Some 10mm thoughts from a new guy...

[Ridgerunner665]

I'm not a new to reloading, not by any means...just new to the 10mm.



A few things I've realized after much reading and research...I welcome your additional input.

People say the 10mm case would be stronger if it used small pistol primers...at a glance, that would seem true, but the 10mm case was formed from the 30 Remington (a rimless 30-30 that hasn't been commercially loaded since the 80's). The 30 Remington had an operating pressure of 42,000 psi and used standard large rifle primers.

The 10mm operates at 37,500 psi...the case is plenty strong enough to support this pressure with a large primer. The 6.8 SPC, which is also made from 30 Remington brass, operates at 54,000 psi using large rifle primers, the 6.8 can be had with small primer brass...so can the 10mm, but it is unnecessary for both.

Magnum primers...some folks say they are needed, and they will work...but I don't think they are necessary.  The 40 S&W uses small primers with only slightly less case capacity. The 10mm doesn't have enough capacity to need magnum primers, even with slow powders...the large pistol primer, in a case that small, is plenty.

And lastly...I thought it'd be bigger!

[happy trails]

another issue I heard about brass being 'too weak to stand up to reloads'.....

I'm no beginner at reloading pistol cases, although fairly new to 10mm reloading.
Even my local lead casting supplier, of much exposure to the frailties of all sorts of reloader blues, told me not to expect more than 'just a couple at most' reloading cycle before case failures.

I've been reloading the same basic 800 Starline cases repeatedly since last February.  Have gone thru 8 cycles so far, using same brass with a variety of recipes from 180/165/155 cast and plated boolits.

These have all been in the 1050-1250 fps range as published by the Lee 2nd & Hodgdon on line data.

The only brass I've lost to date was one I stepped on and mashed too bad to recover.

These have loaded in the same 2 handguns, either S&W 610 revolver or Sig 220-10.

I'm pleased with the round so far.

[TSP45ACP]

Love my Delta......only time the 45's get shot is when my wife comes shooting. Wanted to shoot the nuclear loads....i.e. Underwood, so I had a Clark Customs ramped/fully supported bbl installed, Trijicon nite sites and a host of other "personal preference" mods done to it.  I've got about $2400 into a $1000 gun.  It's my EDC gun.


Haven't had much trouble with brass going bad so far......bigger problem is getting brass at reasonable prices.

So far I've only used Longshot and I'm happy with it's performance, so I doubt I'll use anything else unless I can't get it.  Currently have some Power Pistol, Silhouette and Unique if needed.

Also, I have only loaded lead 180g Penn bullets, 155g Lucky 13 green coated Zombie bullets, and 180g Blue bullets.

My hot load is 8.8 (with the Penn 180's), and I've gone down as low as 5.6 for some gun games comps. For everyday range time, I've settled on 7.8-8.0 for all the above referenced bullets.....nowhere near max, but still some pretty good pop.

I haven't chrono'd any of these loads, but the 8.8's have more recoil than some of the factory fmj loads I've bought.   Tracy

[Ridgerunner665]

Haven't had much trouble with brass going bad so far......bigger problem is getting brass at reasonable prices.

I got the last 2 bags Bass Pro (Bristol) had for $25.99....they still have it online looks like.

Midway has it $20.99 (I had a Bass Pro gift card)

[sqlbullet]

I buy brass by the 1000 from starline.  When I break open a bag of 1000, I order another.  Happens about every 5 years or so.

I almost always loose them before I have any case failure.  I have had maybe 10 split mouths in 10 years of reloading.  All of them were from brass from the early 90's.


I agree that small rifle primers, while they may make the case theoretically stronger, are not needed.  And that magnum primers aren't needed.

[fltbed]

I've always looked at it from another direction.  Why do so many handgun calibers use a large primer at all?  If you look at rifle calibers, with today's smokeless powders, you don't really need the extra amount of priming compound available in a large primer till you try to ignite 40+ grains of powder.  Why do so many pistol calibers use a large primer when it's not really needed at all?  It sure is nice being able to use the same primer from my 223 in the 454's I load.  Why can't I use the same primer from my 357 magnum in my 44 Special?  It sure would make stockpiling components easier.  (and yes, I'm one of the few that love the small primer 45acp)

As for using magnum primers, I ran some chrono tests during the recent primer shortage and discovered, there are a few powders that just don't care what primer you ignite them with till you get near max.  A lot powders show higher extreme velocity spreads and sometimes loose accuracy with a magnum primer.  and very few actually show a slight improvement in consistency and accuracy.

Jeff

[happy trails]

re: "as for using magnum primers,"

I too ran chrony tests years ago and had little data supporting any conclusion one way or another.

My own observations from using mag/standard primers, has been absolutely ~zero~ differences in my target groups or (admittedly large POI) results on steel targets at least out to 50 yards.

There was a move to run small primer 45 acp a few years ago.

The argument for large/small primer sizes is a different discussion.  Seems to be 2 groups similar in the vague advantages of either as the 'daylight savings time' conundrum.

[sqlbullet]

If you are a 1K yard benchrest shooter, small primer pockets offer some real advantages as the SD and ES produced by small primers is less than those from large primers.

For a pistol round with an effective range that is, at very most, 1/10th that distiance, it seems there would be no real advantage.

[Ridgerunner665]

Agreed on the benchrest shooting... That's the one discipline where one could, and would, notice the small differences.

[The_Shadow]

10mm brass is strong enough for the most part.  But different makes may not fare well at the very upper limits because of several factors.  Understand that the 10mm semi auto is a very dynamic firearm & cartridge in the shooting situation.

1.) Case support is a number one issue, over size / loose chambers coupled with lack of case support at the feed ramp will allow expansion and even over expansion.  Faster powders can spike to near upper pressures faster snapping the casing outward to expand fully.

2.) Brass alloys differ across the various makes with some softer and more malleable (these can stretch / flow / smile)(better for reloading over all) and some stiffer and less malleable (can only stretch so much / split easily / can tear, fail catastrophically. (not as good for reloading)!

3.) I have seen the larger primer pockets stretch with heavy loads to the point the primer popped out during firing.  This tells me that the limits have been exceeded and loads need to be adjusted and backed off some.

In closing, understanding the limitations of your firearms and the properties of your brass, as well as the potential of your loadings can help with your safety, and longevity of your equipment...

I usually do load work ups using magnum primers so that the load is safe doing so, whereas non magnum leaves no room if the swap is done inadvertently.