Modern Sporter UPDATE stock compatibility Oct 31 UPDATE NOV 12th

[alberta tactical rifle]

We just today discovered that buffer tubes for the A2 fixed stock and Magpul UBR do not protrude far enough into the lower to engage the buffer retainer on lowers with serial numbers 000001 to 000224.
On lowers with a higher serial number (2nd production run) this has been corrected and not an issue.

For those who are intending to install a butt stock that employs an A2 or any fixed stock style buffer tube, we have 4 options to correct this problem.
1) Run the rifle without the buffer retainer altogether. Given that the upper slides forward to disconnect from the lower the buffer and spring are not going to cause any problem for takedown like it does on an AR15.

2) Send us your buffer tube and we will modify it for you at no cost. The modification requires taking off about .050" from the ring that locks up against the lower. This WILL leave a very tiny gap between the stock and the lock ring but will not effect the performance of the assembly at all. We will be posting photos as soon as possible so you can see the small cosmetic issue.

3) We will provide a JP Silent Capture System to you at a considerable cost saving. This is likely the best option as it is a far better system than the conventional buffer and spring.

4) Return the lower and we will exchange it for a lower from production run #2 where this issue will not exist. This will mean not having your lower until mid summer of 2019 however, but for those who want to avoid the backdoor registry we can still accommodate this up until C-71 becomes law.

Please contact us at the shop directly should this discovery effect you and you wish to know more about the options.

Sorry guys we thought we had all the bases covered.

November 12th update
We FINALLY got pricing from JP this morning.
Everyone with a lower will receive an email with the information. We need to know how many of these kits we need to get ordered no later than NOON Friday Nov. 23rd 2018

[jiffx2781]

Is that how much the buffer retainer holes are drilled off?

I'm just taking a wild guess here because I don't have my lowers yet to see what the issue is but perhaps the buffer retainer pin hole was drilled straight down from the edge of the receiver instead of angled back in by the standard 6°?

That alone would be enough to account for the .050" of difference.

I'm only speculating of course, but I've had one other firearm that was drilled straight instead of angled and it caused the exact same issue when I switched to an A2 stock. Still works fine but I have to remember that the spring is going to come out when I take it apart.

[benwilliam]

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[alberta tactical rifle]

I'm just taking a wild guess here because I don't have my lowers yet to see what the issue is but perhaps the buffer retainer pin hole was drilled straight down from the edge of the receiver instead of angled back in by the standard 6°?

That alone would be enough to account for the .050" of difference.

I'm only speculating of course, but I've had one other firearm that was drilled straight instead of angled and it caused the exact same issue when I switched to an A2 stock. Still works fine but I have to remember that the spring is going to come out when I take it apart.

Being as the Sporter is a direct variant of our Modern Varmint, we employed many of the same dimensions. One of which is the thickness of the rear of the lower where the buffer tube threads in. This area is thicker than a standard AR15 and as a result buffer tubes with a "collar" on them for butting up to the lower do not have enough tube to protrude and retain the buffer retainer. The Modern Varmint has always run the JP buffer system and we missed the fact that we needed to change this dimension when we started the Sporter project.

I am going to delete many of the posts in this thread in an effort to keep this thread for information only.
We are working with JP at the moment on pricing and should have it available later today.

An order for JP will be going into them VERY SOON so we will need numbers as well as payment for the system of your choice, there are 4 options from JP.

PLEASE NOTE THIS OFFER IS ONLY FOR THOSE WHO HAVE PURCHASED EFFECTED LOWERS AND IS LIMITED TO 1 KIT PER LOWER

[alberta tactical rifle]

I purchased a BAD Sabertube Stock (rifle length) with JP Enterprise Silent Capture for my build.

From what I read in your post above, this set up should not be subject to this issue?

Can you confirm?

Correct

[GUNNZ]

Do you recommend the standard version or the heavy H2 version? Thinking standard version will be perfect for rifle length gas system shooting 223. Please advise.

Also, what are you thoughts on the Alternative Spring Kit? It is worth the $20-30 extra dollars? I have no experience with the JP silent captured spring kit. Thank you.

[alberta tactical rifle]

Do you recommend the standard version or the heavy H2 version? Thinking standard version will be perfect for rifle length gas system shooting 223. Please advise.

Also, what are you thoughts on the Alternative Spring Kit? It is worth the $20-30 extra dollars? I have no experience with the JP silent captured spring kit. Thank you.

I have been running their standard version is rifle length 223 applications for years, and it works just fine. Our MV comes standard with the JP standard system and only a few guys wanting to run truly weird stuff have had any issue and I suspect if they had standard AR buffer and spring would have exactly the same issues.
Avoid weird stuff and you avoid problems it seems.

[Kornerupine]

Being as the Sporter is a direct variant of our Modern Varmint, we employed many of the same dimensions. One of which is the thickness of the rear of the lower where the buffer tube threads in. This area is thicker than a standard AR15 and as a result buffer tubes with a "collar" on them for butting up to the lower do not have enough tube to protrude and retain the buffer retainer. The Modern Varmint has always run the JP buffer system and we missed the fact that we needed to change this dimension when we started the Sporter project.

I am going to delete many of the posts in this thread in an effort to keep this thread for information only.
We are working with JP at the moment on pricing and should have it available later today.

An order for JP will be going into them VERY SOON so we will need numbers as well as payment for the system of your choice, there are 4 options from JP.

PLEASE NOTE THIS OFFER IS ONLY FOR THOSE WHO HAVE PURCHASED EFFECTED LOWERS AND IS LIMITED TO 1 KIT PER LOWER

Is the rear of the lower exactly .050" thicker? If so, some carbine stocks that almost touch the castle nut when collapsed will need to have some plastic filed-off from the face otherwise they won't fully collapse.

[jiffx2781]

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[alberta tactical rifle]

We were hoping to have pricing info from JP today. Hopefully we will have it available tommorow.