Bullets, Powder, Load Data, and Other Things
There is very little to no load data for the 7.62x45 Czech. Most people, myself included, use the upper end of the 7.62x39 data as the starting point to work out loads. For bullets, I use the bullets that I pulled from the dead original ammo, or the bullets available for 7.62x39 work as well. If you pull down the old Czech ammo to use the bullets or cases, DO NOT try to reuse the powder. I have played around with it, and it has not aged well. Very inconsistant and just not worth the risk. Save it to use for fireworks and such. My pet load is to reuse the 130gn Czech FMJ bullets over 25.7gns of IMR 4198. Again, lawyerly discalimer, doing any of this is at your own risk.
Now what you will want to do is use some fine files, emory cloths, sandpaper, and finally some super fine 0000 steel wool to slightly reduce the outside diameter of the case until it will slide into your chamber. Go slow, and just take enough away to get the results you need without making the case weaker than you need to. Keep using your chamber as a case checker.
As you slim the case down, each time you check it in the chamber, you can put just a little pressure on it with your thumb, and then use a cleaning rod to pop it back out. This will leave marks on the case (see picture above) to show you where more work is needed. When you have it where the case slides into the chamber correctly and headspaces on the shoulder like it should, then you can let the bolt close on it and pull the bolt back open. if the case ejects, you are done. If not, trim a little more. When the case chambers and ejects as it should, load it and enjoy!!
7.62x45 Czech Information
Now you will need to use your rifle as a case checking gauge, so make sure your chamber is cleaned spotless. In the photos above, to the left you will see what the case should look like if it is properly sized. On the right, you will see what the case you are working like will look like when you put it in the chamber just after sizing and trimming. This is due to the 6.5 Carcano having a slightly large web area than the 7.62x45 Czech. If you have a lathe, then you probably already know what you need to do, just skin it off until it fits the chamber properly, and you will be ready to load it up and head to the range. However, if you do not have a lathe, get your drill out (I used a dewalt cordless) and a Lee lock stud for .308 to hold the case in the drill.
Trim the case down to the top of the neck, and then run it all the way into your forming or sizing die. Clean off your lube, and final trim the case to it's final length of 45mm. Now you have something that looks like a 7.62x45 Czech case, but nothing is that easy, we are not quite done.
Starting with cleaned and decapped 6.5 Carcan brass, run it up into your sizing die just enough to expand the neck, but don't push the shoulder back just yet. You will need to trim the case down some before pushing the shoulder back. In the photo above you can see the 6.5 Carcano case on the left, and the same with expanded neck on the right.
So you have a Czech VZ52 rifle, and have discovered that the only ammunition you can find is surplus Czech berdan primed 7.62x45 from the 1950's that rarely fires and if it does fire, it is extremely corrosive and has unpredictable hang fires. So what can you do?? Well there are ways to make your own boxer primed ammunition, and I will explain below the two methods I have used with great success. However you will need to find a set of reloading dies to use. Unfortunately, there are no off the shelf die sets that I know of. I have a set of CH4D custom dies, and a set of Lee custom dies. Either set works well, but you will have to custom order them before you can make any ammo. These directions assume you are familiar with the basics of reloading. This is provided as a courtesy, We are not responsible for your results.
Making Boxer Primed Brass from Czech Berdan Primed Brass
The Czechs made two kinds of 7.62x45 ammo. The first kind they made had brass cases, and the second had steel cases. If you can locate some of the brass cased surplus, you can convert the cases to take a large rifle primer. In the above photo, you can see an original berdan primed case on the left, and a converted case on the right. To do this, you will need a good, accurate drill press, or a lathe. If you use a drill press, you will also need to make or buy a jig to consistantly hold the case centered on the press table. I have one that I bought years ago in a kit for 7.62x39 that does the job, or you can make one yourself out of a block of wood or UMHW plastic. Just make it with enough friction so the case does not spin on the drill or mill, but can be knocked out after completion. You will also need a No. 2 center drill bit, a 13/64 end mill, and a large rifle primer pocket uniforming tool on a case prep center (I use a Lyman). Using either the drill press with jig or a lathe, what you want to do is use the No. 2 ccenter drill to drill through the center of the berdan primer, strait through the bottom of the primer pocket and just into the case. This makes your new centered boxer style flash hole. Then use the 13/64 end mill to rough out the pocket. Be sure not to go to deep, the large rifle primer pocket should be between .1250 and .1320 deep. Once you have this done, remove the case and use the primer pocket uniformer on your case prep center to clean up and cut the pocket to it's finished size. You now have a boxer primed case, with correct headstamps that you can reload. With proper care and annealing, it should last through many reloads.
Making 7.62x45 Boxer Primed Brass from 6.5 Carcano Boxer Primed Brass
It is possible to make 7.62x45 Czech brass from 6.5 Carcano Brass. I have done this using once fired Privi cases, so if you start with fresh new brass or some other manufacturer, you may have to adjust some, but the basic work should be the same. Also I trim in two steps, some people will want to do it in one. Whatever way works for you, this is how I do it.