Nifty50 still has upside potential after its record-setting rise to record levels despite second wave of pandemic. However, technical experts warn that bulls could be losing steam and volatility will be more common.The index has increased by more than 13 percent in 2021, and more than 50 percent in the last year. It reached its peak of 15,915 on June 28, 20,21.Experts believe that if momentum continues, the next target will be 16,800-17,000 within 6-12 months. However, the journey wouldn't be linear like it was for a year. Most of the good news, whether it be earnings, vaccinations, or economic recovery is already priced in.Stock-specific actions will continue but traders should not use excessive leverage and stay invested in quality stocks across the market-capitalisation.Technically, Nifty50 was able to break from its May 2021 all-time high of 15,431 and form a bullish candle.Since the beginning of 2021, RSI has remained flat. Now it is trying to move into the overbought area. This indicates that bullish momentum could be regaining.The index trades above all its major moving Averages (50, 100 and 200 SMA), indicating short-term strength.In June, the index was subject to follow-up buying. It formed higher high-low formations and has been consolidating between 15,600-15,000.Since April 2021, Nifty has made a series higher highs than lower lows. Once the index breaks through the critical resistance at 15,900, it can rally towards 16300-16500 levels, Rajesh Palviya (VP Technical & Derivative Research), Axis Securities stated.The lower end of the range is 15,350-15,450 which remains a crucial support level to monitor over the next 3 to 6 months. He said that the trend will remain bullish if Nifty trades are above 15,000 on a weekly closing basis in the short- to medium-term setup.The bullish zone is where the monthly strength indicators are, which suggests that Nifty could continue its upward move to 16,800-17,000 over the next 6-12 months. Palviya recommends that any minor correction should be used as a buying opportunity.Market breadth has increased significantly, as the midcap and smallcaps indexes are both in a bullish zone. This indicates that the wider market will continue its upward move over the next few months.The bullish zone is also indicating a bullish bias in the Core Sector, such as IT, Metal, Cement and Banking & Financial.