridge pickup delay time' is the time required for the slide to travel from 'fully to the rear' to when the cartridge pickup rail of the slide contacts the base of the cartridge.

'Charge time' is the time required for the slide to travel from when the cartridge pickup rail of the slide contacts the base of the cartridge to battery. (While the terms 'Return time' and 'Charge time' are typically used interchangeably, for the purposes of this presentation, I've split 'Return time' into two discrete parts, such that 'Return time = Cartridge pickup delay time + Charge time'.)

Mathematically expressed...

Total cycle time = Recoil time + Return time

or

Total cycle time = Recoil time + Cartridge pickup delay time + Charge time

For the data presented, the 16 lb spring weight is 'standard', the 12 lb spring weight is 'light', and the 20 lb spring weight is 'heavy'.

Also, my guess is the tables contain minor extrapolation errors... and, to simply the numbers, I know the tables include rounding errors. However, the errors are small and are irrelevant to this particular presentation. Accordingly, they may be ignored.

For what it's worth...

Best regards,

Bob



Last edited by rbbeers; 02-24-2017 at 04:48 PM. Reason: 'Cleaned up' post.
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