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View Full Version : 45-70 - pyrodex select - flash hole size



hiram
01-30-2007, 05:19 PM
I'm cleaning up and sizing some cases for pyrodex. I'll be using the group buy mold that finished a couple of months ago-Lee 45, plain base, 360 grain, flat nose. Does anyone have experience on opening the flash hole to help ignite pyrodex select? I'm using the fed 215m to start with. Does it make sense for a mag primer to have a larger flash hole to allow the larger ignition to reach the powder rather than to impede the flash with the standard size flash hole? Thanks.

SharpsShooter
01-30-2007, 07:07 PM
Do not change the diameter of the flash hole. De-burring is ok, but opening it up allows more pressure from the charge to focus on the primer cup itself and potentially cause a failure / rupture and allow dangerous gasses to be blown back into your face.

SS

hiram
01-30-2007, 08:53 PM
Thanks--I appreciate the response.

joeb33050
01-31-2007, 07:02 AM
Do not change the diameter of the flash hole. De-burring is ok, but opening it up allows more pressure from the charge to focus on the primer cup itself and potentially cause a failure / rupture and allow dangerous gasses to be blown back into your face.

SS

I'm working on this, can you tell me how you know this? Source/s, references, experiments???
Thanks;
joe b.

44man
01-31-2007, 10:23 AM
Be wary of Pyrodex in cartridges. A little too much compression will not let it burn in the bore and large chunks will be blown out to burn on the ground. You can imagine what that does to accuracy and SD!
How do I know? Hee, Hee, we made fireworks at a shoot. It was fun to see the flares come out and burn for quite a time. Never shoot these in the dry woods.

hiram
01-31-2007, 02:59 PM
I read about the high ignition temp of pyrodex and the mag primer use. The mag prime is producing a larger flame, and the larger flash hole allows a larger flame in. Why contrict the larger flame with a smaller hole? Just trying to find out; unless the standard hole is already the right size for mag primers.

SharpsShooter
01-31-2007, 09:54 PM
Joe,

When you open up the flash hole to a larger diameter you have weakened the structural integrity of the case head, particularly the primer pocket. By allowing excess gasses (read pressure) to enter the pocket, you have the potential to enlarge the primer pocket. A over spec primer pocket will eventually leak dangerous high pressure gasses into the chamber, possibly into the shooter’s eyes. Many people bevel their flash holes and Lyman makes the proper tool for it. There is a caution included that indicates you should not in any fashion enlarge flash holes, just deburr and bevel it slightly.

Bottom line… use the right primer…do not enlarge the flash hole. The risk of injury is not worth the insignificant gain in ignition.

I light off 70gr of heavily compressed Goex Cartridge with Federal 215 Magnum primers. The burn is clean and the flash holes are stock dimensions.

SS

hydraulic
01-31-2007, 11:02 PM
Spence Wolfe in his book on trapdoors measured the flash holes in several Frankford Arsenal .45-70 cases from the l880's & l890's and found them larger than modern web head brass. I think they were .10, if memory serves. All the guys in our club drilled out the flash holes and used Federal magnum primers. We shoot black powder only. Those old solid head cases were much thinner than modern brass, and I would think they would have been much more likely to have had problems.

joeb33050
02-01-2007, 06:40 AM
Spence Wolfe in his book on trapdoors measured the flash holes in several Frankford Arsenal .45-70 cases from the l880's & l890's and found them larger than modern web head brass. I think they were .10, if memory serves. All the guys in our club drilled out the flash holes and used Federal magnum primers. We shoot black powder only. Those old solid head cases were much thinner than modern brass, and I would think they would have been much more likely to have had problems.

Would you tell us more about these cases with drilled out flash holes? Cartridge, powder, bullet, flash hole diameter now-drilled out, results, why it was done? All the info? I need it.
Thanks;
joe b.

SharpsShooter
02-01-2007, 07:40 AM
I read about the high ignition temp of pyrodex and the mag primer use. The mag prime is producing a larger flame, and the larger flash hole allows a larger flame in. Why contrict the larger flame with a smaller hole? Just trying to find out; unless the standard hole is already the right size for mag primers.

According to Speer, Magnum primers are designed to contain a greater amount of priming composition that yeilds a longer not larger burn and thusly provide the ability to ignite slower burning powder in a standard size primer flash hole.

The Speer #10 manual also shows several good pictures of what can occur when the prime pocket enlarges and the resulting failure that occurs.

As far as the experiments conducted circa 1890, I'd like to think we have progressed a bit in both chemical composition of priming compounds that are more capable and have become more concious of the dangers involved with weakening an area of the case head.

I'll readily agree that Black powder does not produce the pressures as it's white cousin does, but what will occur when you inadvertently mix up some cases and do not notice. Load up that large flash hole case with a good stiff charge of 3031 and I'd say the results will be less than favorable.


SS

hydraulic
02-01-2007, 10:10 PM
I went down into the dungeon and dug out an old newsletter of Wolfe's. The following is a quote.
"Complete ignition is the key to accurate ammunition. The powder charge must be able to build enough pressure to form the bullet into the bore/barrel. This means the cases for ALL (caps his)loads need to have the .096" flash hole and Federal 215 or Winchester WLRM primer. A heavy taper crimp is required to hold the bullet in place so that sufficient pressure is created before the bullet moves out of the cartridge case."

I think Sharpshooter is right about avoiding white powder loads with drilled out flash holes. But then, who shoots white powder?

joeb: .45-70 Springfield Trapdoor, 500 gr. soft lead bullet, 1/2 beeswax, 1/2 deer tallow (mutton will work) lube, 62 grs. Goex or Elephant 2F, taper crimp die from lee, avoid the factory crimp die from LYman or RCBS, they are for jacketed bullets, powder compressed down to the last band before crimping. Can't think of anything else. Hold the rifle very steady. Why was it done? To make the rifle shoot straight. Results? The rifle shoots straight.

hydraulic
02-01-2007, 10:20 PM
Oh yeah! I meant to mention that we are Company C, 1st U.S. Infantry of Fort Randall, S.D. Our range is at Wagner, SD, and we have our Springfield shoot the third Sunday of each month. We also sponsor the South Dakota BPCR state shoot in August. Come out and shoot with us. Blackpowder only.

felix
02-01-2007, 10:30 PM
Hydraulic, I hear ya! But, to me, only WP is to be used in primed cartridges, and BP reserved for flinters or earlier ignition systems. ... felix

Bad Ass Wallace
02-01-2007, 11:36 PM
The primer chamber being a closed vessel in scientific terms is subject to the old pressure volume temperature equations (P1V1T1 = constant)

When igniting powder, the primer flame penetrates into the center of the powder column and then the column burns outward toward the inside of the rifle case.

The primer compound when ignited delivers burning gas through a vent hole (volume) at a certain pressure. Enlarging the hole lowers the pressure and therefore reduces the penetration of the hot gas which you rely on to ignite the powder.

Detonation in small charges of WP occurs when the ignition flame passes over the surface of powder right up to the base of the boolit and the whole lot ignites instaniously.

The answer to drilling out flash holes is therefore a trade off between more flame to the base of the powder column and less penetration deep into the powder cloumn. Both schools of thought work, but I believe enlarging the hole actually increases the powder burning time resulting in the powder column being pushed forward out of the case and causing more fouling as the powder now burns in the barrel ahead of the chamber.

The amount of variation would depend on the size of the case and the amount of powder being ignited. I shoot a 50/90 with 105gn FG with standard flash holes and standard LR primers without any ignition problems:confused:

Bad Flynch
02-02-2007, 07:01 PM
Well, here are a couple of things to add to the fracas:

Modern experiments indicate that flash hole diameter, even in smokeless powder loads, does not produce problems until things get well beyond the dimensions under discussion.

If you read the Treadwell Report (Frankford Arsenal, 1873, available in reprinted form) you will see where the FA experimented with frontal ignition, etc., and flash hole diameter even back then. They had cases with two and three flash holes, like modern-day Berdan cases ( and what about those? they have a lot more area in the flash holes than our usual Boxer-primed cases)

It appears that the need for magnum primers and large flash holes is somewhat dependent on the degree of compression used in the black powder load. In this day and age, there are two types of primers--those that use more and hotter priming compound and those that use stuff like aluminum powder to spread a longer-lasting conflagration via burning particles into the powder column. The results and the need for compression/enlarged flash holes/crimps varies a lot, depending on each round's particular makeup.

Not enough reliable information in this discussion to come to any reasonable conclusons, I'd bet.

When I shoot 40 grains of FFg compressed like crazy in a .45 Colt case ( it is essentially a solid mass), I usually use enlarged flash holes and at least stout primers like W-W. When I use 60 grains of FFg in a .45-70 and just a little compression, standard cases and standard primers do just fine.

W-W has a new line of ammo, WinClean, I believe. One of the distinguishing markers for these cases is the enlarged flash hole to make allowances for the new lead-free primers (no lead styphnate). Winchester states that it is OK to reload the cases with standard primers and standard loads.

Not a simple black-and-white question, I'd guess.

hydraulic
02-02-2007, 09:06 PM
Bad Flynch: The mention of the Treadwell report rings a bell. It may well be where Wolfe got his information. At any rate, the flash holes in those old balloon head and solid head cases were larger, .096, than the holes in modern web head cases and the powder was packed in so tight it takes a drill bit to get it out.

NickSS
02-02-2007, 11:52 PM
Actually I have read several articles in the Single Shot Exchange magazine where the authors were experimenting with smaller primer flash holes and pistol primers and even adding thin paper over the flash hole to reduce the flame from the primers. This seams to be the latest trend in making black powder shoot more consistently. Personally I tried Wolf's idea of boring out primer holes to .096 inch and I found that it did provide slight improvement in accuracy with heavily compressed loads. My 45-70 brass will take 60 gr of GOEX FFG and a .030 fiber wad and my 535 postel bullet will slightly compress the charge and gives me good accuracy. If I use a powder compression die and squeeze 70 gr in the same case along with the same wad and bullet the accuracy is less unless I use large flash holes, magnum primers. Then accuracy is about the same but velocity is about 100 fps faster. However. If I load 10 gr of FFFFG and 60 gr of FFG in a standard case I get the same results with a standard large rifle primer. So its all about ignition.

Larry Gibson
02-03-2007, 11:47 AM
Let us not take Wolfe out of context; his book is about replicating the service loads for the M1873 Trapdoor. To do that, as mentioned, you compress 70 gr of BP into the case. It becomes a solid mass just as the original powder charges were compressed and became. It takes a hot primer flame to break up and properly ignite this column of compressed BP. The .096 flash hole is essential for this if you want good consistant ignition with these replicated loads. I have proved and reproven it too many times over the chronogragh to have any doubt. If you are using other loads and techniques for BP loading that does not involve a heavily compressed powder charge then it probably isn't necessary to drill the flash holes. It is as simple as that.

I will add that all my 45-70 cases used in theTD have their flash holes drilled to .096. I use them with BP and smokeless wihout problem. However we must remember that pressures, even with smokelss loads, are not that high for TD use.

Larry Gibson

hiram
02-03-2007, 05:16 PM
Well---I tried it. 20 rounds from 43 t0 50 gr of Pyrodex select--- .5 gr apart. All shot into the same target and I kept track of the hits on paper at the bench. Large flash hole, fed 215m primer. No ignition problems or blown out primers. The best cluster centered around loads 7, 8, 9, 10, and 11. 9 is the middle load. Load 9 is 47 gr. Now I'll try 5 with 47 gr for group, and 5 with 47 with the standard flash hole, 215m primer, and the same again with the large pistol primer. I use 1 milk container wad and 3 newspaper wads. The bullet was as mentioned originally, the 360 gr, FN from the group buy. Homemade lube--close to Emmert's.

Bad Flynch
02-04-2007, 11:17 PM
>where the authors were experimenting with smaller primer flash holes and pistol primers and even adding thin paper over the flash hole to reduce the flame from the primers.<

I have no idea about these authors intent, however flash hole sealers are common in the shotgun world and the .45 ACP has been loaded that way. Years ago, I loaded .38 Special that way with glassine paper (it was a pain). The avowed purpose for most of this is to keep fine powder from migrating through the flash hole and getting into the priming chamber where it would create high pressures. Such is known and well-documented with fine ball powders getting into the primer of shotgun shells. They are large enuff to produce a problem. I seems that the .45 ACP version of this technique was done for the same reason, only to keep BullsEye out of the priming chamber.