Does this sound like a gun issue or an ammo issue?

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Thread: Does this sound like a gun issue or an ammo issue?

  1. #1
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    Does this sound like a gun issue or an ammo issue?

    Gun: FN PS90 converted to SBR by TROS (incredible job), using Octane 45 silencer
    Issue: Sevenish rounds out of 150 would not chamber fully, causing a stoppage mid-magazine
    I've been shooting my PS90 carbine since I bought it in August of 2015 with probably 1500 or so rounds through it now (99% SS197). My SBR stamp came back in October 2016 and TROS did the conversion. The OEM barrel, both pre and post SBR conversion shoots unbelievably well. I was even hesitant to have it cut and threaded because it shoots such nice groups. Luckily, the conversion and subsequent silencer use have had absolutely zero impact on group size. Up until yesterday, the only jams I have had with it have been when I had it on the bench and shot enough to where the casings filled up the ejection port (obviously my fault on that one). Yesterday I probably had seven jams in the 150ish rounds I put through it which was a little disappointing considering this is my absolute favorite gun currently. All of them were the same, squeeze the trigger after having just fired another round and CLICK. I remove the mag and find the bolt forward on a live round that is not all the way in the chamber. Keeping the gun pointed down range I rack the charging handle all the way and about half the times I had to do this the round would still not fully chamber nor would it extract so I had to use a rod to poke it out. Upon inspecting a couple of the rounds that did this, I could not for the life of me see any visible difference between the problem round and the other presumably normal rounds. The ones that did chamber after racking the charging handle a couple times then fired and extracted fine.

    One other thing I had happen was a round that I fired didn't even cycle the action... but it still grouped with the others!? It was not one of the ones that had chambering issues.

    Now, I have read a LOT about people not trusting SS197 due to consistency issues but up until yesterday I hadn't experienced any of them first hand. I'd hate to just write it off as an ammo issue if there really is something underlying with the gun itself. I have accumulated a lot of SS197 so if it is the ammo I would really hope the whole lot doesn't have this trouble.

    Things I have tried/looked at:
    *Gun was lubricated with a light coat of 10w30, not running bone dry
    *Barrel still rotates perfectly freely
    *Tried the only ten rounds of SS198 I had with me at the time, no stoppages (but, again, it was only ten rounds)
    *Manually manipulated the extractor, operated fine
    *Pulled and cleaned the moving parts group including bolt face, pretty uneventful just a little carbon
    Edit: *Inspected and cleaned chamber, nothing I could see and it didn't even seem that dirty

    Any ideas please fire away, I'd love to hear what you guys have to say. Thanks!

    On a completely unrelated note, yesterday was the first day I was able to shoot it with the new Holosun HS503GU sight with 2 MOA dot and 65 MOA circle. All I can say is wow, complete perfection for this gun IMHO. The height over bore (I'm using the standard peep sight rail) was a bit of a challenge when it came to trying to make reliable hits on small targets at close range using a standard micro dot because I had to sort of guess how high to aim. The bottom of the 65 MOA circle correlates EXACTLY to the POI at 10 yd. I was shooting quickly at multiple small 1" targets at ten yards and did not miss a single one, it was boringly easy As long as the sight winds up holding zero and such, I will be adding one to the Tavors as well.
    Last edited by cake5150; 02-03-2017 at 11:38 AM.


  2. #2
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    Don't use motor oil for a lubricant. Clean the chamber with brake cleaner or carb cleaner. Make sure you keep it away from the polymer. The rounds have a coating on them that helps with feeding and extraction. Use a very light gun oil sparingly then run a clean patch though to get the excess out.

    Give us the lot number of the ammno because we can not identify issues without it.

    Are you using anything to catch the expelled rounds like a brass bag?

    Do you have anything in the ejection port that might interfere with the brass ejecting properly?

    Do you have any of the rounds that did not chamber..a picture of these pleases.
    Last edited by HK SD9 Tactical; 02-03-2017 at 12:57 PM.
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    My thoughts....probably SS197.

    I'm going to purchase an Elite Ammunition case gauge to check every round before I load them into the magazine.

    As to your failure to eject issue, I had the same problem with four rounds of SS197, my son who was with me even said that they sounded "light".

    Face it, SS197 should only be used for practice and malfunction drills.

    BTW, I do use motor oil, Mobil 1 0W-40 Fully Synthetic. I currently run it in every gun I own.
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    Senior Member Buffman's Avatar
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    ^^ Yeah there's nothing wrong with using Motor Oil for gun lubricant

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    Quote Originally Posted by Buffman View Post
    ^^ Yeah there's nothing wrong with using Motor Oil for gun lubricant
    I don't disagree, there are just better alternatives.
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    Senior Member Kakashi66218's Avatar
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    What's wrong with CLP, I run my Ps90 almost dry. No problems Hopps number 9. I've played with oil too.

    problems with motor oil is in automotive is goes thru a filter, particulates build up from internal gas and carbon. Plus the extreme temp is not helping if the oil cooks off and loses its qualities to lubricate.




    Buffman ever done a vid using odd ball products as lubricants for ships and giggles, might be interesting.
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    I vote for varnish in the chamber making it just enough out of spec that the cases are not sliding in easy enough. A good cleaning with some brake cleaner (again avoiding all plastic), and a good polish using a dremel tool will keep it going for another 1500 rounds or so. That coating from the cases is not cleaned out with the normal gun cleaners, so takes some special attention to get it out.

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    Quote Originally Posted by Kakashi66218 View Post
    What's wrong with CLP, I run my Ps90 almost dry. No problems Hopps number 9. I've played with oil too.

    problems with motor oil is in automotive is goes thru a filter, particulates build up from internal gas and carbon. Plus the extreme temp is not helping if the oil cooks off and loses its qualities to lubricate.
    In 2015 (the most recent year available) ExxonMobil spent over ONE BILLION DOLLARS on Research & Development!

    An internal combustion engine is an extremely harsh environment and oil takes a beating.

    How much do you really think that "Joe Bob's Miracle Gun Oil" spends on R&D? Do you really think that he actually refines his product?

    IMHO, one of the absolute worst Gun Oils on the planet is Remington Rem-Lube, it's better than water (but not by much)

    I can purchase a quart of Mobil 1 0W-40 Fully Synthetic Oil for around $8.00 at Autozone and it will last me for years, in addition it STAYS where I apply it unlike many "Gun Oils".
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    FN Supporter Mark McWillis's Avatar
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    Quote Originally Posted by kmiles View Post
    I vote for varnish in the chamber making it just enough out of spec that the cases are not sliding in easy enough. A good cleaning with some brake cleaner (again avoiding all plastic), and a good polish using a dremel tool will keep it going for another 1500 rounds or so. That coating from the cases is not cleaned out with the normal gun cleaners, so takes some special attention to get it out.
    This would be my take, as well.
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  11. #10
    Senior Member Kakashi66218's Avatar
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    Quote Originally Posted by PursuitSS View Post
    In 2015 (the most recent year available) ExxonMobil spent over ONE BILLION DOLLARS on Research & Development!

    An internal combustion engine is an extremely harsh environment and oil takes a beating.

    How much do you really think that "Joe Bob's Miracle Gun Oil" spends on R&D? Do you really think that he actually refines his product?

    IMHO, one of the absolute worst Gun Oils on the planet is Remington Rem-Lube, it's better than water (but not by much)

    I can purchase a quart of Mobil 1 0W-40 Fully Synthetic Oil for around $8.00 at Autozone and it will last me for years, in addition it STAYS where I apply it unlike many "Gun Oils".
    I didn't answer this in order so bear with it.

    The military uses CLP and LAW only in their massive inventory of firearms. Per technical manuals, Army & Nav/MC.
    --A lot of smart people prolly sat around asking if there was something better like motor oil, and I'm sure it came up. To me, motor oil will get it done in a pinch. And I'm sure they tested it. But someone making way more money than me said let there be specific oil for guns, and it was written. FWIW 4oz of break free CLP is $6.50 at Midway and I'm sure I can find it lower elsewhere.

    AmsOil makes a specific gun oil, automotive oil company with a specific oil for firearms.

    Prolly no doubt Automotive oil companies spend x billions of dollars in automotive r&d, the fact is its engine lube and marketed as so. Cars and the market for motor oil is way more financially risk based, r&d is a Quality Assurance for the CEO that his product would not present him with nightmares down the road. So as you know if a car did breakdown and it was found that the oil caused the problem the company is sought legally to fix the issue or pay some sort of compensation, if the parties agree with the evidence.

    In cars, oil is pushed thru a filter (guessing usually 5-25 micron), then it is returned to an oil pan for the oil pick up. Oil squirters for the crank are tiny, the valve train/head gets a hot bath in oil. Oil is pretty clean till it degrades over use 3-5 months or 20k-60k miles. Sludge is contaminated and thick oil, from the elements and environment that build up over time.

    In firearms, oil is static and subject to harsh environments if only just carried or stored, lint, dirt, dust, hair, and sweat. Motor oil may be redeemed as a lube and protectant only for so long as it stayed pure and didn't break down. Same amount of effort goes into cleaning it; but of the two CLP is long term.

    Oops 2k-6k miles average
    Last edited by jhs27275; 02-03-2017 at 05:11 PM. Reason: merge posts
    It's not the things I did that keep me up at night.. it's the things I didn't do, but could have done, that's what has me losing sleep. - Me

    I support veteran owned businesses. They supported America. Thank you for your service.
    Joshua 24:15


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