mpom

My misfires were very rare, but first one occurred pretty early, maybe 3-400 rounds through the gun. Since this is a weak point with the JM930, why not just practice preventative maintenance and do something to help reduce the likelihood? Said help, not simply eliminate, as it seems others have had misfires from dirty piston rings and burrs on locking lug, not just weak firing pin strike. Mark

If the hammer cocks with a full length spring, then go with it, as the goal is to increase the hammer force. If the added spring length causes interference issues, then I would trim it a coil at a time until its resolved. Mark

Learned the hard way to have a separate shooting bag and EDC bag. Used my Camelback MotherLode bag for 3g and one day going through the airport almost missed a flight as TSA kept going through it till they found the loaded mag. Luckily the local PD officer they called over only issued me a warning and TSA kept the mag. Thought I cleaned out the bag after a match but its pretty deep and has lots of pockets. Now have a bag dedicated to each endeavor.

check with scott at liberty optics. mark

Would not worry about hammer flopping around, as that cannot happen in SG, since back of bolt/firing pin stops forward hammer travel. If you look inside, hammer can only go to vertical position. I did not try full length 10/22 spring as my particular spring was made of slightly thicker wire than the one LTS has, so figured I had gained velocity with factory length, but if it works full length, then go for it, as we are trying to maximize hammer force! Suspect aluminum cocking indicator weighs very little so not likely to impact hammer velocity a measurable amount, but lighter is lighter, and the cap should keep spring from rubbing sides of channel. Would be concerned if you lend your SG to someone who has an AD and then turns around and blames it on the lack of cocking indicator. Mark

just a guess, but if the premise is that the 10/22 spring is stronger than oem hammer spring then energy imparted to hammer is greater than oem spring, and if hammer mass remaims constant then hammer velocity has to be greater, using energy =mvsquared, divided by 2mark

I polished up the front of the shell stop a few months ago and have not had any incidents of double feeds. My 930 ran fine last Sat at a match, but a couple of other 930s choked; one had multiple light hits and the other had double feeds. Hopefully with the few mods I've done it will continue to run well. Will continue to clean and lube every few hundred rounds. Did have a gouge in the mag tube inflicted by an end of the strong spring inside the gas cylinder the piston runs in, and dremeled the offending end of spring down a bit, also months ago. Have not looked into the springs controlling the shell stop as I don't want to start messing with the balance needed for the shell stop to function as intended. However if the spring(s) take(s) a set, will have to. Yes, its rough around the edges, but if it keeps on trucking and lasts, I will not regret buying it. Versamax sounds good, but not crazy about increased weight. Mark

Glad I have something worthwhile to share! I appreciate the fact that although many here are very competitive, they are very willing to help out fellow shooters. Hopefully will not have to find a replacement spring for the shell stop, although with the numerous complaints of double feeding, that may become a future project... Mark

Something is wrong if your JP has a 1/4" pull. Mark

No problems running light loads, sample size of 1, soon to be 2, maybe more. would be surprised if this slightly more powerful spring would soak up enough energy to impede normal function, but anything is possible. mark

Believe cheek pad is called Cheek-Eez, or something like it. Comes in different thicknesses from 1/16" to 1/4". Running the 3/16", seems like it helps soften the blow, probably not needed on a gas gun, but why not. Mark

You might be comparing apples and oranges; the lengths people mention is for the Nordic spring, which has thicker wire so can be cut shorter than your stock spring. Do NOT cut your spring. Mark

vort Vortex is very sensitive about dealers advertising at less than MSRP, hence reluctance to publicly disclose price. Not a conspiracy on the part of dealers and customers.

let me/us know how it works out. Mark

No doubt the stiffer hammer spring takes more energy to cock, but it does not seem to have any noticeable effect on function; I often run 1190 ft/sec shot shells and have had no issues. Ejects, loads and resets hammer just fine. Believe some ammo had 1145 ft/sec printed on box and that ran fine as well. Its not like the spring is twice as strong as the factory, would guess that with wire diameter of 4 thousands difference and original at around 39 thou, we are talking about a 10% difference keeping length the same. A bit more if using a longer spring. Mark

Tried the Nordic, but have had issues just hand cycling, so just polished the snot out of the factory one and placed it back in. Did not take the time to try and diagnose problem, just went with reliability for now. Delrin sounds good, but $14 shipping? Mark

I trimmed the hammer spring a bit, around a quarter inch, as I was afraid of spring binding when compressed and not letting hammer cock, but you could start with full length. Don't remember where I got the spring, but its made from thicker wire than Mossberg, still .25" OD, which allows it to fit. Harder to compress when trigger housing is out, so have to assume it hits harder. Don't see any downside. Trigger pull has not significantly changed. Yeah, if no slot then makes sense there is no clip. My JM has the slot, so I ASSumed they all do. Mark

Weak hammer spring can cause misfires. I replaced mine with a Extra Power Ruger 10/22 hammer spring, no more light hits/misfires. The JM DOES have that very small cotter pin described in the video. Mark

Different Mark, but also running a 22" JM with a +2 Nordic extension. I cut down a Nordic spring to 8" beyond mag tube, no malfunctions. Just for grins I installed the factory spring, which sticks out quite a bit more but has thinner wire. Runs just fine and is significantly easier to load shells, so left it in place a couple of hundred shells ago. With a +7 or +8, I would follow Nuke's advice if factory spring does not work.

TB- the lady at wolff said they have no plan to make xp hammer springs for the 930, not much demand. dont know how high on the chain of command she is. the spring manufacturer i hot linked is a good option as they use 0.042 wire, thicker than even wolf's xp, and springs are 2" long. downside is $25 minimum order plus shipping, but that $25 gets you a boatload of springs! if someone takes the risk and orders, they could easily triple their original investment, selling the springs for $1 each!

would think you should look at the spring pushing bolt carrier into battery, which lives inside the stock, if problem is bolt out of battery. can test theory to see if out of battery hammer drop could give a shallow indent by priming a fired hull and dropping hammer on it while pulling back on bolt handle to unlock bolt a bit. suspect there will be np primer indent. would try it but dont have a 209 primer. could it be linked to ammo choice? are all the light hits same ammo?

Got to talk to Wolff and their XP 1022 hammer spring is made from ,040 wire, so not much different than Mossberg stock, but is longer at 1.6" vs 1.3", so 23% longer, which should require more compression force at cocked hammer height. Power Custom uses Wolff springs. SKU for Wolff single spring is 16801 for $7,50 or a 10 pack, SKU 16803 for $30. Hope this is a solution for some folks. Has worked for me. Wonder what hammer spring Mr JM runs, if not OEM. Mark

All this done with lower and upper separated. As above, make sure trigger is not binding in slot cut just above trigger guard. If good, then issue is likely to be "disconnector timing". A good explanation and remedies are in the JP Trigger Installation instructions, available on the Net, and apply to you mil spec components. An easy fix as long as you go slow. Stone the disconn just enough to release hammer onto trigger and stop. Too much clearance can lead to doubling when trigger is released. Could be a weak trigger return spring, so worth trying that out if you have a spare.

heavier spring is what it took to get reliable ignition. will replace fp if/when needed, but had no choice, as unreliable shotgun with unmushroomed fp is a paperweight.also thought about a lighter fp spring but did not want to risk an ad. my new hammer spring is marginally stronger than oem, as trigger pull is not noticably heavier, yet cocking force is a bit heavier. a light primer indent with a bolt in battery begs for a harder hit. its working so will have to accept possibility of shorter fp life, although dont really think this will happen if fp steel and heat treatment are decent.

No joy on getting info from Wolff on wire diameter of XP 1022 hammer spring, as they are closed today. Imagine that, a 4 day weekend! Will try again monday. Found out Power Custom also makes an XP hammer spring for ruger 1022. Of course they are closed too.