Barrel Bushing = Cone of Probability?

[MadDuner]

I recently purchased a P-01.  When shooting it vs my SP-01 Tactical, I notice a fair amount of difference between groupings when comparing results.  Of course there is a difference in barrel length and sight radius, but I suspect that it?s also a function of those differences plus the barrel bushing.

I measured the diameter of the P-01 barrel, and it?s .505?. 
I measured the existing barrel bushing, and it?s .509?.
I verified the Cajun barrel bushing is .506?.

I charted out this ?tolerance?, and the ?cone of probability? for bullet POI gets pretty large over very much distance.  It equates to roughly 1? of variation per 10? of bullet travel distance.  But I would imagine that the barrel locks up in almost the same position most of the time.  I doubt that the end of the barrel moves from one extreme to the other between locked up positions.  So now it comes down to how much does it move?  I have no way of knowing that.

So my answer was to buy a new Cajunized barrel bushing for this P-01. 
The bushing opening on it is .506?.
This effectively cuts the barrel/bushing tolerance to just 33% of it?s previous allowed range of travel. Tightening this tolerance means the ?cone of probability? is now much smaller than it was.  I will be sure to let you guys know what the outcome is after I replace the bushing.

Also, as a side note:
Shooting yesterday out in the desert - at a steel silhouette at 100 yards - I managed to shoot my 2.2? barrel Sig P290RS DOA trigger better than my new P-01. The trigger on it is horrendous when compared to any of my CZs.  I believe it?s more about how the barrel/bushing lockup occurs than it is the sight radius or the trigger.  I managed 8/8 with it 3X in a row with it.  All standing, no bench. Modified Weaver stance. I didn?t do nearly as well with the P-01 at 2 out of 10 in 3 attempts.  I went 9/10 with the SP-01 in 3 attempts, but will admit I wasn?t trying very hard by then.  We were all still laughing too hard at the results from the baby Sig.  I enjoyed harassing my shooting buddies all the way home about outshooting them with that little Sig.  Of course, they got me back by pointing out that they didn?t video the feat, and know that nobody would believe me anyway! LOL

P-01 ?cone of probability? with factory bushing looks to be 30? at 300?. 
I?m gonna fix that.

[retteryer]

Out of all of my CZ?s only polished stainless has very loose bushing and it does affect accuracy a lot,compare to my other CZ?s.The only thing that stops me from installing CGW bushing is because I don?t like chrome vs stainless barrel combo and also I barely shoot it.And if you are ?lucky? and have loose barrel bushing and loose slide to frame fit than it does have even more impact on the accuracy.
Did I get your question right or do I need to read it 9 more times?Or it wasn?t a question at all,just a statement?

[MadDuner]

More like a theory?

I can measure how far the barrel can possibly deflect, but have no way of knowing how much it actually changes from round to round.  Just stating that I expect that reducing the possible travel distance or movement will improve the results.

[retteryer]

This is kind of rhetoric theory 

[MadDuner]

More like a mental exercise to prepare myself for the improvements to my shooting by way of placebo effect.

[earlan357]

Assuming zero deflection at the rear locking lugs, 120"(ten feet) / 3.75"(barrel length) * 0.003 (deflection) = 0.096"

or 0.72" @ 25 yards
or 2.88" @ 100 yards

[MadDuner]

Hahaha...... Off by a single decimal point makes a big difference in the math!

[retteryer]

Do math teachers allowed to be on this forum?

[copemech]

what's the math on the ammo?

[MadDuner]

what's the math on the ammo?

It?s obvious that math is not my strong point.

[M1A4ME]

If a barrel/slide/slide lock set up was so precise/tight/repeatable that the barrel didn't need to touch the bushing to return to the same position after every shot - would you call the barrel "free floated?"

How the barrel locks up front and back is important to grouping ability.

I'm going to assume that CZ's (some) can lock up pretty tight in the chamber area as some will break slide stop pins and you can see the wear on the top of the pin where it rides "hard" in the peanut on the bottom of the barrel.  I have some that you will not rock the barrel back and forth in and one or two where you can force the barrel to move a very small amount.

I let the pistol "tell" me if it needs a CGW bushing.  If I shoot 4 (sometimes 5) bullets into a large, single hole at 10 or 12 yds. off hand the pistol is good.  That one round a short distance from the others is my fault.  On the other hand if I've got a 3" group at 10 or 12 yds. I'll order a bushing for it.

[MadDuner]

I am hoping that the bushing helps.
I?ll accept placebo effect or actual mechanical tolerance as the fix - as long as it groups better.
It feels just like my Tactical, but doesn?t group like it.