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Discussion Starter · #1 ·
I've seen this happen to other people that I run as an SO in IDPA and always wish mine would do the same. Has not happened to me in the 10 years I've had my XDm 5.25 Competition until this year. The odd thing though is when it does happens, sometimes this does not lead to a round being loaded and I end up trying to shoot an empty gun, racking the slide and loading a round fix this.

I have tried to test to see if I can reproduce this at home by putting the gun in slide lock and then jamming in a fully loaded mag in hard but with no success.

Anyone has this happened to them and have you figured out the cause?
 

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^ And this occasional hiccup is precisely the reason why many top instructors (Hackathorn and Vickers are just two names) insist that the "auto-forward" is not a feature or welcome technique, but instead is a recipe for failures caused by a truly inconsistent inconsistency......


That said, others are proponents of this "feature."

The vast majority -be they for or against auto-forwarding- recommend developing consistency towards the "angle" of the incoming mag so that the shooter has the ability to send the slide hone via inertia, bypassing additional manual manipulation.
 

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Discussion Starter · #3 ·
Thanks a bunch TSiWRX, excellent advice here and thanks for the video. I will make sure I adjust the angle of the reload to avoid this. Having it happened to me once on two Tier 3 match recently definitely put me in the "not welcomed" crowd on this "feature"
 

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S&W redesigned their M&P slide stop to NOT allow the 2.0 M&P's to auto forward.

I wonder if you could modify an XDm slide stop to do the same thing?
 

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Discussion Starter · #5 ·
It would depend on what needs to be done? In general, I try not to mod my guns to fix a problem unless it is the only possible option. It would seem that unless I am doing something very different suddenly (I have been shooting these guns for 10 years of more..), there is likely something changed in the gun? Perhaps a weakened slide stop lever spring?

I also want to thank TSiWRX again as using the technique in the video, I was able to reproduce the auto-forwarding feature which I was unable before. It's about once every 4-5 tries but it completely explain my problem. Now if someone else can write in and come up with a simple fix that would be super.
 

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^ I think the only way to do it is to make sure your technique has you shoving that magazine straight upwards - Vickers' demonstration has him doing it rather robustly, yet that slide does not follow. I've seen similar demonstrations -both on video and live in-person- by Chris Costa, taking even random students' pistols.
 

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Discussion Starter · #7 ·
That's pretty much what I have tried to do, but as you can imagine, that is just another thing to add to the complexity of shooting when you are running & gunning in a match - something that I rather not have to remember on top of everything....

It is actually kind of odd because at least at first blush, the greatest degree of shock to the gun is when the mag bottoms out against the slide which it of course also pushes up against when you have 10 rounds loaded up in the mag. So if that is the case, why would a round not be loaded???? The only way this can happen is the slide is released and is moving forward before the mag is up high enough so that the slide cannot catch the top round... How this happens is the question?
 

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Discussion Starter · #9 ·
I have not investigated all the mags, but with the one I was testing which I know was not one I used inn the match (a dedicated dry fire mag), it does not cause the auto-forward feature even when I don't load the mag intentionally pointing forward, only 1 in 4 tries and never when I load the mag straight up. My assumption is it is not mag related.
 

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Discussion Starter · #10 ·
So I did some more tests and found something surprising.

First, you cannot cause the auto-forward using an empty mag regardless of how hard you insert it and even if it was inserted at an angle.
Second, soft insertion of the mag never cause auto-forward.
Third, hard insertion with a 10-round loaded mag inserted straight with force cause 5 auto-forward out of 10 mag inserts.
Fourth, hard insertion with a 10-round loaded mag inserted at an angle with force caused 5 auto-forward out of 10 mag inserts.

All four of the above test used the same mag.

So this tells me it is not the mag and auto-forward has more to do with force of insertion than angle of insertion and you must have ammo in the mag to cause it to happen. This tells me that it is the rounds at the end of the mag that is pushing up against the slide causing the slide to pop off.

The only unknown thing here is in all the cases of auto-forward I saw above, all resulted in a round loaded. I still don't know how I can get an auto-forward but no rounds loaded....

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I have never had an "auto-forward" on an XD, but I don't do competition shooting. Could your slide release lever - slide interface be worn out? If you have a spare slide release lever you could try replacing it and see if it resolves the issue.

Edit:

What about the recoil spring? If that is under-tensioned, I would imagine that the slide release could "slip" out of position with a great enough insertion force.
 

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Discussion Starter · #12 ·
All good points, although I have shot an XDm 5.25 Competition for close to 10 years, this one is actually my second one so only 5 years old. A worn slide release lever is one possible reason I did check with a magnifier and I could find no visible wear. Recoil spring is a possibility - that is harder to check, but I will look into it.
 

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@jlow - That's good science you're doing! :)

Inertia is the problem in most cases, and the skip-over is related to that. You're causing the top round in the stack to bounce just ever-so-slightly enough that the slide doesn't get a chance to strip it. When "slamming things in hard" weird crap happens...I'm sure you've seen fellow competitors -or even perhaps yourself- slam the magazine home hard enough to pop an unfired cartridge loose and cause an immediate in-line misfeed....or maybe you're one of those folks who's able to just "tap" a smokestack stoppage away, without even the need to rack. ;)

With your specific issue, I'm wondering if it's possible that the feed lips on your mags have spread just enough or if for another reason you're seeing the bullet of the top or even second cartridge in the stack tap that slide-release just right, causing the slide to forward? I'm curious as to what would happen if you tried a magazine that has a "fresher" or even new magazine spring, or even a new magazine (thus not allowing the cartridges to bounce as much)

The "alternate universe" manifestation of this -which is much more common- is the bullet coming into contact with the slide stop while the gun is under-recoil, and actually causing premature slide-lock (Slide Lock-not empty).
 

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Discussion Starter · #14 ·
Some good points and as it turns out, I have a brand new mag that has never been used so I used it for testing.

First, with the new mag loaded with 10 rounds or 19 rounds, I cannot get the gun to go auto-forward i.e. zero out of 20 slam loads.

Second, with the old mag either loaded with 10 or 19 rounds, I can now get most slam loads to auto-forward....

The reason I tried 19 rounds is because of your comment about stack bouncing. The rationale is with the mag fully loaded and the spring fully compressed, the top rounds are less likely to bounce than when it is loaded with only 10 rounds regardless of whether there is a problem with the mag spring or the lips. As it turns out, if anything a fully loaded mag caused slightly more auto-forward 7/10 (10 rounds) vs. 10/10 (19 rounds)...

I also took a pair of calipers and measured the feed lips of the two mags 3 times each:
Old mag - 0.3345", 0.3375", 0.336" - average 0.336"
New mag - 0.3380", 0.3375", 0.337" - average 0.3375"

So the new mags are actually slightly spread further apart but nothing significant - BTW this is a testimony to how tough the SA mags are since the old mag probably have seen over 10,000 rounds through it.

Good news and bad news...
Bad news is I still don't know what is causing the auto-forward.
Good news is whatever it is, the problem is in the mags and not the gun, and I can test all 10 of the ones I use and pull the problem ones so that they are not used for reloads i.e. only used for starting loads.
 

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Some good points and as it turns out, I have a brand new mag that has never been used so I used it for testing.

First, with the new mag loaded with 10 rounds or 19 rounds, I cannot get the gun to go auto-forward i.e. zero out of 20 slam loads.

Second, with the old mag either loaded with 10 or 19 rounds, I can now get most slam loads to auto-forward....

The reason I tried 19 rounds is because of your comment about stack bouncing. The rationale is with the mag fully loaded and the spring fully compressed, the top rounds are less likely to bounce than when it is loaded with only 10 rounds regardless of whether there is a problem with the mag spring or the lips. As it turns out, if anything a fully loaded mag caused slightly more auto-forward 7/10 (10 rounds) vs. 10/10 (19 rounds)...

I also took a pair of calipers and measured the feed lips of the two mags 3 times each:
Old mag - 0.3345", 0.3375", 0.336" - average 0.336"
New mag - 0.3380", 0.3375", 0.337" - average 0.3375"

So the new mags are actually slightly spread further apart but nothing significant - BTW this is a testimony to how tough the SA mags are since the old mag probably have seen over 10,000 rounds through it.

Good news and bad news...
Bad news is I still don't know what is causing the auto-forward.
Good news is whatever it is, the problem is in the mags and not the gun, and I can test all 10 of the ones I use and pull the problem ones so that they are not used for reloads i.e. only used for starting loads.
AWESOME!!!! I love where this is going!

Thank you for taking the time to do this, @jlow . (y) I'm going to have to save this thread to cite back to at some point, for sure!

That's definitely interesting to see that the feed-lips really haven't spread more. I've actually never measured mine, and just assumed that they would have migrated over time. I'm going to have to do so at next opportunity (likely next week/weekend, as this one's already booked with activities, I'm afraid). It's cannon that the XD-series magazines aren't the toughest out there, so this definitely comes as a surprise to me - but hey, numbers don't lie.

I have 6 older mags (with at least 11,000 rounds through them, each), 5 more with considerably less use, and then another...er.....lots? that haven't seen any use at all. I'll have to do a sampling, for-sure.

It's also interesting that auto-forwarding seems to be happening more with the full stack of 19 versus a partial stack of 10. I'd also imagine that with less compression of the magazine spring (i.e. shorter stack), that it should stand to-reason there would likely be more cartridge-bounce and thus increase the likelihood of a bullet perhaps tapping the slide-stop with just enough force to jar it from its perch. I wonder if the full load of 19 just has so much inertia that it makes that a non-factor? But if-so, then why doesn't the new mag, loaded-to-capacity, do it, too?

Maybe it's the magazine spring?

Are you still on the OE spring for each of those old magazines on which you are seeing the auto-forwarding issue? If so, I wonder if maybe even at full-compression, there's still enough play at-reload that a bullet may be making contact?

Are the magazine springs between the old and new magazines that you tested above compatible for a cross-mag-body swap? I would imagine that since we can essentially rule out feed-lip spread, that maybe the problem will follow the old spring?

And just out of curiosity, what happens if you remove the follower and magazine spring altogether (but keep the base-plate, to prevent over-insertion)? Is there a pattern as to which magazine body auto-forwarding may follow?

What happens if you simply slam the heel of the grip, without a magazine in-place at-all?
 

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What happens if you simply slam the heel of the grip, without a magazine in-place at-all?
So, I just did this with all four of my XDms. Two 4.5-inch, two 3.8 Compacts. My NRA-crest 4.5-inch is the oldest, with 55k rounds live-fire. The two 3.8 Compacts were a year apart, one at around 25K live-fire, and the other at around 14K. The last, another 4.5, was purchased much later, and has only about 3K rounds on it. All are chambered in 9x19, and all use factory/factory-weight RSAs/recoil springs.

I can auto-forward all four by slamming the heel of the grip at a forward angle, without a magazine in-place at all.

With my usual angle-of-attack for reloads, I can't get it to auto-forward at all.

I didn't want to use live-ammo in my home (both the kiddo and the wifey are upstairs, to-boot :p ), and I didn't have enough snap-caps/dummies readily at-hand to fully load mags (even if I did, they wouldn't be the proper weight), so I just did the quick and dirty. Even so, my results would lead me to believe that this is - at least in my hands and with my guns - completely angle/inertia related.....

I'm unfortunately not a competitive shooter, but I do routinely attend training classes and also engage in a bit of self-guided practice in the lulls in-between. Whether live-fire or dry, I have yet to incur auto-forwarding in any of my XDms -or any other of my autoloaders- over the last 10 years. I honestly do not remember a single instance of this being something that I either used to my advantage or having had it induce a stoppage - I really can't remember it happening, at all. When I started shooting, I consistently used the overhand powerstroke. Years later, I re-trained to use the slide-stop.

I'll start looking at my mags at first opportunity.
 

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Discussion Starter · #18 ·
Interesting, I am unfortunately on a tight schedule right now (going out to shoot 600 yard practice....) so will comment more later. A couple of quick points.

1) I am loading the gun with live ammo (don't have 19 snap caps) but the top two are dummies I made so safe.

2) As to what HngnHunter said, not totally true. It is true that most of the mag does not touch the slide when the slide is open, but the striker lever on the trigger assembly does touch the mag and in turn the striker lever touch the slide where the striker exit the slide. You can see this in this photo of my gun - look at the red arrow for the striker lever. I suspect this is what push the slide up and may be how TsiWRX can cause an auto-forward without a magazine.

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^ That's the ejector, and is a part of the frame, not the slide. ;)

Whether your top round -or the magazine body- contacts the ejector upon insertion should not play into this equation (and since I have no magazine in the gun, this piece is not displaced forcefully into the slide, as you have demonstrated with a loaded magazine in-place), but may have long-term implications in terms of ejector damage.
 

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Discussion Starter · #20 ·
Yes, I called it the striker lever but if the correct name is the ejector, it does not matter. It is as I said part of the trigger assembly which is part of the frame. BUT the ejector is up against the slide (see above photo), so pushing on the ejector either with the mag or just banging on the frame will push up on the slide.
 
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