Your problem is not the setting the bounces property of the scrollView but rather trying to access the scrollView property of the webView1 and webViewB objects. Before iOS 5.0 this property was not public so you cannot access it like that.
You would have to go trough all the suviews of the webView1 and webViewB and find the one that's a UIScrollView and than set it's bouncing property. You can do that like this:
if ([self.webView1 respondsToSelector:@selector(scrollView)]) {
    self.webView1.scrollView.bounces = NO;
    self.webViewB.scrollView.bounces = NO;
}
else {
    for (UIView *subview in self.webView1.subviews) {
        if ([subview isKindOfClass:[UIScrollView class]]) {
            UIScrollView *scrollView = (UIScrollView *)subview;
            scrollView.bounces = NO;
        }
    }
    for (UIView *subview in self.webViewB.subviews) {
        if ([subview isKindOfClass:[UIScrollView class]]) {
            UIScrollView *scrollView = (UIScrollView *)subview;
            scrollView.bounces = NO;
        }
    }
}
Let me know if that works for you.