reading primers

[dangerranger]

I'm loading 9mm Largo using 38 Super cases and 9mm+p data. With a 125 gr cast bullet I loaded 10 each with 5.0, 5.5, and 5.9 grains of Herco powder. I got best accuracy at 5.9 but the primers showed a little bit domed, and the pin mark was pushed back out. possibly a little warm? At 5.5 I did not see this at all. I also loaded some 124 grain Berrys plated bullets with the same results. But at 5.9 I also had one pierced primer. So what do you all think? Should I just drop to 5.5 or a little more? This is a combo that doesn't have a lot of data out there for it so I'm kind of having to wing it. I am using Winchester primers and could move to a harder primer if need be. What do you all think. Thanks DR

[220swiftfn]

IIRC Speer has data for the Largo, I'll post back tomorrow when I have it in front of me......


Also, Starline has 9mm Largo brass new in stock, ready to ship......


Dan

[bhn22]

You can't tell anything about pressure by looking at primers.

[Doc Highwall]

The only thing that you can reliably tell reading primers is the firing pin impact/dent and only that.

[Sweetpea]

Going off the top of my head, the data you're using seems a bit much for that combo.

Best to use appropriate data.

You may just have to go to a firmer primer.

[Harry O]

I shoot the 9mm Largo for two guns. In them, I use the exact same type and quantity of powder that I do for the 9mm Luger. I don't use +P loads. One of the guns is was made in the early 1930's and one in the late 1930's. I personally think that +P is pushing it for pre-WWII guns. The loads I use work the action reliably and are accurate enough. There are no signs of excess pressure.

You cannot tell a lot by looking at primers, but you can tell some things. You cannot tell the absolute pressure, but if you see a ridge around the firing pin depression; if you see a severly flattened primer, particularly with a shiny mark on the brass where the extractor is; if you have a pierced primer without the firing pin being too pointed; you have too much pressure for your particular gun.

[dangerranger]

I shoot the 9mm Largo for two guns. In them, I use the exact same type and quantity of powder that I do for the 9mm Luger. I don't use +P loads. One of the guns is was made in the early 1930's and one in the late 1930's. I personally think that +P is pushing it for pre-WWII guns. The loads I use work the action reliably and are accurate enough. There are no signs of excess pressure.

You cannot tell a lot by looking at primers, but you can tell some things. You cannot tell the absolute pressure, but if you see a ridge around the firing pin depression; if you see a severly flattened primer, particularly with a shiny mark on the brass where the extractor is; if you have a pierced primer without the firing pin being too pointed; you have too much pressure for your particular gun.

This is a post WWII Star Super, Made in 1952 I have another like it made in 1979. No shiney at the extractor, But the primer dent is pushed back out only on the 5.9 load. The 5.0 load cycled the action just fine as did the 5.5 and neither of them showed any primer abnormality's. How far back do you think I should go? The books I have show 9mm loads of Herco to be from 4.0 to 6.5 grains. I have in the past owned Astra 400s that were from pre WWII era. Id agree that I wouldn't shoot them with anything hotter than base 9mm loads. But this gun was supposed to be able to share the Sub Machine gun rounds. DR

[220swiftfn]

Yeah, the older ones were more in line with .38 ACP ballistics (and pressure) than .38 Super.....

Anywho, I have the Speer here and they're calling @1050fps as max loads, no data with Herco......


Dan

[MtGun44]

Primer reading is flaky as heck, on a good day, almost useless. Brands are very different,
guns are very different.

Bill

[44man]

Might sound stupid but are the flash holes larger in your .38 super brass?

[Harry O]

This is a post WWII Star Super, Made in 1952 I have another like it made in 1979. No shiney at the extractor, But the primer dent is pushed back out only on the 5.9 load. The 5.0 load cycled the action just fine as did the 5.5 and neither of them showed any primer abnormality's. How far back do you think I should go? The books I have show 9mm loads of Herco to be from 4.0 to 6.5 grains. I have in the past owned Astra 400s that were from pre WWII era. Id agree that I wouldn't shoot them with anything hotter than base 9mm loads. But this gun was supposed to be able to share the Sub Machine gun rounds. DR

One of mine is an Astra and one is a Star. I also have a post WWII Star in 9mm Luger. It has a side "quick-takedown" lever which is kind of nice. I am afraid that I have no experience with Herco. That powder also doesn't show up in the reloading information I have on the Largo. I can't help much, but from your description, I would think that anything over 5.5gr is too much for your particular gun.

[dangerranger]

Yeah, the older ones were more in line with .38 ACP ballistics (and pressure) than .38 Super.....

Anywho, I have the Speer here and they're calling @1050fps as max loads, no data with Herco......


Dan

1050 fps is my target speed with the 125 grain bullet. Herco loading data is very close to Unique . Herco is the next slower powder. I'm going to have to get my friends speed trap out, I may be surprised at how fast the bullets are really traveling! I think for now Ill call 5.5 my top load.

[dangerranger]

One of mine is an Astra and one is a Star. I also have a post WWII Star in 9mm Luger. It has a side "quick-takedown" lever which is kind of nice. I am afraid that I have no experience with Herco. That powder also doesn't show up in the reloading information I have on the Largo. I can't help much, but from your description, I would think that anything over 5.5gr is too much for your particular gun.

I like these Spanish guns. I used to shoot them with only the Blazer ammo but that's mostly dried up. The blazer had a 130 grain bullet at 1000 fps. That shot well in both guns. With this gun I got a supply of 9x23 Win Mag that the previous owner bought to shoot in this gun. I talked him out of trying it. Even the post WWII guns I don't think would hold up to that. They have copper HP bullets that Ill be pulling to make a defensive load with. Any Idea whether an all copper bullet will be faster or slower? the maker says it needs to go 1000 fps or faster to expand well. Have any of you created a defensive load for yours? DR

[rintinglen]

I'd definitely back off a smidge or three. You're using 38 super brass which is slightly shorter than the Largo, and perhaps a bit thicker in the head and walls since it is designed to run at higher pressures. Chances are, things are hotter than they should be. While primer pressure estimation in handguns is very imprecise, what you describe troubles me. and pierced primers are never good. My Modelo Super won't feed 38 super brass , unless I turn the head down to 9 MM diameter. Unless you are seating the bullets out, I'd consider 5.4 grains my top end (10% reduction, rounded up). My own defense load uses of 6.5 grains Alliant Power Pistol under a Hornady 115 JHP. IIRC, I paid $99.99 for mine back in 93.

Here you see my Super with the afore mentioned defense load. There is a 9mm load with the same bullet for reference.
Here's a picture of my Star, with a defense load bullet next to a 9mm Luger loaded with the same bullet.

[Harry O]

Speaking of the 9mm Largo, I started like you did with .38 ACP/.38 Super brass and a really old set of RCBS .38 Super dies. It worked for both the Astra and the Star.

Some time later, I found some once fired 9x23 Winchester brass on a gunshow table cheap and tried them. They worked in the Astra, but not the Star. The Star has a tighter chamber. Keep in mind, this is just using the brass, not the loading data for 9x23 Winchester. I took just a little bit of brass off the outside rear of the case with a drill press and a file and the cases now work in both. It was a lot of work and I won't be doing that again. BTW, I sectioned a case and even after removing a little brass, the sides of the case were thicker than a standard 9mm Largo or .38 Super case. The 9x23 Winchester was made heavy for rifle pressures.

Still later, Starline started making 9mm Largo brass. Unfortunately, they only run it once a year or so. When it is sold out, it is gone until the next run. It took a couple of tries before I found some in stock. It is good brass. I recently ran across a newer set of RCBS dies for the 9mmLuger, 9x21, and 9x23Win. It is actually marked that way. I use them now for all of the brass I have and it works great.

My 9mm Largos seem to like the 124/125gr bullet a little better than the 115gr bullet, but the difference is not much. I had better luck with plain-base, cast bullets with the Largo than I had with the Luger, probably because it was running at a little lower pressure with a little lower velocity. However, cast was indifferent in the Largo and downright bad in the Luger. I have since found a gas-check 9mm bullet and don't have any problem with cast no matter what I shoot it in nowadays.

I have used Bullseye, Unique, and HS-6 in the cases and all work about equally well. There is no "preferred" load or powder that is better than the rest.

[jonp]

Primer reading is flaky as heck, on a good day, almost useless. Brands are very different,
guns are very different.

Bill

Primer reading can tell you one important thing every time. STOP DOING WHAT YOU ARE DOING.

[dangerranger]

I have a good lot of 38 Super brass left over from a 1911 that I once had. They are only 1 to 2 thousands short of the surplus largo brass I have. Both guns seem to cycle the 38 brass. Ill load some more of the dialed back loads and fire them over a Chrono to see what they are really doing. While Im shooting the Berrys bullets I,ve ordered a 125 gr round nose boolet mold and a couple of Lee sizing kits so I can shoot them in both the 9 largo and a 38 SPL. Thanks All DR

[Slinger]

I disagree with you fellas that discourage reading a primer. If you know what your doing, it can tell you much about your load development with a given powder/bullet. Wildcatters used it extensively along with case head measurement and bolt lift. I've been using it for well over 40 years with no ill effects. I'm a firm believer in it and can't be swayed as I've seen too much of its value if you know what your looking at.

[Bonz]

My thinking about primer inspection on pre-fired brass is that professional companies that reload pre-fired brass do not inspect the primers at all. They run the brass thru case processors that first check the brass for cracks with air pressure and then they de-prime the brass and then finish the process.

I wet tumble my brass with SS pins, de-prime, run cases thru a roll sizer, wet tumble with SS pins a second time to clean up scuffing from roll sizer and to add a layer of wax to brass, manually inspect each piece of brass looking for cracks/damage/etc. and then begin the reloading process.

[220swiftfn]

I disagree with you fellas that discourage reading a primer. If you know what your doing, it can tell you much about your load development with a given powder/bullet. Wildcatters used it extensively along with case head measurement and bolt lift. I've been using it for well over 40 years with no ill effects. I'm a firm believer in it and can't be swayed as I've seen too much of its value if you know what your looking at.

There's a picture in either ABC's of reloading or Nonte's Book of Reloading (can't remember which) that shows .44 Mag brass fired at something like 23,000, 38,000, and 53,000psi next to each other WITH NO VISIBLE DIFFERENCE IN THE PRIMERS..... No flattening, no cratering, no flow, nada, zero, zilch..... Think about it, if primers were the absolute pressure indicator, every 220 swift out there would blow primers (55,000psi ish), as would every "short magnum" or belted magnum..... But they don't, so why would they in a .223 at pressures LOWER, but still beyond the safe limit of the individual rifle??? Also of note are the several pictures floating around of "blown up" revolvers (definitely excessive pressure) with the round that took off the topstrap and half a cylinder sporting a "normal" looking primer......



Dan