First time Grand Power K100 9mm

Intercooler · December 24 2015 02:22:27 PM MST

The 250 rounds I put through the Grand Power. Up the ladder... Geco 115gr FMJ, Sellier&Bellot 115gr FMJ Police, Samson IMI 115gr FMJ NATO, ZQ123gr NATO and Speer Lawman 147gr TMJ. Pretty standard run of the mill offerings all FMJ's. No hollow points this time out to see how they run.

First time out with the Grand Power and it's a mixed bag! I Chronographed some ammos I have ran in the other pistols today. I had some stoppages and got some pictures of them:

Most were with the higher impulse ammo, although I ran into a total stoppage shooting the S&B 115's. I had a FTE and after clearing it, I couldn't get the slide to go back into battery at all! It was about 1/4" from going in and no luck which prompted a pull-down, cleaning and re-oil. I was able to get it going again after do this. I'm hoping the aren't that sensitive to powder, crud...

Intercooler · December 24 2015 02:30:29 PM MST

ZQ1 123gr NATO round that wouldn't extract from the Grand Power chamber. You can see the weird line the barrel puts on in chambering. More on that later when I get the calipers on some of the spent shell casings:

Grand Power accuracy with me painting a straight line. It's very accurate if you do your part and is fun to shoot like a Witness. The grip is really similar:

sqlbullet · December 24 2015 03:02:58 PM MST

Is the line because the brass is turning in the chamber while still under pressure? The way the action works it seems either the brass would have to turn against the chamber walls, or the case head against the breech face.

Intercooler · December 24 2015 03:12:51 PM MST

I'm going to take some measurements and better pictures of some brass here in a bit. If the barrel rotates, something like you talk of has to occur given the rotating barrel.

Intercooler · December 24 2015 03:46:06 PM MST

Chronograph results:

Geco 115gr FMJ Grand Power K100 4.25" 1160, 1165, 1162, 1170, 1145. Average = 1160.4 FPS/ 344 LBS... XD was 1174 FPS and Limited 1214 FPS
Sellier&Bellot 115gr FMJ Police Grand Power K100 4.25" 1186, 1198, 1195, 1163, 1178. Average = 1184 FPS/ 358 LBS... XD was 1216 FPS and Limited 1234 FPS
Samson IMI 115gr FMJ NATO Grand Power K100 4.25" 1258, 1266, 1244, 1262, 1245. Average = 1255 FPS/ 402 LBS... XD was 1286 FPS and Limited 1303 FPS
ZQ1 123gr FMJ NATO 1179, 1183, 1178, 1182, 1173. Average = 1179 FPS/ 380 LBS... XD was 1209 FPS and Limited 1251 FPS
Speer Lawman 147gr TMJ Grand Power K100 4.25" 974, 988, 974, 981, 964. Average = 976.2 FPS/ 311 LBS... XD was 989 FPS and Limited 1026 FPS

The Grand Power's barrel length falls between the XD and Limited, but gave results lower than both. Just like my hunch in the Grand Power video, it has a gas seal issue similar to a revolver.

Intercooler · December 24 2015 05:22:23 PM MST

Grand Power spent brass from today's testing. Pre and post measurements and the second picture is of three ZQ1 brass from the malfunction pictures (worst case). Measurements are case end and right above extractor groove.

Geco 115gr FMJ Pre .378" .388"
Post .382" .391" +.004"/.003"
Post .382" .391" +.004"/.003"
Sellier&Bellot 115gr FMJ Pre .378" .388"
Post .382" .390" +.004"/.002"
Post .382" .390" +.004"/.002"
Samson 115gr FMJ NATO Pre .378" .388"
Post .383" .393" +.005"/.005"
Post .384" .393" +.006"/+.005"
ZQ1 115gr FMJ NATO Pre .379" .388"
Post .383" .393" +.004"/.005"
Post .384" .393" +.005"/.005"
Three malfunction ZQ1 Pre .379" .388"
Post .385" .393" +.006"/.005"
Post .383" .393" +.004"/.005"
Post .383" .394" +.004"/.006"

Intercooler · December 25 2015 04:47:56 PM MST

I tore the pistol down earlier today for cleaning and inspection. I found two semi-circle pieces of brass in the pistol.

Tonight I decided to look at the magazines and had a rattle in one:

https://www.facebook.com/206257602745613/videos/976652699039429/?theater

I tore it down and found an intact piece inside of it:

Brass thickness

Intercooler · December 25 2015 06:20:07 PM MST

Okay... It's looking like the brass length is having something to do with the issues.

Brass OAL measurements for 10 cases each
Speer .742", .743", .742", .745", .743", .746", .745", .746", .746", .745" Average = .744.3"
IMI .744", .744", .747", .745", .745", .744", .747", .746", .745", .743" Average = .745"
Geco .742", .747", 741", .743", .743", .746", .742", .742", .741", .743" Average = .743"
S&B .748", .744", .743", .751", .748", .744", .748", .744", .748", .747" Average = 746.5"
ZQ1 .752", .748", .753", .749", .750", .752", .750", .753", .754", .751" Average = 751.2"

So the ZQ1 had most measurements >.750" and those were the main stoppages. Why? I possibly had one issue with the S&B which was second longest, but can't remember exactly. I never had an issue in any of my other pistol barrels, so what gives???

DM1906 · December 25 2015 06:53:19 PM MST

They are still well short of spec. length (.754"). I've seen blow-back actions shear case mouths, but never screw-bolts. The ring pictured doesn't look exactly round, but the dia. is smack-on spec. OD.

Intercooler · December 25 2015 06:57:32 PM MST

It was probably one of the total stoppages I had and the brass ended up a little mangled freeing it. Are you familiar with the design step inside the chamber?

Intercooler · December 25 2015 07:14:55 PM MST

Could the increased length cause the casing to bottom out on the forcing area step?

DM1906 · December 25 2015 09:00:11 PM MST

None of the cases you measured are too long, with only one ZQ1 actually meeting the spec. The chamber should accommodate significantly longer, yet.

The step-chamber isn't a new concept (although less than ideal for handloaders). The "forcing area step" is just a ramp, of sorts, and only reduces the chamber dia. to spec in the forward area. I don't see how it could cause the issues you are seeing. I'd suspect a rough or under cut chamber, and/or substandard ammo. Try some Blazer to see just how abusive it can be on cases. The aluminum cases will exaggerate any flaw.

Intercooler · December 25 2015 09:33:44 PM MST

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? Next set will show the rounds in just the barrel.

Intercooler · December 25 2015 09:59:06 PM MST

ZQ1 and Geco rounds inserted into barrel. Hopefully the pictures show which is seated deeper into the chamber.

DM1906 · December 25 2015 11:08:17 PM MST

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.