Mumbles Marble Mouth
CGN Ultra frequent flyer
- Location
- Lower Mainland
Been hearing a bit of complaints about upper to lower fitment. Whats the upper to lower fitment like on these rifles? Is it M&P Sport II fit or worse?
Modern Sporter - Build Discussions
- Thread starter ATRS Shaun
- Start date
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...
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?
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.
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.
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.
The tolerance was kept wide to allow more fitment options... you can shim it to remove some of the play...
You can buy shim kits which will come with several washers of different thicknesses or you can just buy some shim stock and use hole punches to make your own
PinaKaleada
CGN Regular
- Location
- South of most
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.
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.
Now that is some ingenuity... well done!
