Springs
Shmackey nailed it. Overspringing can bring on functional issues and
overstressing of the lower barrel lug and slide stop pin. Oversprung
1911s also require that your magazine springs be in top condition, or
the slide will outrun it on the return to battery.
Rule of thumb for figuring the spring rate with a 230-grain bullet:
Multiply the velocity of the bullet by .2 (Point Two) Lighter or
heavier bullet? Add or subtract the percentage difference above
or below 230 grains.
Examples:
230 at 850 fps X .2 will give you 17 pounds. Since the GI hardball
ammo spec-ed out at 830 fps plus/minus 25...the spring rate would vary
from 16 to 17. Browning split the difference and specified a 16.5 pound spring.
200 grain bullet at 900 fps X .2 says 18 pounds MINUS the 11%
difference in bullet weight...and we're back to about a 16 pound
spring. FYI, the original hardball loading that Browning developed
for the pistol was 200 at 900 fps. Interesting, what?
200 grains at 1,000 fps dictates 20 pounds minus 11%..and you
come up with a figure of roughly 18 pounds. This formula won't be
exact in all pistols...each one being a law unto itself...but it will get
you in the ballpark. Bullets heavier than 230 grains use the same formula,
but the difference in weight is added. ( FPS X .2 + the percentage.)
Keep in mind that the heavier the spring, the faster the slide will return to battery. The faster the slide moves forward, the more critical the magazine spring becomes.
Hope this helps.
Tuner