[Taterhead]

Originally Posted by pasky2112

I'm glad to see you have been using Blue Dot for so long. I just purchased a new G20 and reloading/handloading componants. I chose Blue Dot and Starline brass. But I'm not sure if i should go with CCI 300's or 350's. What is the logic of choosing a mag primer over a std primer?... slower powder = mag primer?

Thanks!

Go with 300s. There is nothing about 10mm auto that requires mag primers. I do use 350s for a couple of my pet loads with Accurate no. 9 (A9). A9 is about the slowest-burning powder suitable for 10mm Auto. It doesn't necessarily need mag primers. I did workups with mag primers years ago and I have loads that work great. Standard primers would probably work fine too. I just have not fiddled with re-tests since I have loads that work very well.

Bottom line is that mag primers can alter the burn speed of powders and impact presure in an undesirable way. All of the powder manufacturers that I know of call for standard primers (or in-between Winchester LP) for 10mm. Speer calls for mag primers for certain powders, but they are a rare exception in the various 10mm manufacturer data.

[pasky2112]

Originally Posted by dm1906

Good habits is the best laboratory. Never assume what you get is the same as what you had, even within the same name brands. In my case with this incident, had it been a full-on KB!, it wouldn't have been much more, if any, eventful. More alarming, perhaps, but not necessarily more eventful or dangerous. New loads get the full treatment. Spectra gloves, eye and face protection (ballistic hearing and eye protection is standard, in any case, all the time), and no mag. When a case fails on these, it will blow out the bottom (unsupported or least support at the ramp). With a mag in place, cartridges or not, the gasses build until something gives. This is usually the mag latch, mag, followed by the sides of the frame. An empty grip gives the gasses a path to exit quickly, almost always enough to prevent a pressure build, and pistol damage. Revolvers and single shots aren't so forgiving. They just blow apart. Ideally, we should be testing with a machine rest. I've never had one (although it's been on my list for 20+ years).

I've seen this happen a few times over the years. Most of them were new common name brands. The first was .41 mag, which resulted in separated case heads on Federal factory rounds. My Model 57 handled it fine, and has been fine since, after several thousand rounds. It did make a trip to S&W for inspection after that, though. The next was a bunch of "Eastern Block" 7.62x39 new brass. One crack and two blow-outs and I tossed the hole lot of 2500 (after disassembling 500+ rounds....not fun).

Great point about the mag removal. I've seen 2 blowouts in 5.56 AR's and the mags were destroyed, thankfully... and not the face of the shooter.

Man! I'm really getting some great tips for handloading from you all... THX!

[dm1906]

Originally Posted by pasky2112

Thanks. I see the value in them for added protection now. I don't think I could purposefully load rnds hot enough that I'd want to wear gear for blast protection. I appreciate the 'top fuel dragster' mentality, mind you. Magnums are great fun and useful. But to the point of risking life/limb? ....naahh...

Each to his/her own, but I wouldn't call it "risking life/limb". Only getting the most out of a potential, minimizing the risk at every opportunity. Start reading post #105 of this thread, and you'll see bad things happen, even when you do everything right. I don't cross hard lines. Those KB!'s weren't even warm, let alone up to 10mm pressure. Top fuel? Yeah, that's a pretty good comparison. I run 1320 faster than John Force. Eddie Hill was the first on asphalt, I'm first on paper (or freezer-fodder). I won't try to talk you into anything uncomfortable, unsafe, or compromising. Don't do anything that doesn't feel right. Ever. You'll live longer that way. I've been doing this for near 4 decades, and ain't slowing down now.

[pasky2112]

Originally Posted by dm1906

Each to his/her own, but I wouldn't call it "risking life/limb". Only getting the most out of a potential, minimizing the risk at every opportunity. Start reading post #105 of this thread, and you'll see bad things happen, even when you do everything right. I don't cross hard lines. Those KB!'s weren't even warm, let alone up to 10mm pressure. Top fuel? Yeah, that's a pretty good comparison. I run 1320 faster than John Force. Eddie Hill was the first on asphalt, I'm first on paper (or freezer-fodder). I won't try to talk you into anything uncomfortable, unsafe, or compromising. Don't do anything that doesn't feel right. Ever. You'll live longer that way. I've been doing this for near 4 decades, and ain't slowing down now.

I hear you. I wasn't trying to be critical or implying anything. My apologies if I came off that way.
I like to creep toward the edge too. My first reloads we .40 S&W out of a G22 with a MG 180g CMJ SCREAMING at 780 fps! :-) The guy who's chrono I was using said "These would be great for your wife to shoot." LOL Now, I need a 10mm to go the next level. I do appreciate your points about safety and carefully measuring and reducing risks and to expect the unexpected... Mr. Murphy rearing his ugly head! Sometimes we find ourselves at the edge without having walked up to it.

[pasky2112]

Originally Posted by Taterhead

Go with 300s. There is nothing about 10mm auto that requires mag primers. I do use 350s for a couple of my pet loads with Accurate no. 9 (A9). A9 is about the slowest-burning powder suitable for 10mm Auto. It doesn't necessarily need mag primers. I did workups with mag primers years ago and I have loads that work great. Standard primers would probably work fine too. I just have not fiddled with re-tests since I have loads that work very well.

Bottom line is that mag primers can alter the burn speed of powders and impact presure in an undesirable way. All of the powder manufacturers that I know of call for standard primers (or in-between Winchester LP) for 10mm. Speer calls for mag primers for certain powders, but they are a rare exception in the various 10mm manufacturer data.

Thanks Mr. Taterhead. Speer is exactly where I saw the #350's referenced. I've seen them in some rifle loads in Hodgdon 2012, too (for BLC2, I believe). I ordered 5# of BD and 1# of A7, W231 from PV for new 10mm. I already have kegs of powders for my .40 loads like A5, Power Pistol, Unique, WST (favored in that order). If mem serves me right, PP is the slowest but i don't think it'd warrant LPM's except maybe for experimenting. Don't think I'll b experimenting too much for now in 10mm. I've only been handloading/reloading for about a yr. but have gotten into it heavily. Precision Rifle forces you to do that ;-) It's fun to me.
So have you used any of those powders above I mentioned for my .40 loads in 10mm?
Seems most folks use BD.

Thanks again for sharing.