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Glock 27
if 16# is stock, ammo changes from muzzle energy 365ft-# to 525ft-# do I buy 18# or 14# TUNGSTEN spring?
 

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NRA Life Member
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18# - more energy = stronger spring, less energy = weaker spring.
 

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Glock 27
if 16# is stock, ammo changes from muzzle energy 365ft-# to 525ft-# do I buy 18# or 14# TUNGSTEN spring?
Don't change anything from the OEM RSA.

Why are you messing with the OEM RSA? It is NOT bullet muzzle ENERGY that determines the required RSA spring force...it is bullet muzzle MOMENTUM. Whatever momentum is imparted to the bullet is imparted in the opposite direction to the pistol as recoil.

Bullet momentum is proportional to its mass x velocity.
Bullet energy is proportional to its mass x velocity x velocity.

It is very possible to have one round with HIGHER energy, yet significantly LOWER momentum than another round even in the same caliber. The RSA should be selected for the round with the highest momentum. In US firearm society, bullet muzzle momentum is referred to as the stupidly-named "power factor".

PF = bullet weight in grains x bullet velocity in fps / 1000

If you perform a PF comparison of your two rounds, you will likely find that the percent change in PF is much less than the percent change in ME. It is very possible if bullet weight is being lowered in exchage for higher velocity that ME will increase, but PF will actually decrease. An RSA spring force increase would not only be unnecessary, it would be potentially harmful.

The exact same RSA is used in ALL subcompact models G26, G27, G33, G39, even though the associated cartridges are typically rather different in mass, velocity, ME, and PF.

Example using typical non-premium ammo:

G27 40SW 180gr 1000 fps => ME=400, PF=180
G33 357SIG 125gr 1300 fps => ME=470, PF=163

In the two near-identical pistols above with the same RSA, the .357SIG produced 18 percent MORE muzzle energy ME, but 10 percent LESS recoil momentum PF. Increasing the G33 RSA spring force because of the greater muzzle energy would be exactly opposite to what physics shows to be appropriate.

The only time that an increase in RSA spring force is needed is if the loads most often used are causing the rear of the slide's RSA boss to impact the polymer ledge at the rear of the frame's dust cover.

Outside that, RSA spring change is mostly just another aftermarketer's hoax sold to a lot of gullible victims who lack understanding of how their Glock functions. That "tungsten anything" nonsense is just another part of the fraud. The aftermarketers' secret business slogan must certainly be: "You can't fix stupid...but you sure can make a buck on it!" :)
 
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MacGyver
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Purpose or goal of spring change?
Tungsten is not a good spring material, either.

Additionally, that polymer ledge that the slide impacts on inside the frame is probably the strongest part of the frame - there is a U shaped length of metal half-pipe imbedded under the polymer at that point. It will take a lot of ammo to wear out a Glock frame (despite what it looks like); even when it starts to delaminate at that point, it will still function normally for a long time. SO- recoil springs and buffer tubes are just things that only on the surface, seem to make sense- but not necessary for protecting the Glock slide.

Competition shooters will "tune" their recoil springs for different ammo loads for the goal of improving time back on target, but that usually involves lighter loads and lighter springs to use those loads. Many 10mm shooters think they need a heavier spring...but often misguided and for the wrong reasons.
 
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