Reducing Velocity in an Open Gun

[touji]

Good afternoon folks,

 

After spending half a year lugging around two different loads of 9mm major for my two open guns, I'm wondering if anyone here has any ideas on reducing velocity output of my backup gun. At the moment, I am shooting an Atlas Open gun and my backup is a CK Arms Hardcore Open. It would be great to be able to carry around one set of ammo to matches, but I'm not sure of any way to do so without shortening the barrel of the CK or adding more popple holes. Would a different compensator possibly bleed off some velocity?

 

My Atlas load:

7.2gr WAC @ 170-172pf

 

My CK load:

6.9gr WAC @ 170-172pf

[zzt]

If no, or very little gas is jetting out the front of the CK comp, changing comps will do nothing for velocity.

 

What happens when you shoot your Atlas load through the CK?  If there are no downsides, shoot the heavier load.  There is no rule that says you have to stay at 172 or below.  My gun shoots better at 175PF with faster powders like WAC or Silhouette.

[MikeBurgess]

Does the 7.2 load show too much pressure in the CK, or is it just that it runs 178 or so PF?

If it is just the higher power factor, just run it in the CK, it most likely will not make much difference if any in your score. 

[Maximis228]

Different Barrels. Different Ports. Match the two and you will be close.

[touji]

So I have yet to chrono the ammo through my CK at the moment, but my main worry is the longevity of the Ck slide as I’m guestimating about 178-180pf. Am I being overly cautious of the wear and tear these open guns go through?

[jcc7x7]

I load to the slower BBL for PF.

Seems mine shoot flatter with 175-177 PF and since it's a back up gun your match is probably over if you've had to switch to it.

[Maximis228]

I shoot 7.5 of WAC with a 124 JHP out of a 5.4 Hybrid SV barrel with 3 holes. PF is 178. I have 3 guns like this (Recently sold 1) and the one with the highest round count is 35K. Still shoots clovers at 25. Slide to frame fit is tight.

 

All barrels shoot within .5 PF of each other with the same ammo.

[touji]

1 hour ago, jcc7x7 said:

I load to the slower BBL for PF.

Seems mine shoot flatter with 175-177 PF and since it's a back up gun your match is probably over if you've had to switch to it.

 

I agree that if I'm switching guns, my match would most definitely be over. I guess if my gun hits the dirt half way through, I'll only be putting 200 or so rounds to finish out the day. I'll just throw in a shock buff and call it a day with some higher than normal pf (for me) as it seems like people are running this pf in 9 major on the regular.

[MikeBurgess]

Running in the 175 neighborhood is very common, I know all 4 of the guys I traveled to Nationals with chronoed north of 174. I know one of the guys has about 35K at that PF through his gun.

[GrumpyOne]

I know of several guys that run north of 178 PF in their open guns because it shoots flatter. It should be no issue even running at 182 or so in any open gun. The comp bleeds off so much gas, that the slide hammering is pretty much a moot point. 

[kneelingatlas]

14 hours ago, touji said:

 

I agree that if I'm switching guns, my match would most definitely be over. I guess if my gun hits the dirt half way through, I'll only be putting 200 or so rounds to finish out the day. I'll just throw in a shock buff and call it a day with some higher than normal pf (for me) as it seems like people are running this pf in 9 major on the regular.

 

You're over thinking it, just use the same ammo in both guns.  If you want lower pressure loads, use a slower powder.

[jcc7x7]

48 minutes ago, kneelingatlas said:

 

You're over thinking it, just use the same ammo in both guns.  If you want lower pressure loads, use a slower powder

Agree

[touji]

You guys are right, I'm definitely over thinking this. I'll just throw in a slightly heavier recoil spring and a shock buff, and let er rip when shooting the CK. Thanks as always everyone!