powder-puff 10 mm load

[Buck13]

I've ordered an 8# recoil spring for my 10 mm auto, with the intention to use it with a very light load to let recoil-shy friends try the gun, and ideally for cheap plinking. Any suggestions for bullet/powder combos that WON'T cycle a normal 10 mm recoil spring? I was thinking something like a 140 gr lead bullet and about 4 grains of Trail Boss, just because that's the fastest powder I now have...

 

[orionengnr]

Ummmm...
Type of gun might help.
Just sayin'...

 

[Buck13]

It's a Tanfoglio (EAA) Witness, base model steel frame 4.5" barrel. IIRC, the original spring rate is 16 pounds.

I'm also getting a 20 pound spring for the fun stuff.

 

[rsrocket1]

I think you'll have a hard time cycling the action with any load of Trail Boss in 10mm. It's so bulky you won't be able to get enough in there to launch the bullet to any decent velocity.
I've loved using it in non-autoloading guns like 38 Special because you can't double charge it and the recoil is very light.

I tried a load of 3.5g Trail boss in my 4.25" M&P 40 and averaged ~640 fps. This load put the powder in contact with the base of the 180g bullet so I couldn't fit any more in the case. The gun cycled properly about 80% of the time and failed to lock the slide back once. That was too light for reliable plinking for me.

3.0g Clays gets me 800 fps and feels almost exactly like a 9mm load. I've gone down to 2.5g with full reliability (so long as you don't limp wrist it) and even lighter recoil, but like the 3.0g load and use it with the boys when they want to shoot the gun.

I don't think you can put more than about 4 grains of it in a 10mm case without compressing it when you seat the bullet and that probably won't generate enough recoil to cycle it.

If your goal is to make single shot loads that WON'T cycle the gun, then your load in question will probably work.

 

[Buck13]

rsr1, was that with the stock recoil spring on your .40?

I rechecked the order, I simply got the lightest spring available which is 6#, not 8#. I'm not going to drop down to a lighter hammer spring, since that's less convenient, but this should make the action way easier to cycle. I wonder if the wimpy spring will even return to battery. The gun has less than 50 rounds through it (hope to break that tomorrow), so it's not what you'd call silky-smooth.

I haven't put any Trail Boss in the cases yet, but by the volume conversion factors from the Lee PPM chart, 4.0 gr of TB should be the same volume as the 13 gr of AA #9 I am loading now, which fits under a 180 gr bullet with a little room to spare. With a little 140 gr bullet, using 4.4 gr as calculated from the "max usable case volume" stated by Lee seems realistic. I should have checked that before I loaded up all my brass this week.

Clays sounds interesting, but at the rate I shoot, a 14 oz. bottle would last several lifetimes. Unless I get something that gulps down powder (like a .44 or .45 revolver, which is on my "maybe buy" list), my little bottle of TB is also going to be hard to use up, so I'm not enthusiastic about collecting lots of powders.

 

[readyeddy]

W231 will give you 40 S&W velocities and should be enough to cycle.

 

[noylj]

You can work down as low as you want--just stay above 500fps. The only "problem" going down in recoil spring is not having enough powder to close the action.
A case full of TrailBoss (do not compress the powder) will give you a light load just like in .38 Spl or .45 Auto. Contact Hodgdon for any data/recommendations for TrailBoss and 10mm Auto.
Have fun and watch for squibs.

 

[Buck13]

I'd buy a chrono, but I don't know of anywhere I can use it at a range in metro Seattle. One of the minor drawbacks of living in the city. So, I have to fly kinda blind WRT velocities.

 

[hAkron]

W231 (HP-38) proved quite accurate in my tests.

 

[rsrocket1]

Buck13, yes that is with a completely stock M&P 40 full size (not compact). I am not a fan of changing out springs simply because if one day I forget to switch springs, I'd bang up a gun with normal loads and a light spring. I like to tailor my loads to suit my guns.

Much more than working up a load, I tend to keep a good margin from the top of the loads and like to "work down" loads when wanting lighter rounds. I'd pick a fast powder like Clays or Red Dot and work down from the mid-range load until I start getting FTE's, stove pipes or failures to lock back. This would happen way before a stuck bullet and still retain high enough pressures to prevent sooty cases, gas blow back in my face or inconsistent burning of the powder. Once this starts happening, I go back up a reasonable margin and if I get 100% reliability, I make note of it and use it from there on.

Coincidentally, most of the optimal light loads I've found for 38/40/45 have been right in the 2.5-3.0g range with Clays and 3.0-4.0g Red Dot. I've worked down loads with Bullseye and Unique but would only use them in a pinch because those powders tend to generate lower pressures don't do as well with low recoil loads.

 

[ZeSpectre]

with the intention to use it with a very light load to let recoil-shy friends try the gun

Isn't that sort of like "trying" skydiving by jumping off a 2 rung step-stool? If they want to try a 10mm then make it worth while rather than risking a squib or other issues.

 

[rsrocket1]

Maybe he doesn't have any other guns like a heavy frame 357 to shoot light 38 specials in.

 

[Buck13]

Exactly. The only other centerfire handgun I have now is a 96-year-old revolver. I'm more interested in adding a .357 or maybe .44 to the collection than another, lighter, auto.

 

[Buck13]

To follow up with my results, I had loaded up some 140 gr TCFP bullets with 4.0 grains Trail Boss a few weeks ago, but hadn't had a chance to shoot them since my last couple trips to the range were at an indoor range that doesn't allow unjacketed bullets.

I took a couple of hours for lunch today and tried them. I only had a few, so I didn't bother to change the spring. To my surprise, they mostly functioned OK with the original Witness recoil spring. There was one failure to feed, and the slide locked open on the empty mag only about 50%, but this was way better than I expected. The Witness *does* have a reputation for being undersprung for full-house 10mm loads, so that may explain it.

Accuracy was very nice, and while not quite the weakest target load I've ever shot (I made some .32-20 with Trail Boss that, even in a revolver that weighs only 2/3 of the Witness, feel like a standard velocity .22), they were close enough to kitten-ticklers that I don't know if I'll bother to drop down a few more tenths and try the lighter spring. Probably instead I'll go up 2 or 3 tenths and see if I don't get back to perfect function with the original spring.