Repairing old fencing

[Keitai]

I've got some concrete posts which the old bolts have rusted so badly inside the bolt holes. Can they be knocked out so new bolts put in?

Was gonna add new rails on an old fence and just leave the old ones.

 

[Why Not Indeed]

I rate your chances of knocking out those rusted bolts without ruining the posts at somewhere in the low zeroes %. You could in theory drill them out but I can't see that it would be worth the candle.
You would be better off cutting them off flush [if necessary] and carefully drilling new holes. Presumably drilling vertically in line with the existing holes will avoid the rebar, if there is any.

 

[foxhole]

There is a wide variety of metal brackets for securing fence to concrete posts.

 

[Keitai]

I rate your chances of knocking out those rusted bolts without ruining the posts at somewhere in the low zeroes %. You could in theory drill them out but I can't see that it would be worth the candle.
You would be better off cutting them off flush [if necessary] and carefully drilling new holes. Presumably drilling vertically in line with the existing holes will avoid the rebar, if there is any.

Will an sds drill new holes through concrete posts?

I've put new rails on back of large fence but few nails missed, what's a good way to know position of rail when nailing from other side of fence? Couldn't get nail gun to fire through small trellis gaps too.

The lap joint I made was from chop saw so rough but figured for an old fence repair would suffice.

 

[Keitai]

There is a wide variety of metal brackets for securing fence to concrete posts.

I asked about these in fence shop but just got told to screw on 3 x2. What they look like?

like in pix