22 mag mystery

[montveil]

I have a 22 mag Handi sportster.  I has had about 150 rounds fired through it and is 3 years old.
I was at the range the other day doing an ammo test at 50 yards. Much to my dismay, the shot groups with 30 grain bullets were dismal, approximately 11/2 + inches with several brands and bullet types. The performance was somewhat better with 40 grain bullets. However when I fired 50 grain bullets the group closed down to 1/2 groups. At least I have bullets that this rifle likes.
My question is why are the heavier bullets so strikingly better?
Is there anything I can do to improve the lighter bullet performance as I really don't like being trapped into one bullet, especially since it is rather unique.

Any suggestions

[montveil]

As a follow up, here is some more information with the ammo I used and what I have done to the rifle
Federal premium TNT HP 30 grain
 CCI V max 30 grain
 Winchester JHP 34 grain
 
 Winchester FMJ 40 grain
 Fiocchi JHP 40 grain
 Federal FMJ 40 grain
 CCI JHP 40 gr
 CCI Gamepoint 40 grain
 
 And the winner
 Federal JHP 50 GRAIN
 
 Would changing the forearm screw from 20 pounds help?
 I have free floated the barrel with a hard foam shim at the end of the forearm

[3leggedturtle]

Did any of things help.  You could also  try putting a shim under the front of the fore=end to put slight upward pressure on the barrel. Barring that I would lay in a supply of 50 grainers and be happy with it....    Todd

[montveil]

I have the executed the mods as stated earlier and the 40 grain groups closed up some. I  think the barrel may need more break-in as it seems that the groups are getting somewhat tighter with the 50 grain still the best.
I think I have to just shoot all the test ammo, a brand and box at a time, and see if there is improvement.
The rifle has had about 300 rounds through it and maybe it just need more bore polishing.
I will take the rest of the boxes, starting with the 30 then 40 finally the 50 and see what happens.
I need the practice anyhow.
At least I will find out the best of the weights and brands

[gcrank1]

This is going to cost you in ammo and time.
Take the forestock off, and shoot groups, then add an O ring, shoot, then go for the forestock tip pressure and maybe try different amounts of screw torque, etc., etc.
Use the best bench and bags and technique you can. Change only one thing at a time. Save targets, well noted and study them out making more notes. This could take a year or more.
OR
Just shoot it more. Mine has become better over time (make sure you keep the latch and shelf clean and dry!)
I can depend on my Win. Dynapoints (flash copper plated lead HP 45gr.@ 1500fps chono'd out of mine) and with a 50yd. -0- the 40gr. jacketed go about 1" higher, so Im good for distance too, no scope changes.
It is not the most accurate rifle I have, but it is OK.
(FWIW, most accurate: Martini International MkIII, 22LR, c/w 20X)

[montveil]

I have shot without the fore arm and there was no discernable differences so I figure the pillar bed and fore arm end shim is probably OK.
Looks like I have some homework and more shooting to do.. Thanks for the advice and help. My goal is to get to groups less tha 1 1/2 inch at 100 with 40 grain ammo as that is what I can get with Federal 50 grain. I have shot the 50 grains at the beginning and end of my testing to negate shooter fatigue
It takes a long time to shoot several hundred rounds out of a Handi, not like my 10-22

[cwlongshot]

That old Federal 50gr HP is one of my "secrete" weapons. YES they do shoot great!!
 
Surprisingly that 34gr HP Winchester always shot very well in my rifles as well. (NOT pistols) I am hoping to get my hands on some of the new critical defence ammo soon and check that!!
 
For me over 10, 22Mag firearms the CCI 40Gr FMJ is the most accurate bullet I have found.
 
CW