Hybrid Glock 35 Doubles Real Bad

[BlackBuzzard]

With 75 rounds of 40SW (CCI, brass, 165grn, about 1050fps) fired today, on four occasions my hybrid G35 doubled or tripled at least three times. By hybrid I mean I put a modified G34 lower on to a stock G35 upper*. The G34 lower has all polished parts, 17 pound recoil spring, triggerkit.com parts (trigger bar redrilled, different trigger spring, lighter striker spring, and lighter safety spring, 3.5 pound connector). The entire attached G35 upper is stock.

This problem does not occur with the completely stock G35 lower and upper. This problems does not occur with the combined G34 lower and G34 upper, shooting 9mm Blazer 115grn ammo.

I combined the G35 lower and G35 upper so I could see how the 40SW feels with the lighter-than-stock trigger of the modified G34 lower I've been shooting for years. The G34 lower has at least 25,000 rounds through it by now.

Am I correct in assuming G35 and G34 lowers are identical as shipped from Glock? In my case the G34 lower is an older two pin model while the G35 is three pin.

Any thoughts on what the offending parts are on the modified G34 lower that cause the it to double when attached to a stock G35 upper?

I plan to modify the now stock G35 lower in the same way at I did the G34.

((*sorry for the AR speak, by "upper" I mean the entire slide assembly.))

All input appreciated.

BlackBuzzard

[ihatepickles]

What you're doing is about as dangerous as it gets. The ejectors are not the same between 9mm and 40 guns. Your gun is not doubling, it's firing out of battery when the 9mm ejector is striking the primer on the .40 rounds while out of battery.

[racerba]

I don't recommend you use the 35 upper on the old 34 lower for too long. The reason is that the 2 pin lower are not as strong and cannot handle the .40 cal for very long. However, you can try switching the firing pin on the 34 upper and the 35 upper. You can also switch parts from the 34 lower into the 35 lower except for the ejector and try the 35 upper on the 35 lower.

I believe that the new 34 frame and the 35 frame are identical except for the ejector.

[HK Dan]

The ejector (in the rear of the frame) can't hit a primer unless you rack the slide with a live round in it (unload and show clear). If it was firing out of battery in that position the gun would be in several pieces. I agree with you that the 9mm ejector could be a HUGE problem in that case, but not while firing.

That said, what on earth made this look like a good idea? Please be safe, keep the .40 parts with the .40 bullets and the 9mm parts with the 9mm bullets. We don't need another stinking "KB" story floating around out there.

HK Dan

Ps--I had the same problem when I went to a light trigger on my G35. The higher recoil impulse of the .40 takes a bit of getting used to, and with a sub 2# trigger pull it can easily double on you. If you can't master it, ditch it.

Pss--The striker spring and safety plunger spring are in the slide, not the frame.

Edited April 20, 2007 by HK Dan

[bountyhunter]

With 75 rounds of 40SW (CCI, brass, 165grn, about 1050fps) fired today, on four occasions my hybrid G35 doubled or tripled at least three times. By hybrid I mean I put a modified G34 lower on to a stock G35 upper*. The G34 lower has all polished parts, 17 pound recoil spring, triggerkit.com parts (trigger bar redrilled, different trigger spring, lighter striker spring, and lighter safety spring, 3.5 pound connector). The entire attached G35 upper is stock.

This problem does not occur with the completely stock G35 lower and upper. This problems does not occur with the combined G34 lower and G34 upper, shooting 9mm Blazer 115grn ammo.

I combined the G35 lower and G35 upper so I could see how the 40SW feels with the lighter-than-stock trigger of the modified G34 lower I've been shooting for years. The G34 lower has at least 25,000 rounds through it by now.

Am I correct in assuming G35 and G34 lowers are identical as shipped from Glock? In my case the G34 lower is an older two pin model while the G35 is three pin.

Any thoughts on what the offending parts are on the modified G34 lower that cause the it to double when attached to a stock G35 upper?

Glocks carry a serious risk of multiple or uncontrolled fire because the firing pin blocking safety is lifted by the trigger bar. If you pull the trigger and the slide cycles after firing (while the trigger is still pulled) the slide will come forward and the trigger bar bump will again lift the firing pin block out of the way..... you don't have to release the trigger and re-pull as you do on a XD, beretta, SIG, or HP to clear the FP safety.

If the striker slips off the trigger bar tip and falls when the slide hits the frame coming into battery, the gun will fire again without a second trigger pull.

For this reason, extreme care must be taken when stoning the tip of the trigger bar that engages the striker tab. Also: since slides vary, the amount of play between slide and frame could cause the striker to "slip" if it had too much vertical play.

I don't know if that's what caused yours to multiple fire, but it might.

[miyamoto]

Considering that glock parts are mostly just stamped out, inconsistent parts. The gun itself must account for this with rather loose tolerances. Then glock puts out new iterations of parts every now and again that are *slightly* different than what came before.

I don't know of too many folks that have not eventually had problems with all the tweaks you have going, myself included. I especially had trouble with drilling second/higher hole in trigger bar/trigger spring mounting hole. It works for a while, then if not enough lube, or too dirty, reset troubles arrive at the most inopportune time.

I backed away from that mod and have great results since.

Then I shoot them tens of thousands of times and that really smooths/lightens it up.

But definitely put the kabosh on your current set-up. Check engagement of striker/cruciform. You should/can test most of this before rounds go downrange.

good luck,

Will

[eric nielsen]

You have to check the trigger-bar's acute-angle: the tab that pushes & releases the striker.

It will start to show wear and rounding-off just before the gun goes full auto - which it will if the nose is recontoured - where it contacts the connector. The contour that Glock puts on the nose will normally not cause the above wear that leads to Full Auto.

Once you see any rounding or wear at the tab of the trigger-bar, it is trash, throw it away. There is no cure & a new part is cheap anyway.

Most Glock full-auto episodes happen when you slowly release the trigger from a shot. One forum member even got the knack of doing this on purpose - NOT recommended.

Also if the parts are mismatched [this is all relative - glock parts never fit exactly the same] you will see more Full-Auto with one combination of upper & lower than another combo.

[a repeat from past threads]

Edited April 21, 2007 by eric nielsen

[kevin c]

Other thoughts here from when I asked the same question:

http://www.brianenos.com/forums/index.php?showtopic=36129

[Nik Habicht]

Am I correct in assuming G35 and G34 lowers are identical as shipped from Glock? In my case the G34 lower is an older two pin model while the G35 is three pin.

Any thoughts on what the offending parts are on the modified G34 lower that cause the it to double when attached to a stock G35 upper?

BlackBuzzard

I had the same experience when trying to mate a third generation G19 upper with a second generation lower ---- occasional doubles, and one interesting more than triple....

While the frames will often interchange without issues, there are times, especially when the lowers aren't identical vintage, where you'll have issues. It's unlikely that it's the Sotelo parts, it's more likely that it's the lower.....

[nphd2000]

Striker and trigger bar latching tang thingy not having enough engagement surface. All of these parts vary slightly, some just don't get along well especially after polishing. And it was said before, 34 and 35 lowers are interchangeable, I do it all the time, but it's advisable to use a 3 pin frame when shooting major ammo. JMO