Bull shadow upper question.

[Rolly9]

Hello, I am a new member in this Forum and need some helps from the experts here.
I recently purchased a bull shadow upper from czc and I absolutely love it. I live in California and there hasn’t been any new models available for many years. So it was exciting to have something different from fitting a bull shadow to my sp01 frame.
What I noticed is my group seems to open up with the 147 grain while it shoots well with 115 grain. I don’t reload and typically shoot bulk ammos from federal.

After looking into it further, I noticed the bull shadow barrel cam down as soon as the slide unlock or moved back. I am a believer that the bullet leaves muzzle after the slide slightly moved and I am suspecting this is the problem to my group with 147 grain. 
I also have another sp01, a 85, and a tactical sport and all three seems to have the barrel stay locked for a couple mm after the slide moved. However, I couldn’t figure out what is the difference between the bull shadow upper and my other Cz 
 

[Stuart]

Did CZC fit the upper to the frame.
I shoot syntech 150, 130 and 124 Zero in mine with no change in accuracy.

What kind of bullet? Jacket? Have tried a different oal? Different crimp? Etc,

[Rolly9]

Thank you for the reply. I am trying to figure out if I did something wrong.

I shoot full metal jacket federal american eagle in both 115 and 147 grains.
I put the gun together myself by opening the dust cover of the sp01 frame. Cgw kit was used because I like how it feels on my other sp01.
I also checked the barrel lockup using layout fluid and confirm the slide lock fit at the end  of the barrel lug hole when I put it together.

I only shot 200 rounds on my first outing with it because I just put it together maybe two weeks ago. Maybe it’s me did a poor job. I just didn’t get the accuracy from it comparing to my sp01 with cgw kit and 10x bushing. However, I do have a cut down czc match barrel on my sp01.

I might try it again this weekend after I buy some other ammos.

[Ktm45]

Rolly9..... 
 I also live here in California and put together a Bull shadow based off the B SA frame. (This state is a pain) I shoot predominately 147s. I do reload almost everything I shoot out of my BS. I do shoot 125 grain rounds every now and then but almost never shoot 115s. I just like the heavier bullets. It has always been my findings that I shoot 147s higher poi vs 115s. When I first bought my BS upper (fixed rear sight) I had CZC/Stuart blend a 75BSA. I was laughing the first time I shot it. It was like cheating. If I aimed at it I hit that spot... My sights were spot on from CZC. I’ve never ever got a setup that I didn’t play with the sights before. I’ve never touched these. Well I did make another BSA into a BS but I had CZC change it to DA/SA. That frame setup shoots exactly like the other SA only frame does.
I’m thinking I have a little over 2K (maybe closer to 3K) rounds through this slide now over the past 45ish days.  If I had to bet (I thought the 49ers would have won also) I think you are just feeling the shooting difference between the 115 and 147.  I loaded up some magazines for a friend to shoot awhile ago. He was shooting the lights out with his 115 rounds and I snuck in some 147 magazine loads. I could see he was wondering what he was doing wrong. Then when he adjusted to the heavier loads I switched him back to lighter loads...and again he was perplexed . I told him finely what I had done. He up to that time didn’t think it made a difference.     For a steel challenge round I like shooting 147s much better. If I was only going to shoot paper for accuracy only I’d shoot fast 124(125).  For just me I don’t shoot 115s much at all...if ever.     

IMO both POA and POI between those two weights are different. I noticed it also in my PCC. I only shoot 125s in my PCC.         

[coolbox]

What I noticed is my group seems to open up with the 147 grain while it shoots well with 115 grain. I don’t reload and typically shoot bulk ammos from federal.

After looking into it further, I noticed the bull shadow barrel cam down as soon as the slide unlock or moved back. I am a believer that the bullet leaves muzzle after the slide slightly moved and I am suspecting this is the problem to my group with 147 grain. 
I also have another sp01, a 85, and a tactical sport and all three seems to have the barrel stay locked for a couple mm after the slide moved. However, I couldn’t figure out what is the difference between the bull shadow upper and my other Cz

If you shot them the same day (meaning you did not have an off day), it could simply be that the ammo does not suit this barrel. Or it is a bad batch of ammo.

Maybe a stupid question, but do you have same rating recoil springs in all uppers? The bullet probably leaves the barrel before the slide moves anyways.

Do check the slide to frame fit. There should not be any front to back slop when the pistol is assembled. You should always feel the resistance of the recoil spring in the slide. There can always be a bit of side to side and up/down movement (very minor, in fractions of inches or mm) but never front to back. Since you 115s are shooting fine, you probably dont have an issue here.

If you could post a video or a few pics comapring different pistols as you have mentioned, you might get better advise.