The Continuing Mag Problem, Part2 w/Pics

[AzizaVFR]

It has been an while since my last posting. Work has interrupted about every hobby I have. I was able to spend a little bit of time this past week addressing the issue of rounds hitting each other, causing the infamous nose dive.

For everyone who is watching this thread, it is NOT a magazine issue. It is the relationship to how far the barrel drops as it comes out of battery when the slide moves rearward. The only three things that influence that are the locking lugs/feed ramp area of the barrel, the locking block location and the underside of the slide just in front of the barrel. These three areas dictate the minimum (barrel to slide clearance) and the maximum (locking block to feed ramp clearance) the barrel can move while the action cycles.

I removed the stainless shim I had in there prior and cleaned the area on the barrel. The shim helped to minimize the extracting case/next round interference, yet it presented a new issue. With the barrel raised above the surface of the locking block, the bullets would get stuck on the sharp edge of the feed ramp. The real way to tackle both the drop in the barrel and the feed ramp clearance was to fix both at the same time. The first thing I did was to put the slide in the mill and clean up the area the barrel hood slides under while cycling. My particular model had a weird hump at the front area. Using a set of diamond grinding stones, I leveled the area, making it prefectly flat as below.



After that was done, the barrel hood received the same treatment.



The contact points on the locking block needed to be raised, since it is easier to address there than dealing with the underside of the barrel. I filled two areas on the flat surfaces of the locking block with Devcon Metallic Putty. This stuff is quite hard and machinable. Once it was set, I place the block in the mill, cutting the Devcon with another diamond wheel to slowly grind the putty to the correct clearance. Here are two shots of the end result.




Once all the cutting and fitting was done, here is what the clearances look like from the barrel and feed ramp angles.




The striker was removed from the slide, then some testing with loaded ammunition was tried. Using the worst case scenario ammo for this pistol (200gr Moly SWC, COL: 1.251"), I hand cycled the slide, feeling for any resistance on the loaded case hitting the next round in the magazine. Amazingly, there was none. After trying to move the slide back and forth a couple of times with the same round, I removed the magazine, loaded 13 SWC's into one magazine, 10 into the other, put the striker back into the slide, and the recoil spring and headed outside. To test cycling all 23 rounds, I racked the slide as hard as possible by hand until all rounds were cycled. There were no collisions, nor deformations of the cases/bullets like before. The test was also done with some 230gr RN, COL: 1.272" rounds. Again, the results were the same.

Hopefully, the live fire testing can be conducted this weekend, if one of my clients does not blow up their critical system today.

[fearless1]

Aziza:

Ths success of your modifications will depend on how much of the extracting case was generally exposed to the top round in the magazine before you made your mods. The more the extracting case was exposed, the bigger the size of the modifications one would need to make. Why? Because I have discovered that there are actually TWO causes to extracting case exposure that could lead to impacting with the front of the top round in the magazine. The first, already discussed extensively in this thread, is case exposure due to low barrel bedding allowing the case to show below the middle slide rail. The second cause which I already alluded to earlier in the thread but few are even aware of, is from the extracting case shifting into an even lower position during the initial 3/8 inch of barrel unlock from the slide. How did I discover the case shifting?

Using empty cases and snap caps in my own XD 45, I was able to confirm without doubt that the slide middle rail completely shields the extracting case from the top round of the magazine when no case shifting occurs (with the barrel just out of battery and pressed into the slide). Also confirmed when I [too] do the slow feed cycle test (gun assembled without the striker and recoil assembly), there is no contact whatsoever between the empty case and the top roud in the magazine. However, the margin between the edge of the case rim and the bottom surface of the middle slide rail is only about 1.5 mm. So, there should be no extracting case impacting when the gun was fired. This was unfortunatelyi not the case at the range. Inexplicably at first, impacting was still occuring. Further study of the feed cycle and gun dimmensions proved beyond doubt that the ONLY way for case impacting to occur is if the empty case shifted position and dropped below the level of the middle slide rail without additional downwared movement of the barrel during the initial portion of the extraction. Performing the slow feed cycle test confirmed without doubt the base of the extracting case rubbing along the bullet then eventually making contact with the lip of the cartridge when the base of the empty case is pushed downward.

The only remedy I pursued to attempt a fix for this was to modify the extractor to rigidly hold the case against slippage. I was mostly successful with this method, dropping the percantage of impacting from 100% to about 15% (from every round to about 1 in 7 rounds). So, for the 7 rounds fired where there is no impacting, extraction of the empty case was "perfect" without case shifting. The amount of downforce on the base of the extracting cartridge must be considerable since the heavily modified extractor has a very tight hold of the case rim.

So, a quick test for your recently modified gun before even test firing it, would be to follow the 4 diagnostic steps I outlined in this thread.

1. With an empty case in the chamber, place the slide/barrel into full battery.

2. Unlock the barrel.

3. Slide the barrel forward about 3/8 inch then press the barrel back into the slide.

4. Holding the slide and barrel stationary in the just out of battery position, use a narrow object to press downward as far as possible, the base of the exposed cartridge towards the bottom of the slide middle rail.

If the base of the case still becomes exposed beyond the slide middle rail, then impacting will still occur. If not, then you've come up with a temporary solution to the problem. THE PERMANENT SOLUTION IS FOR SA TO FIX THE PROBLEM AT THE DESIGN AND MANUFACTING LEVELS.

If/when you proof your design changes with live fire tests, recommend you weld and mill the locking block for a more permanent solution for your own gun. Perhaps you can also send your design mods to SA for implementation too....which may be a pipe dream.

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[AzizaVFR]

Using your test as stated, here is where the case head will ride as it comes out of battery. Notice the distance from the top of the slide to the case rim is 0.279".





Your are most correct. If I can prove this is the solution, it will be better to weld the block after measurements are taken. After building my own 1911, the tolerances are much more lenient on this XD. I will take pictures of the rounds before and after the test firing.

[fearless1]

Throughout the thread, participants have been doing the test with the slide/bbl off the frame then photographed the upper assembly upside down to get a much better view of the base of the case in relation to the middle slide rail. I guess I should have mentioned disassembly of the gun first.

In your pics, the cartridge looks parallel to the chamber. Were you not able to push the base of the cartridge down? You can when the gun is disassembled and there is no top round in the mag placing an upward force against the extracting case.

I'll try to post pics of my own gun later....

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[AzizaVFR]

Are you referring to this sort of picture?



That was the first thing I did by grinding out the inside of the slide and top of the barrel hood. I needed just about 0.021" of clearance to make sure as the round is extracted from the chamber it would not fall below the middle rail.

The pictures I posted above showing the chamber open was with no magazine installed. That is where the extractor holds the round as it cycles.

[fearless1]

From your latest image, even after all your mod work to the gun, it would appear that your straight edge tool is making contact with the extracting case. When I do the same test with my gun and view it from the same angle as in your image, I see a little bit of space between the case and the straight edge. During live fire testing, if the extracting case shifts, then collision will still occur.

Below is an image of my XD 45 depicting perfect extraction of a snap cap without shifting. Notice the middle slide rail is offering some protection to the the bullet of the top cartridge in a magazine from the base of the extracting case . The clearance from the edge of the case’s rim to the flat of the middle rail is only about .015 inch.



The image below depicts a case that has shifted loosely from the barrel and drops beyond the protection of the middle slide rail.


Reverse image of shifted case below. Notice the large amount of case now exposed to collision with the bullet of the top round in a magazine.


Below are two images of a Taurus PT 1911 with snap cap in perfect extraction (no shifting) and barrel just out of battery similar to XD45 above. The clearance from the edge of the case rim to the middle rail flat surface is a much larger .030 inch.




The two images below are of the same PT 1911, but this time I manually shifted the cases as far as possible towards the middle slide rail flat. Notice that the middle slide rail is still shielding the bullet of the top round in the magazine from collision with the base of the extracting case. I’ve checked other auto pistols such as XDm, S&W, and Sig and was able to confirm the presence of this magnitude of shielding in those pistols. Glock has a unique solution to shielding the case. Glock uses an angled ramp on the end of the middle rail to create the shield (the method I was contemplating trying on my own XD45)!





I’m going to assume my gun with correct shielding was manufactured correctly according to HS and SA manufacturing specs. When I study the design, “on paper” it should work but doesn’t. When I live fire the PT 1911, Glock, XDm, etc, there is no collision occurring whatsoever (using lead SWC as a diagnostic tool). When I compare what I think are critical specs between the 1911 and the XD45 and see they are almost the same, this also tells me the XD45 should work. Yet one works and the other one doesn’t. I’m going to have to take a lot of measurements to figure out this mystery.

Better yet…I'll just satisfy myself with the tune up work I’ve done to the XD45 to date and enjoy the gun for once, which I do immensely now that it is “working”!

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[AzizaVFR]

I was able to take the pistol out yesterday and squeeze 50 rounds through it. Not a single failure to feed, nor fire with the 230gr RN nor the 200gr SWC. There were no deformed case mouths nor dented case rims. The only negative thing is the POI has been lowered. I guess I will need to find a good set of adjustable sights for her gun. Oh well, more gun parts to buy.

[fearless1]

Cool!

I'm sure you knew POI would change while you were making the changes to your gun (shoots about a foot lower now?). Just file the front sight down the next to you go to the range.

Problem now though is your solution isn't one that is readily implmented by Average Joe XD 45 gun owner. SA may not care for or need it either, especially if your mods reflect what the true specs of the XD 45 are supposed to be (implying you bought an XD 45 that was manufactured way out of specs to begin with).

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[AzizaVFR]

Just a quick note on the progress. My wife is happy! She ran the pistol this past weekend with 300 rounds. It was her first major outing. Not a single FTF, FTE, no nicked cases. By the end, she was putting all her shots while moving from 20 yards to 5 yard and stops between in a 4" circle. It has no issues shooting the SWC or the LRN intermixed in her two magazines. All she needs now is more magazine, and I have go load more ammunition.

[jmj8355]

Quick update on my situation. I recieved a new pistol from SA earlier this week. They didnt bother doing anything with my original gun and just shipped out a brand new one similar to the OP. The new one looks to have the same problem. The casing is still exposed above the middle rail while doing the test that has been mentioned earlier in the thread. I havent even bothered shooting it as i know it still has the problem. There is a Gun show in my area this weeked so i will be taking it along to see what i can get for it. IMO, every stock xd 45 has this problem and is more prevelent with certain types of ammo, although i never fired anything other than factory stuff. SA has probably lost me forever as this is simply not acceptable for a mass production tier 1 gun.