Possible Spring Problem - Minor Loads in M&P Pro

[ZackJones]

I'm trying to understand something that happened at the range yesterday and I'm not sure if it's a spring problem or something else. My M&P .40 Pro is 100% stock. I shoot production so load minor loads at around a 135 PF. Normally I use Bayou bullets but picked up some Xtreme bullets to use for practice. I know that with plated bullets you normally need to bump the charge up a couple of tenths but I loaded these using the same load that I use for my Bayou's. I normally load to 1.130 but a few of these were a little long at 1.133 or 1.134. I had two problems when trying to use these loads: first sometimes the bullets wouldn't feed into the chamber. I'm suspecting this is due to them being a little long and second when one would chamber it would fire but would not eject properly. If I manually racked the slide then the round would eject but on its own it wouldn't.

I'm thinking a lighter weight recoil spring could fix the problem. What I think is happening is the stock spring is designed to work with more powerful loads and because I'm running light loads that the recoil spring is overpowering the slide and not allowing it to cycle completely. Would you agree? Assuming so I guess I'll pick up an uncaptured guide rod and some different springs and do some more testing. Recommends for these components would be appreciated. FWIW I had some Bayou's with me and loaded 10 of them and they cycled the gun just fine. I guess the lesson to be learned is once you have a combination that works don't mess with it . Thanks in advance for any advice you can provide.

[wgj3]

Zack Definitely try a couple slight adjustments with the rounds before doing anything else if you're set on leaving the gun stock. Add a little powder, maybe .2 grs or so; shorten OAL a hundredth or 2. Most all of us run lightened recoil springs though, so nothing wrong with that at all. Some folk even cut a few coils off stock springs.

[Hi-Power Jack]

I had two problems when trying to use these loads: first sometimes the bullets wouldn't feed into the chamber. I'm suspecting this is due to them being a little long and second when one would chamber it would fire but would not eject properly. If I manually racked the slide then the round would eject but on its own it wouldn't.

Sure sounds like new springs might help, but possible that your cases are not fully sized back to factory specs??

Have you tried the plunk test with your reloaded rounds?

[ZackJones]

Thanks for the replies. As luck would have it I was able to get back out to the range today. Yesterday after things didn't go well I came home and reseated all of the cartridges so they were at 1.130. I was thinking the shorter OAL may give it a little more uumph to cycle the slide. Today the results were the same though . Still not feeding even though they are all at 1.130. All cartridges were case gauged prior to shooting so I know they would all pass the plunk test with the barrel. About the only other thing I can think of is bullet profiles. Attached is a photo showing the 3 bullets. There's slight differences but I wouldn't think there's enough to make that much of a difference. I guess I'll start looking for a guiderod and spring kit.

P.S. I'm not set on leaving it stock - I just haven't yet invested in any upgrades for it.

Edited April 22, 2014 by ZackJones

[bowenbuilt]

Sometimes it takes .4 more to make the plated bullets run over the coated with a stock recoil spring. I would bet that is the problem.