PT709: 9mm Extraction Problems, Ammo Comparison Photo

[agksimon]

Here is a comparison of three different types of 9mm ammuniton as you look at the photo:

Sellier & Bellot 115gr on your left
Winchester White Box 115gr in the middle
Gold Dot 124gr +P HP on your right.

The S&B and the Gold Dot micrometer at .389 at the head and just below the head.
The Winchester White Box micrometer at .385 at the head and just below the head.

I realize they all swell up to fill the chamber when fired, but why the WW Box is .003 smaller in diameter to start with and still not always extracting from some Pt709'S is a puzzle, expecially when the rims are all cut sharp and clean for the extractor to fit into.

Our two PT709 shoot all three brands and all others without any problems at all. As a matter of fact, I find the WW Box to shoot quite tight groups and I use it in my PT709 to shoot informal IDPA matches.

[nbh40]

I did have a theory and your measurements bear this out (a bit). Now this seems far fetched and I do not really see how it should happen, but. I noticed with WWB that the feed ramp and chamber got really dirty. In theory this should not happen as burnt gases should escape, for the most part forward. What I considered that what if WWB was expanding enough to nearly seal the chamber and hold the case, but was letting enough gas escape to the rear (while case still expanded in chamber). This would cause a 'soft' slide movement, but a 'hard extraction' (case still expanded). This would correctly and safely cause the extractor to release the case prior to extraction.

Of course the other theory is that the slight difference in case size allows gases to escape to the rear prior to enough case expansion, the slide movement starts and then the case expands enough and locks, causing hard extraction and extractor to release the case. Basically the slide movement, case expansion and extraction all happen in the wrong order due to gases escaping to the rear too early.

I only say this because of the circumstances; the difference in case size, dirty feed ramp/chamber, my cases extract about 1/4 inch from chamber before extractor releases them (still in chamber). Theory being that if the extractor manages to pull the case that initial 1/4 inch, it should not release it until ejection unless there is a force acting against it (late case expansion).

Just a thought and theory, although I know it is a bit 'out there'.

[agksimon]

One thing I did to our PT709's as soon as we got them, is buff and polish the tool marks out of the chambers till they were shiny. This may have helped with extraction, as we have not had one problem with either one.

[nbh40]

One thing I did to our PT709's as soon as we got them, is buff and polish the tool marks out of the chambers till they were shiny. This may have helped with extraction, as we not had one problem with either.

That is next on my list. I did the feed ramps (common feed issue with truncated JHP ammo), but have not yet hit the chamber.

That said, since not using WWB, I have not had a single FT (anything) so...........if it ain't broke!

[loghomeshooter]

I did have a theory and your measurements bear this out (a bit). Now this seems far fetched and I do not really see how it should happen, but. I noticed with WWB that the feed ramp and chamber got really dirty. In theory this should not happen as burnt gases should escape, for the most part forward. What I considered that what if WWB was expanding enough to nearly seal the chamber and hold the case, but was letting enough gas escape to the rear (while case still expanded in chamber). This would cause a 'soft' slide movement, but a 'hard extraction' (case still expanded). This would correctly and safely cause the extractor to release the case prior to extraction.

Of course the other theory is that the slight difference in case size allows gases to escape to the rear prior to enough case expansion, the slide movement starts and then the case expands enough and locks, causing hard extraction and extractor to release the case. Basically the slide movement, case expansion and extraction all happen in the wrong order due to gases escaping to the rear too early.

I only say this because of the circumstances; the difference in case size, dirty feed ramp/chamber, my cases extract about 1/4 inch from chamber before extractor releases them (still in chamber). Theory being that if the extractor manages to pull the case that initial 1/4 inch, it should not release it until ejection unless there is a force acting against it (late case expansion).

Just a thought and theory, although I know it is a bit 'out there'.

Thats a good theory and I can't really argue with it, however mine did exactly what yours did (1/4 way in chamber) but after extractor replacement, no problems. I don't know how that changes case fit.

[nbh40]

Thats a good theory and I can't really argue with it, however mine did exactly what yours did (1/4 way in chamber) but after extractor replacement, no problems. I don't know how that changes case fit.

Did you change the extractor yourself? Will Taurus ship one? I am tempted to try it, but not if it means losing the gun to Miami fo a few weeks.

[SpodWo]

Intriguing and I am thankful that someone is trying to dive into the "why" of WWB extractions. I thought my problems were over with WWB extractions after my Taurus came back from Miami [extractor replaced and slide lock "adjusted" - but alas...

I fired 77 rounds [11 mags] of WWB, 115g, FMJ and had 5 FTEs. Oh crap...

I also had one where the slide stayed open with several rounds still in the magazine - the case ejected but the slide lock engaged, leaving the slide open. Oh crap again...that was weird.

I also suspect it was all from one magazine. I didn't note the first 2 times which magazine had the FTEs associated with it. I started to observe which magazine was getting the FTEs.

I do recall that the first FTE occurred after the 2nd round fired

So – after my 2nd faiIure to eject, I started paying closer attention.

I began shooting and got an FTE on one mag, then went to the other mag – pistol performed perfectly. I then went back to problem mag - FTE. Back to other mag - perfect. Then I had one run of no FTEs with the problem mag. Then I had one more go with the problem mag - and I got an FTE. I shot the "perfect" mag again - no problems. So - I am thinking...the mag? I closely examined both mags – even took a dial caliper to measure the mags – no difference. Springs seem to act/react the same when pressing mag follower down with a screwdriver...

?
I also noted that it seemed to have the FTE after the 5th round was fired of the mag in 4 of the 5 times.

I noted that this is very dirty shooting ammo. Probably even more so than before because I was shooting several types of ammo in with the mix previously.

I will give it a good cleaning and run another 50 rounds or more with the WWB first, then another brand 2nd. If I make it “dirty” and then the other ammo performs well...then – I have a pistol that doesn’t like WWB.

I have the "problem" mag marked so I know which one was giving me issues....

[agksimon]

Sounds like the bad mag is hanging up. Try taking the follower out and get any burrs off of it, as recommended in another post.

[SpodWo]

Sounds like the bad mag is hanging up.

Yah - I will take it apart. I had them both apart shortly after I got the pistol thinking there might be an issue.

Also - about polishing the champer and ramp? Use what to do that? I read something in another thread about that ....

Lapping compound?

[agksimon]

Yah - I will take it apart. I had them both apart shortly after I got the pistol thinking there might be an issue.

Also - about polishing the champer and ramp? Use what to do that? I read something in another thread about that ....



I used a Dremel with a bullet shaped polishing head with rubbing compound, but it will go faster with very fine lapping compound, then rubbing compound.

Lapping compound?