Oh boy, I need some help...UPDATE

[Black Mamba]

I just got my Shadow 1000 back from CDT and something ain't right.

It broke and he had to make a part to fix it for me as well as replace a broken spring.  He gave it a Turbo Tune in the process.  (Thank you Charlie!!)

Once I got it back I took it out to get it sighted in and couldn't seem to.  I was getting scattered groupings with Gamo Hunters that previously grouped within 1" (10 shots) at 30 yards.

I tried other pellets that I have been very successful with in the past such as Crosman Pointed, Benji Diabolos and Predators.   None were grouping well and all of them had what would seem to be one or two flyers in a 5 shot string.

I checked my screws, I cleaned the barrel, I checked my scope, I checked the barrel crown and I chronoed the gun.  Nothing seems to be amiss with the exception of the chrono speeds not being too even between shots.  My first chrono checks showed some really wild variances with as much as a 150 fps change between some shots.  3 of my pellets were shooting about 80fps or more below normal.  I hung it up and tried again the next day.  The numbers were much better for all pellets so I just don't think that's the problem though because some of the off shots are....way off.

Anyone have any suggestions?  I have no idea what is left to check and I'm worried that there is something wrong that will need another trip for repair but I just got it back from The man.  What am I missing?


**Update** Talked to Bob this evening and he had a couple suggestions.  As Gene figured though, the best bet is to shoot it...alot.   So, I'll do my best to shoot it till my fingers bleed and let the parts break in.

[Gene_SC]

Hey BM

Here is a simple solution. Run about 1 or 2 tins of pellets through it. When CDT does a Turbo Tune, internally you virtually get a new gun back. He makes the new guides for the spring to fit a bit tight. He does that for a reason. Once your shadow 1000 is cocked and fired many times, it will all come together.

Another thing. Did you happen to chrony your shadow any time before you sent it to him? If not it may have been shooting at a lower fps. If that may be the case then the same pellets may not work as well because of fps changing. There are virtually many reasons why you may be having issues. Try a RWS Superdome or anything other than what you already have.

Good Luck

Gene

[Black Mamba]

I figured it might be the real issue.

When I got the gun originally tuned (Supertune) I had to put probably 400 rounds through it before it shaped up.  Then it was a tack driver.

I suppose I'm just nervous because the groups are pretty awful right now and I'm used to hitting whatever I want.  Heh.

The chrono history of this gun is pretty calm.  No real massive changes in the past which is another reason why I am a bit worried with the numbers I saw the other day.  As I said though, the day AFTER that it was chronoing properly and a bit higher (not enough to make a foot pound different) than previously.

Just can't help but wonder if I'm missing something simple that is adding to the lack of accuracy during break in.

[CharlieDaTuna]

Hey BM...check your e-mail.

[daved]

Hey, Greg,

Don't know if Bob suggested this, but I read a post recently where someone was having similar velocity variations from a Shadow.  They ended up shimming out the breech seal with a thin piece of wire or something, and solved the problem.  Might be worth a try, maybe check with Bob and see what he thinks.  Just trying to help.

Dave

[Gene_SC]

Question Dave

What holds the thin piece of wire in place under impact and combustion? Just wondering...

Gene

[vinceb]

I suspect the shim goes under the breach seal, where it would be effectively trapped.

I did the lil shim thing. I pulled out that long breech seal and put a small staple under it. Then slid the seal back it. It shimed the seal out just a tiny bit and pretty much cured the issue i had with the velocity variations. That seal was almost completely flat with the breech face. So i thought for awhile and tryed it out and it did the trick.

here's a link : http://www.gatewaytoairguns.com/airguns/forums/thread-view.asp?tid=1154&posts=1&start=1

[vinceb]

It's one of the few parts they sell.