after about 30 shots my flints will just round off and stop sparking.  How do i keep them in shape? ive gone thru  3 flints and have only fired about 40 shots! Sometimes the corners will just break into pieces. But all i need is some info on how to keep them in working order so they dont round off.

Frontier,
One of my locks did the same thing for a while. A buddy of mine suggested I wrap the flint in lead versus leather. Leather can act like a shock absorber and the flint may "bounce" down the frizzen, he said. I doubted him, but for that particular rifle, the lead fixed the problem. I still prefer leather, but whatever works. To make one, just beat one of your round balls flat with a hammer to about 1/16 inch thick.

Frontier,
Does you frizzen show cuts where the flint hits it?  Could be the frizzen is not hard enough.  I have had some flints that just aren't any good, only one or two shots and they break in the middle, others last a really long time.  The lead Stryker mentioned works, but it will slow your lock time down just a little.

All the advice sounds pretty good  FG.  I've made Siler locks for many years and made many others from castings that were pretty raw.  

Heat treating the  frizzen needs to be carefully done so that it sparks but does not fracture.  Typically a frizzen can be replaced in a factory offering... or you can try to heat treat it again... or you can re-sole it.

I've run across frizzens that were too straight or the hammers have been bent so that the flint comes in at the wrong angle.  Once it turned out to be that the hammer looked correct but was actually a little long... it was made for a different lock.  I've tried bending both the hammer and the frizzen with so-so success.  On a finished rifle you are pretty much looking for trouble when you start bending lock parts since they can break... not the frizzen, of course, if it is correctly heat treated.  But if you heat it...

My experiences with man-made 'flints' has been depressing.  They seem to work for a short period and then let you down at the wrong time. I've pretty much stuck to real flints that are provided by those who really stand behind their product.  I even have some original french flints that were found in a New Orleans warehouse.  They are musket size so I really can't use them in anything else.

Here are a couple of links (one deals with too thin flints) to peruse:


http://www.onagocag.com/knapping.html

http://members.aol.com/illinewek/faqs/locktime.htm

Hmmmm....I seem to be having a simular problem with the flint shattering after a few shots.  When the flint strikes the frizzen I have great spark, but not great ignition.  The darn thing takes 3 or 4 strikes to get an ignition.
 
Since a picture is worth a thousand words, I will post a few, to give further insight.

Well....it seems that I have solved my own problem. I took some 2f triple seven and mortored it down to fine dust. I put this into my priming tool & gave it another try. Primed my pan 15 times and had it flashed 13 times. Found by wiping down the frizzen, pan, & flint between firings, I was able to acheive 10/10.
 
So....now I will be casting some roundball and will be heading out to the range this evening so I can shoot this flinter for the first time!
 
PS you probablly wondering why triple seven...well I can not get any black powder anywhere near here.....so I will have to travel to get some. The fella at the shop told me the triple seven would not turn to mush like pyrodex in humid conditions so I decided to give it a try. Range report and target photos to come.

Great 'miner.  I'll be looking forward to your next post.

Miner,
one thing from the photo's I would suggest. It looks like your flint is to large. The edge of the flint should be pointing directly towards the center of the pan when at rest. It's going to throw the sparks at that position, it looks like yours is pointing more toward the frizzen. Also at half cock, it appears to be pushing on the frizzen enough to crack open the pan. The flint should be close to the frizzen but not pusing against it. If you hunt with this rifle having a gap will do to things. Allow powder to fall out, and allow excess moisture to get in. From the pic's I think the flint position could be the cause of your slow ignition.