I seems to miss pin 10 spare regularly. I could be getting 90% of them one week and the next week drops to 20%. Been practising but still inconsistent.
I am using 14lbs strike ball and same weight for the plastic ball on pin 10 spare. for rest of spare, I use my strike ball.

1. Do I use a lighter (13lb) ball for spare?
2. How can I improve on my pin 10 spare?

thank you.

get a coach, develop a system, and practice.

Here's what I did when I returned to the game almost two decades ago. (I've had youth experience, but I still sought the help of coaches available to me)

1. got a coach.
2. bought a spare ball that was the same weight as my other ball. 
3. I was introduced to the 4th arrow system.
4. And practice.


I'm 91% 10 pin because I repeat, well not always, but i repeat the same "steps" prior to shooting a ten pin.

1. off the approach, I "putt my ten pin".... visualize the balls path from the foul line through the arrow, and then to the pin.

2. just like most here have mentioned, line myself up/square up to the ten pin. at this point too, I draw a line with my third eye ball from the pin to the arrow, then to my ball, and then back to arrow.

3. I do throw 1 to 1.5 mph faster (17.5-18 mph) with my spare which can hook. I should flatten out my shot, but I'm tired of buying spare balls or fixing the thumb hole - I roll over my thumb hole.

If I followed these steps 100% of the time, I'd be better than 91% 10 pin shooter.  I do at times use my strike ball and throw back up following the same method but the speed. The faster I go, the easier I miss......

Great advise here, xrayjay hit the nails on the head here, as I've repeated the same steps that he has, only I did it all myself w/o a coach.

Some excellant replies already. My 2 cents... stand as far left as possible and definitely stay square to the 10 as you progress through your approach. Be diligent about reaching up at AT your target. Also, consider ditching the plastic. I think it decreases conversion percentages when playing cross lane, at the 10. Good luck.

Really? Please... 

Recently I have been concentrating throwing my plastic spare ball with the same speed and release as my strike ball. Think before I was babying it a bit. Think my % has gone up since then.

Absolutely, Milo. A hooking ball increases my miss area. I understand folks feeling plastic is required for spare conversions. It is not, but to each their own.

^^^^^^^

Absolutely, Milo. A hooking ball increases my miss area. I understand folks feeling plastic is required for spare conversions. It is not, but to each their own.

No one is saying plastic is required, it just makes things simpler

One of the main reasons for using a plastic ball is to take the lane conditions out of play. This along with going cross alley at a 10 pin gives you the widest margin of error.

Yes if your really good at flattening out your shot, you can use your strike ball. Especially if your just bowling in league, but if you start bowling on different conditions.

Then you better really be good at it, because resin balls (and urethane) can hook when you least expect it. Especially if you slip up on your release a little bit.

Most players that "hook" at the 10 pin, do so because when they tried using a plastic ball. They found out just how wildly inaccurate they were and didn't want put in the practice to improve it.

Throwing harder and Hooking at the 10 might help if the player is always missing right when they throw straight at the 10. But they then tend to over look all the times the ball hooked pass the 10 and had a open.