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Herk308

Magazine Catch

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Hi all,

My first ever .308 build is assembled now and I will shoot it for the first time on Saturday.  I have been function checking this build as much as I can before shooting and I've found an issue: when I press the magazine release button in hard, the magazine catch bar is able to swivel out of the slot in the lower and fall against the outside of the receiver.  I can't tighten the magazine catch assembly any more than I already have and even now it's at the point where inserting a magazine has become a little difficult (it's possible, but lots of force is needed).

My lower is one that I machined myself from billet and it is based on the DPMS LR-308 lower.  The magazine catch is from a Smith & Wesson AR15 LPK.

Is there a mag catch bar that I could purchase that would correct this problem?  Some other solution maybe?

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Are you SURE you're using a .308 mag catch? An AR15 version will fit, and sometimes work properly, but there is definitely a .308 version. 

 

Personally, I swapped out to an AR-10A model. There's a comparison around here somewhere. 

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      Sounds like your Lower Receiver is out of Spec . Fixing it is still going to give you other issues , you can extend the Threads & trim ( if needed ) the Catch Threaded shaft , so the Release Button can be threaded in more on the shaft, to keep the Mag Catch with in its operational parameters , but this will also make it more difficult to insert a Mag. with out depressing the Mag release Button , to do so.

    You should not have to depress the Mag release Button in farther then flush with the receiver .

    You may be able to make the ramp on the Mag Catch steeper , so as to allow the magazine to slip in a little easier . If you look at the Mag Catch , it will have a lead into the Pad itself to help with inserting the mag.

    The AR 10 ( Armalite ) Mag Catch has a longer Shaft & a larger Pad area , compared to the DPMS LR308, I believe its the "B " model Catch . Not sure it will help your situation . It sounds like Your Receiver width or the Mag Catch well is to short .

  How about some Photo's .Take some measurements & I will take some off one of my DPMS Lowers & Mag Catches . I also have a AR 10 Mag Catch as you can see .

LH1835.thumb.JPG.1dc5f440e288a1ee435087e9364cd066.JPG 

 

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17 hours ago, Robocop1051 said:

Are you SURE you're using a .308 mag catch? An AR15 version will fit, and sometimes work properly, but there is definitely a .308 version. 

 

Personally, I swapped out to an AR-10A model. There's a comparison around here somewhere. 

I'm actually sure that I'm NOT using a .308 mag catch; I am using one out of an AR15 (.223) LPK, so I guess that could very well be the problem!

Is this what I should order?:

https://armalite.com/shop/ar-10-magazine-catch-replacement-kit/

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Quote from another Forum :

Essential LR-308 Lower Receiver Parts 

Many AR-15 lower parts are compatible with the LR-308, but the parts listed here are NOT AR-15 COMPATIBLE and must be included in your build. DPMS part numbers to the screw 
Other things to note: 

  • The pivot and takedown pins are 9/32".
  • The magazine catch, spring and button are AR-15, but when assembled correctly the threaded rod part of the catch will be about 3/16" short of flush. I used a 10-32 set screw ground to fit and filled the hole. It looks much nicer.
  • The 308 Bolt Catch Screw has a 1/16" socket head. Very easy to assemble, just screw it snug, I used a little blue Loctite on the threads.
  • The pivot and takedown pin detents and detent springs are the same, but the takedown detent comes up from the grip rather than from the back. I found that cutting a small (>1/32") divot in the grip to hold the bottom end of the spring kept the spring from squirming to the side while tightening the grip.
  • All fire control parts, including the safety selector, are identical to AR-15. Carbine_Man installed a RRA NM 2-stage trigger with no problems.
  •  
Edited by survivalshop

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 OK , so it is a AR 10A component , I wasn't sure because I purchased it so long ago . 

 I still would like to see some photos of the posters set up , From what I am reading into his issue , pushing the Mag release Button in , the Mag Catch protrudes past the raised area that keeps it in alignment or guide & it is loosening up . A longer shaft will not help in that situation , but with out photos to see what his set up looks like & how far the Button is being pushed to make this issue happen , hard to say .

  That AR10A Mag Catch assembly is worth it .

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I don't have the ability to download photos into my computer (my computer is old and I don't have a smart phone either) but I'll try to get help from one of my friends to download some.

I have searched online for an "AR10A magazine catch" and only found the link that I posted above, which says it's an "AR10" magazine catch, not "AR10A".  Can someone post a link to where I could buy that AR10A magazine catch if the link that I put in my previous post isn't it?

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The Armalite Part Number for the AR-10B mag catch is EA1108 - not the one you need, but it will certainly work better than an AR15 mag catch.  You will need to call Armalite Customer Service to find the part number for the 10A catch. 

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11203200 is the part number for the A magazine catch, odds are you would have to buy the whole LPK to get it directly from Armalite.

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13 hours ago, Herk308 said:

I don't have the ability to download photos into my computer (my computer is old and I don't have a smart phone either) but I'll try to get help from one of my friends to download some.

I have searched online for an "AR10A magazine catch" and only found the link that I posted above, which says it's an "AR10" magazine catch, not "AR10A".  Can someone post a link to where I could buy that AR10A magazine catch if the link that I put in my previous post isn't it?

 

On 4/19/2017 at 11:10 PM, Herk308 said:

My lower is one that I machined myself from billet and it is based on the DPMS LR-308 lower.

How about some measurements then , 

Distance or thickness of your finished lower Receiver at the Mag Latching system ? Need to know if there is difference in your finished product & a DPMS LR Lower Receiver , I have two to compare to. 

On 4/19/2017 at 11:10 PM, Herk308 said:

issue: when I press the magazine release button in hard, the magazine catch bar is able to swivel out of the slot in the lower and fall against the outside of the receiver.  I can't tighten the magazine catch assembly any more than I already have and even now it's at the point where inserting a magazine has become a little difficult (it's possible, but lots of force is needed).

  If you have the Mag release Button tightened all the way to the end of the threads , Spring Pressure on the Mag Catch will make it difficult to insert a mag , with out depressing the Button . Not to mention if the Specs are not correct & it being over tightened , it may not be able to move enough to allow insertion of a Mag.  Some over travel of the Latching system going on , usually it just an adjustment issue , but I don't think that is whats going on here with yours .

    Need more info & I've never seen a PC that you couldn't down load Photo's on , you have an Email , as you said , have a friend take some photos & Email them to you & if you have to ,as you have said . Just trying to help, I find this issue interesting on many levels .:thumbup:

  

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3 hours ago, survivalshop said:

How about some measurements then , 

Just trying to help, I find this issue interesting on many levels .:thumbup:

  

Measurements I can certainly do:

The length of the slot for the catch is 1.508"

The thickness of the mag well wall is 0.099" except for a channel that runs the entire height of the well.  This channel is about 0.385" from the back of the mag well, is 0.531" wide at it's widest part and it radiuses (is that a verb?) down to about 0.425" at its deepest portion.  This channel reduces the receiver wall thickness to 0.042".  The mag catch slot is 0.660" from the top of the receiver.  The outside thickness of the receiver at the mag well is 1.292".

I thank you all for helping me out with this.  For what it's worth, I shot my build for the first time yesterday and it worked great, including the mag catch assembly.  I plan on shooting this rifle in competitions where I'll be on the clock and I don't want to mash the mag release too hard under stress and have it swivel out of position; that's the only reason that I'm making a big deal out of this.  Also, as you mentioned, this is an interesting issue for builders and if someone else can learn from my mistakes/issues then so much the better!

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Having issues with my mag release catch on my AR10 build as well.The threaded portion or bolt isn't long enough.KAK Industries has what we need but they are out of stock.Eveyone wants to sell the thicker button,but that doesn't really solve the problem. Its just a bandaid. 

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8 hours ago, Zoomer said:

Having issues with my mag release catch on my AR10 build as well.The threaded portion or bolt isn't long enough.KAK Industries has what we need but they are out of stock.Eveyone wants to sell the thicker button,but that doesn't really solve the problem. Its just a bandaid. 

Pics of what the issue is - you can put any AR15 magazine catch in any .308AR, and we did it for years before all the fancy mag catches came out.  I don't think I have a single "special" .308 AR magazine catch in any of the 5 or 6 that I have, and I'm being honest.  Just AR15 parts, nothing special. 

Since you're building an AR-10, as stated, just use the factory Armalite AR-10 parts, and you'll have ZERO issues. 

Edited by 98Z5V

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On 9/6/2020 at 3:41 PM, 98Z5V said:

Pics of what the issue is - you can put any AR15 magazine catch in any .308AR, and we did it for years before all the fancy mag catches came out.  I don't think I have a single "special" .308 AR magazine catch in any of the 5 or 6 that I have, and I'm being honest.  Just AR15 parts, nothing special. 

Since you're building an AR-10, as stated, just use the factory Armalite AR-10 parts, and you'll have ZERO issues. 

This one I have to disagree on . With 308's  vs AR15's ... Mag Catch , Mag Release , P &T Pins come in a kit now , just buy one. A decade ago we had to buy these separate or get a 308 LPK for $30 more than an AR15 LPK. I always used a DPMS mag Catch or an Armalite mag catch. The couple millimeters of height always helped.

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On 9/9/2020 at 10:24 AM, MikedaddyH said:

This one I have to disagree on . With 308's  vs AR15's ... Mag Catch , Mag Release , P &T Pins come in a kit now , just buy one. A decade ago we had to buy these separate or get a 308 LPK for $30 more than an AR15 LPK. I always used a DPMS mag Catch or an Armalite mag catch. The couple millimeters of height always helped.

Mag catches are different, brother.  There's zero reason you can't just run a standard AR15 mag catch in just about any .308AR build.  This doesn't count the difference between the Armalite AR-10A and AR-10B mag catch differences, that they came up with for those two distinct platforms. 

I have AR15 mag catches in all my .308ARs.  Never done anything special.  They hold the mag in place, they release they mag when I push the button.  All Aero Precision M5 receivers, and the lone Matrix Aerospace receiver set.  All AR15 junk, for mag catches. Doesn't take much to keep a mag in place, and release it.

Once you start getting fancy, and using all the fancy shiit - or milling your own 80% receivers - that's when things change, and get FUBAR'd.  Armalite AR-10A/Armalite AR-10B shiit not withstanding.

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