uscra112 wrote on May 25^th, 2023 at 11:44am:


I've been meaning to do that - so I just did. I drove a .259" bullet in about 2" from the breech end. To my surprise it is .253" also. I was expecting to find it larger.

And you haven't even met Alice or the Mad Hatter yet!

bullshop wrote on May 25^th, 2023 at 2:09pm:


They just arrived - thanks !

It may be that the employee who always seemed to have pulled the 0.257” barrels out of the bin to chamber for .25 Stevens Rimfire (causing the avalanche of comment on how 0.252” for the rimfire diameter is a “myth”), finally ran out of 0.258” bores and had to put a rimfire bore barrel into service for a centerfire.

Or maybe it was the guy on the rifling machine, totally hypnotized by the back-and-forth motion, who pulled whatever sized reamed blank out of the cart for the next setup.

At one of my jobs, a boring industrial magazine called Package Engineering circulated through the offices.  The things those guys could do with a sheet of plastic, paper or cardboard was nothing short of marvelous sometimes.

But, alas, the success of the actual package didn’t depend on the genius of the designer.  It depended on the cretin at the end of the package line, with his bag sealer or glue pot and utter lack of interest in the job.

In cartridge/rifle combination that I am concerned with pressure, I always use Remington 1 1/2.

The reason is that they are probably the softest, thinnest  cups on the market. There are specific warnings on the box not to use on high pressure loads. 40 S&W, 357 and such.

You get very early warnings with flattened primers. It’s not much of an indicator, but it’s something. They are pretty flat and will flow into a loose firing pin hole as low as 20,000 psi. I don’t trust them over about 32-35,000 in a modern pistol. It’s like they never updated them from the Blackpowder days. REM 2 1/2 seem to also be a holdover. 

They do seem to have very good ignition with most powders.

Two thoughts that popped into my head when I read your post. First about the Primers.  Normally when starting to develop a load for smallish small bore case I start the process with SP primers.  In your case with such a long case and powder column standard SP primers may prove inadequate.  That is a long powder column for that spark to have to penetrate. What I suspect is a primer with the longest flame duration is what will work best and that likely means a magnum primer. I believe the longer flame duration is what will be needed to get good ignition uniformity in that long case.
  The other thought that popped into my head was what you said about case neck tension when sizing bullets smaller than standard.  If it becomes a problem what I would do simply because I have them is to slightly neck size your brass in a 25 ACP sizer die and carbide would be better but not necessary.  If you already have a bushing die for your 25-25 then no problem just add the correct bushing to your loading kit.
I will also mention that I have successively sized down bullets as much as you now need to and had very good performance with those bullets but those were sized in steps of about .002" increments.  Sizing down several thousandth's in one step seems to not work as good.  Sizing in small increments seems to eliminate bullet base finning and sizing nose first keeps things far more concentric than sizing base first.   
A regular lube sizer can be used to size nose first in a separate operation from lubing.  I can explain how if you wish.

BS - Thanks for your thoughts, and yes I agree about use of magnum primers with partially filled long cases. 

I have been using a carbide .25 acp sizer for my .25 Stevens cartridges and can use it for this too. I don't want to work this pricey brass any more than necessary, but frequent annealing will mitigate that concern to a good extent. I also make my own neck size bushings for use in Lee universal expander die bodies. I have no use for the internal flaring parts that come with these dies, but the bodies are wonderful for a variety of uses. So if the .25 acp die isn't quite right, I'll make a bushing to suit.

I've ordered NOE bullet sizing bushings in .001" increments down to .254", so I can sneak up on the needed size without drama. The lube grooves will be reduced, but the addition of a light coat of JPW/Alox tumble lube should offset the loss.

Paper patching these little guys could be a challenge with my aging fingers and eyes, but its worth the effort to try out the concept.
Steve

Back from the range.

First firing of the RMC brass and 85gr, .257" diameter Winchester bullets. Nothing spectacular, but I'm pleased for the first time out with them.  I tried 10.5 gr of Reloader 7 which gave 1504fps avg. 11.0gr gave 1617 fps avg. No signs of excess pressure. No visible signs of leading, but I haven't cleaned it yet.

When I did my part, both were good for about 1.5" at 50 yards. Not great, but better than the last time. Next time I'll size the bullets down a bit. 

Great fun, but much more work remains.