The lever screw is about a 10-40, link sccrews are about 8-40, however they are generally a little bigger than modern spec's. I don't have the exact pitch dia info but if I needed one I would just cut the thread till it fit the mating part to whatever clearance I felt was appropriate. A properly fitted Ballard should "snap up" without any barrel screwed in. If not, work on the parts to remove any excess play anywhere in the lever/link/block relationship. You can get a little extra here by making a new link and adding .010" between hole centers. An old trick to tighten one up is to peen the end of the breechblock tail down. Maybe that's ok for a .22 but it won't last long with heavier calibers. A better way is to run a set screw through the front tang sight hole. Then you have an adjustable lock-up. Another advantage of the screw is the thrust of firing is away from the screw where as thrust is directed towards the peened area of the the breechblock tails which is why that way don't hold up as good. The "snap" comes from the top of the breechblock tails contacting the reciever. this snap should start when the lever is about 3/8" from closing and it should go over center. If it closes but feels mushy instead of snapping the lever needs to be timed by bending it slightly down. Likewise, if the lever gets tight an inch before the reciever it needs to be bent up. All of this fitting should be done with a threaded plug in the barrel hole to hold the breech block to the rear against the recoil shoulder of the reciever. However, the blocks aren't right if if they require the barrel or plug to provide the snap". when you are done you should have an action that snaps up without a barrel screwed in.
Maybe this a lot more info than you wanted, my apologies if that's the case.
kootne

Kootne,

Thanks and no it is not too much info. It is just what I need to get started. The wear points on the block and receiver are mated with no excessive wear evident. I don't think the blocks have ever been separated as the screws show no signs of being removed(damaged slots).I am going to measure all the screw dias. and mating holes then hone any out of round conditions and make new screws to fit. If I need a new link where can I get one? Is new Ballard still selling parts?

JHolland

kootne wrote on Sep 15^th, 2013 at 6:33pm:

 
Just looked--don't see it listed.  Wish someone offered it.

Campbell's first Win. SS book shows a new link being made just as you described it.

Wyoming Armory carries links for Ballards as I have purchased from them. Look under "Services & Prices", bottom of page. "Wyoming Armory has begun production of replacement parts for the Ballard single shot rifle, as well as the Winchester Model 1885. Parts commonly in need of replacing such as firing pins, springs, sears, extractors, lever and breechblock screws, breechblock links and hammers are in stock. Major components such as breech blocks, levers, double set trigger assemblies will be available soon. Small supplies of original production parts are available for restoration projects. Due to the nature of original 1800’s production tolerances, replacement parts should be hand fit by a competent gunsmith. Give us a call with your needs and we will do our best to get your old Ballard or Highwall back into shooting condition." 

Richard

The screws on the ballard .172X40 closes tap i found is a 6x40 STI tap or as most know it a heilcoil tap. the lever and hammer .227X40 so a 12X40 tap  is .010 to small. next tap 7/32x40 is .2187 is about .008 to small. I most likley look at the STI taps in this range and all the std specials and didnt find any close. at one time I was going to have some costom taps made in this size but never did  still could be done 12 taps would be under $200 I think its been a long time next screw are the DST plate screws .135X42 no tap costom only Ken CCS&M