Lehigh XD 135 Feeding Issue

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Lehigh XD 135 Feeding Issue

Postby Hoot » Sun Mar 05, 2017 10:08 pm

I'm still working on my first 2017 Range Day thread, but in case folks were considering buying the Lehigh Xtreme Defense 135gr bullets, I felt compelled to pass along an issue I experienced today. It is important to say that issues like this can often be associated with how the cartridges ride in a give magazine as well as the topography of the feedramps your perticular 450b barrel comes with. In my case, both my Franklin and Bartz uppers have nearly identical feed ramps, but those are all I have to compare. They are not your average Rifle or M4 variations, no doubt to perform well with single stack large calibers.

I only had 9 bullets to test with that were generously donated by a member here. Throughout the course of shooting them, I had jams during feeding on about half. Close scrutiny of one of the jamming rounds revealed small indentations indicated by the black circles as best as my smart phone could catch them. On a hunch, I rotated the round in my mag as indicated "Good" in the following image and it stripped and chambered fine. I extracted it and rotated into the suspect position and again it jammed during feed. Again, it fed fine with the "Good" alignment. This has led me to no longer consider those bullets as appropriate at least in my rifles. Controlling how each round indexes as it rises up the column in a magazine is a fool's errand. OK so on to the image:

Image

I'm not certain how far out of alignment they have to be to start or stop feeding reliably. I only tried two orientations to test my gut feeling at the shooting line.

I suspect that the short seating necessary with these light bullets (2.04 COL) causes them to strip, strike the feed ramp and deflect upward with the attack angle being steep enough for the nose to impact the 12 o'clock lug when riding in mag in an X pattern. When riding in the + pattern, the round slips on by the lug and funnels into alignment further into the chamber. The two circles in the ensuing image would be IMHO, near where the two on the previous image strike and wedge against. The cause is theoretical but the jams were undeniable.

Image

I did not have any of the other weight XD or XP bullets to test with but if Lehigh reads this, feel free to contact me about sending me some free samples. My guess is this bullet was designed around the 45 ACP and probably was never intended for use in an AR 15 platform.

Caveat Emptor...

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Re: Lehigh XD 135 Feeding Issue

Postby Al in Mi » Mon Mar 06, 2017 7:37 am

I "dehorn" all those sharp edges on all my extensions before assembling the upper, more for minimizing scrapes and scratches on the cases, but might be of help for feeding of some types bullets too, althou those might be an exception.
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Re: Lehigh XD 135 Feeding Issue

Postby Hoot » Mon Mar 06, 2017 8:23 am

I agree about "melting off" the sharp edges on the barrel extension. I've done all of mine with the exception of the Bartz. Unlike most AR's I've seen, it came with no edges that could cut your finger and its NiB treated. Didn't want to break through the NiB so I left it alone. IMHO, half of the benefit to having an NiB treated bolt is lost if the mating surface is not NiB treated also. Same applies to NiB bolt carriers. While it definitely improves the cleaning process, its friction reduction is not fully realized if its scraping its way along on a matte finish black phosphated upper receiver. At least until it is polished from repeated use.

Three other members came through the Rifle Range while I was there. Everyone was curious about those bullets. Their appearance sure draws eyes. I can only speculate that the XD & XP bullets that are heavier (=longer) and can be loaded to COL's approaching 2.26, may not experience the jamming issue.

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Re: Lehigh XD 135 Feeding Issue

Postby Bmt85 » Mon Mar 06, 2017 4:34 pm

Interesting, I'm going to have to play with mine again. I didn't have any feeding problems with the dummies I made up. I wonder if maybe the feed lips on your mag require a little tweaking for these bullets?
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Re: Lehigh XD 135 Feeding Issue

Postby Hoot » Mon Mar 06, 2017 5:23 pm

Bmt85 wrote:Interesting, I'm going to have to play with mine again. I didn't have any feeding problems with the dummies I made up. I wonder if maybe the feed lips on your mag require a little tweaking for these bullets?


Hard to say as that's the first time I ever had that particular issue. It fed all 20 of the resized 325gr bullet loads and half a dozen foulers and sighters without a hitch. Try purposefully orienting your dummy round in an X pattern and see how it goes. I'll get a picture of how the top round rides in my mag and post it. I'd love to be wrong though I can't comment on the velocities I achieved as not one of them would register on my new chrony, but that's another painful story. I save bullet number 10 for my reference collection, but may have to load up a dummy and see how it behaves with my other 450b mags of different pedigrees. Its tough when you run into snags when you're at the range on the firing line. I bring just about ever smithing tool and widget I own in case I need it along with a full cleaning cradle and chemicals. I've bailed out my share of unprepared members who show up to shoot with weapon issues over the years. Hard to not get interrupted while trying to get some shooting in, but I'm the guy who can't say no. Watching a tornado pass about 25 miles to the north of me. Strangest winter I can recall in the 41 years I've lived here. The frost isn't even out.

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Re: Lehigh XD 135 Feeding Issue

Postby Hoot » Mon Mar 06, 2017 9:10 pm

For the sake of argument, here's four of my mags, including the one I was using:

Image

Image

Image

They're all pretty much the same though my oldest Bushmaster, the one I was using, shows a little more wear.
Of the four, the Bartz 1st Gen holds the rounds a little closer to the vest, but not by much.

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Re: Lehigh XD 135 Feeding Issue

Postby Bmt85 » Sat Mar 11, 2017 5:48 pm

I played with em again, and only had one issue. With one of my ASC 10rd mags, I accidentally rode the charging handle down a little, and that caused it to jam into the lower part of the barrel extension/lower receiver. Tried turning it in every direction and dropping the bolt carrier using the bolt catch, everything else worked. However I am using Slash's XH buffer, so the bolt comes home with authority.

However, couple things I noticed between your mags and my 5rd mags, mine hold the front end a little more up and the very front of my mags feed lips are tweaked up. My factory mag came that way, the 2nd bushmaster mag I ordered, I tweaked the same way. My 10rd ASC's though, look just like yours, I haven't tweaked em yet. They still ran though.

I have a couple pics so you can see, but photobucket sucks, so it'll take me a little bit.
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Re: Lehigh XD 135 Feeding Issue

Postby Bmt85 » Sat Mar 11, 2017 5:53 pm

Here's a side view

Image

Here's a better view of the feed lips

Image
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Re: Lehigh XD 135 Feeding Issue

Postby Hoot » Sat Mar 11, 2017 9:50 pm

Your experience actually makes sense:

A) I rode every round into the chamber. I do that when I'm doing load testing.
B) I never looked at a round in the chamber when it jammed. I dropped the mag out, pulled back on the bolt and let them fall out the bottom into my hand.
So, they could just as well have been hanging up on the bottom lug, contrary to my assumption that they were hanging up on the top one.
C) The previous statement would be consistent with the way my mags hold the rounds lower at the front than yours.
D) in my case, orienting the rounds like a cross, would have kicked them up into the chamber, as opposed to the X straddling the bottom lug and binding.

This gives testimony to the fact that it never hurts to have more sets of eyes on a problem. My two Bushmaster mags are 7 years old this month. IIRC, the compelling reason for keeping them parallel to the lips was to prevent them from jumping out of the mag during extraction, before they are supposed to be stripped by the bolt moving forward. That was a problem a few years back and led to folks tweaking their lips down a little more in the front. There's that "table with one short leg" conundrum again. :roll:

Thanks for your observations!

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