1911 recoil spring space

[oldbenn]

I do not have access to Colt 1911 schematic with dimensions but I understand that the space allowed for a compressed recoil spring is very close to 1 - 7/8 inches. When I compress the recoil spring I use in my Gold Cup, which has 26 coils . . . (with all coils touching), the compressed size is 1 - 1/4 inches. At a point of compression very near "all coils touching" the poundage is 13 pound. When vendors advertise a certain weight spring as a replacement, let's say 16#, does that mean the weight reaches 16 pounds just before it is compressed to coil on coil ?? I have 3 springs I have used in this Gold Cup. One has 32 coils but it does not show to be any stronger than the 28 coil when compressed.

 

[RecoilRob]

A 32 coil spring vs 28, if of the same diameter wire and like material will always be softer being that coil springs are really just a torsion bar wrapped around a mandrel. The longer the bar, the softer it becomes.

Most springs are rated in #'s needed per inch of compression...at least most that I'm aware of. How much preload is applied will determine the force needed to begin movement and how much total travel (and thus compression) will determine the final poundage at coil bind. If you can compress the springs accurately on a good scale I think you'll find the #'s per first inch a reliable measurement which also could show when the spring has softened and needs replaced.

 

[oldbenn]

Much appreciate your response: I guess I had it back words, thought the more coils, the stronger the spring. I'm trying to get my mind to comprehend your statement: "I think you'll find the #'s per first inch a reliable measurement". can you please elaborate ? I have a reliable scale. oldbenn

 

[RecoilRob]

If you set up a spring vertically on a rod to contain it as you compress it, and zero tare the scale it's resting on (include some vertical scale to show how far you are depressing it) then push down the spring until you've compressed it exactly 1". That 'should' be the rating or at least that's what it IS at the moment.

Many automotive valve springs are specified to be a certain poundage at a certain installed height so you put them on a special tool that can compress and measure both height and pressure to verify if they're still within spec. I'm not aware of gun springs being done this way...but have never actually wondered that much about them, just always assumed they were more like motorcycle and suspension springs where things are rated in kg/mm or lbs/inch. So if a spring has a '#' rating...but not installed height to go with it, I think it's fair to assume they mean 'per inch' if lbs is the measure and 'mm' if 'kg' being used.