Occasional Half Cock When Shooting Fast

[GunBugBit]

I have an issue with my Prodigy that shows up only every 100 to 150 rounds.  It has happened exactly once in each of my last four range sessions in a row.

 

Before today’s range trip, I had increased the over-travel adjustment by about 2/100”, since I thought this could be a cause.

 

My first 140 rounds were all good.  I was shooting doubles with splits in the 0.13 to 0.18 range.  The 0.13 splits were rare but I had a few and was happy about that.

 

Somewhere between round 140 and 150, the hammer fell to half cock between trigger presses on what would have been a fast double.  I cocked the hammer all the way back and was able to continue, with no further occurrences for the rest of the 173 rounds I had with me.

 

If this happened every time I executed a fast double, it would be easier to figure out the cause.  But only once per range session makes it harder to diagnose.

 

This does not happen in slower shooting.

 

At the moment I have two candidates for a cause.

 

First candidate is:  it’s me.  Maybe every so often I don’t keep the trigger pressed back through the full slide cycle, or I don’t even press the trigger all the way back at all before I release it.  However, I never get this with any of my other guns with a 1911 ignition system.

 

Second candidate:  maybe the disconnector is rubbing on the magazine, but I doubt it since I think the Harrison Design disconnector is shaped such that this is avoided.  Or maybe the disconnector is being impeded some other way.

 

The sear is a short pre-stoned EGW and the hammer is from Harrison design.  I haven’t touched either one.  They are a good match - there is no creep.

 

Other than this one intermittent malfunction, the gun works great.  There has never been a failure in feeding, extraction or ejection.

 

Anyone else have the same issue on any 1911/2011-type gun?  Happening this infrequently?

Edited January 16 by GunBugBit

[shooterDrew]

I had this same issue a few years ago. Only ever happened when I was really hammering splits in the low teens. It was on 2011s, not the prodigy tho. I could duplicate it with several guns, both steel and plastic grips. It gave me fits. I never figured out exactly what the issue was or how I caused it… but ultimately I was having a new gun built anyway and in that gun I had the trigger kept a little heavier, at 3lbs rather then tuning it way down. I’ve since stopped shooting nearly as much as I used to, but I haven’t had that issue in a long time.
 

Sorry I’m not much help with this, but I’ll be following to see if anyone has any input- I’ve been curious about that ever since. 

[DesertTortoise]

I think Insufficient tension on the disconnector / sear spring can cause hammer follow ?

Edited January 16 by DesertTortoise

[jim vaughan]

Bend the left hand side of the sear spring forward approx 0.25 - 0.5 mm.

This should fix your problem.

[konkapot]

Ditto on the sear spring fix. Not a full "ooga booga" of tension maybe just a "ooga." Test fire after. 

[Racinready300ex]

I assume you checked the contact between the sear and the hammer? Good even contact on both sides?

[OPENB]

I had this happen with a Para, sear spring tension was too light.

[GunBugBit]

3 hours ago, Racinready300ex said:

I assume you checked the contact between the sear and the hammer? Good even contact on both sides?

As I said above:  “The sear is a short pre-stoned EGW and the hammer is from Harrison design.  I haven’t touched either one.  They are a good match - there is no creep.”

 

 I checked the contact, too.  Very even.

Edited January 16 by GunBugBit

[GunBugBit]

I agree that additional tension on the sear leg of the leaf spring might remedy this.  I didn’t want to think the sear could occasionally slip off of the full cock hooks, but that might be what’s happening.  The pull weight is currently 2.5#.  I’ll go up to 3.0# and see if the issue still shows up.  Might be a while since I’m out of 9mm bullets and I have plenty of .40 that I want to use with another gun for matches.

[GunBugBit]

Thanks, guys, for answering!

[Dr Mitch]

Increase tension on sear spring leaf per above

[Racinready300ex]

55 minutes ago, GunBugBit said:

As I said above:  “The sear is a short pre-stoned EGW and the hammer is from Harrison design.  I haven’t touched either one.  They are a good match - there is no creep.”

 

 I checked the contact, too.  Very even.

 

Just because you buy two things and they don't have any creep doesn't mean the sear is contacting the hammer correctly. That's why I asked. Good luck getting it running. 

[mveto]

Had the same issue on one of my prodigy’s but with the Brazos Pro Tuned trigger kit, would get the occasional hammer follow when trying to go really fast. The trigger pull was about 1.5lbs, called Bob at Brazos and he informed that the trigger pull was probably to light and should be set around 2.5lbs, I bent the left sear spring leg, set the trigger to just over 2lb. Now have close to 1k down range since and no more intermittent hammer follow.

[jcc7x7]

Check a few thing first

Is the MS strut contacting the sear spring anywhere along the hammers travel

Make sure you have some pre travel and check that your half cock notch clears the sear with post travel

then if those are good:  go to appox 14 ozs of disconnector pressure at least.

And adjust the sear leg accordingly for what weight you want without hammer follow.

 

Sometime if you have a light hammer spring (main spring) you might go up a pound or two on it's weight also.

 

[HOGRIDER]

4 hours ago, GunBugBit said:

As I said above:  “The sear is a short pre-stoned EGW and the hammer is from Harrison design.  I haven’t touched either one.  They are a good match - there is no creep.”

 

 I checked the contact, too.  Very even.

@GunBugBit

You may already have Bob's excellent Tuning document; but just in case, here's the link:

 

https://www.brazoscustom.com/post/trigger-group-tuning-and-maintenance

 

IMO, it contains some very pertinent information when dropping in an upgraded sear/hammer combo!  Pay close attention to setting both over-travel AND pre-travel!  Lack of pre-travel can definitely cause hammer follow............

 

If you have the new fire control group out of the pistol again, measure the thickness of the lower legs of that new sear.  Compare to the OEM sear..... 

 

HTHs!

 

 

Edited January 16 by HOGRIDER
update

[GunBugBit]

I measured pull weight again and was getting readings as low as 2 lb 4 oz (2.25#).   The lower readings are probably more accurate since heavier readings reflect over-pull pressure.

 

Anyway, that’s pretty light.  So another 10oz of tension on the sear leg will probably do it.

 

The theory that makes the most sense to me is:  the slide slamming home is bumping the sear nose off of the full cock hooks.  The issue manifested exactly once in four consecutive shooting sessions.  I would think it would happen more often, but if the sear leg’s tension is right on the line of not being adequate, the malfunction will occasionally happen.

[HOGRIDER]

1 hour ago, GunBugBit said:

I measured pull weight again and was getting readings as low as 2 lb 4 oz (2.25#).   The lower readings are probably more accurate since heavier readings reflect over-pull pressure.

 

Anyway, that’s pretty light.  So another 10oz of tension on the sear leg will probably do it.

 

The theory that makes the most sense to me is:  the slide slamming home is bumping the sear nose off of the full cock hooks.  The issue manifested exactly once in four consecutive shooting sessions.  I would think it would happen more often, but if the sear leg’s tension is right on the line of not being adequate, the malfunction will occasionally happen.

IMO, adjusting the pull weight by bending the sear spring should be the LAST tuning step after a trigger job and/or replacement sear/hammer combo has been performed!  Start with sear/hammer engagement.  Sometimes variables in frame specs and tolerances can cause a drop in trigger kit to yield worse results than the factory/OEM trigger performance.

 

This was posted by a highly respected 'smith that truly understands 1911/2011 fire control operation.  He suggested this for those questioning the sear/hammer interface........

Quote

Lock slide back, and with your finger off the trigger release the slide with the slide stop, on the empty chamber. Slam! If the hammer stays cocked all is as it should be. If the hammer is at either the half cock or all the way down, do it again with the trigger held back. If with the trigger held back the hammer stays cocked, then you have a trigger bounce situation. If the hammer again follows then you have a sear/hammer hook interface problem.

 

Could be an option if your still looking for that unusual occurrence.........

 

 

[blasterboy]

I'm not familiar with this make of 2011.  I did have this problem with my 2011 a few years back.  Make sure the 2 grip screws are tight, they had barely moved, but it was enough. Now I use blue Loctite.

[sfinney]

Does sound like trigger bounce.

Could be sear spring tension, as stated above.... or poor sear/hammer interface (no matter how nice a brand each are, were the fit to each other properly?). Or both.

 

Once you fix those items.......   .13 splits is cooking, at match speeds - are you really aiming between shots or just hitting the trigger twice on one sight picture, I assume you are just doing close in hammering? Not saying you have to slow down.... but see what you need to see.

[GunBugBit]

The 0.13 splits, and all the other split

times, were NOT aiming the second shot, but using grip control and familiarity with the gun’s recoil impulse to make a second A zone hit at 7 yards very likely, which it was.  I believe this is called “predictive” shooting.  I do also watch what’s happening so tactile input is working with visual input.   Beyond 7 yards, yes, I see what I need to see and each shot is aimed - quickly, of course.

 

I think I counted 15 C zone hits out of the 173 rounds I shot.  I think there are many B and C shooters, and definitely higher-classed shooters, who can easily meet or beat this.  Anyway, I was in more of a function check mindset at the time.

 

 

 

 

 

Edited January 26 by GunBugBit

[shred]

On 1/16/2024 at 7:18 PM, GunBugBit said:

The theory that makes the most sense to me is:  the slide slamming home is bumping the sear nose off of the full cock hooks.  The issue manifested exactly once in four consecutive shooting sessions.  I would think it would happen more often, but if the sear leg’s tension is right on the line of not being adequate, the malfunction will occasionally happen.

If that were true, why would the split time matter?

 

[GunBugBit]

On 1/19/2024 at 8:41 AM, sfinney said:

Does sound like trigger bounce.

Could be sear spring tension, as stated above.... or poor sear/hammer interface (no matter how nice a brand each are, were the fit to each other properly?). Or both.

I agree.  Brand name doesn’t mean anything.  To check sear-hammer mating, I used magnification to inspect and I marked up the sear nose and hammer hooks and dry fired, and saw even rub-off of the marker.

 

I passed on the Harrison sear because there was a weird feel when I first installed it.  However, now that I’ve checked its match with the Harrison hammer, I see that it is very good, so I reinstalled it.  This sear was stoned by Harrison with the newer generation True Radius jig.  There is more primary sear surface than with the EGW.

 

I tuned the disco and sear leaf spring legs to a 4# pull, which probably won’t be the final setting.  I’ll test fire soon.

[GunBugBit]

5 minutes ago, shred said:

If that were true, why would the split time matter?

 

The split times are incidental information.  I just know that the issue manifested in the midst of fast doubles.   The split times came from the many times the gun was functioning perfectly.  Again, the half cock situation happened only once per 100+ round range session.

Edited January 26 by GunBugBit

[shred]

It does it for most people upthread too (same for me years ago on one pistol).  You said in your OP "this does not happen in slower shooting", so I think it's safe to assume it's somehow related.

 

 

[GunBugBit]

Related possibly to releasing the trigger at some precise instant, making it more likely the sear nose will slip past the full cock hooks if sear spring tension and/or sear-hammer mating are not right?