PS90 SBR reloads with Longshot 40gr VMax

[jhjenkins4th]

I figured I would share my testing results, since there is a lack of load data for this round. I worked off of the the load data provided by iFire. http://www.fivesevenforum.com/viewtopic ... 9429&hilit" onclick="window.open(this.href);return false; I was not sure what length barrel PS90 iFire used on his testing.

Running the results through QuickLoad, adjusting the burn rate Ba to match my velocities gave me outputs that say my gun should have blown up...but I've read on this forum that QL is not reliable for this caliber.

As always, this load information worked for my firearm but others may different.

for Factory SS197, I got velocities: 2143, 2133, 2091, 2108

4.7gr Reload Pic 1


4.7gr Reload Pic 2


5.5gr Reload Pic 1


5.5gr Reload Pic 2

Please Note: the ring on the external of most of the brass just below the shoulder was there before firing. It is a minor coating damage from Hornady dies during resizing.

I only took pics of the 4.7gr and 5.5gr loads, as all the brass looked nearly identical except for a little more flattening of the primers along the progression. No cratering was noticed on primer strikes. Above 5.3gr, most of the primers were flat. However, most of the factory SS197 ammo I shot also had flat primmers so I'm not sure if its a significant pressure sign indication.
For all my reloads, I did not notice the bright ring that indicates neck separation mention at this thread: http://www.fivesevenforum.com/viewtopic ... 8520&hilit" onclick="window.open(this.href);return false; According to the data, the 5.5gr was the most consistent. However, being a noob on reloading this caliber, I'm not sure if I should really stay with the loadings that showed fewer flat primers (5.3gr or less).

I had an interesting find from the brass I collected after shooting factory SS197 ammo with my SPECWAR726 suppressor. It was roughly 10% only had extreme shoulder movement like the below pictures. Inside all these rounds with excessive shoulder movement did appear there was the 'Ring' on the inside. Pictures of these factory brass are provided below. The majority of the other factory brass looked similar to the brass from my reloads. I do not know if this was caused by quick succession rapid fire (hot barrel/chamber) or something else. These brass pictured are not likely from the same rounds I fired in the above chronograph data.

SS197 Primers


SS197 Casings


SS197 Ring inside


Any thoughts or input is always appreciated.

[jhjenkins4th]

BTW, it would be awesome if one of the admins could set up a permanent sticky for all the loading information that has been provided so far, or provide a designated section for load info to the inserted for future post.

A great example of this is the 300BLKtalk forum, where I have posted data and used data in reloading. Searching load data on this forum currently take a good bit of time digging through endless threads. Just a suggestion. This hyperlink is the example from the 300blk forum: http://www.300blktalk.com/forum/viewtop ... 41&t=81567" onclick="window.open(this.href);return false;

PS, I'm not sure if its against the rules here to post a link to another forum, so admin please delete if so.

[panzermk2]

Your can was keeping the chamber pressure higher longer stretching out the brass. You are very close to a neck separation.


Here is a thread covering this in great detail including detailed pics.

http://www.fivesevenforum.com/viewtopic ... hilit=ring" onclick="window.open(this.href);return false;

[panzermk2]

QL was designed to work with bolt action rifles which mimic pressure barrels. With the Pistol being delayed blow back and the PS90/P90 straight blow back it's simulation model does not work.

[jhjenkins4th]

Jay, thanks for confirming my suspicions on the ring on the factory brass. The thread you referenced is the exact information I used to make my assumption.

When you were referring to me being close to neck separation, you were only referring to the factory brass with the ring/excessive shoulder movement correct? Does the brass from my handloads seem ok from the pics I posted? I know you have a great depth of experience on this round, and I appreciate your input.

BTW, thanks for getting the case gauge out to me. It lowered my stress level while making this first test batch.

[panzermk2]

Your pics are nice but without the brass in front of me to look at and also section I can't make the call.


Your welcome on the case gauge!

[shopsmart]

You sir, just saved me ALOT of RND. Wanted to replicate SS197 with longshot, but have to load them up yet. This will come in real handy.

[panzermk2]

Adding our rate reducer will help.

The P90 was designed from the outset to have a 10 inch or so barrel.


When FNH added the longer barrel they never did anything with the bolt to compensate timing wise. It's like you have a 2 cylinder flat engine and then make one connecting rod longer and then wonder why it has issues.

Our reducer increases the mass of the bolt and slows it down. This allows extra time for the increase in chamber pressure duration caused by the longer barrel.

If you get it though KEEP the factory recoil springs installed. If you swap in our HD springs the springs speed the weighted bolt cycle back up again.

[jhjenkins4th]

In my case, my PS90 is the barrel length of the original 10" design. However,the heavier weight would help with the added suppressor. I'm starting to second guess suppressing this gun now with my latest end cap strike, so it may be an issue I may no longer have to worry about in my case.

[DoubleJ]

I get shoulder movement like that with the new barrel in my FsN. I'll have to take a second look and see if I've got a ring going on in there. That would suck if my brass goes in the garbage after 2 firings.

[panzermk2]

I get shoulder movement like that with the new barrel in my FsN. I'll have to take a second look and see if I've got a ring going on in there. That would suck if my brass goes in the garbage after 2 firings.

Jarvis barrel correct?

[jhjenkins4th]

I have a question to ask.
I understand the possible risks of shooting my reloads through another PS90 with 16" barrel, that were tailored to a 10" barrel version. I could be facing bad over pressure failure due to the casing ejecting before the bullet leaves the longer barrel.

My question is, would there be any safety concern with shooting these rounds from a FiveSeven pistol? I know typically the pistol should be able to handle hotter loads in this regard due to shorter barrel. Is it only a functionality concern, like the chance of short stroking the slide and becoming a 'single shot' pistol? I know I saw from iFire's data from initial research that Longshot powder played well between the pistol and PS90 platforms.

I understand that safe practice with reloads should only be fired from the gun it was developed with and re-development starting at lower charges is recommended for testing alternate guns/chambers.