Sig P938 magazine spring

[ameridaddy]

I went and bought a P938 after many years of being very happy with its little brother, the P238.
The recoil, or buffer spring, is much stiffer than on the P238, which I expected, since it has to absorb the recoil of a more powerful cartridge in the same distance.
I found to my dismay that the magazine spring, in both the 6 round and 7 round magazines is so stiff, I cannot get the last round in without the assistance of a Maglula.
Every other auto loader I have, single stack or double stack, 380, 9mm or 45 ACP is no problem for me to load to the last round with just my fingers.
Why on earth is this thing so stiff and is there a fix or another spring out there to ease the problem? I've looked on the internet and found nothing definitive.
I'd sure appreciate some advice if any of you have found a fix.

 

[Erich]

Yup, they're tough (tho not as tough as the ones on the extra-capacity ETS mags for Glocks). I'd not substitute a weaker spring, though: I think these 938s are kind of engineered on the knife's edge of performance, and monkeying around with springs is likely to mess with reliability.

A photo, just because . . .

 

[bigwheelzip]

I went and bought a P938 after many years of being very happy with its little brother, the P238.

Besides the stiff spring, what's your impression of the 938 in comparison to the 238?

I've been happy with the P238 also, and considered the P938, if for no other reason than to stop stocking .380.

 

[ameridaddy]

Besides the stiff spring, what's your impression of the 938 in comparison to the 238?

I've been happy with the P238 also, and considered the P938, if for no other reason than to stop stocking .380.

That was my thought process as well.
I just bought it, looked it over very carefully, but haven't shot it yet. The grip/magwell is a little wider fore and aft, feels good in my hand and it came with a polished feed ramp, unlike my 238 which had tool marks in the ramp from the factory. I polished them out and then it ate everything I fed it.
Like the 238, I didn't like the short 6 round mag grip feel on the 938, and bought the 7 round mags with the pinkie extension. I have shot the hot Buffalo Bore 380 (~1100 fps) out of my P238, and it's still pleasant to shoot, so the P938 should be fine with standard pressure 115gr loadings.
I'll put up a post after I mess with it a bit.

 

[ameridaddy]

...I think these 938s are kind of engineered on the knife's edge of performance, and monkeying around with springs is likely to mess with reliability.

I agree and if I play with any changes, I'll do so very carefully, as this is my intended EDC.
I was thinking about the need for the heavy spring, much stiffer than the P238, even though the mags are the same length and holding the same number of rounds.
The 238 and 938 seven round mags are the same length at the heel +/- 0.1 mm. The stack of seven 9mm is 3.33 mm taller than the .380, so that's that much more spring compression in the same height magazine, and the slide, having the same length barrel, will move faster because of its heavier recoil spring needed to prevent battering the frame from the more powerful 9mm round, yielding less time for the cartridge stack to move up, hence needing a stronger magazine spring to accelerate the mass up in time to put the next cartridge in place for the returning slide.
All that and the lengthy time before the 938 appeared after the 238 makes me think Sig had to fettle the 938 quite a bit to make a 9mm work in a 238 size package. I have a Maglula, it works fine, but I just might fiddle a little. Erich and bigwheelzip, thanks for the interest. It made me think a bit more.

 

[686-380]

My wife bought a beautiful 938. My complaint is the guide spring is difficult to replace during reassembly. She likes how it shoots though.

 

[Erich]

There really are a lot of complaints about the guide spring: you're not alone. Because I'd read so much about the issue, I was really concerned when my gun arrived from the GunBroker dealer and I first took it down and reassembled it. I lucked out and haven't had issues (ask me about my Beretta 70, though! ).

Just because ameridaddy mentioned loadings, I thought I'd post some chrono info. I decided to go with standard pressure ammo, too.
(Range at 5950’ > sea level, c. 73°F, c. 45% humidity - ran some exemplar rounds through the LCR-22 and determined everything was working correctly.)
Aguila 123-gr FMJ: M 996.7 fps/S 42.67/D 13.62 (3” high)
Aguila 115-gr FMJ M 1048/S 27.42/D 9.94 (at POA)

I had problems with the 147-grain Gold Dots: they were too long for the mags, and tended to bind up in the front and nosedive. They worked well enough one or two at a time in the mag (running right at 885 fps almost 3” above POA), but on the last one of those I did, the gun bucked up against my wedding ring and tripped the mag release, shooting out the 7-rounder. Nope, no 147-gr Gold Dots for this gun.

Short-barrel 124-gr +P Gold Dots were one of the first groups I did with the thing, before I really figured out the trigger:

These did 1114/20.02/12.76, and had some STOUT recoil compared to the not-much-slower standard pressure 124-grain JHPs.

Remington Ultimate Defense 124-gr BJHP M 1056/61.29/23.28 (this is what I’m carrying).

Hornady Critical Duty 135-gr +P FTX rounds showed (once again) that they need a longer-than-3” tube: M 989.9/46.46/18.81

Remington old school HTP 147-gr JHPs were remarkably consistent but not all that accurate (3” high and sloppy grouping): 885.9/9.04/3.46 (!!!). Just goes to show that consistency doesn’t guarantee accuracy.


No failures of any kind but for the too-long-for-the-magazine 147-grain Gold Dots. I didn’t put any +P+ through the gun, because it strikes me as a little delicate: I’m grateful that it shoots 9x19 from a platform this size, and I just don’t feel the need to abuse it. The standard pressure Remington 124-grainers were a lot easier to shoot than the blastier +P Gold Dots, and they weren’t all that much slower. I’ll baby the gun and avoid the +P+ loads like the RA9TA, etc.