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STI DVC Open gun ejection advice needed 9mm Major

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Brand new STI DVC Open (9mm Major) gun and I'm having trouble developing a reliable load.

Mags used are new MBX's.

Used Atlanta Arms 147gr 9mm Major Load and gun ran fine.

 

Trying to develop a load that will run at 9mm minor levels (for steel matches and such).

Tried this 153 power factor load (1229fps):

-124gr Blue Bullet

-6.0gr of AutoComp

-Federal Primer

-1.16OAL

This load with a 7lb recoil spring ended up with the jams you see in the pictures (about 2 malfunctions in 43 rounds).

I pumped up the powder to 6.3gr AutoComp and it ran fine with an 8lb recoil spring, but malfunctioned with a 7lb spring.

How can I get this thing to run with lighter loads? Do I need an even lighter spring? Or am I stuck shooting full power loads in this gun to get it to run right?

Thanks.

 

STI1.gif

STI2.gif

STI3.gif

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I would run full power loads gun will shoot flatter than reduced power loads try 7.5 hs6 about 160 pf cycles my gun just fine 10 pound spring. The other difference is I have a 90 degree mount. U might have cases hitting mount bouncing back in

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First use 8lb recoil spring sq.ejector.

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Good luck lol . You have to perfect the ejector and extractor to that gun. Some say shape of ejector x works and some say the opposite. Ive been searching this topic for a while and the general consensus is install an aftec properly tuned and play with the length and shape of the ejector to see what it does. Also slo mo video helps. Hand cycle some empty cases and record it in slomo on an iPhone if you have one. It might appear to be ejecting too high but could actually be hitting the bottom of the ejection port and bouncing up

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Also make sure all of your mags have fresh springs and the feedlips are identical dimensions. Too wide could cause ejection problems and appeared double feeds. 

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Good luck.My dvc open is back at sti just to get it to shoot a major load . All of my jams look like yours.I did track it down to 1 mag that was more prone to malfunctioning but it still did it with all the mags.sti was very helpful with the warranty  but it still sucks that I don't have my gun right now!

 

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can i ask did you run it in? use full loads and just shoot it for around 500 rounds then start to play with it

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I was having the same problems with mine after about 1k rounds. Went with a aftec extractor and cheely setback mount because I was getting fed up. Runs great now plus I like the lower sight picture. It will run Remington umc 115gr with a 8 or 7 pound spring. Major loads I'm using are 124 pd hp @ 1.165" 8.1 gr hs6 

Edited by Kepo

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Hello: Try the factory mag that came with the pistol. Check the extractor tension and make sure it is not too tight. For minor loads try a lighter bullet like a 95-115 grain one. 8lb spring should work fine. Thanks, Eric

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Mickd1 if you were referring to my post the answer is yes I did.It started jamming from day 1 round 1, to 3 weeks and 6 or 7 hundred rounds. I called sti and told them that a 4000.00 dollar gun should work without me shelling out more money for a 90 degree mount and extractor work.My 600.00 glocks shoot and eject everything.yea I know apples to oranges.

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I load closer to 7.0 gr of WAC at 1.165" to make 175 power factor. I had a ton of problems with the gun early on. Sent it back to STI and they replaced the ejector and extractor. It seems to run fine now but I've moved to a CK Arms open gun as my primary so the STI is relegated to backup duty.


Sent from my iPhone using Tapatalk

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I just saw he is trying to run minor loads,, my Trubor don't like minor.

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I just recently saw 2 new STI open pistols locally the did not have enough extractor tension to even hold a round in it. Both had jams like yours. 

 

It is the first thing I would check. 

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I agree with the extractor tension it seemed like mine got worse with time. I just wanted the best so I got a aftec.

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MIne has 9lb + buffer(for major), original 8lb works with minor.

Aftec with both springs

 

I think that original extractor is messed up by the STI in all of these. It's almost violently filed to extinct. Well at least you guys in states have on opportunity to send them back to factory. We usually have to solve these problems by ourselves.

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10 hours ago, tswisher21 said:

  All of my jams look like yours.I did track it down to 1 mag that was more prone to malfunctioning 

 

^^^^   Exactly the same problem      ^^^^^^^

 

I tried new loads, new springs, new extractor, etc etc etc.

 

Turns out, it was one of my mags - fixed the mag, voila, the problem disappeared    :) 

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7 hours ago, EEH said:

I just saw he is trying to run minor loads,, my Trubor don't like minor.

 

His load is PF 153 - only 12 less than Major.

 

My TruBor, with 10 lb spring, will run factory minor ammo iff the gun is Very Clean

and Very Well Lubed, and that's PF 127.

 

My TruBor has NO problem with PF 153 - I use a lot of them for steel.    :)

 

 

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9mm Major Cons:
1. Erratic ejection because of mixed headstamps
2. Unreliable with upright mounted C-mores “because of #1”
3. Snappy compared to Supercomp
4. limited powder choices when making major
5. short brass life “2-3 reloads max”
6. Need to use micro dot sight or side mounted C-more

https://nilsjshooting.com/2016/08/25/open-guns-9mm-or-38-supercomp/

Get a microdot. Nils knows a little bit.

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1 hour ago, Hupperware said:

9mm Major Cons:
1. Erratic ejection because of mixed headstamps
2. Unreliable with upright mounted C-mores “because of #1”
3. Snappy compared to Supercomp
4. limited powder choices when making major
5. short brass life “2-3 reloads max”
6. Need to use micro dot sight or side mounted C-more

https://nilsjshooting.com/2016/08/25/open-guns-9mm-or-38-supercomp/

Get a microdot. Nils knows a little bit.

Hello: I would disagree with that statement. If the pistol is designed to be a 9mm from the start with the correct parts and a good comp it will run fine. I get 5-7 reloads out of my once fired range brass and use an upright mount with a standard C-More slide ride. Thanks, Eric

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4 hours ago, Hupperware said:

9mm Major Cons:
1. Erratic ejection because of mixed headstamps
2. Unreliable with upright mounted C-mores “because of #1”
3. Snappy compared to Supercomp
4. limited powder choices when making major
5. short brass life “2-3 reloads max”
6. Need to use micro dot sight or side mounted C-more

https://nilsjshooting.com/2016/08/25/open-guns-9mm-or-38-supercomp/

Get a microdot. Nils knows a little bit.

 

1. Nope

2. Nope

3. Eh, load right.

4. Yes, limited in comparison but plenty of good options available.

5. Nope

6. Nope

 

Everyone is allowed their opinion, and that's cool.  But as blanket statements this is just spreading bad information for those doing their research.  Please, shoot what you like, but be reasonable enough to understand how a gun runs and shoots is all about the build, fit, tune, and loading practices and mostly irrelevant of chamber dimensions.

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Looks like 9 major was well represented in the majors.

image.png

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Back to OP,  May just need aftek

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13 hours ago, Kepo said:

I agree with the extractor tension it seemed like mine got worse with time. I just wanted the best so I got a aftec.

 

I'm on this boat.  I've found when these types of malfunctions occur and when brass ejection gets erratic it is most often lack of strong, consistent extractor tension.  Yes, guns may run with little to no tension, but for consistent ejection a tightly held and located piece of brass struck in the same orientation and in the same spot by the ejector is paramount.  Extractor tension is something to monitor as maintenance.  I notice when it gets weak, first ejection gets erratic and then it starts stovepiping with one mag, then the next, etc.  Not until your gun refuses to feed are you overly tight.

 

Make sure it gets picked up off the inside of the tunnel to hold the brass.  Also avoid closing the slide on a round in the chamber which will really speed up loss of extractor tension.

Edited by theWacoKid

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