Mystery is driving me nuts - what's wrong with that round?

[Foxbat]

Yesterday in practice the gun failed to go into battery, the slide stopped about 1/10" short.

I took the round, they all have been gauge AND chamber checked. It goes into the gauge with room to spare, and falls into the chamber all the way in and out.

Checked the extractor grove - it is .342", well within the range. No bulge, no nothing that attracts attention. No high primer. Brass is marked PMC 38 Super +P.

That is driving me nuts... what is wrong with it? Tried it about ten times, it CONSISTENTLY gives the same result.

Edited May 4, 2010 by Foxbat

[Supermoto]

coat it in Dykem blue and see where its binding

[eric nielsen]

Same thing was happening to me and the answer was ratty range pick-up brass. 38 super.

Measured the groove diameter on the ones that didn't fully chamber and usually they were 3 or 4 thousands on the big side, but not always.

The main common fault was that the bad rounds (which drop-check just fine) had rims that weren't round. Flat spots, rough edges, etc.

I set that whole batch of ammo aside until I received a spare firing pin. Cut that down so it's too short to hit a primer (tested with a pencil down the bore) and then used that "safe" FP to rack-check every single round, twice. It was either that or rack-check at an indoor range. I don't like chambering rounds in my house, definitely not 300 of them.

Kind of dumb for me because I've since found a huge bag of once-fired RP super brass hiding in a closet.

[lynn jones]

check you crimp, should be around .377

lynn

[lneel]

Does your gun have a 9mm or .38 Super breachface?

Have you used this brass before?

Lee

[Foxbat]

Breachface is 38 Super. The crimp is fine, and as I mentioned, it drop-checks fine, with room to spare. The grove is smaller than on some other rounds which cycle fine. Don't really know if I used the very same brass before, as it is from a mixed bag, I will try to find more of it. The round locks up the gun 100% of the time.

That pisses me off, because I used to think a gauge or chamber checks were more than sufficient.

Edited May 4, 2010 by Foxbat

[shooterbenedetto]

Maybe a small piece of brass got stuck in between?

or a sand or something. Do you tumble your brass and loads?

[Toolguy]

Looks like the bullet might be seated too far out and hitting on the rifling just ahead of the chamber.

[Foxbat]

No, the bullet is not too far, it is actually on the shorter side, I have shot much longer ones without issues, plus again, it drops into the chamber fine. OAL is 1.245".

Round is clean, nothing attached to it, scratches on it from repeated chambering.

Rim diameter is .401"

Edited May 4, 2010 by Foxbat

[CocoBolo]

Actually 1.245 is long for 38 Super RN. Most load at 1.225 or shorter. I load mine at 1.235-1.240. I have run loads as long as 1.280 with no issue. If it drop checks it should run in the gun.

I use a CasePro so I only deal with near perfect brass. With that in mind the symptom you have has happened to me. I use AFTEC extractors when the extractor tube gets full of goop and gunk it will start failing to go into battery, a quick slap on the back of the slide and continue. A cue tip dipped in brake parts cleaner and swabbed around in the tunnel cures it. I do this now about every 2K rounds to prevent the problem. Hit the firing pin hole while you are at it.

One more thought, how old is your recoil spring, do you know what weight it is, maybe throw a 10# in and see how she runs and feels.

Edited May 4, 2010 by CocoBolo

[Foxbat]

The gun uses Aftec, but it is clean, recoil spring is fine, but when it locks up I can't even push it into battery, at lease not without VERY hard push which I have not done yet... a normal push does not help.

BTW, I just checked it in my other Open gun - it fed it fine.

Understand about the OAL, I meant that longer rounds work fine, so that is not rifling, especially since it drops into the chamber without any difficulty.

I have seen high primers do that, but this one doesn't have it.

Edited May 4, 2010 by Foxbat

[Aircooled6racer]

Hello: It looks like no crimp on that round. Use your barrel as a gauge for the reloads. If they don't drop in coat them with Dykem or black marker and see where they are binding. Also look in the chamber to see if a piece of material is stuck in there. Let us know what you find. Thanks, Eric

[TONY BARONE]

Pull the bullet and check the case length.

[Glockcomma]

It doesn't look like enough crimp but if it drops into the chamber that probable is not the problem. Mine stopped just short of going into battery but would go in if I pushed on the back of the slide, I had to go from a 9# spring to a 10# but yours wont go if you push on it so that isn't your problem. Did you recently clean your extractor tunnel? have you checked to see if you have to much extractor tension? Is it only that one brand of brass? if so have you measured the rim thickness? (maybe your other gun is more forgiving). It seems like the problem has to have be related to the interaction between the rim, extractor, and breach face.

Good Luck, Tim

[Foxbat]

Gentlemen, I already mentioned several times - the round drops freely into the chamber, there are no lose particles, protrusions, etc.

Case length is fine, and I also mentioned the action stays open by about .1".

[Foxbat]

It doesn't look like enough crimp but if it drops into the chamber that probable is not the problem. Mine stopped just short of going into battery but would go in if I pushed on the back of the slide, I had to go from a 9# spring to a 10# but yours wont go if you push on it so that isn't your problem. Did you recently clean your extractor tunnel? have you checked to see if you have to much extractor tension? Is it only that one brand of brass? if so have you measured the rim thickness? (maybe your other gun is more forgiving). It seems like the problem has to have be related to the interaction between the rim, extractor, and breach face.

Good Luck, Tim

Yes, the gun is clean, perhaps 300 rounds through since last cleaning, and of course both the extractor and the firing pin channels get cleaned every time. I agree there is some sort of an interaction, but I just can't spot it, all the cartridge dimensions are well within normal range.

[DWFAN]

coat it in Dykem blue and see where its binding

[Chris Keen]

If it worked in your other open gun, then it has to be something related to the gun, not the round.

I think Glockcomma might be on to something. Check your extractor for TOO MUCH tension. Do you know how to check extractor tension?

[Aircooled6racer]

Hello: Make sure the Aftec is in there correctly and the parts have not moved around. If all is good then remove the most forward spring and try it again. If it works then you have too much tension. Thanks, Eric

[NoSteel]

Could you place a "good" round along side the bad round and take a pic for us? This will allow you to magnify the cases together and look to see if there is a critical dimension issue. I would suspect that there is a dimensional issue at the base. If it's holding the slide open .1" I would guess it's not going to be a huge difference.

dim.doc

[G-ManBart]

Check the extractor groove thickness on that round and compare with brass that works. Same headstamp as the other brass? If it drops in the chamber of both guns, and cycles normally in the other gun, the most likely culprit has to be the extractor hook/rim relationship. R,

[Mark K]

I had a similar problem with some 40SW rounds. The would go into a case gauge just fine, but not chamber. Turns out I probably short stroked the reload just a smidge, and the belling was not completely taken out during crimp stage of the process. The little bit of slightly larger case was hitting the transition between the rifling and the chamber.

Mark K.

[G-ManBart]

Actually 1.245 is long for 38 Super RN. Most load at 1.225 or shorter. I load mine at 1.235-1.240. I have run loads as long as 1.280 with no issue. If it drop checks it should run in the gun.

I use a CasePro so I only deal with near perfect brass. With that in mind the symptom you have has happened to me. I use AFTEC extractors when the extractor tube gets full of goop and gunk it will start failing to go into battery, a quick slap on the back of the slide and continue. A cue tip dipped in brake parts cleaner and swabbed around in the tunnel cures it. I do this now about every 2K rounds to prevent the problem. Hit the firing pin hole while you are at it.

One more thought, how old is your recoil spring, do you know what weight it is, maybe throw a 10# in and see how she runs and feels.

I've loaded RN at 1.235" for my guns with no problem at all and don't load anything shorter than 1.230". In my old Open gun I ran 1.260". Factory .38 Super is normally around 1.270-1.280 with a 130gr JRN. With 2011s most of us run them shorter than that because of the mags, and so live rounds eject cleanly, but most of the guns would feed and fire longer OALs fine.

Since he's having the problem with just this one round, and not others, it's not a problem with the recoil spring or extractor being gunked up....or he'd have random problems with other rounds as well. R,

[diehli]

It sounds like a problem with it sliding up the breechface, so as others have indicated, check the rim, extractor rebate diameter, and anything else you can think of on that end of the round.

[Foxbat]

I am about to give up. Here is what I have done so far.

I have pulled about 40 such PMC stamp rounds out of the batch, and they all fed and ejected just fine.

I pulled out the extractor... no difference. The action still stays .1" open.

But what is very puzzling, if I apply enough force to close it - and it takes perhaps 20lb of force - then it closes. It is then hard to open, but you can do it.

While doing this, the bullet is being pushed in the case, and there are visible signs of rifling engagement on it.

On other bullets there is no such sign.

The bullet diameter is identical, as measured. I of course can not measure the ogive, so perhaps this is the issue?

I will pull that bullet and put another one from the same bag into it, if the problem is gone then it is the bullet, not the brass, extractor or anything else.

All this still doesn't answer this question - why would the round then drop in nicely?