You do not need the best equipment in the world to start shooting Smallbore Rifle Silhouette but the riflescope is an extremely important piece of the equipment. The scope must be able to adjust reliably to the four different settings required to shoot each animal. If it doesn't, you may as well shoot from the hip. You can get away with a 9x scope to start with if that is all you have. If you have less than 9x it is going to add to the difficulty because of not seeing the targets clearly, if you do not want to invest in anything new, then go ahead and give it a try. In general the better scopes are the ones with target type adjustment turrets. These are much easier to adjust in the match. From some statistics taken at the NRA Smallbore Rifle Silhouette National Champiopnships, the vast majority of Smallbore Rifle Silhouette competitors use scopes with magnifications ranging from 20x to 40x. It is about equally split with half having scope magnification of 20x to 29x and the other half having 30x to 40x scopes. I use the 36x because I prefer to see more of the targets. With the extra magnification of the 36x scope comes the appearance of magnified movement. Some people do not like it and that is why some use the lesser powered scopes. One other thing is the field of view. With the wider field of view using the lower powered scopes it is easier to see that you are on the correct target. If you shoot the wrong one, it does not count - been there, done that! I am scanning regularly to verify my target.
If you are going to try what you have, take it to the range and test it for how well it will track for you. On a calm day sight in on the center of a target at about 50 yards and note the scope setting on the elevation adjustment so you can return to it. Adjust the scope up exactly four minutes (16 clicks on a 1/4 moa per click scope) and shoot five shots. Do not worry that it is not centered on the previous point. It will be shooting about 2 inches high. You will be checking the grouping pattern not how well it is centered on the target. Be sure to note the setting on the scope because you will need to come back to it. Adjust down exactly eight minutes, or four minutes lower than where you started, and shoot another set of five shots. Again note the position of the setting so you can return to it. Now randomly adjust to each of the previous three settings and see if it is shooting in the same place it was before. If your scope is tracking reliably you will be shooting similar groups in each of the 3 places as you adjust to them. If it does not track well it will not be useful for Smallbore Rifle Silhouette. That does not mean that your scope is worthless. For general purposes a scope just needs to adjust to where you want it set and stay there. It can still be a good enough scope for a squirrel gun.
It is hard to recommend inexpensive scopes. There are numerous brands of inexpensive scopes and in general, you get what you pay for. For most purposes an inexpensive scope will work fine on a 22 rimfire rifle if it is only going to be sighted in for one point and not adjusted frequently. When you are required to make multiple adjustments reliably as in Smallbore Rifle Silhouette target shooting it can be a problem. If you are putting it on a high power rifle, it must live up to the recoil without altering the sight setting.
Again, I am not claiming to be an expert in optics and have not made it a life study to find out about every scope on the market but the following is what I know to be quality name brands and models of rifle scopes.
Leupold $500 - $1,000 - This is the most popular brand of scope in Rifle Silhouette. It is 2:1 over the second place Weaver brand. They make numerous models which are well suited for Smallbore Rifle Silhouette.
Weaver T24 or T36 - $430 - I have a Weaver T36 on four Silhouette target rifles 2-Smallbore and 2-High Power rifles. I have a Weaver T24 on a CZ452 American I use for practice. Each one has worked reliably. One started having a problem, I sent it back and it was replaced with a new one at no cost. Needless to say, I like these scopes. Weaver is the second most popular scope for Rifle Silhouette by far. Based on 2007 NRA Smallbore Rifle Silhouette National Championship equipment survey only 13% of all rifle scopes were not Weaver or Leupold.
I am sure that Burris, Nikon, Swarovski and a few others all have some quality optics on some of their more expensive models. Shop around and get something you have confidence in, that is the most important thing. There are some very expensive ones you could probably throw down a mountain and it will still work fine but, is it worth the expense? It is up to your rifle shooting budget!
You should shim up the rear mount of your rifle scope if you are going to shoot Smallbore Rifle Silhouette. This will help to center the adjustment capabilities of your scope in the area it will need to be adjusted. If this is not done, you may not be able to adjust up enough to sight in on the Rams. I use two layers from the side of an aluminum pop can. These can be easily cut to size with scissors. Cut them to nearly the width of your scope mount and they will not show. One inch in length would be fine. Place them under the scope tube at the rear mount.
Frequently a shim is required High Power Rifle Silhouette. There are shims made to be placed under the mount bases where they attach to the rifle. If you are not sure if you want to add the shims, I would recommend verifying the ability to adjust the scope from the Chickens to the Rams before going to a match. Sight your rifle in perfectly at 100 yards. Then see if you can adjust your scope to a point where it shoots 12 inches high or about 12 minutes of angle. That is aproximately the adjustment required to hit the Ram Target.