mpom
-
Posts
749 -
Joined
-
Last visited
Content Type
Forums
Profiles
Events
Store
Posts posted by mpom
-
-
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
-
Second time out shooting with the 16" Ranier Select Medcon profile, 5 shot groups at 100 yards, 1X4 Vortex, front rest rear supported by left hand resting on right bicep, sitting at bench.
Hornady 52 gr BTHP steel case- 1", PMC and American Eagle XM193 equivalent into 2". Am sure a better shooter with match ammo would get better results, but believe I got my money's worth.
Mark
-
So after dry firing my JM I realized I also miss the stronger reset present in other firearms. The spring behind the sear, which I think is responsible for the reset is about .186" outside diameter and is made of wire .028" thick. Found a spring made of .030" wire and replaced it after trimming to same length. Unfortunately while reset was much stronger, pull increased from 3.75 lbs to 8.
Using shorter spring was also a dead end as I was back to original super soft reset.
Went back to original spring and gently stretched it a bit. Now have a noticeably stronger reset and a 4.25lb pull, half a pound heavier. Seems a good tradeoff. Expect the spring will hold for quite a while as it does not seem to be stressed very much. Hope this helps.
-
I suck as a shotgunner but detailed my work on how I reduced the engagement and trigger pull distance to .021" in the thread discussing trigger work on the Stoeger 3000. Bottom line, I only need to let my JM930 trigger forward .021" for a reset, so while its a soft reset, it happens so easily it has not been an issue.
-
Would check gas key bolts to make sure they are tight, look for deposits showing gas leakage at gas block interface to gas tube and barrel. Wonder if gas tube is clear of any partial obstruction. Easy enough to remove, blow through it or replace if rifle has a lot of rounds through it. Would clean inside of receiver extension and action spring. Would definitely try the bolt lock back exercise with single loaded mags, and consider trying a lighter buffer, altough it would be best to diagnose the problem.
-
Easy to check the gas rings; pull bolt forward and stand complete bolt carrier on bolt. If bolt collapses into bolt carrier from weight of carrier, then rings need to be replaced.
How many rounds through the system, and was the Stag well lubed?
-
Seen that happen with low powered ammo.
Would set up a few mags with single round each of the weakest ammo you plan on running, say PMC, and see if bolt locks back. If not then short stroking. Problem is either a gas leak or excessive friction, unless you have an adjustable gas block that has been turned down too much. A too strong recoil spring or too heavy a buffer can do this too, but I assume you have not changed those items.
Gas leak can happen at gas block, carrier key or bolt rings, if they are worn.
Excess friction can come from insufficient lube. Would also check to make sure no interference from new fire control group.
-
I can believe it..050 inch? Is that a typo?
Reduced engagement and adjusted overtravel in my JM930 and would estimate its down to this as well, excluding short takeup, which measures ounces.
Mpom, can you describe how you made the modifications to the JM930 trigger? My trigger is not terrible, but if it can be improved, why not.
Sent from my iPad using Tapatalk
First I polished the contact surfaces of hammer and sear. Then watched interaction between the two as I pulled the trigger with hammer cocked. Clearly too much engagement. Took out hammer and stoned perpendicular to contact surface to reduce engagement. Did this in steps until I could see some movement as sear pulled away from hammer, but could not feel the process in the trigger. Did not stone the hammer contact surface to avoid losing surface hardness. Reset the over travel screw, and checked for hammer stability on sear by banging butt into carpeted floor with safety off. Ended up with a 3.75 lb fairly crisp pull. Still have a light takeup before trigger hits wall for the release, but its like a 1911; super light and no reason to try and eliminate it. Can slip a .021" feeler gauge between over travel screw tip and back of trigger with trigger up to the "wall", total of .054" with trigger fully forward. Reset is obtained by letting trigger forward .021". With the chrome or nickel plating on the sear and hammer, don't expect significant change anytime soon. No change over past year, although have only fired maybe 300 shells and done at least as many dry fires since the work.
Would guess pull weight would have been even lower had I kept the original hammer spring rather than the heavier 10/22, but its pretty good for a shotgun. As OpenClass says, better than a lot of AR15s.
Now, just need to learn how to shoot the son of a bitch to its potential!
-
.050 inch? Is that a typo?
I can believe it.
Reduced engagement and adjusted overtravel in my JM930 and would estimate its down to this as well, excluding short takeup, which measures ounces.
-
Another option @ $259 is the Ranier Select Medcon https://www.rainierarms.com/?page=shop/browse&category=ar15/m16_barrels_rainierarms_selectseries
May not last as long as a chrome lined barrel, but likely more accurate, at a similar price. Out of stock, but should return as its a good seller.
Is ammo loaded with copper washed mild steel bullets capable of MOA?
-
No marksman here, using a 1X4 Vortex, getting 2" groups at 100 yards from bench with M193, which is better than what I was getting with a chrome lined barrel. Running a 16" Medcon Select.
Agree its a lot of barrel for the money. Love the profile; thinner in front of gas block than behind.
Mark
-
Running a different gas gun, JM930, and always lube piston. No issues. Switched to Fireclean for easier cleaning. Only a hundred rounds, so too soon to tell if its better than other lubes, but figure metal to metal contact needs some lube to minimize wear
-
Amazing on the JP. Considering how little engagement there is in a crisp JP, that says a lot abot the quality of steel and heat treatment. Wear has to be practically nill to avoid doubling, or failure to reset. Hope my JP will be as trouble free. Sure is crisp and super short reset.
Mark
-
Assuming the OP is talking about Remington shotguns, as this is the SG forum. Typical front bead thread for Rem is 6-48, and Brownells carries lots of them
http://www.brownells.com/shotgun-parts/sights/front-sights/sight-beads-prod1886.aspx
Mark
-
Would congact BCM and see if they will replace it.
-
ISWOPE, did you consider cutting the Nordic follower to match the stock length? Might be worth a try, especially if you cannot return it. Did that for my JM930 and runs fine now.
Mark
-
Not all blue locktites are the same. 272, which is red, is rated for 450 degrees F, no different than 246 (blue). The common blue locktite, 242, is only rated for 302 degrees F. Did not want to use red, as high heat is required to diassemble, rather than tools. Advantage of 246 in addition to higher heat tolerance than regular blue is resistance to oils.
Mark
-
no expert here, but i searched the errornet prior to replacing my barrel, and got the impression that its a possibly useful technique for maximizing accuracy. so got some medium strength higher temp loctite and went ahead. have not shot match grade ammo yet, just pmc and m193, so not sure if its of benefit, but since i installed a ranier arms select match barrell, figured why not. should be able to disassemble when needed, as its blue locktite, not red. dont remember #, but its not 242, maybe 246?
mark
-
Based on the title of the thread, was hoping you were asking about locktite on barrel extension/upper receiver interface, which some folks advocate, but NOT on barrel nut. The gas tube, if using a mil spec barrel nut, makes this unnecessary.
Mark
-
If it was leaking to any significant degree, you would probably have a failure to lock back on last round at the very least. What lube are you using, looks thin.
-
Would try a hammer spring stronger than the lightest JP, say a red JP or a standard mil spec, while retaining the yellow trigger spring.
-
No problem seating and locking in my mega lower based carbine, but does it wiggle forwards and backwards! More than my gen 2.and'P30's and Lancers. Have not tried live fire, but just might sell off the P40's. Does not inspire confidence, yet might run 100%...
mark
-
Think I used the Tru Glo 950 to solve the exact same issue. Really tall and much smaller fiber optic rod.
Mentioned the item# in the mega thread on the JM930 in case I am giving you wrong info.
Mark
-
No expert, but wonder why? Has to be a good reason, as there is a benefit to case "hugging" chamber during high pressure period; reduces thrust on bolt. If the chamber is rough, I would contact the barrel maker/marketer. If I was to to do it, would probably wrap 600 grit wet/dry paper around a long tight fitting brush, coat with Kroil and turn at slow to moderate rpms, using a piece of cleaning rod to connect drill to brush. Check results frequently.
Mark
Crucible Armament Versamax
in Shotgun - Technical
Posted
Show off!
Damn that is nice, and unique.