I have seen the updated rules .pdf from February.  Pretty cool you can fully load mags now....but I have a few gun related questions.  For reference, I am planning to modify a glock 9mm for this role.

1. No magwells allowed whatsoever?  Even small ones?  Confused by the 1/4" rule.


2. I understand that a slide can be aftermarket milled for serrations, but no lightening holes through the slide. Does that mean a ZEV slide like below is OK?  


3. How much milling is too much?  Is a Taran Tactical slide cut ok without the holes?  (The 34 with the low angle cut on the dust cover?) How about an Agency Arms?

4. Trigger - Can I use a flat face trigger like an agency arms or other?

5. Previous rules stated that stippling had to be done in a specific grip area like production.  It appears that had changed.  I believe I can do a double undercut of the trigger guard, full grip stipple...but can I do an "accelerator cut" and stipple for the support hand thumb?

Your help is appreciated in creating my new multiuse blaster.  

1.  No attachable magwells.  You may internally bevel your magwell as long as you do not create external flaring.

2.  The Zev slide *should* be okay, seems like they are taking a pretty liberal stance on milling "serrations" and grip aids

3.  Anything that is for the purpose of lightening the slide is prohibited.  No windows, no cutouts.  Better safe that sorry before you go buy an expensive milling package just to get bumped to open.  

4.  No.  Production rules apply

5.  Go crazy, AFAIK all grip work and stippling is approved in CO
 

Thanks for the clarification.  Now, what mag extensions is everyone running, and how many rounds are you cramming into a g17 mag?  I have a few of the TTI extensions for other guns and like them, but I see a few other brands such as Zev.  

Which is the best for carry optics?

edit to clarify....to reach 140mm or 141.whatever.

I was using TTI extensions, but I wasn't completely satisfied, was having reliability problems. I've switched to Magpul 21 rounders. They have been 100% for me, and I can buy 3 for the price of one TTI extension.

I coat the inside and outside, springs and followers of the Magpul mags with Mag Slick.

ETA: half of my TTIs hold 22 rounds and half hold 20 rounds.

Are you talking about 9mm or .40?

I have two of the TTI 140mm extensions and also had issues, particularly in .40.

My hypothesis is that the included mag springs are too weak so I swapped them for ISMI 170mm springs, cut off one coil, and they have been perfect since then.

I can fit 23 rounds of 9mm in both mags, but in competition I will only load to 22 for increased reliability and ease of reloading.  

I can endorse the TTI extensions if you are okay with swapping springs.  

Also make sure you gauge them to make sure they fit the mag gauge.  It would suck to be a little long and get bumped to open.

Looking at 9mm mags.

9mm. I'll check the springs. I have a EGW gauge and they check okay.

I've tried swapping the ones that will only do 20 on to different mags and they still only do 20.

This thread will likely get more responses in the Training | USPSA forum.

You can probably modify the follower to fit more in those.

There are tutorials online.

I'm sure you are correct, I remember stumbling across the tutorial once upon a time, and its been on my to do list for a while. But, honestly since the Magpul GL9 21s came out, it has slipped down the list a ways. I have 10 21 round pmags and they just work. Plus they are so much easier to take apart and clean and maintain. The TTI extensions have been relegated to the parts drawer.

I now have over 3K problem free rounds through the pmags. I have about the same money in 10 mags as 3 extensions. So, there's that.

All that being said, you are making me want to get them back out and get them sorted out.

I guess I'll have to bump them back up the list a notch or two.

Why is there another area that covers USPSA?  Doesn't it make more sense to bring that under the "competitive shooting" forum umbrella?

This site sometimes.

@wtturn
Can you link the 170mm spring you bought?  The only one I can find via google is the one for STI mags.  Is that the one?  I am having problems with lockback after empty because the spring that came with the +6 basepads is still too weak IMO.  It doesn't push up the follower far enough for it to have enough force to push up on the slide lock.  I could feel it from the first time I loaded them, that the spring was weaker than a comparable factory mag with no extension.

https://www.brownells.com/magazines/handgun-magazines/magazine-parts/magazine-springs/sti-170mm-high-capacity-premium-magazine-springs-prod24809.aspx

@captnstabn

Just get the OEM Glock 18 (33rd) spring and cut coils off.

It's easier and cheaper.

Thanks.  I kept reading online and that seems to be the way to go.