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Thread: How many “failures” are acceptable?

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    How many “failures” are acceptable?

    I just picked up my RPB M10/9 and put a Lage upper on it.

    I had to do some tweaking to the Lage bolt as the magazine sat too high for the Lage, but not the factory upper (probably should’ve just sent it in to Lage or PS but I could see what the issue was and it only took a few minutes)

    I shot about 350 rounds after “fixing” it and had four failures. Ammo was a literal mixed bag of 115gr from all sorts of makers - Blazer, Winchester, S&B, Aguila, PMC, Speer, UMC, you name it, it was probably in there.

    One was a failure to ignite the primer on the last round of a mag
    One was a failure to strip off the 10thish round of the mag (OEM factory mag, I’m using FTFs for all the others)
    One seemed to be a live round popped out of the mag and into the action during ejection
    I don’t remember the last one

    Coming from my simple life of semi auto quality AR15s where I don’t think I’ve had a failure of any kind in many years, I just want to see if this kind of thing is “acceptable” for the MAC family. I don’t want to go chasing gremlins if it will just invite more problems.

    Thanks

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    Are the upper and mags new? If so, I think your numbers will get much better. I use a Max-31a with Z-mags, and haven’t had a malfunction in a couple of years. I use brass cased 115gr fmj ammo.

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    It’s a subgun- put more rounds through it and see if you have consistent failures running a single type of ammo.
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    The only issues I run into is ammo. All the issues you named could be ammo related issues. Weak ammo tends to create FTF and light primer strikes. Keep the ammo brands separated to figure which brand does work the best. Some ammo is very weak and will not function well unless you remove some spring coils. I try to avoid this and buy hot ammo.

    I have a video I will try to upload using mixed ammo. You can heard the rate of fire change.
    Last edited by gorillastomp; 09-28-2020 at 08:48 AM. Reason: added info
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    Took a long time and plenty of tweaks to finally get mine 100%.

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    I have had similar issues running mixed ammo. These guns are open bolt and thus recoil impuse is dependant on ammo. I had a mixed bag of 9mm that caused an embarrasing amount of failures, but the same gun runs great with consitent ammo.

    Try a batch of common factory ammo.

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    You tweaked the bolt?

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    Quote Originally Posted by DistalRadius View Post
    You tweaked the bolt?
    Not sure if you’re pointing out my incorrect terminology or baffled at my home gunsmithing.

    Specifically, I milled deeper grooves on the underside of the bolt/bolt carrier (all one piece) as they were contacting the feed lips. I didn’t want to mess with altering magazine height because I wanted to retain the ability to use the gun in factory configuratio (Which the mag height is fine for)

    Plus, I can buy a new Lage upper tomorrow if I butchered it up. I can’t exactly do that If I make a mistake with altering the mag height in the lower.


    Quote Originally Posted by Gaujo View Post
    I have had similar issues running mixed ammo. These guns are open bolt and thus recoil impuse is dependant on ammo. I had a mixed bag of 9mm that caused an embarrasing amount of failures, but the same gun runs great with consitent ammo.

    Try a batch of common factory ammo.
    Come to think of it, I shot two boxes of 124gr S&B and I don’t think I had a single failure with that ammo.

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    Huh. I don't think most of us would have gone after milling the bolt as the first solution but if it works...

    As others have said, 100% reliability is achievable but with the M10/9 mags will be a bit more of a challenge.

    Do yourself a favor and get a Max-31. It's 100% out of the box.

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    Quote Originally Posted by tlk View Post
    Huh. I don't think most of us would have gone after milling the bolt as the first solution but if it works...

    As others have said, 100% reliability is achievable but with the M10/9 mags will be a bit more of a challenge.

    Do yourself a favor and get a Max-31. It's 100% out of the box.
    Lage must have just released the Max 31 recently. I didn’t see it on their site when I ordered my 10/9 Mk2 a few months ago. Where can we find those Suomi mags?

    Out of curiosity what would be the first solution if one’s bolt carrier was hitting the magazine feed lips?

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    Quote Originally Posted by Eurodriver View Post
    Lage must have just released the Max 31 recently. I didn’t see it on their site when I ordered my 10/9 Mk2 a few months ago. Where can we find those Suomi mags?

    Out of curiosity what would be the first solution if one’s bolt carrier was hitting the magazine feed lips?
    Cheapest part, mag catch... assuming it’s a problem across all mags

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    Quote Originally Posted by Eurodriver View Post
    Lage must have just released the Max 31 recently. I didn’t see it on their site when I ordered my 10/9 Mk2 a few months ago. Where can we find those Suomi mags?

    Out of curiosity what would be the first solution if one’s bolt carrier was hitting the magazine feed lips?
    The Max31 has been around for a while. I bought mine back around may.

    True single feed suomi mags are expensive. Shockwave makes some mags that work for the Max31.

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    Quote Originally Posted by Mackjack View Post
    Cheapest part, mag catch... assuming it’s a problem across all mags
    Then they would sit too low in the factory upper.

    Quote Originally Posted by Deerhurst View Post
    The Max31 has been around for a while. I bought mine back around may.

    True single feed suomi mags are expensive. Shockwave makes some mags that work for the Max31.
    I didn’t remember seeing the 10/31. I’ll check it out. 72rd drums would be sweet.
    Last edited by Eurodriver; 09-28-2020 at 08:30 PM.

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    Unfortunately OOS.

    https://max-11.com/529.php

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    Just so I have this right, the gun is new to you, mags are new, the upper is brand new, and you put a mixed bag of ammo in the mags, and you had four problem rounds out of how many total? Most everything mechanical tends to need a break in period. As PP, open bolt subguns tend to like hoter ammo. I would recommend breaking in using a 1,000 rounds of 9mm NATO spec ammo. UMC is known for being very weak ammo. I would also number your mags. Could all four problem rounds fed from the same mag? Tiny burrs,sharp edges, and rough surfaces can add a little extra drag. Four problem rounds out of how ever many rounds with new stuff sounds pretty good to me.

    Scott

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    Quote Originally Posted by A&S Conversions View Post
    Just so I have this right, the gun is new to you, mags are new, the upper is brand new, and you put a mixed bag of ammo in the mags, and you had four problem rounds out of how many total? Most everything mechanical tends to need a break in period. As PP, open bolt subguns tend to like hoter ammo. I would recommend breaking in using a 1,000 rounds of 9mm NATO spec ammo. UMC is known for being very weak ammo. I would also number your mags. Could all four problem rounds fed from the same mag? Tiny burrs,sharp edges, and rough surfaces can add a little extra drag. Four problem rounds out of how ever many rounds with new stuff sounds pretty good to me.

    Scott
    Thanks Scott.

    You’re 100% correct. in hindsight, I guess I had it pretty good. I am trying to hit the range up again tomorrow. I did stock on up on 9mm when this went pending but even by then availability was getting a little scarce. I was trying to shoot up the random junk before getting to the good stuff.

    Also good idea on numbering the mags. You’re absolutely right that this could’ve been caused all by the same magazine (save for one which was the shiny OEM mag)

    I also was unaware the Lage/Mags required a break in period. I have noticed already the bolt sliding much more smoothly than when it was new. Fingers crossed it only gets better from here!

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    Buying a machinegun is a big expense. I am glad that you took my comments the way that they were intended. There is a lot of knowledge here. "Vegas SMG" was the guy that taught me about numbering the mags. While it doesn't say anything about break in in the Lage manual (I did look it up) I have found that to be true about most anything mechanical. Lage Manufacturing makes great products. I have heard good things about the FTF Industries magazines. But the original mags are the best. But those are hard to find and over $100 each.

    Personally I find subgun matches fun. Every once in a while I have met guys that take the competition part a little too serious IMHO. The vast majority of the guys I have met through the matches have been great guys that enjoy the competition for the comradery. They are more than willing to share the things they have learned. It is also great to get together with like minded individuals. I feel the same way about this site. I might get ribbed a little for something obvious, but most guys here want to be helpful. Sometimes it is hard to see the forest through the trees. Congratulations on your M10. Hopefully we will start getting some of the determinations for the new stuff soon.

    Scott

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    Just thought I'd add with certain magazines we clearance the magazines, ie let the bolt file a little bit off the feed lips. I did this with Lage MAX-31a and Zmag-S31 mags. The bolt would close over all of them out of the box, it was just rough or sticking at some point. Something to consider. If the mags are all WAY off, I would recommend fixing your gun as this will be better than modifying every upper you buy.

    Modify the cheapest part first, and if a $20 mag catch is casuing this, it's an easy fix. I suggest getting a replacement one and working on that. Might even spring for an extended release from Practial solutions. I filed one to fit my JAWS and I like it.

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    You want to eliminate variables. Numbering the magazines and using a known good quality ammo suitable for a subgun will both help you eliminate potential sources of problems.

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    Don't use Blazer aluminum cased ammo in your gun. Don't use anything but ball type bullets.

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