Nuke8401

+1 Griz, My money is also on dirty piston/rings. Why a dirty piston/rings keeps the gun from going into full battery. (I could be wrong) What I think is happening is that the buffer spring is the main force moving the bolt forward/loading the next shell in the chamber. The spring on the mag tube returns the piston to the full forward position. I'm not sure if the design relies on any force from the recoil buffer to move the piston forward but it seems when there is resistance/dirt on the piston and rings that extra friction causes the bolt to stop short of full battery. The piston transmits force to the bolt via the plastic sleeve on the mag tube and the double rod assembly and this also transmits force in the other direction as the bolt moves forward. I think when the piston moves too slowly or stops short the bolt does not go firmly into battery. When cleaning and assembling my gun I make sure the piston returns to the fully forward position with just the force of the spring on the mag tube. When reassembling leave the forend off and just hold the barrel in place, grab the piston and slide it to the rear and let go. It should snap forward into the piston bore. On my gun, I can induce extra friction when assembling the forend and screwing on the mag tube if I allow the assembly to twist. You can do this with e forend off, twist the barrel and you will see the extra friction slows/stop the piston from going fully forward. When you think you have the piston clean, take a steel scribe/pick and try scraping the inside of the piston rings (groves) and the groves on the outside. These areas are hard to clean even with a wire wheel on a dremel. They are not seating surfaces so even if you did manage to scratch them it would not impact the function only make it harder to clean in the future. Most of the times I clean my piston/ring with a wire wheel on a dremel and check afterwards with a scribe I find more dirt/carbon as it hides from being polished by the wire wheel. Check with a scribe, you might be surprised, I was.

I just shot a local 3 stage action shotgun match yesterday, 75 rounds WIN bird shot with my 930 and Nordic spring cut to 4 1/2 “ past the tube, ran flawless. I've run maybe 150 rounds through the gun with this setup which I initially did as an R&D project to see what failure would happen with too short of a spring. Might get around to cutting the spring until the gun malfunctions this weekend. So Nordic’s recommendation of 10-16 past the tube seems really long. I had been running with the spring cut to 10” (9 1/2 after 2 years) for the past two years with no problems. It does make loading and hand cycling easier with a full (10rd) tube. I think I'll end up in the 6-8" range depending on when the gun malfunctions. Just a data point.

I just shot about 75-80 shells practicing a stage with my Nordic spring cut 4 1/2" past the tube on my MOSS 930 turkey with a 10 round tube. No failures, full tube to one in the tube. Prior to that I was at 9 1/2" (2 years) with no malfunctions. I plan to cut the mag spring an inch at a time until failure and then deciede on a final length. Nordic tube, spring and follower. My guess would be shells would not get on the lifter fast enoung and get trapped by the lifter. Too strong? double feed, FTF, hard to hand cycle.

I'm not promoting any given length but think it's worth experimenting with to ease hand cycling.

I shot maybe 75-80 rounds today with the spring 4 1/2 past the tube under match conditions, hot , dry, a mix of fed and win bulk. No problems. I think I will keep cutting the spring until it mayfunctions and go half way between that length and 10". Makes me wonder how nordic picked 10" as the minimum? There seem to be some really strong opinions out there on spring length, I wonder how many are based on actual testing?

There is significantly less tension at 4 1/2". Super easy to load. While I plan to test at 4 1/2", I have been running with a 9 1/2" spring. Depending on how the testing goes Saturday I might split the difference and run 7" or so to get the best of both worlds. I could see during a match where the extra spring pressure might be needed. Recoil works against the mag spring (forces the shell in the tube forward vice back) so maybe a tube full of slugs might FTF or even one slug left in the tube might FTF. It seems many people have problems with 930s and maybe more so the JMs, maybe I have been lucky but mine has run 100% after I figured out the piston/ring cleaning thing.

See the "Mossberg 930 issues" thread and the " another 930 turned popper slayer" thread for shell stop work and other stuff. Besides the shell stop I just smoothed/polished the bolt and "carrier" = the flat piece the bolt sits on. No real metal removal. I did all the work myself. The only failures I have ever had were due to dirty piston/ rings.

Yes 4 1/2" nordic spring works in MY 930.

Added to above post.

Ok, a little R&D this evening. 4 1/2" past the tube measured with the cap off and it runs great! A little background, I last cleaned my 930 before the FNH match last year and I have only shot maybe 10 slugs thru it since last fall. Today I took it out of the safe, put a few drops of M1 on the bolt, hand cycled and started testing. Measured my mag spring at 9 1/2" past the tube, pretty sure I cut it to 10" when I installed it maybe 1 1/2 years ago. Cutting an inch off at a time I shot 2 rounds from full 10+1 and then 1 in the chamber and one in the tube. I kept this up until I got to 4 1/2 inches. I decided to stop there and ran a mixed of 2 00buck, 2 fed high brass 6, 2 rem slugs, and the rest a mix of bulk rem and win 8s. As fast as I could shoot 11 rounds no failures. I will be shooting with some friends this sat and should get some significant rounds through it then. A few things I remembered when cleaning it after shooting today. 1. Make sure the outside of the mag tube is clean. It is easy to think it’s clean because the carbon can be deceiving, you should end up with shiny metal, I use a scotch brite greeny. 2. The piston rings are easier to clean if you soak them overnight in hops. I always use a wire wheel on a dermal. 3. The first/large/wide piston ring can only be installed one way but the second ring can be installed backwards. I install the rings by installing the small ring in the large and then large on the piston, easy. The small ring should be held in place by the large ring. I also wire wheel the cylinder where the piston seats. 4. I use rem oil on everything just as a protectant after cleaning. 5. I lube the tube, piston, all other parts with M1. I wipe as much lube as possible off the piston and rings before installing them. 6. During a match I might put a few drops of M1 one the bolt as You would an AR. 7. When installing the mag extension, install the coupling first and tighten Just beyond hand tight, then install tube. I used blue Loctite on the ext tube to coupling on mine and from then on remove the extension tube and coupling together. Concerning mag spring length, I did some simple some work (fluff and buff) on the shell stop and other parts so all guns would respond differently to different mag spring lengths..

At least with the 930 I would say each gun would be a little different (mag spring lenght/force) because of the way the shell stop interacts with the bolt/carrier and the differences in friction/force required to operate the shell stop. I would guess a slicker shell stop/parts with a stronger shell stop spring could tolerate higher mag spring tension but I'm guessing a mag spring on the shorter/weaker end of the scale that still allows the gun to function reliably would be the best set-up and perhaps the most reliable. If is were going to set-up a new 930 without polishing the shell stop or other work I would go with the shortest/weakest mag spring that lets the gun operate reliably. No brainer I guess.

I believe the nordic instructions say 10-16 past the tube. Most likey this is generic to all extensions they sell. I would be interested in what failure would result from a weak/too short spring. I would imagine the shell would jam between the tube and the lifter. Still might R&D this my self.

+10" on my 930 turkey with either my 8 or 10 round setup. I seem to recall others going to +9. Less tension = easier to hand cycle, less chance of FTF, and less chance of double feed. Since the shell stop is moved by contact from the bolt carrier through a lever/spring; the more tension from the mag tube spring the more likely FTF while either shooting or hand loading. In some cases high mag spring pressure cases double feed when the shells come out of the tube faster than the shell stop can move back into place. I got to +10 by trimming the spring until I could hand cycle with a full tube and also buffed the shell stop parts and very slightly stretched the shell stop coil spring. If in doubt, springs are cheap, buy 2 and cut one until the gun malfunctions with only one shell left in the tube. I might R&D this just for the heck of it, I have an extra spring.

I would hesitate to use a heavier hammer spring as the firing pin already gets mushroomed from the oem spring. Might be worth loking at a weaker firing pins spring but that might lead to slamfire.

I havent tumbled mine but should be ok, its at least as tough as brass. Again, I'm not claiming the is the exeact cause of your problem but history here says it is the most likely cause. Empty chamber starts/hamd cycling seems to be the other isue. Good luck.

Yes inside the rings seems to be the key. Even with a wire wheel on a dreml it is easy to polish the dirt and not get down to metal, I use a scrib to check, some clean with a scrib. Also look in the cyl where the pistol goes, there may dbe a ring of dirt wheremthe rings normally stop going forward, as long as the piston goes fully forward this shouldn't matter but I clean it every few times I clean the piston. I would say a clean piston with minimal lube should be trouble free for 600-1000 rounds. I usually clean mine just befor a match and test fire. Of course it could be something else but this is kost likey the cause.

I believe the short length spec for the spring is 12" past the tube. Sounds like your is way long. Some, mine , are cut to 10" past the mag tube and work great. Cutting the spring to the short end of the spec improves hand cycling along with streaching the shell release spring which you must have had out when polishing the stop. Also, you have to cycle it hard, almost as hard as the gun cycles when firing. The shell stop moves indirectly from the bolt compressing the shell stop spring. See "Mossberg 930 issues" thread for hand cycling.

Can't find the post now, but "Benny" has commented on this sevveral times in the past. Wire wheel on a dremil is the easy way. Also lubrication of tube and rings; use whatever you want, I use Mobil one, most important thing is to wipe all lube off. Lube just makes the rings gum faster. With the forarm left off assemble the gun, you should be able to move he piston by hand and it should return forward by spring pressure. With the bolt not in full battery the firing pin basically has to reach across the gap betwen bolt face and shell or if you assume the shell is touchimg the bolt face the shell can move forward in the chamber thus not givimg a solid firig pin strike. While I have replaced my firing pin, I don't think slight mushrooming of the hammer end is a problem.

Read "mossberg 930 is a bolt action now" thread

Dirty rings, not going into full battery. Dirt on inside of rings make piston tight in bore. Also firing pins peens over on the hammer end. Check it for mushrooming. Both rings should be connected to the piston, wider ring captures the other ring. Search and you will fimd dirty rings as the cause most of the time.

10 Burpees/sprint 400 yds repeat 3 times as fast as you can. 3 times a day. Have emt standing by! Seriosly though, burpees will help you get into and out of shooting positions faster and both will improve cardio. Sent from my stupid tap talk thing that spells worse then me!

I just recieved a S&W replacement barrel form MIDWAY USA for my FS 9mm http://www.midwayusa.com/product/150824/smith-and-wesson-barrel-s-and-w-m-and-p-9mm-luger. Drop in fit, not sure of the twist rate but it is faster than my original barrel. No range report yet. So it looks like the new S&W barrels are avalable for FS 9mm but not listed for L or Pro.

Just mailed my app. Not sure I will have legal gear. Is a post 94 ban legal ar ok? Are 30 rd mags ok if they have to 10 round limiter inside? Assume my g34 is out without 10 rd mags.

NY Laws, 7 round mags, I too hope this match is held. Nothing on their site: http://www.westpoint.army.mil/uscc/dca/clubs/guns/news.html

i used one on a TI rifle, the brightness of the FO detracts from the crispness of the post outline. Bruce Piatt used a FO on his rifle years ago and said he sighted in with the target sitting on top of the post vice splitting the target. Never tried it that way.