Large vs. Small Flashhole Diameter

[South Pender]

The available PPC brass (Lapua .220 Russian, Norma .22 or 6 PPC, which is what I'm using) has a small-diameter flashhole, .060"±. Presumably this flashhole size imparts a slight accuracy advantage over the larger flashhole. Correct?

The Lapua .222 Rem. Match brass that I've bought has the larger-diameter flashhole (.080"±). Note that this brass is labeled "Match." So my question: if the small flashhole is advantageous in small-caliber match and benchrest cartridges (at least the PPCs), why does the Lapua "Match" .222 Rem. brass have the large flashhole?

Is there some empirical evidence on the effect of flashhole diameter on accuracy?

 

[Dusty Stevens]

each case has different properties. with the testing thats been done with the PPC it has been found that the smaller flashhole works better. not sure that you could ever shoot the difference with any other cartridge.

 

[ShootDots]

I can not comment on the PPCs. However, a little insight from Large primer pockets to Small. I have a fair amount of experience with the .260A.I., with both Large and Small (as in Palma brass) primer pockets. Grain-for-grain, the large will give you better velocity. However, having said that, you can run the Palma (S/R) to considerably more pressure, thus ultimately getting more velocity! NOW, it has also been my experience that the L/R primers will give consistently a shade better accuracy. Whether all this translates to an answer you're seeking, I don't know, BUT I think there is a link between a larger flashhole and better accuracy!

 

[dmoran]

Firmly believe the outcomes would be dependent on what cartridge, case capacity, powder type, and possibly other effecting aspects as well. I did test flash-hole diameters for myself with 6Dasher brass (Lapua) by opening up a set of brass incrementally. Accuracy degraded each increment as I opened up the flash-holes.
Donovan

 

[avidflyer]

Firmly believe the outcomes would be dependent on what cartridge, case capacity, powder type, and possibly other effecting aspects as well. I did test flash-hole diameters for myself with 6Dasher brass (Lapua) by opening up a set of brass incrementally. Accuracy degraded each increment as I opened up the flash-holes.
Donovan

I know the old school guys liked to open them up to .0625 how far did u go? (dasher)

 

[mikecr]

Presumably this flashhole size imparts a slight accuracy advantage over the larger flashhole. Correct?

Yes, this is correct.

why does the Lapua "Match" .222 Rem. brass have the large flashhole?

Obviously Lapua knows nothing about 6PPC, or they would just make it.

 

[South Pender]

I can not comment on the PPCs. However, a little insight from Large primer pockets to Small. I have a fair amount of experience with the .260A.I., with both Large and Small (as in Palma brass) primer pockets. Grain-for-grain, the large will give you better velocity. However, having said that, you can run the Palma (S/R) to considerably more pressure, thus ultimately getting more velocity! NOW, it has also been my experience that the L/R primers will give consistently a shade better accuracy. Whether all this translates to an answer you're seeking, I don't know, BUT I think there is a link between a larger flashhole and better accuracy!

Interesting. I wasn't concerned about large vs. small primer pockets, but rather large vs. small flashholes. Both the PPCs and .222 Rem.-class of cartridges have the small primer pockets, but there seems to be difference in flashhole diameter between them.

 

[dmoran]

...... how far did u go

Went in increments up to .080" (large rifle size).
Donovan

 

[South Pender]

Yes, this is correct.
Obviously Lapua knows nothing about 6PPC, or they would just make it.

I think it may be more likely that they know nothing about the .222 Rem.!

 

[ShootDots]

Interesting. I wasn't concerned about large vs. small primer pockets, but rather large vs. small flashholes. Both the PPCs and .222 Rem.-class of cartridges have the small primer pockets, but there seems to be difference in flashhole diameter between them.

Well the Large Primer pockets have a larger flashhole than the Small Primer pockets. You have to change the decapping pins out!

 

[South Pender]

Well the Large Primer pockets have a larger flashhole than the Small Primer pockets. You have to change the decapping pins out!

Except that there are many cases with small primer pockets, but large flashholes. The flashhole diameter is the same (.080"±) in a .300 Magnum case (large primer pocket with diameter .210") as in a .222 Rem. case (small primer pocket with diameter .174").

 

[Dusty Stevens]

I know the old school guys liked to open them up to .0625 how far did u go? (dasher)

i think they went to .0625 because thats what size the flash hole uniformer was. thats the smallest size reamer that will fully clean up the hole

 

[RDavies]

T recently asked the same question with regards to 223s for use in F/TR. I was wondering if anyone had made or tested small flash hole 223 brass to see if it could improve the not so good ES/SD the 223 is apparently prone to. It seems if the big boys have tested it, they didn't make it for some reason.

 

[memilanuk]

I'd asked (on some forum or another, might have been here) a while back, and the answer I got was that there *had* been some small flash hole .223 made a few years back. Sounded like the problem was that back then, your rank-and-file .223 shooters had no inkling of what a small flash hole was, why you'd want such a thing, and were generally pissed that their decapping pins kept getting stuck in the cases when loading their varmint / zombie / blaster ammo - and complained loudly. And the small flash-hole .223 went away...