Modern Sporter - Build Discussions

All my SS and FA uppers fit tight. Better compared to all my AR's. There are a few uppers out there that missed 1 machining step that causes tight mag fitment issues. If you have one of those ATRS will fix it.
 
All my FA uppers fit nice and snug. My one SS upper has a slight bit of play but not enough that I would consider it an issue.

My set has above average play between the upper and lower... nothing a well placed piece of tape can't fix... lol

Been debating drilling and tapping a hole for a set screw... would be nice to see on a future generation...
 
What have y'all done with your Forward Assists? I see some posts replicating a problem i'm having with a milspec FA install. Roll pins seems too big or there's something else going on with fitment. Genuinely a PITA.
 
What have y'all done with your Forward Assists? I see some posts replicating a problem i'm having with a milspec FA install. Roll pins seems too big or there's something else going on with fitment. Genuinely a PITA.
If you're talking about the roll pin for the FA I had to crush mine a little bit in the vice before hammering it in. Even then it mushroomed a little at the very end. I had my set cerakoted, so maybe that might have something to do with it?
 
What have y'all done with your Forward Assists? I see some posts replicating a problem i'm having with a milspec FA install. Roll pins seems too big or there's something else going on with fitment. Genuinely a PITA.

You can use drill bits to measure the hole if you think there is a dimensional issue. Or measure the pin, it's a cheap item to replace if it's too large.
If not you can cone the end of the roll pin you are inserting with a file or grinder. Another great tool is the roll pin starter punch.
And lube, make sure you have lube for all the fine ladies in your life.
 
What have y'all done with your Forward Assists? I see some posts replicating a problem i'm having with a milspec FA install. Roll pins seems too big or there's something else going on with fitment. Genuinely a PITA.

As noted, I would use a drill bit of the correct size to see if it fits without the FA inserted. I'd also suggest that you insert the FA without the pin and look through the pin hole to see if it protrudes into the pin's hole.

On my friends rifle the pin hole was the correct size but the FA's we had protruded into its space so the pin couldn't go past.
 
As noted, I would use a drill bit of the correct size to see if it fits without the FA inserted. I'd also suggest that you insert the FA without the pin and look through the pin hole to see if it protrudes into the pin's hole.

On my friends rifle the pin hole was the correct size but the FA's we had protruded into its space so the pin couldn't go past.

Thank you all.

On the second note, which I am suspecting is the problem, i suppose best bet is grinding down the flat side of the FA itself slightly?
 
What have y'all done with your Forward Assists? I see some posts replicating a problem i'm having with a milspec FA install. Roll pins seems too big or there's something else going on with fitment. Genuinely a PITA.

I had to grind the flat side of the FA to make it fit... the pin hole was sized correctly but was drilled a little too close to the receiver...

From what I've read on here, some FAs will fit but others will require grinding or filing...
 
Has anyone else received a lower where the spacing between the two ears that hold the pin for the bolt catch is too wide? With my bolt catch installed it wiggles back and forth slightly. Rifles functions and fires fine but just a tolerance issue I believe.
 
Has anyone else received a lower where the spacing between the two ears that hold the pin for the bolt catch is too wide? With my bolt catch installed it wiggles back and forth slightly. Rifles functions and fires fine but just a tolerance issue I believe.

The tolerance was kept wide to allow more fitment options... you can shim it to remove some of the play...
 
Personally I wouldn’t worry about it at all. It’s a rifle not a jet turbine. I see nothing to gain from shimming it there.

Actually here's what happened to one of mine.

Gen 3 Pmags are known to cause bolt catches to "slip", sometimes partially due to the bolt catch moving rearwards if you insert an empty mag(I know, why insert an empty mag?). Nonetheless what I did was I took a C clip off of a ejection port door pivot/strut, clamped it a little tighter so it'll fit perfectly on the roll pin of the mag catch. I think a washer works too but they don’t usually come in black. Problem of slippage disappeared after.

IUZvkIM.jpg
 
Actually here's what happened to one of mine.

Gen 3 Pmags are known to cause bolt catches to "slip", sometimes partially due to the bolt catch moving rearwards if you insert an empty mag(I know, why insert an empty mag?). Nonetheless what I did was I took a C clip off of a ejection port door pivot/strut, clamped it a little tighter so it'll fit perfectly on the roll pin of the mag catch. I think a washer works too but they don’t usually come in black. Problem of slippage disappeared after.

IUZvkIM.jpg

Now that is some ingenuity... well done!
 
Back
Top Bottom