FTF due to dirty firing pin????

[GSRswapandslow]

i love my mp15-22...seriously, it's a fun gun. my 2 best friends and g/f all have them as well....and i'm the only one getting FTF's. I'm shooting federal bulk...and the gun, for the most part fires it 100%. The issue is...occasionally, on the last round only, there's a light strike and a FTF. When i cycle the bolt and pick up the round...there's always soot/burnt powder/residue on the strike zone....and that leads me to believe it's basically cushioning the strike.

anyone else seen this occur? I know it's not the ammo...i use it in ALL of my current .22lr's (sig522, savage bolt, marlin 60, 10/22, gsg1911, p22)

my fired cases appear to have normal strikes...with adequate strike depth, but i've never exactly directly compared them to another from a different gun.

additionally, i don't believe it's due to being too dirty....i RARELY clean my guns...and NEVER clean my barrels (on .22lr's)...so my first thought was to clean the bolt up, and i did....and this occured about 5-6 mags later, the same day.

i'll get some pics of it when it happens next range trip (pending no snow this weekend)

 

[matmat417]

never happend to me and ive had around 9000 rounds through mine and i dont super clean either. possibly a bad batch of ammo, not just 1 box but maybe the whole lot?

 

[mrasgt]

Best Guess....

make sure the mag lips are smashed up and if it were me, I'd clean everything after each range trip. Perhaps junk in the firing pin channel.

my 2 cents.

 

[chuck s]

Easy enough to knock out the pin in the bolt and remove/clean the firing pin. But since this is happening on the last round in a magazine I suspect the bolt is not fully closing. Bolt 1/32" from fully closed will result in the firing pin not extending that same 1/32".

Check the bolt rails, extractor, etc.

-- Chuck

 

[GSRswapandslow]

bolt rails and extractor are good...i'll knock the firing pin out of the bolt and check it

and cleaning after every range trip is 100% out of the question.

 

[HalfSwiss]

Can't you just blast the bolt with gun scrubber (or or equivalent) though the various holes in the bolt to clean it out rather than disassemble? Then put in some CLP or whatever?

 

[BSA]

The first suspect and easiest one to check is the magazine. Try a different magazine or two.

 

[CrazyFingers]

and cleaning after every range trip is 100% out of the question.

I've never had this issue, my 15-22 has over 7900 rounds through it and runs perfectly since it came back from S&W over a year ago. But then, I do clean after every range trip...

 

[mud king]

Another thing... are you holding the magazine while shooting?

 

[GSRswapandslow]

i'll check the mag...i have a few others....i tend to just keep loading the same mag, so that very well might be part of the issue...dirty mag and what not


and no, i never hold the mag....i shoot thumb break

 

[stickbug1]

GSR, don't feel bad. I too have wondered about how the extreme build up of funk and junk from the 22LR on the bolt face could be affecting things. At the end of a days shooting session I have seen a good 1/16" of crud built up in the area that the firing pin protrudes from. Essentially it keeps the round spaced out from the bolt face, firing pin and the extractor hook. I my mind I can clearly see how this is possible of causing light strikes. If the firing pin has a stop to prevent accidental contact with the breach face it will only ever protrude a given distance from the bolt face. So it stands to reason that the more buildup, and farther out the rim of the shell is... the lighter (or actually shallower) the pin strike will be. Its simple math and geometry.

Having said all that. I have very few FTF even after a session of feeding 500+ rounds. I get occasional ones like everyone else. But nothing consistent with the last round in the mag. Just part of the game in rim fire world.

 

[GSRswapandslow]

i just scrapped about that much off the bolt face.......i guess that's what it was....i mean, i've scrubbed it a few times (that's the extent of cleaning i do on all of my .22lr's...clean the bolts) and i guess i just have to figure a way to keep the build up at a minimum. it's only going to get worse with the suppressor though...so not sure what to do. wonder if there's any kind of coating that'd not let the lead/poweder stick was easily to the bolt face

 

[Juvicator]

Maybe you should just clean it.

 

[GSRswapandslow]

i cleaned off the bolt, but there's 100% no use in doing a full "clean" of the gun.....22's don't shoot well cleaned.

 

[Juvicator]

Well if that is your way of doing it then that's that. I always clean mine after every range trip. I've found no documentation or hard evidence that says a .22 shoots better coated with lead soot, and whatever else the round holds. Maybe they will come up with a bolt that has small venting holes for the crud to escape to later on.

 

[GSRswapandslow]

a clean bolt is fine...but when you say to "clean the gun" i take that as also cleaning the barrel.....22lr barrels should RARELY be cleaned, if ever. I shoot 2500-5000rds a month of .22lr...and do an honest to goodness clean every year or 2.

 

[Juvicator]

Why is that? I've heard others say that but can't find any gun or ammo maker that says that.

 

[APS]

After ~500 rounds of Federal bulk mine will start to FTF occasionally as well. I remove the bolt, clean the crud out of the recess in the bolt face where the cartridge base sits and take a patch and wipe the breech face. It's back to normal for a while again.

 

[cal_h]

hi
if you shoot old or lead only bullets .......... if you get what seems like an occasional bump fire...... check the chamber for lead build up....

been there........ done that....... trying to eat up some old ammo and have some fun at the same time

rammed a old brush down the chamber and pulled out some ring around the collar
that had built up... keeping the shells from chambering correctly


luck
cal

 

[GSRswapandslow]

Why is that? I've heard others say that but can't find any gun or ammo maker that says that.

i honestly can't tell you....but it's 100% true. I've got a savage mk2 i've had for a LONG time...it's got over 50k rounds through it.....and it's been cleaned maybe.....5-6 times, ever? It's not the most accurate .22lr i have, but it's been shot the most...and will still make a ragged hole at 50yds all day, any day.... When i do clean it (which is when it starts to get some noticeable deviation in group size) I clean it very lightly...and groups will jump up to 2moa or more...for a 100yds or so, then shrink back to normal...it's honestly kind of weird...exact opposite of my centerfires!