STI 2011 9mm slow cycling

[Brandon04GT]

So I have an STI 2011 Tactical DS 5.0 in 9mm. It came from the factory with a 10lb recoil spring and 15lb mainspring.

 

I had since changed the MS to a 17# and have been experimenting with different recoil springs. I had since tried a 12# (would barely cycle), 11# (shells would just dribble out the ejection port) and a 10# (so far has been the best one albeit the slide is still cycling slow)

 

I had put about 600 rounds thru it before sending it back to STI for unrelated reasons which resulted in them refinishing the slide. A few days ago I put it 400 rounds thru it. Shells were ejecting 1-3' away and after a few hundred rounds, the slide really began to feel a bit slow. I am wondering what other spring combos I can try to increase performance while maintaining durability and reliability. Althought I was shooting Remington UMC and Blazer Brass 9mm which seems to be loaded on the lower side, I am setting this gun up for "HD/Duty" instead of gaming so I may also be shooting some stouter HD rounds.

 

So far I am thinking of either:

 

1. Replace the mainspring with a 15# and hope I don't get light strikes.

2. Replace the mainspring with a 15# and go up to an 11# recoil spring to help with speed.

3. Keeping the existing 17# mainspring/10lb recoil spring combo and shooting it more to see if the gun breaks in further and smooths out.

 

I'm guessing since I have a full rail version with a more meaty/heavier slide, that doesn't quite help either.

 

 

Thanks

Edited June 12, 2017 by Brandon04GT

[jcc7x7]

17 MS

8-9 Recoil Spring

7lbs works great BUT if you grip softly it won't cycle the rounds out of the mag, so for a duty gun wouldn't be my choice

[Aircooled6racer]

Hello: 17lb ISMI mainspring and a 9lb ISMI recoil spring works great. Make sure you keep it well oiled as well. I used Mobil 1 15W50 for summer and 0W20 for winter. Thanks, Eric

[Brandon04GT]

Thanks for the responses. I am thinking about trying a 9mm recoil spring, but would't that slow my slide down even more on the forward stroke?

 

 

[Jim Watson]

Just speculating, how about one of the contoured low resistance hammers like the Optimum or Cammer?

[mike4045]

9# spring and minimum 17#ms.

I use a 10# in my guns but I run a heavier load. It run wwb 115 just fine.

I would check mag feed lips for burrs. It could cause rounds to drag coming out of the mag slowing down your slide.

Last year I picked up guide rod that had a few high ridges slowing the spring movement. I found that by accident when detail stripping gun. Playing with spring noticed it was really tight to the rod in a couple spots.

[Ocd666]

I've run a 15# ms for 2yrs no light strikes using Cci federal mag tech and S&B primers. I've used 9,8,7 recoil springs settled for the 7# variable Wolfe with shock buff as my loads are only 105PF. Put about 5000 rounds through it.

[Hi-Power Jack]

Switch to Brian's  Slide Glide - it will really smooth out your gun ....   

[Bob DuBois]

Have two Eagles and a Trojan in 9mm. Love um. All three have 15 pound recoil springs

along with my 40 and 45 guns. Never had a light hit using Winchester Primers.

Trojan has about 30.000 rounds with the same spring runs Great.

Put the 10lb recoil spring back in or a 9lb along with 15lb main,

Put a little Mobil 1 in there when you change the spring it will run.

[spininfirec]

Ive messed with a lot of different springs.  I run roughly 125 pf with 147 gr fyi.  Ive had too high of a main spring, up to 19lb and the gun wouldnt even run my 125 pf loads due to the mainspring slowing down the slide.  I run a 13lb now with a 7lb recoil spring.  Ive tried as low as 5lb but the slide had too much lag and tossed that asap.  The 6 lb felt nice but it was a tad slow to shoot fast and clean.  Not a good thing but I could be a little more lacks with my grip.  I'm working up now trying 8lb soon.  But I have run a 7lb on a 5" and 6" slide both.  

 

Ive also had gun issues and required heavier springs.  Ive gotten my guns cleaned up and could run any spring combination reliable.