STI Problems - Help Needed

[19852]

I had an old Browning HP that I shot a lot, back before I paid attention to spring wear. It started to dissemble itself when I shot it, as in the slide catch began to walk it's way out and the slide did not lock back. A new recoil spring solved the problem. It was somewhat of a collectors item so I sold it to someone who would appreciate it.

[Mr. Smith]

If the springs don't work you can drop me an email that is a platform I have run for years.
I build custom mags and spend a lot of time on those guns so I have many hours on the bench with one.

[opsoff1]

If possible, will you post photos of the old vs new springs? Also any details of the gun itself if there are signs of excessive wear would be great educational material for those that ignore maintenance schedules.

Great idea - and I was curious to see the old vs new springs. I run primarily hardball 45's - so all my guns run 16 or 17lb springs. The OEM spec for the STI is 14lb, so I didn't have anything in my parts drawers to comapre it to. I have a whole range of springs coming in from Wolff.
As far as maintenance goes - he's really good on that - always cleaned / lubed. Pistol feels relatively tight - so we'll see how everything works out.

Barrel looks ok - but I want to look at it closer with a borescope.

[opsoff1]

If the springs don't work you can drop me an email that is a platform I have run for years.
I build custom mags and spend a lot of time on those guns so I have many hours on the bench with one.

I appreciate the offer. Hope to have the springs by Monday - test fire Tues. Fingers crossed.

He runs the 140mm / 17rd mags - those had fresh springs last summer. Feed lips look ok. Same for the followers - anything else that I should be eyeballing?

[Mr. Smith]

I appreciate the offer. Hope to have the springs by Monday - test fire Tues. Fingers crossed.

He runs the 140mm / 17rd mags - those had fresh springs last summer. Feed lips look ok. Same for the followers - anything else that I should be eyeballing?

I will not run factory springs and followers in those mags the factory set ups are flawed.
You can get away with it a little bit in 15 rounders if you don't push them hard but if you push them hard those mags will give up.
If you use proper spring and follower combination the 140mm magazines will hold 20 rounds and 126mm will hold 17.
The factory followers are made of a material that wears in a way that is very difficult for you to catch it causes the magazines to lock the slide open with one or two rounds left in the mag very frequently.
All the things you're looking at need to be looked at but the springs and followers in the factory mags are definitely a problem.

[opsoff1]

I will not run factory springs and followers in those mags the factory set ups are flawed.
You can get away with it a little bit in 15 rounders if you don't push them hard but if you push them hard those mags will give up.
If you use proper spring and follower combination the 140mm magazines will hold 20 rounds and 126mm will hold 17.
The factory followers are made of a material that wears in a way that is very difficult for you to catch it causes the magazines to lock the slide open with one or two rounds left in the mag very frequently.
All the things you're looking at need to be looked at but the springs and followers in the factory mags are definitely a problem.

Bingo - seems this could be the problem - his mags are all factory. He used STI springs in them last summer and they still have the factory followers.
The result is exactly as you describe - slide locks open with 1-3 rds still in the mag -
What is the cure for the spring / follower issue?

[Mr. Smith]

Bingo - seems this could be the problem - his mags are all factory. He used STI springs in them last summer and they still have the factory followers.
The result is exactly as you describe - slide locks open with 1-3 rds still in the mag -
What is the cure for the spring / follower issue?

If you look at the aftermarket springs and followers for those magazines there's a company called grahams and they are the industry standard.
You will have to fit and tune them.
That is what I use in my custom mags.

[Ned Christiansen]

Premature lockbacks-- might look at the slide stop / safety detent spring too (oops, I see you did. Maybe renew it anyway). I wonder if by chance the slide stop has recently been changed and needs a detent to keep it from being influenced into the up position by upward moving rounds in the magazine.... or if he's using different magazines this time that allow rounds more side-to-side movement so they can contact the slide stop? Sometimes one or both detents get a flat worn on it and so does not "detent" like it used to......

[opsoff1]

UPDATE:

Basically what has transpired is a full rebuild / retuning of the mags. The original mags had different length springs and OEM (STI) followers. The mags themselves required reforming of the feed lips - they were way too wide. Some exceeded .410". This situation when combined with worn followers allowed the follower to move too high in the mag - the resulted in the premature slide lock. The lips were reformed with a mandrel to .380" wide. Grams springs and followers were installed. The bottom edge of the the slide lock was polished down about .020 and viola - 20 rds in a mag and no premature slide lock. Fresh springs were installed throughout - 14 lb recoil, 23 lb main and an extra power FP spring.

Pistol runs like a champ.

Thanks to all those who chimed in - especially Mr. Smith.

[Mr. Smith]

UPDATE:

Basically what has transpired is a full rebuild / retuning of the mags. The original mags had different length springs and OEM (STI) followers. The mags themselves required reforming of the feed lips - they were way too wide. Some exceeded .410". This situation when combined with worn followers allowed the follower to move too high in the mag - the resulted in the premature slide lock. The lips were reformed with a mandrel to .380" wide. Grams springs and followers were installed. The bottom edge of the the slide lock was polished down about .020 and viola - 20 rds in a mag and no premature slide lock. Fresh springs were installed throughout - 14 lb recoil, 23 lb main and an extra power FP spring.

Pistol runs like a champ.

Thanks to all those who chimed in - especially Mr. Smith.

Your welcome