RuneScape - I'm not able flip barrows or any other weapon

I merch items with RS gold high purchase limits (10k-25k). I'm almost always flipping. I am focused on food, runes, and pots. I keep track of a few things which i am sure crash regularly and make money off that too. I'm always switching between expensive armours and weapons that I am using to keep my money and make more sometimes. I sold my bgs prior to it crashed and sank to 8 miles, sold my fury before it crashed, and then bought one for 13 mil.

I was able to sell it for 14.5 millimetres. Bought claws, lent for 1 mil total and the rest was sold. Since armours and weapons are typically in a continuous decline, it's good to have a plan like this.

I'm not able flip barrows or any other weapon or armour for any reason very well. Tips? I will buy pretty much everything that people are trying to rush sell and turn a profit on it. This is my example. I also made 150k off one person who rushed to sell his whip on the market for 1 mil. Like that.

My time to flip is based on the current trend of the item. If it's going up the maximum price I'll purchase at the current price (how I determine the maximum and min prices will be explained in the next section) before selling them at their maximum when the transaction is complete. Sometimes, i purchase/sell at 1gp higher than the min/max price, based how much profit I can make and how quickly i am able to purchase or sell.

If the price of the item is decreasing, I'll purchase at min price and instantly sell it for max price while still buying at the minimum price. My reason for this is that if I wait the sometimes 10 mins to max buy something that buy OSRS gold is trending downwards, the maximum will lower in that time.