Modern Sporter - Build Discussions

A lot of times, and 100% out of good faith, I'd wish I can participate in the designing process at ATRS (Like even volunteering). Critical dimensions like BCG travel distance should've been caught had they double checked. Perhaps the reason was they had to make room for the buffer retaining plunger milling so plunger was moved forward, but I'd rather have a half moon notch up on top under the charging handle so that the retaining plunger would be at the right spot, than have my bolt not lock back sometimes. This happened to me too last week.

Where can I hand in my resume? LOL ;)
 
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So to beat this horse a little more, after reading about the bcg travel issues I'm looking at a modern sporter that was assembled using an a1 rifle extension. Hasn't been fired yet. Bcg travels back approx. 1/8" (by eye) beyond the bolt stop when cycled by hand. Compared to approx. 1/4" in two Colt AR's on hand, so definitely a difference in travel length. Any harm in firing it as-is to see if it cycles properly and engages the stop? Old stock 20" pencil barrel with original fsb.....
 
-JP Silent capture buffer system using the black spring ( came with 4 different weight springs i think)
-JP Full mass BCG with Enhanced JP bolt 223
-Maple Ridge Armoury 18.6″ Match V1 Nitride SPR Straight fluted 223 Wylde Barrel
-SLR Adjustable Gas block
-Geissele ssa-e Trigger
- Radian raptor CH, BCM LPK

So the few others that have said a similar situation, changed tubes, etc. What barrels were you all running?

As I have some degree of insider knowledge, and as it's a Sunday (so I'm here for free) , figure I'll start taking bets on the problem....

someone earlier on mentioned a good checklist to follow, but I'll add check the alignment of your gas rings inside your carrier. If you've gone over all of that, it's likely a small gas port.

Reducing the force necessary to send your bcg backwards will also solve the same problem.

What buffer tube are you using?


Also, I believe it was you who asked if the are any longer tubes out there, besides a rifle length tube, I think it's v7 that makes an "a5" buffer tube, spring, and buffer.


A lot of times, and 100% out of good faith, I'd wish I can participate in the designing process at ATRS (Like even volunteering). Critical dimensions like BCG travel distance should've been caught had they double checked. Perhaps the reason was they had to make room for the buffer retaining plunger milling so plunger was moved forward, but I'd rather have a half moon notch up on top under the charging handle so that the retaining plunger would be at the right spot, than have my bolt not lock back sometimes. This happened to me too last week.

Where can I hand in my resume? LOL ;)

...... I don't know what to politely say to that... Here's my best attempt.....

This is NOT an AR15.

Has a single person come back with the issue that there bolt carrier won't clear the bolt catch?

No, you're all just saying "it doesn't clear it by as far as my ar15 does".
 
So to beat this horse a little more, after reading about the bcg travel issues I'm looking at a modern sporter that was assembled using an a1 rifle extension. Hasn't been fired yet. Bcg travels back approx. 1/8" (by eye) beyond the bolt stop when cycled by hand. Compared to approx. 1/4" in two Colt AR's on hand, so definitely a difference in travel length. Any harm in firing it as-is to see if it cycles properly and engages the stop? Old stock 20" pencil barrel with original fsb.....

I’m running a 20” pencil Norinco barrel , rifle length tube. I have 1/8 inch clearance and mine runs 100%.
 
Not sure why some of you guys keep trying different tubes when the PWS is know to work 100%. And has all the clearance in the world.

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Dilligaf: I used the tube I had because when I started I (maybe mistakenly) thought it was a direct transfer of parts to receiver. Only after it was done found out some have had an issue, which is why I asked my question. Just trying to learn.

ATRS Shaun: As for the statement that its NOT an AR, I get that. Was only looking at my Colt for a comparison of the internal parts in relation to each other. Again, here to try to learn.

What I get from this is: if clearances are good, a failure in function at this point would be a gas/buffer issue.
 
Dilligaf: I used the tube I had because when I started I (maybe mistakenly) thought it was a direct transfer of parts to receiver. Only after it was done found out some have had an issue, which is why I asked my question. Just trying to learn.

ATRS Shaun: As for the statement that its NOT an AR, I get that. Was only looking at my Colt for a comparison of the internal parts in relation to each other. Again, here to try to learn.

What I get from this is: if clearances are good, a failure in function at this point would be a gas/buffer issue.

That is my opinion, now if you could not clear the bolt catch manually, I'd start to wonder some more
 
I picked up the Aluminum Radian Forward assist and it protruded too far into the receiver to function properly. Ended up replacing it with a modified strike industries forward assist.

On the topic of forward assists, looking to replace the out of spec TNA one I have that rubbed the roll pin. (at least I hope its not the receiver)
I'm assuming most other "name brand" FA's work fine but has anyone tried Radian's FA in either Ti of Al?
 
This is NOT an AR15.

Has a single person come back with the issue that there bolt carrier won't clear the bolt catch?

No, you're all just saying "it doesn't clear it by as far as my ar15 does".

What I mean is, I know it's not an AR, but you're designing it to use AR parts right? If you're marketting this product to take AR parts, unless compromises needed to be made for another critical area, wouldn't you want to check and maximize compatibility?

Here's the actual problem. Yes my bolt does clears the bolt catch if you charge the BCG on an empty magazine. However, at two occasions(and this is my guess), my well used magazines(dirty?) actually weren't strong enough to push the bolt catch to catch the bolt after the last round in time. However these mags do function normally on my other ARs and Tavors. My guess is that in this case, more margin(more space and BCG travel time) might have given the magazine spring a better chance to push it up.

Has a single person come back with the issue that there bolt carrier won't clear the bolt catch?
Using this logic, we also talked about the ejection port door, it's the same thing. If there's no other constraints, why wouldn't you want to mimic how far the port door closes to maximize compatibility? I know brownell's lightweight carrier wont push it open.

It's all in good faith, and I admire your operation and it must be a nightmare to handle everything. All I'm saying is to check these particular dimensions may only consume a small amount time but just a one-time-thing, and you probably don't need a "parts compatibility thread". People like myself wouldn’t need to trial and error parts compatibility, like the few brownell's lightweight carriers I bought but ended up selling at a loss.

If you ever decide to improve on the next run, I'd love for you guys to:
1.) Mill the buffer detent hole a little more towards the rear, even if it creates a half moon notch where the charging handle rides, so the carrier travel length is exactly the same as mil spec (It'll be covered anyway)
2.) Have ejection port door close at the same angle as a mil-spec AR, so lightweight carriers from brownell's can be used.
 
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Relocating the detent to the rear allows you to screw the buffer tube one thread rearwards and your detent won’t pop out, thus increasing travel distance back to standard AR length.
 
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