First time Grand Power K100 9mm

[DM1906]

That chambering difference is a LOT. I shouldn't be visually distinguishable. However, you need to measure that ZQ1 case before firing. If it meets minimum spec, your chamber is too short.

[Intercooler]

I tried a round of Geco and one of the ZQ1's. When I clipped in under the extractor and rotated the barrel into lock-up it's apparent the ZQ1 is harder to turn it back out of lock-up. I actually had to use something to twist the barrel around and didn't have to do that with the Geco. Does this kind of mean my "slop" isn't enough for somewhat longer brass to headspace?

[Intercooler]

  So what it looks like is I don't have the space needed for even the .750ish ZQ1's to not pinch and get the end of the brass cut off. The Shadow put up the measurements for go/no go by SAAMI:




It's .754-.776 and being in the middle would be .765. I don't know if I need all of that, but at least the .754" of specification.

[DM1906]

That's what I was saying. With the longest case you measured being .754", case length isn't the problem. .754" is a minimum chamber depth (including breach). The drawings you attached are SAAMI specs, which are dimensional extremes. If a cartridge is "pinched" in the chamber, either the cartridge case is crimped too narrow AND headspace is too short, or the chamber is not cut correctly or there is interference (fouling). Chambering a 9mm should be a dead-stop event, not a wedging affect, and the chamber should be cut as to not allow a funneling of the cartridge below minimum OD. It isn't "slop", it's allowed tolerance, intended to facilitate reliable chambering with cartridge dimension variations and an acceptable level of fouling. If a case mouth is over-crimped, it may be able to wedge past the chamber, but another condition must allow that to happen, such as either a too-long case, or insufficient headspace. These are extremes well beyond any reasonable allowed tolerance. This leaves the chamber cut and/or fouling. While it isn't uncommon to have a chamber that shears some cases, it is rarely ever at any location other than where the bullet base seats in the case. This is normally corrected by chamber polishing or corrective reaming. OR, a specific pistol may only have an appetite for specific ammunition, and the shooter accepts and remains within that limitation (most common). What I would recommend is, send some of the suspect ammo to Shadow for tear-down and measurement. Each of your measurements are well within spec, and under in some examples. BUT, we don't yet know if they were manufactured that way, or if it is a condition of firing. Unfired case dimensions may be very telling.

[Intercooler]

The Shadow has pulled the ZQ1 down already, twice as a matter of fact. Reply #157:

http://10mm-firearms.com/factory-ammo-pull-downs/underwood-9mm-115gr-speer-gold-dot-jhp/msg28593/#msg28593

[DM1906]

Yes, but you are in possession of a cartridge that doesn't chamber correctly. THAT is the cartridge that should be examined. All measurements so far are well within spec, so that leaves the chamber suspect. A simple test you can do is, "paint" the entire cartridge with a black Sharpie, then force it into battery. Remove it and identify the areas of interference. I would even go so far as removing the firing pin and extractor to minimize collateral interference. This may be an issue with throat or freebore interference, which can greatly affect pressures as well as function. It's important to identify that, if it exists.

[Intercooler]

The other one from the exact box I shot... newer one reply #187:

http://10mm-firearms.com/factory-ammo-pull-downs/underwood-9mm-115gr-speer-gold-dot-jhp/msg36264/#msg36264

[Intercooler]

I got lucky and my Gunsmith responded. He will be meeting me to check it out at 12:00 today. I will report back when I get the results.

[DM1906]

Both rounds measured are within an acceptable margin of error. However, those rounds were not chambered in that pistol. Your only options are to explore areas of possible inconsistency, or return your new pistol. If the ammo you have doesn't fire correctly in your pistol and the ammo is not suspect, then the pistol is broken and should be returned. This isn't a 20 year old used pistol with a new problem. This is a new pistol that has never not had this problem. That's a manufacturer's defect. Either return it for repair, or accommodate the issue by correcting the defect or avoid ammo that has the issue (and take the chance that other ammo won't experience this when you need it to work NOW). There are no other options. I absolutely HATE returning defective products, of any kind, but I've done it. It's a PITA, but if I pay for a product, I expect to get what I paid for and nothing less.

[Intercooler]

Thanks for your help!

[sqlbullet]

I hate to ask....But IC, in your state if you return a defective pistol and the maker elects to replace rather than repair, does your replacement gun end up in jail like a new purchase?

[Intercooler]

I can't recall exactly what happened when I returned the Ruger Redhawk. I'm thinking my FFL just issued it with a new serial number and I didn't have to go through the full process again.

Here is what we found after just getting back from the Gunsmith.

So here is what we found. The pistol is fine and I'm happy about that! It doesn't have a headspacing issue and the rounds had enough slop plus fit the gauge. Nathan said the circular shaving is Copper from the ZQ1 bullet. He actually wanted to pull one down and have a look while I was there and suspects it could be crimp related. According to him it's just one of those rounds this pistol isn't liking and advised me to not run it anymore. I have read in the past about some pistols being finicky about ammos and just never owned one. Nathan thought I was bringing in reloads and I don't reload, so it shocked him to see this with factory ammo. My next time out I will run 150 rounds of Fiocchi standard 115gr FMJ and see what that gives.

[DM1906]

At least it's good to know why, somewhat. I have a friend who uses the same ammo by the case. His Colt eats it like candy, and it's also a screw-bolt (of a different type). Maybe save what's left and try it again after a few thousand rounds through the pistol. Maybe give the throat a polish to ease the growing pains.

[Intercooler]

  People who know the pistol say they are tightly machined and I agree. I asked a bunch of YouTube video makers running them about issues and most say they have been just plugging away without issue.

  I'm going again this weekend and plan on shooting a ton of just standard 115gr FMJ, but will take one more challenge round to run at the end based on how the FMJ's go.

[Intercooler]

Second visit and she locked up again. Tight! I had to pull it down and clean it to get it right.

https://www.facebook.com/206257602745613/videos/980734855297880/?theater