.45 with very large flash holes

[SQUAREKNOT]

I know this has been kicked around a bit so I will report what I did. I bought 2000 once fired .45 mixed brass. After prepping it I noticed the larger flash holes
The hole were 50% larger in dia than standard. I loaded my standard #231 with 200 gr SWC @ 5.5 grains. They shot but they also flattened the edges of the primer to square.
I also loaded some 230 Winchester JHP's with 8.5 grs and 9.0 gr of Blue Dot.
They showed LESS pressure signs but were still too hot in either load. The 9.0 is max load.
The consensus as I understood it and was also told by at least one factory rep is load it like anything else. I DON'T THINK SO! No way to send a pic but
now I have to figure what to do with the 800 or so brass. I can't get them replaced as I got they two years ago. I sure don't want them mixed up with my good stuff. Maybe just shoot it with one bullet style and work up a load that shoot OK
I'm open to suggestions?

[Tex S]

I'm not sure I understand the question...

[woolleyworm]

What is the head stamp on the cases with the larger flash holes?

[Sevens]

Are you talking about the cases marked FC - NT ?!

If so, they do have bigger flash holes... and IIRC, they use a small pistol primer instead of the standard large size.

I have never loaded them, for exactly the reason you stated. Don't need to wonder about how the pressure is affected. I also have some 9mm FC - NT and I haven't loaded those, either.

Both of them get culled out of my supply. They are Federal "non-toxic" with a less poisonous priming compound. Another piece of crap nobody needed nor asked for.

[SQUAREKNOT]

I guess I don't have a question, other than what should I do with this brass.
From what I have read the hole size doesn't make a difference-IT DOES! BE WARNED PRESSURES ARE MUCH HIGHER.
Its no NT or small primer sized. Its all mixed brass.
The way things are now I hate to just trash it. Any one have an idea on how they would keep these-or if you would keep these.

[Jim Watson]

Strange, I see no "pressure signs" when loading Winclean large primer large hole brass. Maybe I don't load as hot as you do.

If you want to continue as before you must separate out the Winclean and establish a load for it that you are not worried about.

[Smokey Joe]

I load my .45 ACP's to target-shooting levels, i.e. a small charge of Win 231 and a 200 grain semi-wadcutter. The large-flash-hole cases work just like the other ones--No difference in performance, accuracy, feeding through my 1911, nor anything else I can discern.

The .45 cases that use a small pistol primer, however, get scrapped. My life is already complicated enough without sorting .45 brass for primer size.

(Remington did the same thing with 7.62x39 ammo. I hope there's a very unusual punishment waiting for ammo designers who make "special" ammo with odd primer sizes.)

[gwalchmai]

You bought 2000 pieces of mixed used brass and they all had larger than normal flash holes? You may should buy a lottery ticket.

What are you comparing them to?

[Mal H]

SQUAREKNOT - I think you may be worrying about a non-problem.

You said, "BE WARNED PRESSURES ARE MUCH HIGHER." You're correct about that, but not in the way you might realize. A small flash hole acts as a check valve when the pressure in the case is at its peak. That pressure doesn't remain at the max for very long. By the time it can equalize throughout the case system (including the case and primer cavity), it is far from max.

Now, with a larger flash hole and the exponentially larger area to allow the pressure to equalize, the max pressure that can reach the primer is bound to be higher.

In other words, what you are seeing is the effect of the pressure peak affecting the primer much more than with the smaller flash holes allow. The primer will be flattened more which would be a false indication that the actual peak pressure in the case is higher than it should be.

The only way to determine that the pressure in the case is more dangerous with the large flash holes as opposed to the smaller ones is by pressure testing the loads. That equipment is usually not available to us, so the next best way is to chronograph the loads.

Can you chrono a large vs small flash hole load, all other factors being equal? If so, that is your proof one way or the other, not by speculating on the pressure by examining the primers afterward.

[brickeyee]

"That pressure doesn't remain at the max for very long. By the time it can equalize throughout the case system (including the case and primer cavity), it is far from max."

given the denisty of the gas, it is very very fast at reaching all places behind the bullet, including the primer pocket.

Any pressure increase results from the easier access of the primer flame to the powder column, and the ignition of more of the powder slightly faster.

In a low pressure round like a .45 ACP i would be surpised if you could detect any significant change.
The small amount of fast powder ignotes pretty uniformly.

It is an issue in a rifle cartridge with a long powder column and the large amount of powder present.

Remember, even with a small barrle cylinder gap, enough pressure can escape to be a hazard.
That gap is less than 0.010 inch typically 9much smaller than a flash hole) and pressure is normally well below peak by then.

[Mal H]

brickeyee - You contradict yourself. You say you would be surprised if you could detect any significant change, presumably in pressure and the consequential bullet speed and performance. And yet you also imply that the pressure in the case and inside the primer cavity should be the same during the period of peak pressure.

How do you explain the obviously higher pressure signs on the primer cup when a large flash hole is involved as witnessed by the OP? If it is indeed caused by a peak pressure that is much higher than it should be, then he is right and the cases with large flash holes are dangerous to the average reloader.

I'm sticking with the check valve explanation.

[brickeyee]

"How do you explain the obviously higher pressure signs on the primer cup when a large flash hole is involved as witnessed by the OP?"

Primer flattening is a notoriously poor way to try and guess at pressure.

With limited data there are many other things that could be causing the issue.

I did not contradict myself.
The primer cavity is going to see peak pressure since the colume is small and the gas is low density.

It can be an issue with long powder columns in rifle cartridges, but not 5 gr of pistol powder.
That small amount of powder is ignited completely in a very very short time.
It has finished decomposing before the bullet has probably even moved.

The load should have been worked up from a starting load also.

[SL1]

Without having any more data than the rest of you, I think that there is some reason to believe that flash hole size affects peak pressure in the case as well as peak pressure in the primer cavity. If there was not any effect in the case, then I don't think the cartridge companies would be changing the flash holes. That has to cost THEM money, so I don't think they do it on a whim.

That said, I notice that there are also differences in flash holes in brass for some cartridges with regular primers, such as the .357 Sig. Speer produces cases that have a smaller-than-standard flash hole, while Speer's sister-company, Federal, and the others use the standard small-pistol size hole. It becomes obvious when you first try to reload one of the small-hole cases, because it will grab or even bend your decapping pin. But, none of the reloading data that I have seen so far makes any point about that in their texts. Comparing the reloading data from different sources has not helped, because I didn't find data pairs where only the case is different.

So, I have to work-up loads in different case brands separately. The load manuals have ALWAYS said to reduce your loads and work-up again when you change ANY component, INCLUDING the case. So, this is really nothing new.

True, I have often found that I end-up with the same load with two or more different case brands. That is NICE, but not GUARANTEED. There are other factors, ESPECIALLY in AUTO-LOADERS that warrant consideration whenever we change case brands. One of the most important is the case mouth thickness. There have been some threads in this forum and others recently about unusually thin case mouth walls causing bullets to be too loose in the cases. That can be a safety issue because of the setback potential.

So, there are many reasons that using "mixed brass" can occassionally lead to trouble, even with relatively light loads. And, not all of them are as easy to see and sort as the flash hole size. I just chalk this up as one more reason to be extra careful about using mixed brass.

And I still think there is a place in Heaven for the cartridge designers that are making NT loads, whether it is the projectiles or primers that are NT. They all are helping us keep a lot of our shooting venues open in the face of ever-more-restrictive regulations that are intended to close them to us.

SL1

[brickeyee]

If there was not any effect in the case, then I don't think the cartridge companies would be changing the flash holes.

The lead free primers do not have the same brissance as the lead styphanate primers and need some help to ensure even ignition of the powder.

I would not use NT cases for anything approaching full power loads, but if you work up a plinking load it will be fine.

[Jim Watson]

As I understand it, it is not that the lead free primers need help, it is that they generate a sharper pressure rise. So the early Winclean has a large flash hole to vent primer pressure into the case from the hotter Dinol mix. And the current NT uses small primers because it takes less Dinol than styphnate to ignite the powder.

[James R. Burke]

Sevens know what he is talking about, I learned alot reading his replys, also it makes sense to do what Jim Watson suggested. For me I would need to feel comfortable, and that is the bottom line. I can feel for having so many of them, but keeping things safe is more important. Sorry I was not much help to you but there suggestions are good one's.

[SQUAREKNOT]

I thank everyone for the help. It would seem that the best solution, other than trashing the 800 or so of the 2000 brass is to keep them separate and separated. I have 2000 .45 230 gr round nose lead bullets that I suppose I could use only with the large flash hole stuff and work up a safe load. I wish I had a chronograph to see the effects of the flash holes better. There is no doubt in my mind peak pressure come much faster with these huge flash holes. It might be that a lower charge would drop the pressure but maintain much of the velocity.

[Sport45]

I toss the .45acp brass with small primer pockets, but use the large flash hole brass interchangably with the rest. My loads aren't max and I haven't seen signs of any kind of trouble.

Instead of check valve Mal H would have been more accurate in describing the primer pocket as a restriction orifice. The small limits the amount of gas that can enter the primer pocket during the propellant burn process and the primer pocket should see less pressure than the case because of this. It may be marginally less, but it will always be less than peak case pressure. I can see how the larger flash hole can result in more primer pocket pressure without affecting case pressure at all.

So as long as the primer cup doesn't blow I say no harm, no foul.