Punching Above Weight

[PappaWheelie]

Good plan, MeatAxe,

My 1st priority, soon when I'm able to shoot again, will be to carefully watch the spent casing discharge distance, and also shoot one-handed.
https://cajungunworks.com/how-to-select-the-proper-recoil-spring/
I've updated the spring load comparison at http://www.czforum.com/forum/index.php?topic=5506.msg23220#msg23220 to add AVG. LOAD, lbs. and % INCREASE columns: pretty sure now that the increased pressure will be well tamed, and just a bit concerned about the possibility of too much spring until the trials are behind me!

As far as bone penetration, the Xtreme Defender bullet already has YouTube evidence of Honey Badger "Don't give a s**t" in that regard, having a penetration-optimized tip and not requiring expansion (for wound channel size dominance) to boot.



etc., etc.

[MeatAxe]

^ Interesting...

What is the cross-shaped nose on the Underwood round supposed to do, terminal ballistics-wise?

Is it supposed to be like a propeller churning up the surrounding tissue as it passes through or what?

[PappaWheelie]

Hi MeatAxe,

Re: "What is the cross-shaped nose on the Underwood round supposed to do, terminal ballistics-wise?"

Besides providing Ninja-like entry "sharpness" in relatively hard (Copper) material, it simply forms the "grid" for dividing the medium into four equal regions that are subsequently accelerated outwardly to form hydraulic knife blades, as I see it.

From Lehigh Defense's website,
-Progressive nose geometry for deep, straight penetration
-CNC machined from solid copper to overcome barriers to penetration
-Radial flutes that force the hydraulic energy inward to build pressure
-Exceptional acceleration that creates high pressure energy spikes
-Minimal surface area to increase the force at the point of contact and sharp cutting edges that defeat barriers
-A permanent wound cavity that is 2 to 4 times greater than flat or ball nose bullets
-Available for both handguns and rifles
-Ballistics Testing - FBI Standard 10% Ballistics Gelatin
-Barrier:  4 Layers of Denim

Re: "Is it supposed to be like a propeller churning up the surrounding tissue as it passes through or what?"

No, the ~1 in 10" (250 mm, actually) twist only serves to stabilize the bullet in flight.

[PappaWheelie]

Another at-the-range update:
http://www.czforum.com/forum/index.php?topic=5506.msg23284#msg23284

[PappaWheelie]

Here's a YouTube of Underwood Ammo Xtreme Defender (9mm & .45ACP) vs. Lehigh Defense Maximum Expansion (9mm HERO and .45ACP) ammos, showing the improved penetration with preservation of wound channel ferocity that I should have posted ~June 14th:

More than double the penetration with AT LEAST as much water jug "explosiveness."
Instead of creating a (temporary) vacuum blimp that quickly collapses, the Underwood Ammo Xtreme Defender creates four discrete "hydraulic slicing" knife cuts having greater permanent extent (radial distance from line of travel). The lower frontal area (cruciform vs. full circle) of the discrete hydraulic "slice channels" is created with commensurately reduced drag on the bullet, hence the superior penetration.

[MeatAxe]

Here's a YouTube of Underwood Ammo Xtreme Defender (9mm & .45ACP) vs. Lehigh Defense Maximum Expansion (9mm HERO and .45ACP) ammos, showing the improved penetration with preservation of wound channel ferocity that I should have posted ~June 14th:

More than double the penetration with AT LEAST as much water jug "explosiveness."
Instead of creating a (temporary) vacuum blimp that quickly collapses, the Underwood Ammo Xtreme Defender creates four discrete "hydraulic slicing" knife cuts having greater permanent extent (radial distance from line of travel). The lower frontal area (cruciform vs. full circle) of the discrete hydraulic "slice channels" is created with commensurately reduced drag on the bullet, hence the superior penetration.

I definitely believe all copper HPs are the way to go, especially for 9mm defense loads, for both penetration and expansion, especially through bone. The Brass Fletcher did a test between several SD HPs through synbone and ballistics gel and the Barnes Tac XP bullet loaded by Corbon to +P came out on top. Note that Corbon is now loading its own design all-copper DPX bullet, which has a more rounded nose that is more friendly to feeding in the steep-ramped Rami. Barnes, Black Hills and Double Tap still sell factory ammo loaded with the Barnes Tac XP bullet.

http://www.brassfetcher.com/Bone%20Simulant/9mm%20Luger%20Bone%20Test.html

[PappaWheelie]

Happy news, thanks to charlestheforth:
https://czfirearms.us/index.php?topic=102671.msg802000#msg802000
The Wolff Recoil Spring Set 1911 Kimber Ultra Carry 18# outer spring is a better choice than any of the three DPM outer springs when paired with the DPM inner spring and sleeve, adding increased "balance" and robustness to my carry combo.
Thanks again, charlestheforth- you da man!

[charlestheforth]

wow thats awesome!  I'm so glad I was able to help. 

[PappaWheelie]

Update/Warning:
CZ 9mm pistols don't reliably feed Xtreme Defender ammo! (Update) if limp-wristed (like any other ammo).
https://czfirearms.us/index.php?topic=102671.msg803459#msg803459
Virtually every other shot results in FTF b/c the flat cruciform nose of the bullet tends to snag one of its legs on the bottom of the feed ramp in both 2075 RAMI and 75 SP-01. Seemingly a conical face whereby the cruciform legs "cam past" the bottom of the feed ramp could solve the issue. I'll try several different truncated cone angles and flat diameters to see if a 100% reliable configuration is possible. I've contacted both Underwood Ammo and Lehigh Defense (bullet source) with the above URL link. Stay tuned: meanwhile I'm carrying with Xtreme Defender in the chamber only, followed by (alternately) Lehigh Max Expansion 105 gr and Max Expansion 70 gr HERO.

04/10/2019 Update: https://czfirearms.us/index.php?topic=103666.msg804064#msg804064
The ammo is not doomed, trials with shallower cone angles (to minimize with reliability) pending.

[mecenas]

Strange, for my RAMO XTP configuration billets with conical shape are a lot more reliable than Golden Sabers.

[PappaWheelie]

Update:
https://czfirearms.us/index.php?topic=103666.msg804887#msg804887
Limp-wristing was the signal factor; the ammo shoots flawlessly with the grip firmness (so-called "locked wrists") that is appropriate to shooting.

[PappaWheelie]

FINAL UPDATE:
https://czfirearms.us/index.php?topic=103666.msg807725#msg807725
Thanks again to huskerlrrp for the Break Free CLP sample!

Most concealable CZ, with best ergonomics and night sights to boot, "Magic Bullet" ammo, with truly pressure-matching springpack; now it falls to training and practice, practice, practice. I feel like a King (Rom 5.17).

TYJ!

[PogoJack]

This thread is a masterpiece!  Thank you to all involved!

Sent from my SM-G935V using Tapatalk

[cousinmark]

...Ahhhhhhh, now I get it Pappa has experience working on CZ motorcycles!!! Holly Jesus, if you can dial in the ignition timing on one of those babies (ever try kick starting a cold vintage 4 stroke)...
...getting springs to work with +P+ ammo in a RAMI is no big deal.
 
I actually got rid of my easy to start Honda XR250L a few years because kicking her over was knocking my back out of wack!!! Hate to think what I'd have injured trying to kick start an old CZ???

This is a great thread for anyone looking to push the envelope RAMI wise.

[PappaWheelie]

ever try kick starting a cold vintage 4 stroke

I still remember getting the heel of my boot summarily sheared off kicking over a big single four-stroke in my younger years! That was before learning the easy-start key to kicking over any single, including my beloved now 40-year old classic SR500G:
https://drive.google.com/open?id=0B9Nrjk17trvjQ3F5Qm9TUjRVdEVacnJCTk9qT2VOUmZKMVhj
(which features "easy-start" features of decompression lever, cam position window, and even "hot start" idle speed bump throttle button).
The key is to gently kick until the beginning of the compression stroke is felt (the single prominent resistance in the kickover process), then either with the help of a decompression lever or simply patience, ease the piston to TDC whence the resistance suddenly ceases (just a few inches of kick lever travel). Take a fresh top-of-the-kickstarter stroke "bite" (typically one or two ratchet clicks) to assure fullness of kick stroke energy, then do your "mighty whack" kickover. The engine gets the momentum-building benefit of three low-resistance strokes through which to accelerate before hitting the compression stroke again so its angular momentum easily takes out the "wall" of the compression stroke, essentially already rotating at idle speed.

"Suck-Squeeze-Pop-Phooey"

P.S. not many bikes aren't electric start these days, so the above is recognized as being of academic value only for most, but just in case it helps someone...
Another woolduh lesson learned by experience: use the enrichener lever (think "choke") progressively to cold start in moderate temperatures: better to have to kick again with a bit more enrichener than to have to deal with a wet plug from too much gas for the ambient temperature.