Here is the rimfire strike. Excellent contact and 100% reliable.

You know, in the grand scheme of things it’s kind of a silly project, but it’s a whole lot of fun. The amount of labor per shot is pretty high.

Judging by the view count on this thread that is approaching 11,000, there must be a few more closet 25 RF fans out there.

Look forward to seeing some targets. 

One word of caution for folks is that with such a small case capacity and fast pistol powders thing can get interesting real quick. I do all my initial load testing in a 44 1/2, and probably was not as careful as I should have been.

I use Remington 1 1/2 primers because they are the softest ones I know of and did some of the initial load work up with converted Hornet cases before switching to converted 17 WSM cases.

The case volume of the WSM cases was a full grain less. In a case this small it makes a huge difference.

The problem is that there is no way to “read pressure signs” from the primers or case. The 17 WSM is pressure rated to 33,000 psi, even a Remington 1 1/2 won’t really show signs of pressure at 30,000, so your guessing in the dark. Even with Quickload it’s a best guess without bore size added.

Bottom line I was rocking those little 56 grain bullets out at just over 1800 fps.. Bad thing is that those were some of my most accurate loads.

Had that been in something like a Favorite, they could of been that little rifles last loads. 

Quickload guesstimated about a 4,000 psi jump in pressure to just over 20,000 psi.

That’s exactly why I use the 44 1/2 as a test rifle. Less to go wrong.

Just be careful in the older weak actions.

Other than that, have some fun.

Miscellaneous thoughts:

Maybe there's a market out there for the Hornet-based adapters?  Anybody got a tabletop CNC lathe?  Or a turret lathe?

Yeah, the majority of that market is old boys' rifles, some of which are none too strong.  I've done the pressure/bolt thrust calculations, and concluded that most of them should be held down to 1100 fps or so.  Rolling Blocks, 1915 Favorites, and H&A Junior/925 maybe 1400 fps.   

My measurements showed the Hornet based CF adapter to have less case volume than the WSM cases, and much less than original cartridges.  

ndnchf's Hornet-based RF adapter using the acorn blank primer opens the way for a lot of the small rifles that don't have enough hammer blow to fire the WSM cases.  In light of his accomplishment, I'm pretty much done with the WSM route. 

CF primers are in short supply, but so far as I can see the acorn blanks aren't.  But they are expensive by comparison.  But if we start flooding Gun Dog Supply with orders the supply may get tight.  I'm also using them in Jack Harrison's .32 adapters, so I've already got a couple hundred. 

I've been making die parts out of 12L14 steel, which will cut nicely with normal HSS tooling. No need for carbide. 

Now I want a chambering reamer.  And maybe an undersize reamer for making adapters?  

Do I convert my 44 back to rimfire?  And what about the Model 12/101 hybrid?  

The 44 and the 83 will stand 1800 fps pressures.  How do I keep ammo for those out of the 1894 Favorites?  

Phil

I'm glad to see you fellas are enjoying this as much as I     

I thought I'd show my shop made tooling for expanding the case mouths.  First I made this 3-step expander from a 1/4" bolt for use with .17 WSM.  For expanding .22 Hornet, the first step is not needed. It goes in the drill press. I made a simple jig from angle iron and flat steel to hold the case. It clamps in the vise, which is then clamped to the table.  After annealing the case mouth, the expander gets a light smear of Imperial sizing wax. Then with the drill press OFF, the expander is run into the case where it is expanded to .250".   

It wasn't until after I made this expander that I realized my rifle's groove size was .257" . So I made another expander from a 5/16" bolt that opens it up one more step to .256".

It may not be elegant, but it works great. I've done about 50 .22 Hornet cases with it.   

For those that want a centerfire version of .25 Stevens, but don’t want to convert .22 hornet cases, Rocky Mountain Cartridge will turn .25-10 centerfire cases for you. Excellent thread, thanks everyone.

Fortunately my gun club is located between my office and home. So stopping there on the way home from work is very convenient. So I stopped again today for another round of testing.

First off was to test the same 6.0gr of Reloader 7 (RL7) and 72.5gr Arsenal 257420 bullet, but with a CCI SP magnum primer, vice the standard primer. This gave a 45 fps increase in average velocity. 1002fps to 1047fps. Accuracy about the same.

Next was a bump up to 6.5 gr of RL7 from 6.0gr. Same bullet, standard CCI SP primer. This gave an increase of 109 fps, 1002fps to 1111fps.

Last was a bump up to 7.0gr of RL7. This is a full capacity load. From 6.5gr to 7.0 gave an increase of 94fps, 1111fps to 1205fps average. At 7.0 both ES and SD dropped considerably.

Despite the blurry target at 50 yards, the 7.0gr of RL7 seemed to be the best. Out of 5 shots I had one dang flyer high to the right. Grrrr. 

This little rifle is fun to shoot and really easy to load for.

Great thread ndnchf. Those case forming instructions are really helpful, thanks. Currently installing a CF block in my HW .25 RF (#2 weight barrel) and modifying some Hornet cases. I reckon the HW should be able to handle those 6 to 7 gr loads of Rel 7 with ease. I'll be using an Ideal 25720 in 67 gr. 
Spud