New gun a SBR, Adams Arms 7.5 or CZ Scorpion

[BlakWolv]

I'm ready to purchase a pdw type weapon trying to do as much research as I can as I'm not loaded and can usually buy only 2 nice guns per year. I would like to hear any pros n cons from y'all here between a 7.5 Adams Arms piston style AR SBR build, and a CZ Scorpion SBR. When all is said and done I know I can say one benefit will be less money spent if I go the 5.56 SBR route as opposed to the Scorpion. Let me ask this...an AR at a barrel length of 7.5 inches, at 100 yards the 5.56 round will still be more lethal than a 9 mm round at 100 yards yeh? I know both of these are CQB builds I'll be happy at both doing fine within 100 yards. As I have been stuck on the old fence for a good while now trying to make a decision on which way to go i would like to ask you all here for some help in my decision process, any owners of either one of both please speak on out on why I should grab on over the other or vise versa, all info at all possible would be greatly appreciated regarding any 7.5 inch Adams Arms Piston Builds, or Any CZ SCORPION 9MM EVO PISTOL builds.

Thanks y'all much

[raimius]

Out of a barrel that short, you lose about 30% of the 5.56's velocity (which is pretty important to that bullet's terminal effects). KE being one-half mass times velocity squared, you lose a lot. Now, a 9mm starts at a lot less KE, but it was designed for shorter barrels.
Most .223 bullets are likely just going to punch .223in holes at that velocity. A 9mm JHP will likely still expand.

On a personal note, I find .223 out of that short a barrel to be obnoxious. LOTS of flash and concussion.

[Destructo6]

Not much to "build" with the Scorpion: buy it, file paperwork, wait, add stock.

There is a growing aftermarket for stocks, sling attachments, muzzle devices, triggers, etc with new stuff almost monthly. Check out the czfirearms.us board for more.

The box stock setup, however, works well.

[Mobuck]

I'll tell you that a 7.5" AR (5,56) is one of the most obnoxious guns to shoot that I've seen. As a PDW, the idea is worthless. Do you expect the opportunity to place ear protection prior to using a PDW? W/o ear protection, a 7.5" .223 is absolutely mind numbing.
I have a 11.5" AR pistol and I haven't fired it for years(currently waiting on a short barrel rated can).

[Bartholomew Roberts]

Even out of a 7.5" barrel, the 5.56 with the right bullets will outperform the 9mm in terminal ballistics; but when people say they are obnoxious, they aren't kidding. On an indoor range or at dusk, the fireball is enough to blank out a red dot (muzzle flash is brighter than the dot) - so you are left with either a slight bloom when not shooting or losing the dot every time you shoot. And even with hearing protection, the sound is teeth-rattling. Several times the whole rest of the firing line stopped shooting while they tried to figure out what is making that horrendous noise.

[dakota.potts]

I'd go with the Scorpion. Maybe I'm biased because I wanted to get one anyways.

Uses handgun ammo, low recoil, low noise. Got to shoot one as a pistol with a cheek rest and it was alright but I think it would be awesome as an SBR

[Chainsaw.]

http://www.ballisticsbytheinch.com/223rifle.html

So the question is 11.5" 556 or an sbr 9mm then?

How about an AR in 9mm? You can go as short as 4" if you desire.

[MarkCO]

Even out of a 7.5" barrel, the 5.56 with the right bullets will outperform the 9mm in terminal ballistics

If you are talking factory ammo, not true. If you are talking specifically tuned loads for each, it is almost a wash.

95 JHPs at 1650 fps vs 62s at 2250 fps. I got better terminal performance in testing and on game with the 9mm. And yes, I tried about 8 different bullets in the .223 and ones that were rated as the best for low velocity performance.

9mm won me over when I actually started testing it and stopped listening to people who have never shot the loads in tests or on live game. I actually sold my .300BO and short barreled .223s in deference to the 9mms. I have several now, with an integrally suppressed barrel awaiting a stamp.

[Bartholomew Roberts]

How about a 50gr TSX at 2600fps out of a 7.5" barrel? 14.5" of penetration in bare gel, expands to about .45 diameter and the wound cavity is rifle-like, not 9mm like. What kinds of numbers are you getting out of a light, fast 9mm?

And how is this load different then the Blitz Action Trauma or other similar, lightweight, high velocity 9mm loads from decades past?

[MarkCO]

50s are going about 2400 out of a 7.5" barrel. Barrier/ clothing defeat is abysmal.

9mm slugs are opening up to at least .6 and more often into the .7" range with excellent barrier defeat and penetration in the 14-16" range. Bonded high quality, or solids is what I have been testing mostly. Cavity side in gel is very similar to those created with the .223s.

The point is that 9mm from 7-10" barrels with light and tough bullets do as well if not better than the .223 from short barrels. Both are better than 9mm from a 4" pistol and both are worse than .223 from a 18" carbine.

[Bartholomew Roberts]

What specific 95gr 9mm bullet are you using where you are getting those results; because that is certainly atypical of the under 100gr 9mm rounds I've seen.

On 50gr Barnes TSX, I've chronoed Black Hills 5.56 50gr TSX (Red box) at 2618fps out of a 7.5" PLR-16 barrel using a Magnetospeed. I'm sure there is some variation due to weather, lot and brand variation; but 200fps worth? And this testing seems to indicate barrier penetration isn't an issue at 500fps faster (no petals shearing off): https://www.ar15.com/ammo/project/Se...r%20Rounds.htm

If you've got some specific examples of where you are seeing better performance from 9mm in comparable (7-10") barrels, I'd like to see it. My experience has been the higher velocity of .223 still outperforms 9mm even in 7.5" as long as you aren't relying on FMJ-type bullets that require yaw/upset to perform. By the time you hit 10", 5.56 just plain outperforms with all bullets.

The only advantage I've seen to 9mm is consistent expansion over a wider range of velocities which can give 9mm an edge in some scenarios - for example at 100yds if you pop something with a 50gr TSX out of a 7.5" barrel, you probably won't get much expansion and therefore much less effect from the higher velocity. At 100yds, 9mm will still open up because of design differences.

[MarkCO]

Take a look at the Barnes TAC-XP. Also played with the XTP and Gold Dots, but for accuracy and some other issues, those kind of need to be at 115 grains.

[highpower3006]

On a personal note, I find .223 out of that short a barrel to be obnoxious. LOTS of flash and concussion.

I'll tell you that a 7.5" AR (5,56) is one of the most obnoxious guns to shoot that I've seen. As a PDW, the idea is worthless. Do you expect the opportunity to place ear protection prior to using a PDW? W/o ear protection, a 7.5" .223 is absolutely mind numbing.

Yep, there is a way to significantly reduce the noise that a short barrel produces and that is to put a suppressor on it. After a ton of research, I decided to go with a 10.5" barrel on my AR and run a can. It makes all the difference in the world and it has very quickly become my favorite rifle.




I was going to do a 9mm SBR, but after thinking about it I felt that a semi auto 9mm carbine wasn't going to be my cup of tea. I went and SBR'ed a M92 instead.

[Bartholomew Roberts]

OK, here is what I am seeing for 115gr TAC-XPD: http://www.luckygunner.com/9mm-luger...-hp-20#geltest

Here is 5.56 50gr TSX out of an 8" bbl.: https://www.ar15.com/ammo/project/Se...r%20Rounds.htm

What am I missing here?

[stagpanther]

If you are talking factory ammo, not true. If you are talking specifically tuned loads for each, it is almost a wash.

95 JHPs at 1650 fps vs 62s at 2250 fps. I got better terminal performance in testing and on game with the 9mm. And yes, I tried about 8 different bullets in the .223 and ones that were rated as the best for low velocity performance.

9mm won me over when I actually started testing it and stopped listening to people who have never shot the loads in tests or on live game. I actually sold my .300BO and short barreled .223s in deference to the 9mms. I have several now, with an integrally suppressed barrel awaiting a stamp.
__________________
Good Shooting, MarkCO
www.CarbonArms.us

I'm interested to hear about your game loads in 9mm--I converted one of my glocks to a 8" 9 x 25 dillon and short of an xpb or similar monolithic bullet have doubts about conventional 9mm bullets holding up to higher velocities.

[IdahoG36]

This is my POF 7.25" barrel pistol. I just assembled it and will be filing my SBR paperwork shortly.



This was the first time I was shooting it. I was shooting 62gr M855. It is equipped with a Kaw Valley Precision linear compensator, which definitely helps. It directs the flash and noise away from the shooter.

[Onward Allusion]

I went the 11.5" AR route. 5.56 in 7.5" is loud and too much velocity is lost.

As for the 9mm EVO or another SBR or pistol of the mag forward design, I've always asked . . . why? I mean, what additional benefit does it get you that a 21 round Sig or 33 round Glock can't?

[raimius]

Pistol caliber SBRs give you a pleasant shooting, very short rifle.