The "plunk" test for 9mm Carbine?? Also how about lead bullets

[Rule3]

For a 9mm AR style, blow back carbine, How does one determine the best OAL?
If they work in my handguns is that good enough?

Using the regular "drop, plunk and dump" barrel test??

If not, is there a better way?

Also,

How about shooting lead bullets? It is not gas operated so I do not think there should be a problem? Yay or Nay?

 

[JamieC]

The 'ker plunk' test should work as 9mm ammo 'head spaces' off the case. Shooting lead shouldn't be a problem, might have to adjust for any possible leading issues. While not a long time lead user, I have become partial to Bayou Bullets, they are coated with a type of plastic and/or moly substance that doesn't smoke and the barrel on all my 9s, (including a Kel Tec Sub 2K), come out nice and clean.

 

[GLOOB]

"Best" OAL is w/e feeds and functions. Yeah, it would be nice if this OAL worked in all your 9mms.

Lead? Yeah, sure. The only issue with a blowback system is that cast might not cycle the gun.

FWIW, the major issue with loading cast bullets in 9mm is not the firearm. It's the case. 9mm is a tapered case, but when we resize it we turn the tapered case into a narrow cylindrical case with a fat base. This pushes the case in, smaller than it started out, in the area where the base of the bullet sits. This can swage down the bullet, causing leading and loss of accuracy.

 

[Rule3]

I just got the rifle so I may just use a box of "factory" ammo. Remember what that looked like? To test it out. I might have a box squirreled away.

As to the plunk test, just the same as a handgun> Take the barrel off and drop it it? It still headspaces on the case mouth yes?

Lead not to worry if I can shoot them in my CZ's then I can shoot them in this.

Can also use the dreaded LFCD

 

[MichaelK]

I think you'll just have to treat lead reloads as a new load and test it from scratch in your rifle. I have a 40S&W pistol/rifle combo and I developed a new load with side-by-side testing.

Your typical lead bullet is 1 thousandths larger than jacketed to insure the best gas sealing/rifling contact, so bulges are a concern. What I've found to work is a dedicated taper crimping die that tends to remove both the case mouth bell, and also a bit of bulging. If you loads drop into the chamber with a faint metalic "click" as the mouth headspaces on the chamber throat, then most likely you've done it properly.

When the bullet is just off the rifling seems to work best for accuracy, but in my pistols, that's typically longer than what's optimal for feeding. In the past with pistols, I've inserted a bullet back into an unsized case and slowly fed it into battery. I'd subtract 5-10 thousands off of that length and test for functioning. With some pistols that length wouldn't even fit in the magazine. Just keep feeding a dummy cartridge over and over till you've found a length that works just right.

Once you've selected an OAL that works in both guns, make some test loads and shoot them in both guns at the same time. In my case one load worked well in both the rifle and pistol.