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Discussion Starter #1
Recently, I was at my friendly Class 3 dealer arranging another acquisition when I saw a PS90 on the wall. I knew very little about the rifle, but it felt good in the hand and looked completely different from anything else in my collection, so I bought it, too. Call it an impulse buy if you must…

But imagine my frustration – I had a new toy I knew almost nothing about AND I had to wait nearly a week to get any ammo for the thing.

So, I wound up here (and on that other PS90 forum) to learn about the PS90. Lots of good info in both places – thanks very much, guys!

Let me share some chrono data as a way to return the favor. I had the PS90 with SS197 and a 7.5 inch AR with 45gr Remington hollowpoints and some Hornady 55gr TAP FPD. I used my venerable PACT Mk II chrono and had the first screen about 6 feet in front off the muzzle. Each string was 10 rounds. (MAD = Mean Average Deviation of the string). Here’s the data:

SS197 & PS90

Hi 2129.6
Low 2092.5
Spread 37.1
MAD 9.8
Avg 2109.7


45gr 223 & 7.5” SBR

Hi 2538.8
Low 2400.6
Spread 138.2
MAD 37.4
Avg 2480.6


55gr TAP & 7.5” SBR

Hi 2305.4
Low 2246.5
Spread 58.9
MAD 14.4
Avg 2284.1


Hopefully, this will add something valuable to the common data pool.

Once again - thanks for all the great info and opinion hereabouts!

taudo
in the wilds of Montana
 

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Discussion Starter #5
Muzzle flash

Here's hoping this gets into the right thread.

The 7.5" AR can cause quite a signature - but the side blast is awful, too. The PS90 is far more pleasant to be beside. Both are fun to shoot!

I'm hoping the TAP rounds will live up to their claim of reducing flash, but I've had no time to test them after dark. As for blast, as soon as I can find a Noveske KX3 it's going on.

Or, maybe, a G5...

BTW it was interesting to me to note that the 16" PS90 was almost exactly the same overall length as the 7.5" SBR with the stock extended to where I like it. A PS90 SBR would have about the same extension as a relatively small handgun and would be MUCH harder to take away in a disarm attempt.

taudo
 

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Discussion Starter #6
Brief update

It took me a while to get that KX3, but last week I was finally able to get out after dark to check the muzzle signatures of the 223s vs that of the PS90. My informal results;

1) The visible muzzle signature of the 223 SBR was not nearly as bad as was suggested by its felt blast.

2) The visible signature the KX3 was little (if any) reduced DESPITE the KX3's impressive ability to reduce felt side-blast.

3) TAP ammo out of my 7.5" barrel seemed no different from standard American Eagle

4) SS197 out of my PS90 produced NO visible signature we could see from safe angles, and the blast was negligible.

Given that FBI testing has indicated that 223 hollowpoint ammo is LESS overpenetrative than any other round tested when fired against drywall test panels, it would seem to me that a PS90 might make a good choice for use when overpenetration is a prime concern (e.g., serving a high risk arrest warrant in a trailer park - something I hope never to do again).

Of course, the $64 question revolves the effectiveness of available 5.7 ammo against "human-oid" targets - and that isn't something I can opine upon...thankfully.

taudo
in the wilds of Montana
 

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Discussion Starter #7
More chrono & reloading data

Here is some more data for the collective database. This data represents some reloads I threw together and fired over the same chrono and the same PS90 as those data above. The only thing different was the temperature. The previous data was obtained about 75 degrees, this was gotten at about 40 degrees.

Brass = once fired SS197
Primer = CCI small rifle
Powder = True Blue
Bullet = Hornady 40 gr V-Max
Dies used = Hornady Custom Grade New Dimension Full Length 2 die set (stock #546203)
Press = Lee Classic Turret
Shellholder = Lee #34
AutoPrime shellholder = #15
Powder measure = RCBS Uniflow (every 10th charged weighed)
Scale RCBS 505

Each string was 5 shots and the data below gives the reading for each shot in the string, followed by the Average, the Extreme Spread, and the Mean Average Deviation.

Factory SS197
2151.4 2147.6 2138.7 2158.9 2122.8 Avg = 2143.8 ES = 36.1 MAD = 10.5

5.6 gr True Blue
2168.6 2147.9 2118.9 2160.9 2119.9 Avg = 2143.5 ES = 48.7 MAD = 19.5
2203.2 2204.7 2173.3 2203.2 2142.7 Avg = 2185.4 ES = 62.0 MAD = 21.9

5.5 gr True Blue
2129.6 2169.6 2113.7 2176.8 2175.9 Avg = 2153.1 ES = 63.7 MAD = 25.5
2169.7 2115.2 2119.2 2096.1 2113.6 Avg = 2122.7 ES = 73.6 MAD = 18.7


I could see no over-pressure signs including head bulge, which I carefully miked.

With my unique setup, I plan to load 5.5 gr as a pretty good replacement for SS197.



I also just acquired an AR 57 upper, so I put a string through it, too. No individual readings, but cumulative data from 1 string below:

Factory SS197 through AR57

Avg = 2101.9 ES = 23.7 MAD = 7.6

The AR 57 upper seems to be very nicely made and functioned perfectly. The overall package is longer and heavier than the PS90, but if you don't have one of the FN "Stargate" guns, it is a nice way to play with 5.7 X 28. I'm looking for a gunsmith to cut this thing down to about a 10" barrel for SBR use.

MISC FYI

- Brass was washed in Simple Green to avoid removing the coating
- Factory 5.7 X 28 ammo has crimped primers for use in full auto P90s. (Doesn't the 90-degree-from-barrel-axis magazine make this unnecessary?) The fired brass needs to be well reamed or swaged to allow easy re-priming. Otherwise you crush primers
- I set the seating die for NO crimp at all. With that I was unable to force the bullet deeper into the case with VERY strong hand pressure. The rounds chambered and headspaced perfectly.
- The Lyman "Universal" brass trimmer has a chuck instead of a shellholder. It seemed to hold the 5.7 brass just fine.
- THERE IS PLENTY OF ROOM IN THE CASE TO ALLOW A DOUBLE CHARGE - WHICH WOULD BE CATASTROPHIC. VISUALLY INSPECT EACH POWDERED CASE TO PREVENT THIS.

I hope this info proves helpful.


"OUR-LEGAL-SYSTEM-IS-COMPLETELY DYSFUNCTIONAL" DISCLAIMER:

THE ABOVE DATA IS PRESENTED ONLY TO SHOW WHAT A FOOL I AM - FOR YOUR AMUSEMENT. DO NOT RELOAD USING THIS DATA - YOU _WILL_ BLOW YOUR FACE OFF, AND I WON'T BE HELD RESPONSIBLE FOR YOUR INJURIES 'CUZ I WARNED YOU CUZ!

taudo
in the wilds of Montana
 
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