Different recoil springs for Pro Series 1911?

[hokiefyd]

I'm working on a gun that my dad owns. It's a Pro Series 1911 in 9mm; the problem we're having with it is the slide doesn't stay locked back after the last round. It will lock back on an empty magazine when hand cycled, but not after firing the last round. I'm thinking that it could be the ammo we're shooting (115gr), and that the recoil spring could be slightly too stiff.

Is there a recommended recoil spring rate for a 9mm Smith 1911 for shooting 115gr white box ammo? I'm very familiar with swapping springs on Glocks and on my CZs, but not so familiar with the 1911s.

Thanks!

 

[OKFC05]

I use a 12 1/2# ISMI recoil spring for 9mm 1911 using 124gr handloads that make only 130 Power Factor.

If you loads are lighter than that, there are 10# springs made.

 

[hokiefyd]

Thanks; do you know what the factory weight spring is that Smith puts in these?

 

[Jim Watson]

I don't know what S&W uses.
Wolff says Colt 9mms take a 14 lb spring.
Springfields are lighter, some say 10, some say 9.

I will be testing a 13 in my SA today, having changed from the stiff ILS mainspring to a 19 lb.

 

[Harrison]

I would look at your magazine springs and your magazine followers first. Some 1911s can be picky about mag followers. I recently bought five mags of a well known brand with an excellent reputation. None of the mags would provide a consistent slide lock. I changed out that style of follower, and now they all work like a charm. I know of others that have had the same problem with their 1911s.

 

[RGPM1A]

Hokie. Try different magazines. Also if you have another 1911 pistol try swapping out the slide stop. I doubt that your problem is recoil spring related.

FWIW

 

[AveragEd]

I have a Kimber Stainless Target II in .38 Super that would not lock the slide back most of the time on empty Kimber magazines. I stretched the magazine springs slightly, as the follower pushing up on the slide stop is what locks the slide back, and the problem cleared.

What Harrison said about some 1911s not functioning properly with some magazines is very true. That same Kimber will not feed reliably or lock the slide back with Wilson magazines even though their advertising indicates they work in any 1911. I called them and was told that they know about that incompatibility with Kimbers and they paid for the return shipping because their printed and online catalogs do not mention it.

Slide stops are another potential source of incompatibility. I like Wilson extended slide stops as they are easier for my arthritic fingers to operate but they cause the slide of an S&W 1911 to be locked in place. Wilson knows about that condition as well but their advertising lacks that information.

Ed