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AR15.COM
2/7/2011 4:25:13 PM EDT
I thought I may get some other knowledgable opinions posting here in GS/TS. For the original 56k-unfriendly thread, Click Here. Thanks.
2/8/2011 12:06:55 PM EDT
[#1]
Here's what I can offer.

1.  You're trying to diagnose feed problems with reloaded ammo which you know is inconsistent.
Buy some factory ammo to diagnose these issues.  You can't properly diagnose an issue when you're never really sure if it's the ammo or the gun.

2.  It looks like the feed ramp on the barrel has a very sharp edge where the ramp breaks into the chamber.  This will leave scrapes and dents in cases and will cause rounds to hang up on the sharp edge.  
This sharp edge should be LIGHTLY broken with a bullet-shaped Cratex type rubber abrasive polishing tip in a Dremel or Flex-shaft.
The trick is to JUST round it enough to prevent cases from catching, but not so much as to reduce case head support.
Careful, too many over do it and the 10mm needs all the support it can get.

3.  There should be a gap between the feed ramp in the frame and the feed ramp on the barrel.  The usual is a minimum of about 3/32". Your's looks to be a little more than that, but that's not a problem.

4.  The barrel feed ramp has a lip on the very bottom.  Unless the Delta is different than any other Colt barrel, that lip should not be there.
The rest of the ramp looks over-cut and irregular.
The left side of the barrel lug on top of the barrel looks to be undercut.  Again, unless the Delta slide is different, this is wrong.

5.  The frame feed ramp looks a little "short" as though it could be cut a little deeper down into the frame well.  THIS MAY BE NORMAL FOR A DELTA.  Cutting the frame ramp is a major cause of ruined frames.  DO NOT do this unless and until you're 100% certain it needs to be done, and then let Colt do it.

6.  Many automatic pistols will close the slide if a magazine is slammed into place.  This may also be where you're bending the magazine floor plates.
Most any 1911 and many other autos will bend floor plates if the magazine is rammed in.

The reason the slide will close when the magazine is pushed in is because the force of the magazine going in bounces the gun upward.  The slide stop tends to remain stationary and inertia causes the stop to slip out of the slide notch, allowing the slide to close.
This is a oft-discussed phenomenon on the gun forums with some people claiming this is a designed feature of a gun.
It's actually a cause of excessive magazine seating force, or a gun in which the magazines aren't fully engaging the slide stop and forcing it up fully into engagement with the slide notch.  In these cases, the slide stop is barely engaged and the next magazine causes it to slip out of the notch, closing the slide.
The fix is to insure the slide stop is fully engaging the slide stop notch in the slide, and if not figure out if it's the magazines or a defective slide stop.
Next, stop hammering the magazines in.  You should use just enough force to seat a magazine and no more.  The penalty for excessive force is a slamming slide and bent magazine floor plates.

My opinion:
I think you have a defective barrel.  The barrel feed ramp looks mis-cut and the ramp break-in to the chamber is way too sharp.
It's possible the frame feed ramp may need to be re-cut, but this is a decision for COLT or a Master pistolsmith.
Since I don't think you have anything to loose on the barrel, you could use a rubber abrasive bullet or some fine sand cloth wrapped around a dowel to LIGHTLY break the sharp edge of the barrel feed ramp right where it enters the chamber.
This might at least indicate that the barrel is at fault, at which point, you need a new barrel.

I'd be talking seriously to Colt about this and let THEM correct the issues.
On the 1911 forum and on the Colt forum the manager of the Colt Custom Shop posts, and he is known to  personally take care of these problems..
His forum ID is Bjt72.  Check his contact info and talk to him.  You can email him, or PM him.
2/8/2011 1:25:10 PM EDT
[#2]
Quoted:
Here's what I can offer.

<snip>

I'd be talking seriously to Colt about this and let THEM correct the issues.
On the 1911 forum and on the Colt forum the manager of the Colt Custom Shop posts, and he is known to  personally take care of these problems..
His forum ID is Bjt72.  Check his contact info and talk to him.  You can email him, or PM him.


The diagnosis is very much appreciated as are the suggestions. Whether Colt is willing to address this as a warranty issue or not, ALL measures to correct the pistol or address reliability will be done by a competant smith specifically familiar with Deltas.

Your handload issue is understood and agreed upon, though this  there is little practical recourse for a 10mm shooter. The sale and shipping price of a suitable quantity of test JHP would cover a substantial fraction of a competant smith's reliability job, which would be a guaranteed (or at least warrantied) fix/improvement. FWIW, I have spent some time with Winchester Silvertip 175gr JHP and Buffalo Bore 180gr JHP, and have encountered the same problem hand-cycling the rounds.

The magazine issue is duly noted as well. For those concerned, the factory magazines did not warp from this "heel slam" practice. They bent out of servicable use with as few as 60 insertions (2 range trips), while the pistol was stock and I was becoming familiar with it. Thus the floorplate issue is one that is/was going around by some online accounts, and I definitely had first-hand experience of this putting them through their "normal, anticipated" use.

The rigorous "heel slam" fix was employed well after Tripp Cobra mags became the dedicated magazines for this platform. I noticed that despite the same dimensions in the mag catch hole, Tripp's 10 rounders had much more up/down play than their 9 rounders (likely due to the position of the floorplate stop tab). After this discovery, I successfully cleared one of these jams from this method, causing me to wonder if this was due to the weapon, a variance in mag catch hole placement, or a handful of circumstances. Though that heel slam is neither a fix, nor a regular practice IMO/IME, those Tripps are a fantastically overbuilt magazine that can withstand abuse that far exceeds what the standard Delta 8 rounders are designed for (whether conforming or defective). Here you can see the floorplate differences betweem the pre-bent stock mags and the Tripp 9 round Cobra Mag






Delta with Tripp on the right


I will consider where to send the pictures out next. Thanks again.