suppose nifty is range bound say 10-20 points as usual for the whole day … i feel like scalping 10-15 points based on the resistance and support for the range … now if i use 50-100 contracts for that then what could possibly be some issues related to it…like how much of slippage for limit orders or …?
is it sane to go for 50-100 contracts for 10 points or so ?
Karan,
50-100 contracts is not a big deal w.r.t Nifty. Nifty futures are liquid enough to take 100 lots almost all the time. If you are using regular limit orders, there is no question of slippage as you either get filled at that price or you don’t. But, if you use SL-L, i would encourage you to have 1 pt difference between trigger and order price for 50 lots and 2 pt difference min. for 100 lots. But, in runaway markets, there is a risk of your order not getting filled. We all carry that risk in runaway markets.
About the sanity of the idea, it all depends on how comfy you are with 10-20 pts. By the way, taking 10-20 points is scalping for some(for traders who trade for 50-100 points) and absolutely ok for others (traders who trade for 5 points in NF). So, it boils down to your comfort level 
I feel, if you want to scalp, then 10-15 points are too much. Something which is less than five points after brokerage, can be considered scalping. Secondly, I think you should increase the Quantity (No. of Lots) to 200 and above. Even 1 point increment after your brokerage for 200 lots of NIFTY Futures, your profit will be Rs. 10,000/- (1 point x 50 Lot Size x 200 Lots)
See, it all depends on your risk appetite, amount of money you can keep in the trading account, your comfort levels etc. There are many more things to be considered. So it depends on you.
P.S. Whatever I have mentioned above are purely my views/perspective, please don't trade as per my view.
Thankyou madan
Madan, you have mentioned that there won’t be slippage incase of Limit orders, but he can face slippage in stop orders, so do you think its scalping 50-100 lots is still NOT a concern given that slippage can be faced in SL-M orders?
Karunakumari,
Yes - obviously, we will face slippage in SL-M orders and its a valid concern. I was referring to SL-L orders in my answer. Choosing between SL-L and Sl-M orders is always a confusing one. In a real dire situation wherein market is going against us in a jiffy, then SL-M might be of some use.