Modern Sporter builds Q&A

QuickDraw16 said:
My BCG sits proud of the upper even when it is at its farthest point in travel.
I thought that it was a little unusual but if you push the upper backwards the carrier engages the buffer and closes the gap.
It seems like that’s how it was designed to work.

Unless the tab at the rear end of the BCG is too tall to fit inside the buffer tube... it’s hard to tell from the pictures.
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Thats exactly the case. Its the same height a gas key would be, but to make the MS differ from an AR they thickened the lower and shortened the upper so your BCG protrudes. Ingenious really, but in this instance its no bueno.
 
Sweet, just got my phone call my set is all ready. Now have to figure out how this box of parts I have collected actually gets all together to form a complete pew pew machine.
 
Seems like opening the ejection port for the very few who will use big calibers is going to cause a bunch of weird issues and severe uneven wearing for everybody down the road. The top bolt carrier sliding surface on the ejection port side is unsupported, it doesn't contact the upper at all for the lenght of the port, and it hits the ledge created by the opened port when it moves back...

When the bolt carrier is in battery, the rounds in the magazine push up hard on the bolt carrier... having both sides of the top of the carrier contacting and sliding along the upper is very important, otherwise the bolt carrier is getting some weird twisting force and motion during cycling if one side is floating unsupported like that because of the rounds in the magazine pushing up on it.........................no?

Can ATRS chime in on this please?
 
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Kratos said:
It’s a Spikes Tactical Kit, I gutted an upper. I have a lower in run 2, if you can cut a notch over the buffer tube loop I’m happy with that (if there’s an extra cost for machining I’d also understand). The charging handle would cover the notch anyways. The more I look at it the more I think the barrel needs that material, it’s right where the chamber ends.
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I have a cmmg 22 kit my upper is on route. I’ll try it and report back next week sometime.
 
I see the issue with the 22 tab, if it were me and I was dedicated to it I would file the tab.
But that issue aside, here is how the BCG sits if anyone is curious. You just slide it to the rear and pop the front pin in.
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Holycow said:
I've never built an AR before so this might be an obvious question but:
Do you guys have any recommendations for lubrication?
I understand you're supposed to apply some grease to the barrel nut threads?
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For BCGs and general lubrication G96 Gun SPRAY is what we recommend on all of our semi autos. For barrel retention nuts moly grease, we sell both.
 
Kratos said:
Sorry, the tab is too tall, it won’t slide back as it does with regular BCG’s.



Lol I tried pushing back pretty hard before realizing the tab was stopping me.
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Can spring and guide rod be separated from the back plate or is the spring guide fixed in place?

I can’t see any reason why you wouldn’t be able to have that rear plate machined to fit in the buffer tube (like a normal bolt carrier) and have a tab welded an appropriate distance forward on the guide rod.

This assumes that the tab would then fit in the upper.

I can try and sketch out what mean if it’s not clear.
 
QuickDraw16 said:
Can spring and guide rod be separated from the back plate or is the spring guide fixed in place?

I can’t see any reason why you wouldn’t be able to have that rear plate machined to fit in the buffer tube (like a normal bolt carrier) and have a tab welded an appropriate distance forward on the guide rod.

This assumes that the tab would then fit in the upper.

I can try and sketch out what mean if it’s not clear.
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That would be my thought as well
 
Kratos said:
Anyone try a 22lr kit yet? My bolt doesn’t work, looks like the upper is shorter then an AR15 upper by .175 thou, the end of the BCG sticks out and there’s a tab at the back up top to retain the BCG return spring.

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The pictures show the tab and why it won’t work how it’s currently set up. The only part I can see modifying is the area the BCG locks into the barrel, skim that down on a lathe .175” and the whole carrier moves into the upper. Might have to get a different setup if this doesn’t work.

Or cut a notch in my lower where the tab would go... :D
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The tab doesnt sit in the slot in the upper? It looks like it should fit. Is it the tab or the whole end plate that is to big to fit in the upper?

Edit: never mind I see why it wont fit. The whole guide rail is too long. Not just the plate on the end fitting
 
greg olmstead said:
The tab doesnt sit in the slot in the upper? It looks like it should fit. Is it the tab or the whole end plate that is to big to fit in the upper?

Edit: never mind I see why it wont fit. The whole guide rail is too long. Not just the plate on the end fitting
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I’m wondering if there’s enough room for the bolt carrier to travel back if you just cut off the end plate at the rear and take 3/16 or so off the guide rod and metal fork shaped piece at the bottom ? Then weld back together.
 
robab said:
I’m wondering if there’s enough room for the bolt carrier to travel back if you just cut off the end plate at the rear and take 3/16 or so off the guide rod and metal fork shaped piece at the bottom ? Then weld back together.
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Maybe a guy could even just file the top of the tab down.

As for wiggle, (hockey tape aside) I'm going to double check and make sure the front pin from my LPK isnt undersized.
One other thing I thought about was removing the rear pin and making a sleeve that i can slowly remove material from until it locks up solid.
 
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Chiappaman said:
Welp.... My MDI SLR is far better than my MS, I am thoroughly disappointed with ATRS.
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I feel the exact opposite.
When I brought up my issues with the other manufacturer I was completely ignored. ATRS has been very upfront with any known issues and offered solutions. Both are proprietary, not ARs.
I am much happier with the communication, fit and finish, design and warranty with my MS.
I am sure if you aren't happy ATRS will look after you. Or I am sure that someone will pay you more than you paid for it if you wanted to get rid of it and wait for another SLR. SLRs being available in Calgary before fulfilling orders elsewhere and a complete lack of communication to those dealers when they reportedly had to pay upfront are reason enough for me to never touch one again.
Everyone makes mistakes, it just depends on how they deal with them. I'd say there is a clear difference in character there.
 
Dietz said:
Seems like opening the ejection port for the very few who will use big calibers is going to cause a bunch of weird issues and severe uneven wearing for everybody down the road. The top bolt carrier sliding surface on the ejection port side is unsupported, it doesn't contact the upper at all for the lenght of the port, and it hits the ledge created by the opened port when it moves back...

When the bolt carrier is in battery, the rounds in the magazine push up hard on the bolt carrier... having both sides of the top of the carrier contacting and sliding along the upper is very important, otherwise the bolt carrier is getting some weird twisting force and motion during cycling if one side is floating unsupported like that because of the rounds in the magazine pushing up on it.........................no?

Can ATRS chime in on this please?
Click to expand...

Several LARGE US manufacturers have been doing exactly the same thing as we are regarding an enlarged port, and for many years now and this is the first we have ever heard of what we believe is a non issue.
In the thousands of rounds fired in the prototypes and T&E guns we have not seen any issue as you describe. The only "issue" with the enlarged port, which really is non issue is that there is not as much material for the port door catch to engage in, so fitment of the door needs a little more work.
We enlarged to port opening due to the number of guys wanting the ability to do big bore builds.
Given that the F/A uppers have not started production we can shrink the port back to standard AR size. So if this is a huge concern for you I would recommend purchasing the F/A upper if you intent to purchase a Modern Sporter.
 
Chiappaman said:
Welp.... My MDI SLR is far better than my MS, I am thoroughly disappointed with ATRS.
Click to expand...

So why do you come here to whine? IF you are not a shill and IF you actually purchased our reciever set why not man up and let me know so we can see what your problem is and resolve it?
I smell shill but am willing to give you the benefit of the doubt, for now.
 
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