Hey all, name's brian i'm new to the forum, but hardly new to the forum gig. i came here because i have an issue with my new build. this is about the third ar that i've built and it's the first time i've ever had an issue. so first things first, build is as follows

DPMS 3G2
vortex viper pst 1-4x24mm
magpul gen 2 BUS
magpul STR stock
miculek compensator
CMC 3.5 single stage
JP scs w/ standard spring in a carbine tube

so really the guts are factory minus the trigger and buffer. my problem is that the bolt is not traveling quite far enough back which is causing a failure to lock on a dry mag. at first thought it was my heavily worn pmags. nope got the gun home and under closer inspection the BCG was stopping just a hair short of the bolt catch. pulled the JP out and slapped the factory one in and it locked perfectly. after inspecting the jp it seems that if i take it apart and remove a little material from the bump stop this should do the trick. has anybody else had this problem? is it safe to modify this bump stop?

btw besides this issue, this thing is a dream to shoot.

anybody? if no responses i'm just gonna dive in and start sanding.

Is it hitting the bump stop on the Silent Capture Buffer or is the spring to heavy. You can get lighter springs to dial the Silent Capture Buffer in.

it was hitting the bump stop. after an hour of trying to get the buffer assembly apart with heat and elbow grease to no avail, i put my tools down and figured it out. all i needed to do was back the buffer tube out by one turn. also ditched the little buffer retaining pin while i was at it. now the bolt catch has the clearance to effectively pop up into the the path of the BCG and lock to the rear.

also installed a magpul miad 1.1 grip and blackhawk safety selector. which brings me to my next issue. the factory dpms selector was crap. very vague feedback given by it. now the blackhawk's is extremely stiff. went from one end of the spectrum to the other. same spring and detente just new switch. anybody else ever run into this? i'm used to my colt's having a very crisp and positive feel. now i'm dealing with this.

Here's a thread with a bunch of approaches and opinions: http://www.ar15.com/forums/t_3_118/619539_stiff__hard_to_use__safety.html. Coincidentally, user "thepinkmist" describes the original "no feedback" issue on another DPMS gun about half way down, but not the over-stiff issue after tossing the DPMS lever for a replacement.

The safety on my built gun was uber-stiff. My choice was relieving the detent and cutting the spring, rather than drilling the grip or attacking the edges of the depressions in the selector shaft.

However, since my parts were all new and freshly lubed, I sat with my lower and cycled the selector a hundred or so times to make sure the parts were good and married before doing any mods. (watching TV at the same time took the edge off THAT bullshit exercise) After that I also temp fit the grip, spring and detent without the selector installed to make sure nothing was binding or hanging up before cutting coils and rounding the detent a bit. I personally don't mind a lot of trial and testing, so I went about a quarter coil at a time and stopped at "just a tad too stiff" in order to account for some additional future wear in. Several hundred safe/fire cycles later, it's still crisp and positive while not at all prone to easy/accidental activation. YMMV. Mine's not a fighting gun, so use your own judgment and go slow. ...or pick another method from that other thread, etc, etc.. Good luck.

P.S. I had the opposite issue with my JP SCS and dropped a quarter into my buffer tube as per the supplied instruction. LOL. Go figure. That pesky buffer retainer had to go anyway. When the retainer is in place, it's a real bitch getting the SCS in and out without scratching the crap out of the weights.

going to play with it some more tomorrow but i think trimming the spring down and maybe rounding the detente will do the trick.

yeah it really is a PITA getting the scs out with that retainer in. thank god for dental picks.

Yup, buzzing on the cheapest parts of the system in question has it's merits in case you go too far. Plenty others besides me chose this route and are happy with the results and their guns didn't explode. Once you get it dialed in, the flame wars over other different methods don't matter much anymore.

Dental Pick. Great idea in case I ever decide I have to have the retainer back in there. For now I just have some rolled up and electrical taped open-cell foam sheet to wedge into the lower when I have it separated from the upper and am not working on it. Keeps the SCS from whizzing out and smacking the hammer. I prefer that because I feel the relative mechanical complexity of the SCS merits more frequent attention (hence removal) than a normal spring and buffer. The standard buffer retainer would drive me batty. Good on you if you decide later to get a different (in spec) buffer tube and reinstall the retainer and go the dental pick route though.

yeah i have a set of metal picks that i got at harbor freight for cheap. they are life savers every time i need them. not really dental picks but thats the best way to describe them. no lie they are worth their weight in gold.

btw just ordered a JP fmos bc and enhanced bolt. can't wait for that to come in.

Funny, I was just now before I pulled up this post over at the JPR site pricing out a little upgrade:
- 16" Mid gas (comes with bolt)
- FMOS M16 Carrier
- Comp
- AGB w/tube
....now can't get the damn $1000 way-better-than-my-skills-merit stuff out of my shopping cart....

It'll be jazzy to hear how you like the BCG when it gets there, and when it has a few k rounds on it. There's been a lot of controversy about 9310 for bolts, if not done correctly, but JP seems like a place that can do it right. Count me in for one when my cheapy bites the dust.

Glad you got your SCS worked out. I love mine and don't miss "Sproing oing oing" every time I fire my rifle at all.

Best,
-AM5

man for me it has nothing to do with skill or lack there of. it's about driver comfort, just cause i can't push a cadillac cts-v to it's limits doesn't mean i wouldn't enjoy the f*ck out of owning one.

running this gun vs my pig that's locked up in the armory right now...SOOOOO much nicer. now convincing the government to issue us all JP equipped rifles would be a little tricky.

Agree. I was just trying to pretend to be a little humble. No matter the skill of a shooter or driver, performance is at some point limited by the ability of the equipment to do what the operator tells it to do. I've got the SCS, Hogue grip, Miculek and a CTR stock. That'll do me for now until my $150 barrel gets old. THEN I'll have the $500 barrel/bolt package and $280 carrier. See how good I can shoot!

Yah, hold your breath while AF1 gets solid gold toilets before you guys get better gear, and all you'll do is turn blue. For MY money, they ask you to shoot out to 500m and go in first, so I hope you got something better than the 300m Army guys. (Respect to both )

yeah speaking of that i just shot expert last month with my worn-the-f*ck-out m4. and that being the first time qual'ing for me with a short bbl and an ACOG. when i deployed i had an m4 but ditched the ACOG for irons to qual with since that's all i knew at that point. but man that magnification really does make a difference. shot pretty close to perfect on everything right up to the 500, where that short gun starts to show it's limitations. didn't take long for me to pick up that vortex viper 1-4

Damn son! Congrats!! (Oooo Rah???) I'm 50 and lucky if I can hit center mass on a man-sized target consistently at 100 w/irons on the 16" AR. (Drive tacks all day long with glass on 30.30 lever gun at that range though - BFD) What exactly constitutes perfect at 500m? (Speak slowly. I'm a civvy and really have no clue)

P.S. If you ask me, they oughtta spring for the fun FCG for your DPMS and let you use that at work if you wanted.

ETA: Mods might say this thread has gone GD pretty soon. PM me if you want or whatever if that happens. OTOH no offense taken if you're done -