10mm Loads for Ruger Re olvers

[Ramjet]

I found the one I own loves lighter bullets at just under a max load as CW said work your up you will find the sweet spot and many times that's a ways off of !ax loads.

[rognp]

...But factory loads I've tried pass what I'm seeing published for handloads. 220gr Underwood @1170 fps (1200 from a 5" auto claimed) and Doubletap 230gr @1045 fps (1100 from 5" auto claimed)...

That's pretty typical. Couple of things... DT tends to exaggerate their velocity...A LOT. Underwood usually comes in above stated velocity, though in the case of their 220 grain 10mm load, pull downs have shown that the bullet doesn't actually weigh a full 220 grains, while my bullets from the same supplier weigh over 220 grains.

Also, you're never going to get pistol velocity out of a revolver because of the gas escape between the cylinder and the barrel. How much velocity you loose is dependent on the particular gun and even the particular chamber, but a revolver will never equal a pistol for velocity if all other factors are equal.

Loading long might work out well...might not, depending on how far you push it. One thing to keep in mind is that the longer and hotter you load, the more likely you'll encounter bullet-pull. Bullet-pull will freeze a revolver up solid, and it takes time and shop tools to make it spin again. No velocity gains will ever compensate for that fatal flaw.

There are cases and occasions where comparable barrel lengths will produce velocities contrary to intuition. I had recently seen data supporting that, I believe bried somewhere in 10mm-. I couldnt find it this AM, but will see if I can drag it back into the light of day.  Poster had like 50FPS higher vel on some loads in the revolver, but not all of course.

[GarrettJ]

So I started down this path a couple years ago, but not so far as to fall down the rabbit hole. Using Longshot and loading to 1.395" OAL, I was able to get over 1400 fps. with a 180 gr. HAP, and no pressure signs. That's 100 fps faster than the top end book loads got me at standard OAL from the same 6.5" barrel.

I would not be uncomfortable going higher with this one.

I think the heavier bullets are where the long-loaded rounds would really shine. Maybe I'll tinker around with some over the winter.

But in the end I decided this is never going to overtake the traditional magnum revolver cartridges. At least not without going way over SAAMI max pressure. If I want more power, I have other guns in the same platform that are chambered in more powerful cartridges and have the same capacity.

And maybe it's a funny thing to get hung up on, but I never found an ammo box that works well for these longer rounds. They are too long to fit in a typical 10mm/.45ACP box, and too fat to fit in the slots in a .357 box. And they just rattle around too much in a .41/.44/.45Colt box. Silly thing to get hung up over, I know.

[FreeMe]

...But factory loads I've tried pass what I'm seeing published for handloads. 220gr Underwood @1170 fps (1200 from a 5" auto claimed) and Doubletap 230gr @1045 fps (1100 from 5" auto claimed)...

That's pretty typical. Couple of things... DT tends to exaggerate their velocity...A LOT. Underwood usually comes in above stated velocity, though in the case of their 220 grain 10mm load, pull downs have shown that the bullet doesn't actually weigh a full 220 grains, while my bullets from the same supplier weigh over 220 grains.

Also, you're never going to get pistol velocity out of a revolver because of the gas escape between the cylinder and the barrel. How much velocity you loose is dependent on the particular gun and even the particular chamber, but a revolver will never equal a pistol for velocity if all other factors are equal.

Loading long might work out well...might not, depending on how far you push it. One thing to keep in mind is that the longer and hotter you load, the more likely you'll encounter bullet-pull. Bullet-pull will freeze a revolver up solid, and it takes time and shop tools to make it spin again. No velocity gains will ever compensate for that fatal flaw.

There are cases and occasions where comparable barrel lengths will produce velocities contrary to intuition. I had recently seen data supporting that, I believe bried somewhere in 10mm-. I couldnt find it this AM, but will see if I can drag it back into the light of day.  Poster had like 50FPS higher vel on some loads in the revolver, but not all of course.

I'd sure like to see that.

[CtYankee]

...But factory loads I've tried pass what I'm seeing published for handloads. 220gr Underwood @1170 fps (1200 from a 5" auto claimed) and Doubletap 230gr @1045 fps (1100 from 5" auto claimed)...

That's pretty typical. Couple of things... DT tends to exaggerate their velocity...A LOT. Underwood usually comes in above stated velocity, though in the case of their 220 grain 10mm load, pull downs have shown that the bullet doesn't actually weigh a full 220 grains, while my bullets from the same supplier weigh over 220 grains.

Also, you're never going to get pistol velocity out of a revolver because of the gas escape between the cylinder and the barrel. How much velocity you loose is dependent on the particular gun and even the particular chamber, but a revolver will never equal a pistol for velocity if all other factors are equal.

Loading long might work out well...might not, depending on how far you push it. One thing to keep in mind is that the longer and hotter you load, the more likely you'll encounter bullet-pull. Bullet-pull will freeze a revolver up solid, and it takes time and shop tools to make it spin again. No velocity gains will ever compensate for that fatal flaw.

There are cases and occasions where comparable barrel lengths will produce velocities contrary to intuition. I had recently seen data supporting that, I believe bried somewhere in 10mm-. I couldnt find it this AM, but will see if I can drag it back into the light of day.  Poster had like 50FPS higher vel on some loads in the revolver, but not all of course.

A month ago or so I read an article about pistol cartridges reaching higher velocities out of revolvers than out of semi-autos. In this case the study was done with 9 mm, but the conclusion should be valid with 10mm. Revolvers have more distance from the case mouth to resistance (rifling) therefore more room to accelerate (freebore). Until a bullet leaves the cylinder there is no gas release from the barrel/cylinder gap and, given a relatively tight B/C gap (.006") the gas release does not make much difference (after .008" you start loosing significant velocity). So yes, revolvers can exceed published velocities since most published testing is done through semi-autos. I am not just quoting an article, I have found this to be true through my GP100.

[sqlbullet]

Revolvers have more distance from the case mouth to resistance (rifling) therefore more room to accelerate (freebore). Until a bullet leaves the cylinder there is no gas release from the barrel/cylinder gap and, given a relatively tight B/C gap (.006") the gas release does not make much difference (after .008" you start loosing significant velocity).

Do you have a citation for the article?  Not that I am questioning it, but I wanna read it

The other factor that is often overlooked with comparing velocities is that revolver barrels lengths are measured from forcing cone to muzzle.  The chamber and any freebore is not included.  And freebore can be generous, especially when shooting a cartridge designed for an auto-loading handgun from a revolver.  Additionally, most modern revolvers have the case head sit outside the back of the chamber to save manufacturing costs.  It is cheaper than recessing the cylinder for the rim.

A semi-auto barrel is measured from the breechface, so the barrel length would include the chamber, freebore and the case head.

Looking at my S&W N Frame 28-2 with a nominal barrel length of 6" I get the following:
    Barrel Length (Forcing cone to muzzle):  5.885"
    Cylinder length (cylinders recessed):  1.625:
    Gap:  .003
    Total Auto barrel length equivalence:  7.513"

An extra 25% of runway makes a big difference.

[Rock185]

  FWIW, I have routinely seen higher chronographed velocities in 9MM and 10MM revolvers than in semi-autos with barrels of similar length. My 3" Ruger SP101 routinely produces velocities equal to or greater than my 4"-4.4" semi-autos. My 5" S&W 610 revolvers did the same. For instance, CorBon 135 grain tested some years ago was actually about 100 FPS faster in the 610 revolver than the 5" semi-auto.  Id' have to dig through old chronograph notes, but IIRC, the semi-auto produced ~1475 FPS, the revolver ~1585 FPS.  But it varies from gun-to-gun, and is not carved in stone. For instance a 5" Ruger GP100 demonstrated velocities a bit slower than my current 5" semi-auto.  My current 4.2" Ruger revolver is a little slower than the 5" Ruger.

I've reloaded 10MM for a very long time, know it does not equal .41 Magnum, and never tried to approximate top .41 Mag. ballistics with 10mm. I want my ammo to work reliably in both semi-auto and revolver, so have not tried the longer than standard overall lengths to increase usable powder space.  I prefer bullets in the 165-170 grain range for reloading the 10MM. I've used a bunch of powders since the '80s, but have settled on AA-9 for top loads in the 10MM. Using this relatively slow powder has produced top velocities with no unusual pressure signs, and very good consistency since it meters so evenly.  My reloads with 165 grain bullets demonstrate velocities quite similar to the Underwood 165 grain factory ammo. No undesirable issues encountered with either the Underwood or my reloads in my guns.

[CtYankee]

sqlbullet:  I should have taken the time to find the article again when I first posted; it wasn' hard to find.  https://www.shootingtimes.com/editorial/revolver-vs-semiautomatic-pistol-a-ballistic-oddity/360682
It seems so logical that B/C gap would loose enough gas to lower velocity, but then we don't consider free-bore. Reloading manuals always warn about loading rifle bullets out to the lands because of the increase in pressure (but lower velocity and increased potential for accuracy). I never thought about it with revolvers, but neither did the authors of this article - it immediately made sense. The increase in velocity from unrestricted flight more than makes up for the loss of pressure at the B/C gap.

[Rock185]

CtYankee,   I still have that ST article, and have referred others to it.   I've mentioned the higher observed velocities from revolvers on other forums. Some were skeptical, and of course it is logical that revolvers would have to be slower due to that leaky B/C gap.  I was glad to see it discussed in the ST article, so perhaps other forum members would not think I was quite mad;)

[jamestap]

Fascinating.

That must explain why I get as good or better velocity from my 4" GP100 as whats published.

[sparkyv]

In a word, "freebore".

Very interesting...it has suggested to me a revised approach to my loading.  I appreciate the link to the article.  I've glossed over it before,  but this time read it with more dilligence and scrutiny