MemphisMechanic

This is normal. Powders don’t burn consistently until you get enough of the case volume filled. Light loads burn erratically. Yep. See above. Try bringing you load up into the middle of the book min/max and see if your ES stabilizes... then bring your charge weight down until you see where it begins to open up. Also? Don’t worry about ES as long as the load groups well.

No knowledge on Berettas. On the Tanfoglios you can work on the disconnector head to lengthen the hammer-throw in DA nicely.

As a lefty, my gun had to auto-forward. Unlike most other platforms, you can’t swipe your trigger finger down over the slide release because the safety is completely in the way. You have to use a thumb.

In a similar DA/SA (Tanfoglio Stock 3) gun I could run a 13lb spring with absolute reliability, even in double action. For CCI primers (500 or 550) I needed to use a 15.5-16 pounder. I assume you’re aware that double action doesn’t hit nearly as hard as single, since the hammer doesn’t come back as far.

Striker guns hit far harder than a hammer-fired DA/SA gun does in double action. I shoot CCI 550s intermixed with S&B and Winchester small pistol primers. An M&P and a Walther PPQ / Q5 with stock striker springs will eat the 550s like candy. My heavily trigger-jobbed tanfoglio needed an additional pound of hammer spring in order to run 100% on CCI 500 & 550s.

Boom. Here’s the “how to tune:” Is your C/O gun fitted with a different recoil spring than the others?

I use something similar usually. Stock on belt. Muzzle contacting an X on the wall etc, etc.

USPSA HQ heavily encourages things like ‘stock on belt’ over port arms. For one thing a technically correct military port arms is going to have your muzzle at 180.00... For another, it seems everyone has a different picture in their head regarding what this USPSA port arms is. ACTUAL port arms:

I did the same thing when shooting a Stock 3. As soon as I tried a 125gr load I was done shooting 147s. Even in the lighter Walther Q5 there really, really isn’t much difference. I like the speedier recoil & recovery of 125 load. And I already mentioned: a 139PF Prima V 125 vs a 132PF Titegroupv147? The recoil force feels identical.

Good point: I have the oldest fastest batch.

125gr Black Bullet Int’l 1.112”-1.120” OAL variation 3.85gr Prima V (10 drop average) CCI 550 S.P. Magnum primer Walther Q5 Match 65 degrees 10 rounds over the Chrono: 1111, 1112, 1115, 1112, 1114, 1111, 1116, 1113, 1112, 1113 Average: 1112.9 Standard Deviation: 1.66 Power Factor: 139.1 (They went 132.7 PF through a 4.25” M&P) I stagger-loaded a magazine with this load and a 3.0 titegroup/147 BBI load and could not feel the difference in muzzle rise or recoil impulse using the Walther.) Let’s just say that PV really like being loaded for 9mm minor.

@Banacek after 20,000+ rounds or so the plastic on plastic interface at that point wears. Periodically you have to adjust the position of the index cam as it wears. Particularly if you don’t grease this point frequently. Roller bearings always operate smoother than a friction interface, and you can keep the surfaces clean and dry so touching them doesn’t get your hands filthy.

You’re never going to get full burn in this situation, even if you drop the powder charge. You’ll just wind up failing to make power factor.

Unfortunately in short-barrled comp’ed gun (a handgun) with slow burning powder, it doesn’t quite work that way.

The doesn’t help a lefty. ...But it’s good to know that the standard AR mag button widgets do Indeed work.

Excellent info as always Eric. I should be able to mount a traditional AR ambi-mag release on that lower. Correct?

Extremely encouraging. This is really good to know, and it meets my expectations. Are we talking roughly 1/16” - 1/8” of height difference? I pretty much assume you carefully filed the notch open until the bolt would clear the feed lips, and it runs reliably like that. The double-feed is a result of driving the magazine up into the gun too far, I assume? What is your extended magazine setup? Welded two mags together, or something else? I’ll be looking for rough 40-55 rounds in a magazine to give me plenty of leeway in a 32 round steel stage. How does the gun eject and reload for classifier scenarios?

Personally, I’d grab a $20-30 DPMS (or similar, just pick a brand) lower parts kit and drop a mil spec trigger into the gun. As others have mentioned, there are other things in the lower tha could contribute. Change nothing but the trigger and test it, until you’re certain that it’s definitively the trigger. Then look at another comany with a stellar record like Gieselle or Hiperfire or whatever the magic brands are these days... and try one of those.

What actually makes a gun shoot flat is the opposite of what logic would dictate... The heaviest bullet, the fastest burning powder, and the lightest recoil spring are your friends. Trust us. We’ve all experimented for competitions and these ARE the way to go. In a striker-fired gun such as the Glock, M&P or Walther Q5 it’s common to replace the 17lb factory spring with an 11 or 13. I prefer 13s. In a hammer-fired gun you get to go considerably lighter because the slide is also decelerated while compressing the hammer spring in order to cock the hammer... In my Tafoglio Stock 3 which is you gun’s twin brother I ran an 8-9 pound spring. For nothing but lighter factory ammo, I’d run a 10lb spring. I wouldn’t worry about going back up to factory unless you start feeding it really hot NATO machine gun ammo or hundreds of round of +P 115s.

Assuming a quality lower such as a QC10, of course... Why do Glock magged guns seem to be 90% of the USPSA PCC guns out there? As someone who doesn’t have any Glocks anymore, I am not biased since I would have to buy mags anyway. The magazines are also such a relatively minor expense that +\- $100 to set up a few of them isn’t really a factor. I like the aesthetics of the vertical mag versus the sloped Glock mag... but mainly? I’m digging the ability to slap a traditional AR ambidextrous mag release on my gun, since I’m a lefty. I might just be the first one to buy a CMMG guard upper and a QC10 colt mag lower and see if I can get the two to play nice (some machine work might be required, sure). Assuming you guys are getting the mags to run with boring reliability at 40+ rounds.

Nonsense. They’re Italian. Their mechanics aren’t lacking in job security. Speaking from experience. (I understand the point you were trying to make, simply taking a moment to slide an unrelated jibe in there.)

It does. But the gun isn’t Glock-like when it comes to detail stripping, that was my point. Not as bad as an K&K or metal framed SIG, but no Glock.

They’re referred to as a slide racker. So now you know what term to google.

@jaep1911 ... it isn’t easy to remove, that’s for sure. The gun was not designed for effortless detail stripping.

https://youtu.be/UevJjcPTkrs