Modern Sporter builds Q&A

[Kratos]

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.

The tab would fit in the upper, that’s how it’s designed. The upper is just short is all. I might just cut the horizontal mounting plate and find a way to retain the BCG in the upper with .175” of the plate cut out. The spring will want to come back so the plate will fly out during disassembly if not retained in the upper somehow.

The whole mechanism won’t crater if it’s .175” shorter, the actual moving part has lots of room still for those that are thinking of modifying the BCG assembly. The spring may need shortening since it’ll be compressed more then normal.

[robab]

The tab would fit in the upper, that’s how it’s designed. The upper is just short is all. I might just cut the horizontal mounting plate and find a way to retain the BCG in the upper with .175” of the plate cut out. The spring will want to come back so the plate will fly out during disassembly if not retained in the upper somehow.

The whole mechanism won’t crater if it’s .175” shorter, the actual moving part has lots of room still for those that are thinking of modifying the BCG assembly. The spring may need shortening since it’ll be compressed more then normal.

So basically we need to shorten and re weld the cmmg assembly .175. Can’t be more than an hour labour at a machine shop.

[Kratos]

So basically we need to shorten and re weld the cmmg assembly .175. Can’t be more than an hour labour at a machine shop.

Yeah, and then testing the spring but that’s just range time. I might try it myself and ATRS might have to weld it back together if my idea doesn’t work lol.

[Butzy357]

There's no point in having a beveled corner because no matter what you do with the rear takedown pin it is never going to pivot open anyways because the rear of the bcg sticks out of the back of the upper.

These work exactly like the Modern Varmint where you have to push the front pin out and slide the upper forward and then lift it off to separate.

There's technically no point in having a removable rear pin.

Well maybe there is a point now that we realize some triggers interfere with the rear lug during assembly/takedown but once again it's never going to pivot open.

I was just going to ask about this bc I couldn’t separate my newly assembled MS without removing the front pin and sliding the upper forward. I noticed the the BCG was catching on the lower receiver extension female threads kinda (does that makes sense haha), stopping me from pivoting the upper...that’s normal for the MS, MH and MV?

[Knuckles87]

This is what i have happening as well.
One upper seems not that bad. The other is very tight. MFT 10R Pistol is the only one that goes in and drops free.
The Pmags go in but need pulled out. and the 10R pistol C products will go in and is hard to extract and the other upper i deeply regretted
putting it in 10 min of swearing issued. I have been 2 busy to contact them.
They are great and I have faith we can get it resolved.

[Knuckles87]

Anyone having mag seating issues? Both metal mags and pmags won't work in either upper. Have one lower currently. It seems the upper sits rear ward on the lower, creating a lip inside the magwell that prevents the mags from seating. The upper and lower fit snug with very little movement so this seems strange..

This is what i have happening as well.
One upper seems not that bad. The other is very tight. MFT 10R Pistol is the only one that goes in and drops free.
The Pmags go in but need pulled out. and the 10R pistol C products will go in and is hard to extract and the other upper i deeply regretted
putting it in 10 min of swearing issued. I have been 2 busy to contact them.
They are great and I have faith we can get it resolved

[jiffx2781]

...

[no-one special]

AB.blasters new account ?

I think so. Certainly a troll for sure.

[no-one special]

This is what i have happening as well.
One upper seems not that bad. The other is very tight. MFT 10R Pistol is the only one that goes in and drops free.
The Pmags go in but need pulled out. and the 10R pistol C products will go in and is hard to extract and the other upper i deeply regretted
putting it in 10 min of swearing issued. I have been 2 busy to contact them.
They are great and I have faith we can get it resolved

P Mags can act that way in many lowers, being as plastic is hard to hold dimensions on. A little sanding will solve this assuming they seat ok. If they don't seat properly look at the mag catch as possibly being the culprit. I suspect the latter with the comment on the metal mag.

[no-one special]

I was just going to ask about this bc I couldn’t separate my newly assembled MS without removing the front pin and sliding the upper forward. I noticed the the BCG was catching on the lower receiver extension female threads kinda (does that makes sense haha), stopping me from pivoting the upper...that’s normal for the MS, MH and MV?

NONE of the Modern series rifle were ever designed to pivot. These are NOT ARs!! You have to push the front TD pin out in order to slide the upper forward slightly to seperate the upper from the lower.