mpom

If wearing out the firing pin bothers you, then a solution (other than a spare fp) is: http://www.midwayusa.com/product/872223/tma-ar-15-dry-fire-device-delrin-orange Prevents hammer contact with fp and reduces the amount of retraction required to recock hammer. Pretty neat, just drop into bolt carrier, done. Just don't forget to take it out before firing or it goes click instead of bang. Don't ask how I know...

Did the Nordic follower as well, and ended up losing a round capacity, as mentioned above. So cut off around a half inch of back section, smoothed and beveled, so back to 9+1, no hangups. +1 on polishing mag tube where piston lives, as it makes cleaning much easier.

Ranier Arms has a variety of lowers, including some branded for them, which are of very good quality.

As far as cleaning, maybe every few hundred shells. Suspect reason for follower hanging up is poor match at the junction of the mag tube screwed in to receiver and the Nordic extension where they screw together. If you take out spring and follower and shine a light down from receiver while looking down tube from front (MUST make sure firearm is unloaded first, not that anyone on this forum would not) you will see the fixed part of the mag tube. Edge is probably pretty sharp and can catch the follower. Try dropping it down a few times. If so, then you can file and polish or dremel the offending sharp edge so you end up with a smooth transition and no hangup of follower. Reason its not an issue when live firing is probably because of all the recoil and inertia of shells during live fire. Would suggest a complete teardown, cleaning and fluff and buff, since the gun is pretty new. The gas piston and tube it rides on (mag tube) often come with grease/grunge from the factory, no extra charge. Search the SG forum for lots of info on the JM930. Glad yours is functioning well as they have a mixed history. Took some work, but mine runs well also. A good summary thread: http://www.brianenos.com/forums/index.php?showtopic=192975

FWIW, some folks recommend buying 2 springs, so if one is cut in stages, and ends up too short... Since you presumably only have one coming, I would tend to be conservative and maybe run it longer than necessary, since you cannot experiment to find the lower limit. With my XXL cap, its reliable at 10" beyond end of tube with cap off, but am running the original spring as its easier to load. Got the Nordic as a backup. Better safe then sorry.

Nice to hear. Had a somewhat dinged up choke tube in the set when I opened the bag they came in, when I received the new shotgun. Called up CS and they shipped a complete set of chokes. Good to hear not all experiences with Mossberg CS is bad...

Stippled the front of the grip, pretty aggressively with overlapping medium sized "dots". Feels great holding the shotgun one handed. Have not fired it since stippling. Tried the tape first, but could not get it to lay flat due to multiple curves in grip. Took a chance with permanent alteration, but like it. Am considering doing the sides of foregrip, but not sure it would help. Does it?

You mentioned rounds 1-8 feed fine, so its rounds 9 and 10 that missfeed?. Sounds like it might be mag tube spring tension that is the culpirt. Why not replace the XXL cap with original cap and see if problem is resolved.

http://www.carbonarms.us/AR-15-Uppers-and-Parts/Dynamic-Resistance-Muzzle-Brakes.html Main claim to fame is light weight and short length, along with low blast, while still providing excellent function. Believe there is a thread with positive feedback on this forum, which led me to get one. I like it.

Tuflehundon,Learned something, thanks.

What, no love for the Dynamic Resistance comp?

Second the Inforce WML; very light and low profile, and super bright. Changed out my TLR and don't regret it. At least 3 versions I know of; momentary only, programmable and one with IR illum, for NODs.

Kick eeze has a series of comb pads available via brownells, from 1/16" and up, that might help the face/cheek slap.

Personally, I would not be satisfied with the lack of reliability you describe. My JM930 functions in my hands and in the hands of friends, son, etc. I adjusted stock drop to correct poi to poa, not to fix a function issue. If I had a firearm that was only reliable after "fitting" I would look for the cause. Don't believe that is normal or acceptable. Its a tool that can cost points or life or limb, so needs to work under less than ideal circumstances. Just my opinion.

mwc5, I would look at pictures of the 930 fire control group/trigger housing available on the net and compare to yours. My bet is that it was reassembled incorrectly. Fact that there is no firing pin mark on the primers when you attempt to fire, yet hammer drops, leads me to think its not a weak spring problem, but a mechanical problem, probably blocking the hammer from contacting firing pin. Something is where it does not belong. Might be worth the cost of a visit to a local gunsmith that is familiar with the 930, if that is an option. Where are you located?

I would look for a couple of extra pins, to find one that will allow go in completely without altering the receivers. If the interference is only a few thous, the variation in pins should allow you to find one slightly undersized and make it work.

a friend has 2 RUCs and they are well built of very good parts. while not a high volume shooter, he has not had a single issue with the first, so bought another for his son. Great value and great customer service.

Can now see its not necessary to offset the gas blocks, however Noveske did offset the block when they assembled my upper, so thought its prudent to follow their example. No harm and keeps ports concentric.

Saboted slugs are designed to be fired in rifled barrel, so chokes would not be involved.

http://slrrifleworks.com/index.php?route=information/contact That page has phone #. Suspect they know if it fits under a KMR Curious to know as well.

Almost every gas block on the market is sized for the mil-spec handguards, so a 0.025 to 0.030" gap is common when doing a FFT build. Does anyone sell a spacer plate? It would seem like a useful product if so many gas blocks have this issue, but I don't recall ever seeing one. Maybe its my OCD, but when replacing a gas block, I simply use a caliper to measure edge of boss/shoulder to center of gas port, then measure edge of gas block to center of gas port, which is usually less and then use the correct feeler gauge to position the gas block. I also scribe a pencil line along center of gas port on top of barrel to aid with aligning the gas block side to side. Have not installed an adjustable one yet, but lo pro Noveske and clamp on VLTOR do require around .028 space between shoulder and edge of gas block for proper alignment.

Perhaps but, when going to a lighter buffer you want to tone down the gas also to get the desired effect. If you just lighten the buffer without reducing gas, cycling will speed up and can introduce all sorts of malfunctions and probably will not affect recoil very much (lighter carrier hitting end of buffer tube at higher velocity). A5 system is based on reliability. I would not go messing with a lighter carrier. If you really feel the need to tinker you can remove the tungsten weight/s in the A5 buffer and replace them with lead weights (uses same size weights that are found in a typical carbine buffer). I apologize to the OP, millsusaf, for the thread drift I am causing. BBJ, I just may tinker with a lighter weight buffer, as I said in my posts, not a lighter carrier. Will keep everything same except compare how carbine feels with different buffers. Adjustable gas blocks are certainly a possibility in the future, though not an inexpensive one.

No doubt other factors will affect how the firearm feels and recoils; 16", .078" port size, VLTOR A5 system (receiver extension), green Sprinco rifle length action spring. Asking about changing a specific variable, buffer weight, say going from the standard A5 buffer, their H2 which I believe weighs around 5.3 oz to a lighter buffer. Mark

Show off! Damn that is nice, and unique.

So if I am understanding this discussion, using a non adjustable gas block with a midlength gas system and a good comp, varying only the buffer weight, a lighter buffer will not only cycle faster but will also reduce felt recoil and sight disturbance while a heavier buffer will slow down the cycling and the added mass will increase recoil and sight/dot disturbance? Thanks, Mark