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S&W MP 15-22 misfires

otter6412otter6412 Member Posts: 91 ✭✭
edited January 2018 in Ask the Experts
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My S&W MP AR15 in 22 cal has about 3 or 4 failures to fire in each 25 round magazine. CCI 40 gr minimags work great, all other ammo fails. I'm wondering if the firing pin is not making a solid contact. Thanks for any comments.

-Otter

Comments

  • hillbillehillbille Member Posts: 14,121 ✭✭✭✭
    edited November -1
    I have had bulk remington 500 packs, think they were yellowjackets? that had that many missfires, usually one out of every 10-15 not go off, and have a good primer strike. May just be simple ammo problem and not rifle related.
  • charliemeyer007charliemeyer007 Member Posts: 6,579 ✭✭✭
    edited November -1
    I have access to a Browning Buckmark that does the same thing and marks the case in a similar way. I think the firing pin is striking to far out on the rim. I hoping I can just reform the end of the pin to correct the issue. Might take a whole lot more work to correct the channel the pin runs in.
  • rufe-snowrufe-snow Member Posts: 18,649 ✭✭✭
    edited November -1
    Recently I've had the same problem. With a EAA, Witness, small frame, conversion unit. Made in Italy, by Tanfoglio. After many bad words, and working on the unit fruitlessly. Found out the primer sensitivity of the different rimfire ammo(s). Vary substantially.

    To make a long story short. Federal Auto Match and American Eagle, is the best .22 ammo, as far as primer sensitivity is concerned. Above conversion unit will go 30/40 rounds, firing this Federal .22 ammo. Before having a FTF. Other ammo, like Federal Champion, will have 2/3 FTF's per mag.
  • spiritsspirits Member Posts: 363 ✭✭✭
    edited November -1
    Could be the lubricant on the bullet that gums up the chamber and the bolt and chamber faces with the blow back fouling which prevents the cartridge from seating fully in the chamber especially at the rim recess. So the firing pin has to move the rim forward a little bit before the cartridge seats its rim against the recess wall and then the firing pin impacts the cartridge rim against the recess wall with insufficient force to ignite the primer compound. Thus, cleaning the chamber, chamber and bolt faces, and using copper clad bullets only should help. 22LR semi-automatics which get this gummed up fouling quickly suffer this kind of stoppage. You don't see this failure occurring much in 22LR bolt action designs. Nevertheless, I also don't see this failure in Ruger Mk I, II, and III pistols with really gummed up fouled bolt and chamber faces for some reason.
  • Laredo LeftyLaredo Lefty Member Posts: 13,451 ✭✭✭
    edited November -1
    Otter........ The firing pin hits on the shells you posted look like good hits. I would say your problem is ammo related, not gun related.
  • fordsixfordsix Member Posts: 8,722
    edited November -1
    did you take the ammo turn it 180 and try it again
  • HangfireHangfire Member Posts: 3,010 ✭✭✭
    edited November -1
    Before I bought one, 2-3 years ago, I read several reviews..Mis-fires came up now and then..Some suggestions-

    Some experienced drifting hammer and/or trigger pins..Make sure yours are a tight fit in the receiver..There's a kit for the MP15-22..

    http://tinyurl.com/yalebkya

    Don't over-lube the bolt-Best to lube the receiver rails lightly..

    That said, I agree with Joe.. Those appear to be strong hits.. Maybe ammo, even though CCI mini-Mag is a first choice.. That's about all I shoot..I've had no issues with mine..I lightly lube, but didn"t need the pins..
  • TRAP55TRAP55 Member Posts: 8,270 ✭✭✭
    edited November -1
    quote:Originally posted by charliemeyer007
    I have access to a Browning Buckmark that does the same thing and marks the case in a similar way. I think the firing pin is striking to far out on the rim. I hoping I can just reform the end of the pin to correct the issue. Might take a whole lot more work to correct the channel the pin runs in.



    This ^^^....you're getting a solid hit, it's just not deep enough towards the case center to get a good bite on where the primer compound is. You may have better luck with ammo marked "Eley Primed" like Aguila or some of the match ammo until you get the FP problem worked out.
  • perry shooterperry shooter Member Posts: 17,390
    edited November -1
    You would think that after making 22LR for more than 100 years they would have all the bugs worked out [:(] but the sad fact is QC has gone to pot I run and shoot 22 pistol matches every week over 90 % of misfires are caused by primer problems if you have a misfire take a pair of needle -nose and holding the cartridge bullet up rim down carefully remove the bullet from the case mouth by twisting. now pour the powder charge into the palm of your hand. look at this powder I bet you will see a large amount of the primer Light green in color is mixed with the gray powder this shows the primer has broken away from the cartridge rim before it was even chambered . most of this problem comes after the ammo is boxed at the factory but knocked about in shipping and handling
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