Sti 38 Super Competitor

[fastshuter]

Ok, just shot a match yesterday and was having a problem. I was having a hammer fall after pulling the trigger but firing pin is not hitting the primer. It was not happening all the time but it was happening at least 2-3 times per stage while shooting stages that required mag changes. I am using brand new Winchester brass, 115 gr MG CMJ, 9.4 grains SP85 powder, .377 crimp, OAL 1.26,Win small pistol magnum primer. Same thing was happening using old brass as well in practise. Thought maybe some of the rounds might be bulged out too much causing the problem with the older brass. I use a Dillon case gauge checker on every round, new or otherwise. I saved all the ejected rounds with the fired brass, had a look at them after and there is no primer hit at all on the unfired rounds. The fired cases had good hits and no pressure signs that would really flatten the primers. I replaced the recoil master with a new one and on one stage that I needed only 1 mag no problem but as soon as I shot another stage requiring a mag change the problem reoccured. Gun was cleaned thoroughly a few weeks ago. Mags are fairly new but have never changed the springs. They are 140's blocked for 10 rounds. I have had the mags for 18 months. Maybe put 12,000 rounds through the gun so far. There is also varying flash intensity through the comp. This was an indoor match so some of the guys made the comment. Any ideas? Thanks.

[rtr]

Have u pulled the firing pin and inspected the firing pin spring and the firing pin channel for debris that would cause it to not move forward and hit the primer?

[CenTX]

Like rtr said check the firing pin. It could be a broken firing pin, sometimes it binds and you have no primer strike, sometimes it aligns and hits the primer.

Edited April 3, 2006 by CenTX

[eric nielsen]

Very likely you are flowing primers with every shot and the FP is knocking the solidified little bit of primer material back out most [but not all] of the times that you pull the trigger for another shot.

Who makes SP85 powder? I haven't heard of it.

[richard franklin]

Very likely you are flowing primers with every shot and the FP is knocking the solidified little bit of primer material back out most [but not all] of the times that you pull the trigger for another shot.

Who makes SP85 powder? I haven't heard of it.

hi,try a limcat oversize firing pin,they are about .068 longer and make it go bang a little better.

[PaulW]

Sounds to me more like the overtravel screw on your trigger is to far in. Far enough to trip the sear but not move it back far enought to clear the half-cock notches. With empty gun hold the trigger back and with your thumb rock the hammer back and forth. If you feel a little bump that the half-cock notch hitting the sear.

[mda]

SP85 is Nobel/vectran powder and is not sold in the US.

[L9X25]

What Paul said.

The half cock hooks are so low on many of the new hammer designs that you have to look very closely to see that the hammer is back at all. I have even seen hammers that touch the firing pin at the half cock notch. If the hammer is not flat against the FP stop plate (and you are not able to push it there) you are on the half cock. Probably boogered up the sear too.

[fastshuter]

removed double post

Edited April 4, 2006 by fastshuter

[fastshuter]

Ok, stripped the gun down, pulled firing pin and spring out. Both are intact but will change them out anyway just in case. Checked for debris in the firing pin hole, nothing there. I had run the pencil in the barrel check as well yesterday after finishing the match, pops it out pretty high.

I forget to mention I use a felt pen to mark my headstamps. Just for matches, not so much for practise. Not sure if that would cause a problem but have cleaned that up as well.

I also pulled the extractor, now there was some crud built up just behind the lip and have cleaned that all up.

One of the more experienced open shooters did mention to me about primer crud getting back into the firing pin hole and said it could be a possibility. I am going to try some federal rifle primers and see what happens if all this cleaning and fp and spring replacement doesn't clear up the problem.

I also checked the hammer movement back and forth but it seems smooth, no bumps or should say didn't notice anything catching.

I also rechecked my powder throws, nothing out of the ordinary there + - .1 of a grain. I use a Dillon 550B.

Thanks for all the replies, it's appreciated.

[Radical Precision Designs]

What Paul said.

The half cock hooks are so low on many of the new hammer designs that you have to look very closely to see that the hammer is back at all. I have even seen hammers that touch the firing pin at the half cock notch. If the hammer is not flat against the FP stop plate (and you are not able to push it there) you are on the half cock. Probably boogered up the sear too.

This is a re-ocurring problem with some firearms. I have seen it a few times with "special geometry" hammers such as the Doug Koenig. Nothing wrong with the hammer, mind you. Very often the culprit is a "mal-adjusted/buggered" trigger bow that allows uneven rearward travel. I had a "sample" here with a similar problem. It usually was "intermittent" with the owner/shooter of the gun, but it never happened when his friend or I shot the gun. Upon closer scrutiny I noticed that if I pulled the trigger putting in a "sideways pressure" on the trigger (as the owner usually did) the hammer would effectively fall/be grabbed into the half cock, and there would be no primer indentation. But if I pulled the trigger with a straight back pressure, it woudl function perfectly. Upon further examination I noticed that the plastic grip was continually loosening up, and causing some overall flexing compounding the problem. A new "tight fitting" grip and a new "non-peened (wrongly)" trigger solved the problem. Previously I had attempted readjusting the trigger travel screw and "slack-tab", without curing the problem. If you have another similar trigger and (a different) hammer try switching them and see what happens. Then proceed, and if it works, just send me a check in the mail ... just kidding!

Edited April 4, 2006 by Radical Precision Designs

[L9X25]

Very often the culprit is a "mal-adjusted/buggered" trigger bow that allows uneven rearward travel. I had a "sample" here with a similar problem. It usually was "intermittent" with the owner/shooter of the gun, but it never happened when his friend or I shot the gun. Upon closer scrutiny I noticed that if I pulled the trigger putting in a "sideways pressure" on the trigger (as the owner usually did) the hammer would effectively fall/be grabbed into the half cock, and there would be no primer indentation. But if I pulled the trigger with a straight back pressure, it woudl function perfectly. Upon further examination I noticed that the plastic grip was continually loosening up, and causing some overall flexing compounding the problem. A new "tight fitting" grip and a new "non-peened (wrongly)" trigger solved the problem. Previously I had attempted readjusting the trigger travel screw and "slack-tab", without curing the problem.

Venry,

I saw a very similar situation where the trigger pad had come loose from the bow. If you pulled on the bottom of the pad (near the overtravel screw) the hammer would drop to half cock. If you pulled from the middle or top of the pad it would fire properly. Pulling from the top or middle allowed the pad to rotate on the bow while pulling from the bottom was directly against the overtravel screw and it would not allow the sear to clear the half-cock hooks.

Live and learn!

Leo

[Harmon]

while replacing the firing pin, slap a LONG pin in there and see if that helps.

ALSO on the federal primers, they are the shizzle..i dont think ill ever buy another winchester again.

for most sane 38 super loads, the federal 200s work fine. no need for rifle primers.

[fastshuter]

Thanks for the replies. I don't have a *long* firing pin. I can always order one. I guess some gun shops like to push certain primers as well but they just recommended I try the federal rifle primer. I have used the regular winchester small pistol primers as well and had no problems. I just put the old firing pin and spring back in and I will be trying it out today. I have a friend who has some spare parts so I will be there today so we can try and figure out what the problem is. If I recall when I cleaned my gun the last time I may have put some oil in with the firing pin. May have caused the problem. It has been assembled dry this time. I will let you know what happens later today. Thanks again to all for your help and advice.

[gino_aki]

Thanks for the replies. I don't have a *long* firing pin. I can always order one. I guess some gun shops like to push certain primers as well but they just recommended I try the federal rifle primer. I have used the regular winchester small pistol primers as well and had no problems. I just put the old firing pin and spring back in and I will be trying it out today. I have a friend who has some spare parts so I will be there today so we can try and figure out what the problem is. If I recall when I cleaned my gun the last time I may have put some oil in with the firing pin. May have caused the problem. It has been assembled dry this time. I will let you know what happens later today. Thanks again to all for your help and advice.

Are you using a titanium pin? Has to be paired with a stock strength firing pin spring, not an extra power one.

What Paul W. and Rad said if you are using a steel pin.

[fastshuter]

Ok,

Fired a couple hundred rounds out of my gun this afternoon and had no problems whatsoever. Tried white knuckle grip, hard grip, shot strong hand, light grip, whatever, gun still functioned ok. Shot the gun fast, slow, double taps. made a few quick mag changes and kept firing.

My friend thinks that the sharpie (wide felt pen actually) residue may have built up enough on the breechface around the firing pin hole and some of the gunk was getting into the firing pin hole itself. After shooting all those rounds there was a real buildup that we could both see. I have been using a different felt pen lately marking my cases. The one I usually use has been "lost" and just found it today actually. I have never had any problems using that one as it doesn't seem to leave a really bright mark on the case unlike this other one I had been using.

Took the gun completely apart after and checked out the rest of the parts, nothing too worn out yet. All my gun parts(innards) are stock STI except for an ejector and extractor which were replaced at a match last summer. Not too sure if they were STI as a friend loaned(sold) me some parts and got me back in the shoot.

Other than that my friend while watching me shoot said most all my rounds were ejecting into one spot and didn't think I had a load issue. I chrono'ed 20 rounds, all within reasonable variances. My power factor was fairly high today(179), not too warm this afternoon, but the gunpowder may be temperature sensitive. My friend shoots the same load through his STI Trubor so he made the comment about the gunpowder sensitivity. The pf is usually lower when it warms up here(175), thereabouts.

If I have any problems in the future I will post the details. Thanks for all the suggestions and advice folks. It's very much appreciated.

[mikeAZ]

A little late? BUT I had a very similar problem..... It was the GRIP! Nearly drove me NUTS, as it was VERY intermitant. (maybe once every other stage) Try this... unloaded gun of course... grip the frame & grip... try to push them in opposite directions ... if you see ANY movement.... you have found your problem.... replace the grip portion. mine had a very slight amount of movement but it was enough to allow sear/disconnector parts not to be in proper position. Tightening the 2 grip screws didn't help as I had removed material from the top of the grip for "safety" clearence(too much removed?). Little tip---- Sometimes the 2 button head screws are difficult to get started when changing the grip.... I use a small flat washer and longer screw WITH a nut in between the washer and screw head on the outside of grip, then tread into the inner female threaded part , then tighten the nut against the washer... it will "pull" the inner female part into perfectr position... It's a snap to get the short "button" heads in then.

[fastshuter]

Hi, thanks for the reply, all help and tips appreciated. I changed out my grip as well, I have one of those fancy colored grips now. Ugly looking, but not hard to spot in a safety area.

Just shot a double qualifier up here on the weekend and didn't have any problems. One fellow on our squad had what I thought was a similar problem but I think it turned out to be something else in the end. Hammer/sear trouble I believe. Worn parts or crud. I didn't get a chance to talk to him later about it but I will pass your message about the loose grip on to him. Thanks again.

[Black Mamba]

This may sound funny, but try this. Remove the firing pin spring and reverse it. The AGI video says to put the spring on so that it is tight and doesn't fall off. This is the way I did mine after cleaning. I then started having the same problem at a speed steel shoot. I would have one or two rounds per stage that wouldn't fire. Cocking and refiring always worked. If you removed a round after a failure, there was the slightest of indent on the primer. Someone at the club (a STI user) said that the spring was backwards for the STI - he had the same problem. I disassembled between stages and reversed the spring and no longer had a problem. Supposedly there is info on this forum about the same issue, but couldn't find it. Give it a try and let me know.