Ruger P90 Problem?

[bdg146]

I just recently purchased some Buffalo Bore FMJFN .45 ACP +P ammo for my P90. As with any ammunition, I wanted to run some through first to be sure it would feed reliably and there would be no issues. I loaded up my magazine with 8 rounds and started firing. After the 7th shot, something happen. The last remaining round in the magazine flew back towards me and actually went into the top of my jacket. It wasn't going very fast, so no risk of injury. I'm assuming round 7 was ejecting and somehow caught round 8 in the magazine and ejected it as well. I noticed this indentation on the bullet of round 8:



Should I be concerned? I field stripped and inspected the pistol and everything appeared to be fine. The P90 is used, so I'm a little wary of any issues, as I can't guarantee what the previous owner did to it.


I'm also planning on getting into reloading, so I went case hunting after the 7 shots. Upon retrieving three cases, I noticed another thing that made me wonder. The primer strike is very off-center. The pin appears to have initially struck the primer in the center, but 'slipped' and made it's major indentation off-center. Here is a picture:



I'm fairly inexperienced here, so I was hoping someone would be able to help me out. Thanks a lot!

 

[rantingredneck]

Two things jump out at me here.

The round you have pictured there looks a little long. Now I have nothing to go by in terms of scale here, but it just seems long. How does it compare to the other loads you received from buffalo bore? What's the cartridge OAL? Do you have a pair of calipers yet?

The other thing is the primers. It's hard to tell from the pics, but there MAY be some pressure signs there. Specifically some light cratering of the primers.

I'm not so concerned about the off center strikes as my P90 does the same thing. No idea if it's supposed to or not, but it's done that since I've owned it and never had a problem.

Another thing to check is your magazine follower on the magazine that was in the weapon when the malfunction happened. The metal followers can sometimes get either compressed and squeezed together or can get caught on something and lifted out of shape. Compare it to your other magazine(s) and see if it's out of shape. If so bend it back.

One of my mag followers got squeezed once, the last round would then only feed about halfway and jam. Fixed the problem with a little reshaping. If it were to be too open I imagine it could cause the problem you're experiencing here. A cartridge overlength would make it more likely as well.

Good luck.

 

[bdg146]

I compared the suspect round to a couple others to be sure the bullet didn't get pushed back in, and it was roughly the same length (as close as I could tell with my naked eye). I don't have calipers at the moment.

I'm not sure what you mean exactly by the pressure signs. Do you mean the rounds may be functioning at a dangerously high pressure level? If so, would another picture from a different angle help you?

The P90 isn't here with me at the moment, but I did do a quick inspection of the magazine and nothing seemed to be out of order. I've also never had a problem with either mag and they were stored in a padded case so the likelihood of damage since the last usage isn't much. However, I've never run FMJFN through the P90, so it's possible that this bullet shape is displaying trouble with my magazine that isn't a problem with normal FMJ. I'll inspect them closer tomorrow. Maybe I'll run some regular FMJ through them as well to see if I can duplicate the problem with them.

As for the off-center primer strikes, I actually pulled out the spent cartridge that comes with the pistol when you purchase it new. The primer strike is off-center there as well, so it appears to be somewhat normal.

Thanks for all the help. I'm going to hold off shooting any more of the Buffalo Bore through the P90 until I get some more information about this. I should be fine with standard pressure FMJ though, unless you think I should hold off on firing it at all until this is resolved.

 

[rantingredneck]

I think you'll be fine. The pressure signs I'm referring to, if they are even there, are very mild signs.

When you start to reach the pressure limits of the cartridge the first thing that will show it is the primer. Think of the primer like a fuse in an electrical circuit. It blows first as it is the weakest link in the chain.

When primers "crater" it is because the resulting pressure of the cartridge pushes against the firing pin and boltface causing the primer to flow around the pin. This makes it look like a mini-volcano, thus the term "cratering".

The photos don't show close enough detail to diagnose this from them, but it sort of looks like it in a couple of the pics.

If you google "cratered primers" or "pressure signs primers" you'll see some good pics of what I'm describing here.

Either way I don't think you'll have a problem with shooting the P90 with standard or +P ammo. Even the ammo you are shooting is manifesting the slightest of slight pressure signs if at all. Again from the pics it's hard to tell.

If I were a betting man, I'd bet that the problem somehow lies with the magazine follower or too long OAL of the cartridge or a combination of the two. Seeing as this only happens on the last round and all.

 

[bdg146]

I'm overly cautious with anything relating to firearms. I'm not very experienced with pistols and there was no one around to ask, so I erred on the side of caution and decided I'm not shooting it anymore until I ask about this incident. I'll probably have a chance to shoot in the next couple of days, so I'll try both mags again and see if I can repeat the problem and see if it occurs in both mags or just one. I'll also do some ammo comparisons... maybe go get a calipers and see what that shows. Thanks for your help rantingredneck, and if anyone else has anything to add, I'd love to hear it!

 

[Steve C]

I own a P90 and have occasionally had the last round in the mag pop out as you described rather than feed properly. I think its a magazine issue where the rounds move forward when the round above is stripped off. When it gets to the last round the mag spring is at its least pressure so the round pops out of the mag instead of staying in place to be loaded.

 

[lee n. field]

Another thing to check is your magazine follower on the magazine that was in the weapon when the malfunction happened. The metal followers can sometimes get either compressed and squeezed together or can get caught on something and lifted out of shape. Compare it to your other magazine(s) and see if it's out of shape. If so bend it b

Or see if you can get hold of one of the older plastic followers from the original 7 round magazines.

 

[bdg146]

I've been away from the internet for a while, but just to follow up and to get some more suggestions, I figured I'd update this thread.

I have two mags for my P90. One that came w/the pistol and another that I bought a couple months ago. The newer mag is the one that's had this problem, and I've had it happen two more times. This time it happened with standard pressure FMJ.

The newer, problematic mag is a factory mag, but it was marked for another Ruger .45 (a P97 maybe?). The mags appear the same and I'm pretty sure they are. If it wasn't for the sticker on the side of the magazine that came w/the pistol, I wouldn't be able to tell the difference. I took them both apart and both appear to be exactly the same. Any ideas what could be causing this?

Thanks.

 

[lee n. field]

The mags appear the same and I'm pretty sure they are. If it wasn't for the sticker on the side of the magazine that came w/the pistol, I wouldn't be able to tell the difference. I took them both apart and both appear to be exactly the same. Any ideas what could be causing this?

All Ruger .45 autos use the same magazines. Some have stickers, some do not. Older ones have plastic followers and hold 7 rounds, newer ones have metal followers and hold 8 rounds.

 

[bdg146]

Thanks. Both are 8 rounders with the metal followers. I took a hard look at the followers and the area surrounding where the rounds are extracted from the magazines and the suspect mag seems completely fine. Any chance the spring needs time to be broken in?

Now that I know this is strictly a mag issue, I'm not so concerned anymore. I can deal with this no problem, especially considering I at least have one fully functional mag.

 

[novaDAK]

I only have the older 7rd mags for my P90, the ones with the plastic followers. Never had a single problem with it, even when I shot a crap load (case was torn in a few places at the mouth, and it ejected to the LEFT instead of the right, and somehow it hooked onto the trigger return spring and unhooked it from the trigger.

A quick field strip to make sure it wasn't a squib, and then I just pushed the spring back down in the magwell with my finger, and proceeded to shoot the rest of that box, and a second box of ammo. It was Federal American Eagle, which while dirty, isn't too bad for range use.

The P90 is my favorite of the Rugers, and they're built like tanks.

 

[bdg146]

Well, I guess ejecting the last round unfired isn't so bad. I basically just have myself an old 7-round mag with a place to store an extra round

I shoot American Eagle too... most of the time I can find that the cheapest. Actually found it to be a little cleaner than some of the other cheap stuff too.

The P90 is a great pistol, isn't it? The more I shoot it, the more I love it.

 

[MCgunner]

Tried bending the feed lips? I don't know if that's the problem, but I've fixed other guns that way. Always having to do that with cheap surplus 1911 mags I got out of different surplus sources. I've never had a problem with my P90, but I have the older mags, too, and one aftermarket 10 round extended mag that has always worked. Think it's a pro-mag, but not real sure. Got it out of midway usa years ago.

The P90 is awesome reliable, feeds anything, and the most accurate auto loader I've ever owned, almost as accurate as my most accurate revolvers. It's a pretty amazing gun. I've shot mine a lot in competition and have sort of a zen thing going with it, now. I wish Ruger would come out with a P90 in 10mm. I don't quite understand why they haven't. I think it'd sell like hotcakes.

 

[Moonclip]

I'd just buy a new mag. On one of my P90 mags on a P90 I got used, it caused the occasional bobble so I trasshed it. I'd maybe like a 10mm P90 also though I already have a S&W 1006.

 

[bdg146]

a P90 in 10mm

That would be amazing. I'd buy one ASAP. Considering Ruger's recent product line though, I doubt it's in the cards.

 

[Daryl Licht]

I saw your post on the Ruger forum, but could not reply there, since for some reason I am unable to register there.

I had this exact problem with a KP90DC that I bought new in 2001. It started to show up at about 1200-1400 rounds, all this shooting was split equally between the two magazines.

It started to appear first in only one mag, then with both. Later it progressed to a point where it was not always the last round, sometimes it was the 6th or 7th. It is now impossible to shoot this gun with the original magazines without live rounds popping out.

The problem is the magazines. Two new replacements work perfectly so far.

At some point I may try to determine just what is wrong with the original mags, but I just don't shoot this pistol anymore since I have other .45's and just don't like the Ruger anymore. The springs in the old mags are still the same length as the newer springs, but may have weakened anyway. The feed lips don't appear to be bent, nor are the followers bent.

Since it does work with the new mags, I may just get rid of it. That's kind of sad, since it's the only gun I have that I would part with.

 

[longhorngunman]

From most accounts the P90 was originally designed for the 10mm round. After the 10mm lost favor, Ruger scrapped that idea and chambered it in .45acp. Considering Ruger's reputation for overbuilding guns and the fact it went from shooting a high pressure cartridge to shooting a low pressure one most P90's should last a long, long time. From what I've heard the P90 is getting discontinued though. Ruger has decided that the combat tupperware design is where it's at.

 

[RecoilRob]

Two thoughts come to mind. First, the pistol was used and you have no way of knowing how many rounds are through it. A fresh recoil-spring might be in order.

And, considering that the P-90 that I had would sometimes choke on +P ammo but function perfectly with rounds so weak that they barely made it out of the barrel (and it was fresh from the wrapper), I'd opine that Ruger went on the soft side with the stock spring specs.

If +P shooting is in the plans for the future, a heavier than stock spring would be my pick.

 

[bdg146]

Thanks for the input guys. Sorry your P90 lost favor with you Daryl. I'm sure you won't have a problem finding someone to buy it. Not sure this is an old mag issue though, considering the one I'm having trouble with is the one I purchased brand new a few months ago.

And Rob, according to the serial number, this pistol was only about a year old when I bought it. A lot of rounds can be put down range in a year, but I'd say that limits how worn out the recoil spring may be. The fact that it has only occurred with the one magazine also leads me to believe this is a mag issue.

Who knows. Maybe I'll shoot an email to Ruger just to see what they say...

 

[Daryl Licht]

The mags in my gun were not "old" either. They were less than a year, and only had between 600 and 700 rounds thru them.

Replacements fixed it.

 

[MCgunner]

From what I've heard the P90 is getting discontinued though.

Wow, well, I'm glad I have one and I sure as HELL ain't gettin' rid of it!

The recoil spring that came in mine was pretty weak. I'd gotten rid of my 1911s and had a bunch of wilson springs of various weights for a 1911, so I stuck a 16 lb spring in the P90 just goofing around and it's both stronger than the original and preloaded (slide is shorter). Yet, my normal lead 200 grain 900 fps handload functions flawlessly with that spring. I can shoot +P stuff with it without fear of frame battering by the slide, too.

Food for thought. YMMV, but I still have that 16 lb 1911 spring in my gun with thousands of rounds through it of mostly standard pressure. It's one autoloader that I don't ever worry whether it is going to work or not. It's just plain flawless and unreal accurate. And, yeah, it's built tough enough for a 10mm barrel, so I don't think .45 will ever stress it.

 

[bdg146]

The mags in my gun were not "old" either. They were less than a year, and only had between 600 and 700 rounds thru them.

I bought the 2nd mag at a time when I couldn't shoot a lot. This malfunction occurred with probably around 20 rounds shot out of the new mag. At any rate, another mag might just have to be the solution. Thanks for the info.

Sounds like a stiffer spring might be a good addition regardless of this is a mag issue or not. Having never modified a pistol, what exactly would be the effect of a stiffer spring? Keep the slide from moving so quickly? How is that a good thing?

 

[MCgunner]

The P90 is a tough gun and can stand some battering, but the stiffer spring reduces slide velocity and alleviates, to a degree, frame battering, not that it's a problem with the P90, but I got this thing after I'd been playing for 10 years with 1911s. LOL

My P90 used to toss empties into the next county. Now my lighter range loads pile the brass in the same spot about 6-10 feet to my right. That's a side benefit to a reloader who polices his brass. But, the heavier spring just reduces wear, in general. Ain't like I'm fast enough on the trigger for it to affect my double tap speed, either. It actually does reduce recoil muzzle climb a bit, though, I did notice, which actually HELPS double tap speed.

If you get too stiff a spring or limp wrist the gun, it could cause failures. However, I've fired the thing week hand, on my side, every way possible and it doesn't jam with the 16 lb 1911 spring in it. Might be a little tougher for a small woman to jack the slide back with that heavy spring in it, but I ain't that weak. It does make installing the guide on assembly a bit more of a PITA, but not that bad. I have shot the guide across the floor a few times, though, LOL!

The thing that might be happening to your gun that would be caused by the recoil spring is excessive battering of the slide on recoil causing the round, as the magazine spring uncoils toward the last round, to pop forward in the mag under recoil force. A stronger spring would cure that, if so. Also, you can put 10 percent over Wolff magazine springs in the mags, too, would help keep the rounds in place when the slide bashes the frame. I have 3 pro-mags I had problems with from the get go in my P85 that I cured with Wolff magazine springs. They were cheap mags. The Ruger mags I got with it function flawlessly, but I bought these pro mags for cheap back before the 10 round ban lifted. Figured the Wolff springs would not be excessively expensive if they worked and they did. The Wolff springs are added insurance for proper feeding, at any rate.

 

[Daryl Licht]

A heavier recoil spring did improve the feel of my P90 considerably. A 16lb. Wolff recoil spring was the second thing I tried with mine, since the original spring had gone limp pretty early. At first I had thought my handloads to be too hot, but reducing the load and even trying a couple of brands of factory ammo did stop the problem.

I'd be interested in hearing if new mag springs from Wolff solves this issue. If so I would definitely change them out, and maybe even keep the pistol. It's against my nature to part with a gun, even if I don't use it. With a couple of extra magazines, it could also help if I did decide to sell it off, since I wouldn't pass the bad mags on with it anyway.

 

[bdg146]

Hmmmm... Maybe I found the answer to this problem...
The new mag I bought was for the P97, but I was under the impression that the mags didn't change. I checked out Wolff's website to look at the mag springs, and they list different springs for the P90 and the P97 mags. So, if Wolff recommends different springs, then maybe stock Ruger mag springs are different too. Maybe that's why my new magazine is malfunctioning. What do you think? Should I buy a P90 mag spring and put it in my P97 mag? The physical dimensions of the two mags are the same, so fixing the spring should fix the problem.

Onto the recoil spring. I see the factory recoil spring is 11#. Wolff offers them in 12, 13, 14 and 16 pounds. What would you go for? How's 14 sound??