Ammo, Gun or ?

[Seth]

Hardware:

Tripp 2011 with 3k rounds through it. 100% reliable until today with my reloads and factory length ammo.

Gun has 12.5# spring with about 4000 rounds on it (pulled from another gun the day the new one arrived).

Ammo:

N320 at 4.8gr loaded to 1.180"

Brass all rollsized.

Out of 50 rounds about 8 failed to battery. It felt like they were dragging on the round below. All rounds case gauged and will drop in the barrel without issue.

After the failures I ran my regular load (150 rounds of 5.5gr Universal, same OAL) with zero problem.

Felt a little like the gun was running funny... not cycling correctly during the Vit load.

Any suggestions??? Bad recoil spring? Not enough powder and the slide is short stroking?

Help!

Edited November 22, 2008 by Sethmark

[Duane Thomas]

Years ago a pistolsmith told me two things that I've never forgotten, and have stood me in good stead ever since when analyzing gun malfunctions: (1) "Whenever a previously 100% reliable gun suddenly starts puking on you, the first thing you should ask yourself is, 'Okay, what did I change?' Whatever that thing is that you've just changed is probably the source of the problem. Change back to the way things were when the gun worked 100% of the time, it'll probably start working 100% of the time again." (2) "Whenever a gun chokes, people never blame the ammo, they always blame the gun. But the fact is that most gun malfunctions, in guns that previously worked well, are ammunition related."

We get a lot of questions on this forum that, when you get right down to it, boil down to, "My gun has worked flawlessly up til now. I switched to a new load. Now my gun doesn't work. What should I do?" Answer: switch back to the ammo with which the gun worked. Problem solved.

[Seth]

I KNOW that its the ammo... but why? Is the charge just not strong enough to make the system work right???

[Duane Thomas]

Does it really matter? You already have a load that works, right?

Anyway, if it really does matter to you....

Are you using the same bullet with both loads, just a different powder and charge weight? Then run both loads over a chronograph. If you get significantly lower velocities with the load that doesn't work, then you have your answer. At that point you can bump the powder charge the appropriate amount.

[Seth]

It matters because I want to learn and I want to try a different load.

EVERYTHING about the load is the same. Same brass, same primers, same bullet, same OAL. Only delta is powder charge.

[Nik Habicht]

It matters because I want to learn and I want to try a different load.

Only delta is powder charge.

Then there's your likely answer. Did you run them over the chrono? Not that that may matter --- because it likely comes down to slide velocity.....

When you're running at the ragged edge of performance --- .40 major in a custom gun, just enough velocity to comfortably or barely make major, 12.5 lb. recoil spring (which at 4000 rounds might need replacing) --- you're really tuning the gun and load to each other. Change any one thing and you might need to start the tuning process over --- with no guarantee of success....

[Duane Thomas]

Only delta is powder charge.

There's your answer then to, "What did I change?" The problem is the powder charge. Probably too light. You can run the ammo over a chrono to confirm, or, if you don't have access to a chrono, try bumping the charge in .2 grain increments until the gun works - never exceeding book max, natch.

[Seth]

Funny, as I read this it seems so blatantly obvious... but I'm still stupid about it. I guess the load is just too light to work the gun. I was supposed to chrono it today, but it was too cold and blustery.

I'll bump it some and see what happens.

Thx.

Seth

[Duane Thomas]

Yer welcome.

Let us know what happens.

[Seth]

I will. I worked up a 4.8, 5.0 and 5.2 and shot only the 4.8 today. I guess I expected the gun to run anyway and didn't expect a load slightly under pf to make that much difference. I was so surprised, that I was looking in the wrong places...

[Ron Ankeny]

It matters because I want to learn...

That's a pretty good reason to ask a question.

[kgunz11]

Seth I think you need to be at least at 5.0 gr to make PF. My guns seem to all do about the same at that charge weight but I have seen some custom bbls actually have a slower velocity. I don't understand that as it is my experience with rifle bbls that the custom hand lapped bbls actually offer some additional velocity from their tighter bore dimensions.

Try 5.0, some guys are actually having to shoot 5.2gr of N320, but that is usually the most I have heard it take. I use 12# recoil springs in my guns and they run with 5.0gr with a MG 180 loaded to 1.185". All 5 guns are factory STI's.

[Duane Thomas]

Nothing wrong with 5.2 for a little extra cushion in the cycle reliability and chrono stage comfort areas, either, perhaps.

[CJDOUBLETAP]

If bumping up the powder charge doesn't work try a Wolff variable power recoil spring... that might do the trick.

[ChuckS]

My limited guns like > 5.0 with jacketed 180s and ~5.0 with plated. I use a plain old Wolff #12 recoil spring with a unique STI slide.

Later,

Chuck

[G-ManBart]

Seth I think you need to be at least at 5.0 gr to make PF. My guns seem to all do about the same at that charge weight but I have seen some custom bbls actually have a slower velocity. I don't understand that as it is my experience with rifle bbls that the custom hand lapped bbls actually offer some additional velocity from their tighter bore dimensions.

Try 5.0, some guys are actually having to shoot 5.2gr of N320, but that is usually the most I have heard it take. I use 12# recoil springs in my guns and they run with 5.0gr with a MG 180 loaded to 1.185". All 5 guns are factory STI's.

In my Edge 5.0gr of N320 with a MG 180 at 1.200" gave me 177.48pf the first time and 179.85pf the second day. Depending on the case and bullet combo I can drop that down to 4.8 and easily make major. If I just change from the JHP to a FMJ I only drop a tenth to 4.9 and I'm right in the 171-172 range since the FMJ uses less case volume and drops the pressure.

I've even tested loads at 4.6 that still made it with a little cushion...in the end not much else he can do but see what 5.0 or 5.2 does.

[Seth]

My question... why would being off by a few tenths of a grain make the gun unreliable?

[kgunz11]

Without seeing exactly what was happening who knows. You could have just enough of an extractor issue that it is causing a problem with the softer load. BTDT myself. We really need more info to better be able to help. You NEED to shoot the rounds through a chrono.

[Seth]

Agreed. That was the plan for the day, but it was blowing 20+ and was in the low 40s. Not the best conditions...

[kgunz11]

Is there an indoor range anywhere near by?

[Seth]

Yes. Which is where I wound up shooting. REALLY poor lighting....

[VegasOPM]

You know it is funny. I made up 1000, 200gr FP .45 loads for my 1911- after buying 2300 of these in bulk. The first mag through the previously flawless pistol gave me 4 failure to feeds. The round was hanging up on the feedramp. My first reaction was to figure out what I needed to do to get the pistol to feed those rounds. I considered buying a new barrel or sending it to my Gunsmith to fix.

I was going to spend several hundred dollars to get a gun that runs perfectly on hardball or semi wads to cycle flatpoint ammo- instead of just getting rid of the ammo and using the stuff that works.

Edited November 22, 2008 by VegasOPM

[Nik Habicht]

My question... why would being off by a few tenths of a grain make the gun unreliable?

Because you need a certain amount of gas to make the gun cycle completely --- if there's not enough gas for that, the spring doesn't compress far enough to build the energy required to strip and feed a round.....

Would you expect it to cycle after firing an accidentally loaded 9mm round? Same principle -- more or less....

[Seth]

Thanks. I'm learning. I figured as much, but sometimes need a sledgehammer to the head to absorb.

[MemphisMechanic]

Thanks. I'm learning. I figured as much, but sometimes need a sledgehammer to the head to absorb.

Here's an example. A dramatic one.

Identical load, other than powder charge. 147 FMJ, wolf primer, same 1.145 OAL.

3.0gr Titegroup: Average of 467.8 feet per second (10 shots) = 66.7 PF

3.2gr Titegroup: Average of 875 feet per second (10 shots) = 128.6 PF

Load a hair below the minimum in your reloading manual, and you'll have a barely-moving bullet, or a squib. Once the pressure drops below what's required, things stop working in a hurry. Surprised me, too, when I first started loading a few months back.

Edited November 22, 2008 by MemphisMechanic