10mm Cratering normal?

[J.W.Proctor]

Hey long time reader first time Poster. So go easy please.
Being new to hand loading and firearms having come from anti gun family I have somewhat thrown myself head long into it and seem to have swam out a little past my depth.
After the purchase of my first gun I was drawn to reloading for Economic and entertainment purposes. I have started to reload now to my 10mm. Which As I understand is on the higher side when it comes to pressure?
The problem is I have no one to turn to when it comes to advice or experience in such matters.
Which brings me to my question, is this amount of cratering normal or am I in the Danger Zone ?
(I do not recommend anyone attempt to imitate this and accept no liability if you do and it goes south)

I Do have a chronograph to test velocities.
The following is some more data though not sure if it is helpful.
Gun: Springfield Xdm 5.25 barrel (Stock everything)
Bullet: accura 180 gr copper plated HP (yes their not a cheap as lead But they’re not as expensive as name brand bullets either)
case: mixture mostly S&B and some virgin Star-line mixed in
Primers: CCI and Winchester (side note I attempted to see if there was a difference in velocities based on primer and same charge.... there was none that I could tell)
Breakfast: eggs,toast and 3 cups of coffee
Temp:43 degrees according to my car thermometer


The cases are in order from left to right
1. S&B 180 gr -Control for standard
2. Buffalo board 180 gr- control for p+
3. Longshot- 9 gr
4. Power Pistol- 7.6gr
5. longshot-8.7gr

As you can see the only apparent signs of over pressure are the slight cratering a small ding on the head (think that's the right word) of the 9 gr Longshot brass which must be from the ejector?
This is defiantly not present on the factory rounds.
The 9 gr of long shot is .5 grs below the book max for this round. But my question still stands should am I just being overly cautious or have have I the max charge for my specific gun?
Feel free to ask questions and I'll answer best I can.
Any wisdom is appreciated.
Thanks
JWP


Sorry the photo is so blurry its hard to resize without something getting lost in translation

[Nick_C_S]

Welcome to TFL J.W.

I load 10mm, but not a lot. I have two Glocks chambered for it. Glocks strike the primer different than Springfields, so the primers' appearance are rather apples n oranges. That said, I have looked at a lot of primers over the years; and none in the pic raise an eyebrow with me. All of them look fairly normal.

Reading primers for signs of pressure is a bit like reading tea leaves - only, not as accurate.

I do recommend getting/using a chronograph.

And just to give my perspective: The advantage of 10mm is that it's a big, powerful round. One need not load them to the top of the scale to acquire an effective (for self-defense) round. I have loaded up some fairly hot ammo for testing purposes; but all of my "production" ammo has been slightly de-tuned. For me, I see no reason to go hot.

[T. O'Heir]

"...max charge for my specific gun?..." There is no such thing. There's no SAAMI spec for 10mm +P ammo either.
"...copper plated..." Those are not jacketed bullets. Plated bullets use cast bullet data. You're close to Max for a jacketed bullet. Using jacketed data for a plated bullet is likely the cause of the primer flow.
Hodgdon shows the Max load for a 180 grain jacketed bullet is 9.5 grains of Long Shot. 8.5 is the Start load.
Alliant shows 9.3 of Power Pistol as Max for a Jacketed bullet. 8.4 is the Start load.
Dunno how reliable this data is, but there's a cast 180 Max load(8.7) using Power Pistol on the 2nd page.
http://www.castpics.net/project2/Cas...t.php?start=21

[Dufus]

From my experiences, cratering in your photos is not abnormal in that the edge of the primers are still round and not flattened.

I only see 2 primers that indicate flattening. One on the second from top row and one on the bottom row.

I do not see any over pressure signs in your photo other than the 2 I mentioned.

The cratering might be that the firing pin hole is just a few thousands too large.

A bushing could be installed to tighten up the firing pin hole.

[Bart B.]

10mm standard pressure limit is already what 9mm Luger +P specs are.

Why is that insufficient for your needs?

[AgedWarrior]

I really do not see anything alarming. The primers look pretty average for a striker fired pistol; has a little striker drag. What is being referred to as cratering, looks more like a typical striker unable to get out of the way fast enough. However, primers are, as already noted, not the most reliable to read.

[J.W.Proctor]

Thank you for your prompt responses.
I did actually manage to use a chronograph for some of the rounds.
my power pistol 7.6 data seems off from an old lyman book I have- average 1004FPS but maybe that's due to using jacketed as opposed to plated. They did not have any other 180 gr bullets in the book.

[IMG]Edit: Please do not post copyrighted material without the permission of the copyright holder. See the board policy on posting copyrighted materials.[/IMG]

Longshot 8.7 gr averaged 1257-faster than I expected
Longshot 9 gr averaged around 1290 fps which is right around the speed for max charge according to my lee reloading manual, Even though I'm nowhere near that.
Would these velocities be caused by the use of plated bullets?

I am trying to develop the most accurate charge with the right balance of power and cleanliness for target shooting, not go "nuclear" or anything. From what I understand it is often the more powerful loads that lend themselves to this purpose. But maybe that thought comes from spending too much time looking down the rabbit hole that is the internet.
I didn’t think I was in danger until inspecting the cases and collecting the velocities.
Jwp

[Marco Califo]

If you look at the top of the forum (thread list) you will find an official loading data thread with links to published manufacturers data. https://thefiringline.com/forums/sho...d.php?t=435562 Look at different sources; you will different data. I look at Alliant data for using Alliant powders. Bullet makers also have data: Barnes, and Speer present data from a variety of powder makers.

I agree there is not a good reason to up-load 10mm past published loads.

[Nick_C_S]

my Power Pistol 7.6 data seems off from an old lyman book I have- average 1004FPS but maybe that's due to using jacketed as opposed to plated.

Generally, if all things are equal, the jacketed bullet would yield less velocity, not more. And the difference wouldn't be nearly that great. Lyman uses a 5" test barrel, so that doesn't explain the difference either. I don't know why there's such a gap in velocities, but . . .

I checked my chronograph data. And I too have loaded a 180 plated bullet with Power Pistol. Looks like I only chronographed one charge weight and it was something a little over Lyman's max there (It's been 5 years, so I don't remember where I got the load data; but I can assure you that I used something published.) I got 1058f/s from my G29 (3.7"); and 1101f/s from my G20 (4.6"). That jives much closer to your results.

[tangolima]

According to my own experience, friction in descending order.

Plated bullet
Jacketed bullet
Cast bullet

So I expect plated bullet goes slower than jacket bullet. You got faster speed than published jacketed bullet. I would think the pressure is higher than expected. A few of the spent casings show cratering. With 2 signs pointing to the same direction, I would drop the powder charge by 5%. It is just me, who is a known coward.

-TL

Sent from my SM-N960U using Tapatalk

[Mike / Tx]

I load a lot of 10mm and my barrel lengths are longer than any I've seen load data for. I keep the pressure on the lower side using the slower powders for most of my loads. I use mine for hunting so I do want upper end velocity but not so much in a +P load.

Your brass doesn't look bad IMO, but I would not try to push the plated bullets too hard. If you are going to work up to +P territory go with a jacketed bullet and at the very least use the Gold Dot 180gr. I have shot these since they came out and they do VERY well over a load of AA9 up to 1350fps from my pistols. Like I mentioned above my barrels are 6-7" and I get added velocity due to that rather than more powder.

If you can find them in stock, the Winchester 180 JHP is also a good bullet I've shot a ton of. I've recently been pouring my own cast bullets to try out soon. Going off what my good friend has done with them they look very promising at around 1150fps using AA7. These should do fine for hog loads in the areas we hunt.

Good luck with yours and go for accuracy over speed and you'll be better off.

[Don Fischer]

I believe the cratering you see is caused by a firing pin hole a bit on the large side, no problem! Look at the edges of your primer's, they are all round none appear flat to me as in a pressure sign.

[sparkyv]

Originally Posted by Dufus

From my experiences, cratering in your photos is not abnormal in that the edge of the primers are still round and not flattened.

I only see 2 primers that indicate flattening. One on the second from top row and one on the bottom row.

I do not see any over pressure signs in your photo other than the 2 I mentioned.

I agree with Dufus. I reload the 10mm also, and sometimes pretty hot. I shoot stout factory ammo and use those shot cases/primers as a baseline for my reloads.

[Grey_Lion]

Can we get some pics at 90 degrees to what you're showing? - I'd look to see if any of the primers are seating high after discharge as to one thing you might look for in an over-pressure situation. The camera angle you have there might show us severe flattening or holed primers, but wouldn't give us a good view of the primer seating post discharge. But the pic you have there, I don't see anything that'd concern me. You mention mixing CCI and Winchester primers. But you don't mention which ones specifically. Please spec that as well. i.e. - I use CCI 500 SPP in my .40 S&W.

[Dufus]

Winchester primers are no longer plated, so they are easy to spot in his pictures.

I don't use magnum primers except with a few powders such as AA 9, WW296, H110, H4227 and IMR 4227. Just the slower handgun powders in large cases.

[J.W.Proctor]

Can we get some pics at 90 degrees to what you're showing? - I'd look to see if any of the primers are seating high after discharge as to one thing you might look for in an over-pressure situation

To answer your question... I tried. But to be honest there isn’t much to see. The primers can’t really be seen from the side angle at all. I took some photos but they just like 90 degree photos of some slightly dirty cases.

You mention mixing CCI and Winchester primers. But you don't mention which ones specifically. Please spec that as well. i.e. - I use CCI 500 SPP in my .40 S&W.

As to primers I haven't used anything other than the large pistol CCI #300 and the Winchester large pistol primers (couldn't find a number). No magnums or anything. In the photograph the silvery looking ones are the CCIS.

https://accuraoutdoors.com/faq/
I have done a little research and am starting to think that the cratering may be caused by a larger firing pin hole as has been put forth in this thread.
Though the velocity of my rounds is still somewhat alarming. According to Accuras website their jacketed rounds can use the same data as jacketed as long as one does not surpass 1300 fps (which clearly some of my rounds are doing).
I recently got some jacketed rounds (as has been suggested) and will try working up some loads with them to see if there is a difference.
I'm having a hard time finding anyone with the same firearm to compare data with.
I have been thinking about slugging my barrel to see if the diameter could potentially be affecting the speed. I assume a smaller bore would increase pressures and thus speeds and the opposite would be so for a larger so. Would this be worth doing?
Also... and this is just in theory... could jacketed rounds (which are more durable) be pushed beyond the recommended 1300 fps range... If one was still under book max... and there were no signs of over pressure....... just in theory?

[Unclenick]

The is no free lunch in interior ballistics. If your bullets are going faster than a same-length test barrel produces, your pressure is higher. However, your barrel is longer, so you have to add an allowance for that to raise velocity. It turns out, from what my calculators say, that it will be about 12 fps gain from the extra one quarter inch of barrel.

The velocity change caused by bullet construction can be a fooler. You would think lower friction would produce higher velocity with the same powder charge, but typically the opposite is true. This is because the rate at which the powder burns varies with pressure, and if less resistance is present to build pressure against due to lower friction, you typically get a lower pressure peak and lower velocity. When moly-coated rifle bullets were the craze, everyone noted the reduced friction came with 20-50 fps drop in velocity as compared to shooting the same bullet with no friction proofing using the same charge of powder. Powder charges had to be increased slightly to compensate.

Why is your pressure higher? Several possible reasons exist. For one, if you are using older data, you can't rely on the components to have remained unchanged since it was published. Today, most primers have metal added to produce hotter sparks for igniting spherical propellants than they did thirty years ago. Many manufacturers have slighlty different internal case capacities than they did back then, as more case making is outsourced than used to be. Also in that time frame, Hodgdon and others have been able to obtain better instrumentation than they once had and have tightened up lot burn rate tolerances in canister-grade powders. So if you have old data, it may have been worked up with a powder lot that was on the low side of burn rate tolerance as it stands today.

All those are reasons for looking at the most current load data you can lay hands on. If you email the bullet makers, they often will give you their current load data for one cartridge for free, and not make you buy their load manual. The powder companies all have load data online.

QuickLOAD suggests you extra 1/4" of barrel length is getting you about 12 fps more velocity with Longshot. The Hodgdon test barrel with 8.7 grains of Longshot should have got about 1235 fps measured 15 feet from the muzzle, so your barrel, if the chamber were identical, would get about 1247 fps at that chronograph distance. You actually measured 1257 fps, but I don't know if you had the chronograph at 15 feet (the SAAMI standard distance) or not. A ballistic trajectory program shows you losing about 0.87 fps per foot of travel, so if your chronograph were at six ft instead of fifteen, you would gain 7.8 fps from that difference for a total gain from chronograph and longer barrel of almost 20 fps, or 1255 fps. Pretty close to what you got. (Note the devil is in the details.) You gained 33 fps going from 8.7 to 9.0 grains of longshot. The software predicts 35 fps gain. Pretty close.

I agree with the others that your firing pin tunnel is bigger than required and that is causing the cratering. You can get a gunsmith to bush the existing tunnel with a bushing that has an appropriate size hole.