popple hole or not my gun

[Jules1985]

I'm currently shooting a load of 8.7 grain Vectan SP2 behind a 124 gr Alsa Pro round nose bullet. The weapon that is involved is a SPS Vista Short that already has a new compensator (EGW Titanium Hybrid)

 

After I got a lot of helpful tipps here (thanks again for that), i used a thumb rest from range panda which helped my split times again.

The el presidente is routinely shot by me with the weapon in its current setup in 4.2-4.4 seconds, which is a gigantic improvement compared to my previous achievements.

 

My load currently reaches a safe factor of 170 and 160 is required here in Germany.
Going higher as 8,7 gr of SP2 in the 9 Major would not feel safe.

My consideration now was whether a barrel porting or even 2/4 would allow the gun to shoot even flatter.

And how much factor I would lose with what size of the popple holes.

 Is there any empirical value in this regard?

Loosing to much power factor would realy... su*k.

Thank you and have a nice Thursday

 

 

 

[Rnlinebacker]

No, the popple holes would not make the gun significantly flatter. Use a lighter recoil spring. I run a 7 pound spring and the dot tracks very well

[Jules1985]

thank you for your suggestion. I am currently using an 8 lbs progressive spring from Wolff. do you think a 7 lbw spring would make such a big difference?

[dansedgli]

I've had 3 holes put in both a 38 super gun and a 9mm gun. They each lost 3pf. 

 

I was happy with the changes. 

[echotango]

3 3/16" holes in all my 9 open guns.  Would not build more without holes.  It makes a difference.  

If I remember correctly, I lost 2-3pf. 

Edited June 10, 2021 by echotango

[zzt]

It depends on the powder used.  You will lose less with SP2 than say WAC.  More than likely you will have to go up by .2gr to recover the velocity loss caused by two 3/16" poppels.  Poppels WILL make the gun shoot a little flatter at the expense of a harder hit to the hand.  9mm simply does not have the case capacity to allow the gun to be soft and flat at the same time.

 

Do not listen to people who say use a lighter spring.  That will raise the muzzle even more.  You determine which recoil spring you will use by shooting and observing.  I use 25 yards, only because that is convenient at one of the club I shoot at.  Aim at a small target in the berm, fire, then snap off the second shot just as you would in a double tap.  Where did the second shot go?  If high, you need a heavier spring.  It may take several tries to find the correct weight.  If low, you MAY need a lighter spring.  There are other things that force the second shot low.  Dumping the trigger is one.  Too much pressure on your new thumb rest is another.  The thumb rest is not there for you to press hard against in an effort to tame muzzle rise.  It is there to locate your thumb, which orients your weak hand grip in the same position every time.  If you do not have either of these problems and the second shot is consistently low, you need a lighter recoil spring.

 

BTW, if you change the radius on your FPS or change mainspring weights, you have to go through the whole process again.  FWIW, both of my custom Open guns have very tight slide to frame and barrel fit.  Tight as in no wiggle at all.  One has two 3/16" poppels and the other three 5/32" poppels.  I shoot a 115 JHP at 1470fps.  I have an 11 lb. recoil spring in one and a 10 in the other.  The 10 is in a new gun.  I'm probably going to an 11 because the second shot is consistently 2" high at 25 yards.  So don't let anyone tell you you have to run light springs in an Open gun.  If you watch slow motion video you see that most of the muzzle rise is caused by the secondary impulse of the slide bottoming out at the end of the recoil stroke.  You want to minimize that slam, while still ensuring you have enough dwell time for the next round to rise and be stripped by the returning slide.

Edited June 10, 2021 by zzt

[Posvar]

On 6/10/2021 at 12:33 PM, zzt said:

It depends on the powder used.  You will lose less with SP2 than say WAC.  More than likely you will have to go up by .2gr to recover the velocity loss caused by two 3/16" poppels.  Poppels WILL make the gun shoot a little flatter at the expense of a harder hit to the hand.  9mm simply does not have the case capacity to allow the gun to be soft and flat at the same time.

 

Do not listen to people who say use a lighter spring.  That will raise the muzzle even more.  You determine which recoil spring you will use by shooting and observing.  I use 25 yards, only because that is convenient at one of the club I shoot at.  Aim at a small target in the berm, fire, then snap off the second shot just as you would in a double tap.  Where did the second shot go?  If high, you need a heavier spring.  It may take several tries to find the correct weight.  If low, you MAY need a lighter spring.  There are other things that force the second shot low.  Dumping the trigger is one.  Too much pressure on your new thumb rest is another.  The thumb rest is not there for you to press hard against in an effort to tame muzzle rise.  It is there to locate your thumb, which orients your weak hand grip in the same position every time.  If you do not have either of these problems and the second shot is consistently low, you need a lighter recoil spring.

 

BTW, if you change the radius on your FPS or change mainspring weights, you have to go through the whole process again.  FWIW, both of my custom Open guns have very tight slide to frame and barrel fit.  Tight as in no wiggle at all.  One has two 3/16" poppels and the other three 5/32" poppels.  I shoot a 115 JHP at 1470fps.  I have an 11 lb. recoil spring in one and a 10 in the other.  The 10 is in a new gun.  I'm probably going to an 11 because the second shot is consistently 2" high at 25 yards.  So don't let anyone tell you you have to run light springs in an Open gun.  If you watch slow motion video you see that most of the muzzle rise is caused by the secondary impulse of the slide bottoming out at the end of the recoil stroke.  You want to minimize that slam, while still ensuring you have enough dwell time for the next round to rise and be stripped by the returning slide.

Good advice. I agree with the heavier recoil spring theory for sure. It works. Haven't messed with mainsprings much yet.

[Jules1985]

@zzt

 

Thank you very much !

[CocoBolo]

There is a point where friction and inertia meet, and when this happens the next round does not make it to the chamber.   A 7# may cause the gun to stop feeding.   Everyone has to try holes at least once.  If it doesn't work out just replace the barrel and try a different comp.  If your split is improved by .01 or even .02 this could add up to a full 2 seconds in a match.

[EEH]

Can’t say a lot about powder, but my first open gun was Sti Trubor, in 9mm. I use HS 6 powder  8.3 gr with precision delta bullets. I had two holes put in my barrel and with video it recoiled less, and I felt less recoil. 

[zzt]

25 minutes ago, EEH said:

Can’t say a lot about powder, but my first open gun was Sti Trubor, in 9mm. I use HS 6 powder  8.3 gr with precision delta bullets. I had two holes put in my barrel and with video it recoiled less, and I felt less recoil. 

 

If that is the case (and I believe you) you had excess gas jetting out the front of the comp.  That increases felt recoil.  Gas exiting the poppels you added left less for the comp, which was then able to exhaust all of it before the bullet exited the comp.  Your tale makes me want to experiment with a slightly faster powder than AA7 again.

[CocoBolo]

On 6/14/2021 at 11:41 AM, zzt said:

 

If that is the case (and I believe you) you had excess gas jetting out the front of the comp.  That increases felt recoil.  Gas exiting the poppels you added left less for the comp, which was then able to exhaust all of it before the bullet exited the comp.  Your tale makes me want to experiment with a slightly faster powder than AA7 again.

LOL AA7  When I went from 10gr to 10.5 grains it tamed the beast.  That was 38SC with a 124gr 11.2 gr for a 115.  I've shot it in 9 maj with 10gr and it felt good.  

[zzt]

13 minutes ago, CocoBolo said:

LOL AA7  When I went from 10gr to 10.5 grains it tamed the beast.  That was 38SC with a 124gr 11.2 gr for a 115.  I've shot it in 9 maj with 10gr and it felt good.  

 

Yes.  My load is 10.2 under a 115 JHP.  I went to 10.4 and it was a touch softer, but still no gas exiting the front.  I've gone higher in the past, but I get a lot more powder spilling out of the 9mm case when the shell plate rotates.  I get some with 10.4 and almost none with 10.2, so I stay with that.  I'll live with the hit to the hand.