read this has been done in hopes of igniting powder more instantly? does this light slower powders better than the small hole? anybody tried this enough to tell if there is any difference in accuracy or es/sd? just loaded an accurate load last night and will test soon. wonder if one has to work up accurate load all over again. i know the 6xc has a large flash hole and can;t help wondering if tubb tested with the small flash hole and found the larger hole was better. we'll see.[/quote] if i can see you, i can touch you. BANG!
drilling the flash hole in 6x47 lapua
- Thread starter lpreddick
- Start date
lepreddick,
Yes, it most definately does make a difference in ES and SD; it makes them worse. We utilize the smaller (1.5mm) flash hole on a very small number of our cases, and then, only on those intended for extreme accuracy; the 220 Russian (6mmPPC), the 6mm BR, the 6.5x47, the new 308 Palma cases and a few others. The rest all use the standard 2mm flash hole.
Our testing has shown that the smaller flash holes do give better accuracy, reduced SDs and smaller ESs. They require a smaller than normal decapping pin, and a bit more attention to detail during the reloading process. For the accuracy oriented shooter, this seems to be a worthwhile tradeoff. don't enlarge them, you'll be working against what you're trying to achieve here.
Yes, it most definately does make a difference in ES and SD; it makes them worse. We utilize the smaller (1.5mm) flash hole on a very small number of our cases, and then, only on those intended for extreme accuracy; the 220 Russian (6mmPPC), the 6mm BR, the 6.5x47, the new 308 Palma cases and a few others. The rest all use the standard 2mm flash hole.
Our testing has shown that the smaller flash holes do give better accuracy, reduced SDs and smaller ESs. They require a smaller than normal decapping pin, and a bit more attention to detail during the reloading process. For the accuracy oriented shooter, this seems to be a worthwhile tradeoff. don't enlarge them, you'll be working against what you're trying to achieve here.
Thank you for your comments, Kevin.
Not sure of the technology of it all, but in my own shooting the small hole is better. Ruined a bunch of cases by taking bad advice and opening the holes up.
Have also noticed in those pictures of primer tests that the "better" match primers almost always have a smaller flame. Thinking that the smaller hole and/or the smaller flame upset the powder column less and lead to more consistency.
Not sure of the technology of it all, but in my own shooting the small hole is better. Ruined a bunch of cases by taking bad advice and opening the holes up.
Have also noticed in those pictures of primer tests that the "better" match primers almost always have a smaller flame. Thinking that the smaller hole and/or the smaller flame upset the powder column less and lead to more consistency.
KevinThomas said:
interesting insight kevin and one that many believe is true. i have 2 6.5x47's and both shoot great and are extreamly consistant with different lots of powder, temp's etc. BUT it seems when the 6x47 is formed accuracy is more tempremental.
would it be fair to assume that the combination of a slower powder, 4831sc used in the 6x47 vs h4350 used in 6.5x47, AND the small flash hole contribute to the problem? and would a magnum primer possibly help to resolve the issue?
AusFclass,
It certainly could be. It has been very well established that the mildest ignition possible, consistent with good ignition, is usually where the best accuracy is found. Like so much of this game, it's always something of a sliding scale. Faster burning extruded tubular powders or warmer temps on the range, both tend to make ignition easier. Smaller flash holes and a milder standard primer should be no problem in this situation. Very cold temps combined with slower burning powders, especially ball powders, and you may very well need a hotter primer. Possibly even one of the magnum variety. In this case, if these were the conditions you did most of your shooting in (you'd have my sympathy!), then the larger (2mm) flash hole might even be an advantage.
We all need to take a look at the specifics we're dealing with, and make some of these choices tailored to those circumstances.
It certainly could be. It has been very well established that the mildest ignition possible, consistent with good ignition, is usually where the best accuracy is found. Like so much of this game, it's always something of a sliding scale. Faster burning extruded tubular powders or warmer temps on the range, both tend to make ignition easier. Smaller flash holes and a milder standard primer should be no problem in this situation. Very cold temps combined with slower burning powders, especially ball powders, and you may very well need a hotter primer. Possibly even one of the magnum variety. In this case, if these were the conditions you did most of your shooting in (you'd have my sympathy!), then the larger (2mm) flash hole might even be an advantage.
We all need to take a look at the specifics we're dealing with, and make some of these choices tailored to those circumstances.
Out of curiosity i opened p 4 pieces of lapua 30br brass to a .090 flash hole and shot them side by side with standard lapua 30br brass. Velocity was exactly the same as was accuracy. I only played with this for about an hour or about 15 shots each. I saw absolutely no reason to open any more flash holes. The rifle did seem to POP a little more though???? maybe not but it seemed so. Lee
memilanuk
Gold $$ Contributor
I've opened up the flash-holes on mine... albeit opening them from whatever they come as (0.057-0.059") to whatever the Russ Haydon PPC flash-hole uniformer is sized to (~0.061-0.062"). Just enough that I don't have any more problems with even PPC-sized decapping pins sticking in the flash holes...
I haven't noticed any appreciable loss of accuracy or change in ES/SD as a result.
I haven't noticed any appreciable loss of accuracy or change in ES/SD as a result.
Kevin - Quick question for you. In the article listed below on page 3 in the "Norma 6XC - Now available" box paragraph 3, it mentions that the 6XC case uses a large rifle primer because a "detailed study" showed that large rifle primers worked best when the powder charge exceeds 35 grains. Since the 6XC and the 6 X 47 Lapua case capacities are practically the same (48.3g and 47g respectively) what was Lapua's thinking behind using small primers ? Did your in house testing show that the smaller primers work better ? To your knowledge what was the study that was mentioned in the article ?
http://www.accurateshooter.com/cartridge-guides/6xc/
Thanks in advance.
http://www.accurateshooter.com/cartridge-guides/6xc/
Thanks in advance.
I opened the flash holes on my 6X47 after getting mediocre accuracy with my initial try with 107's and 115's. It now groups better and the ES is around 10 fps. The downside is that the primer receives more pressure, so i bushed my firing pin, no more primer issues. I do believe the case is too large to reliably ignite with a standard SR primer.
I have not touched the flash holes on my 6x47L brass just because it's shooting too good to mess with. I am running H4350 and Varget powders ignited by CCI 450s. My hunting loads and match loads both shoot 1/4" or less at 100 yds. Of course though here in south Louisiana we don't worry too much about cold temperatures so I guess that is one advantage.
tested a good load yesterday....80 fowler's, rel 17 in a 12 twist and it was not good. there must be a good reason for the small primer and small flash hole. i'll terminate this experiment. am interested in a response to zipollini's question. [/quote] if i can see you, i can touch you. BANG!
Zipollini,
Haven't seen the "detailed study" in question here, so I can't comment on whatever they observed. I will state that David is an inveterate tinkerer, and is ALWAYS testing something. One of the few guys I've ever seen that will win a national championship with something, and them immediately set out to try something different next time. Leads to some interesting developments sometimes, but can also lead to some dead ends. In any case, that's why he's responsible for som many cartridge/firearm/equipment developments over the years, and I guess that's a good thing.
For what it's worth, He's had several runs of this brass, and they've been of varying quality; some quite good, others . . . not so much. As to the capacity issue, there definately is a limit, but I suspect that it's actually a bit more than the XC. As you may be aware, we are now offering a 308 Palma case, which utilizes the small primer. We had some concerns for this one, but so long as it's used within the parameters that it was intended, it's working quite well. AGiven a very slow burning or dificult to ignite powder, or very cold temperatures, I can definately see a potential for problems. In any case (no pun intended) it's not going to be a set capacity or charge weight that becomes a problem, but a combination of factors. Charge weight, powder type and speed, ambient air temp, etc.. Little common sense and some preliminary testing with your particular component combination should go a long way towards heading off any surprises here.
Haven't seen the "detailed study" in question here, so I can't comment on whatever they observed. I will state that David is an inveterate tinkerer, and is ALWAYS testing something. One of the few guys I've ever seen that will win a national championship with something, and them immediately set out to try something different next time. Leads to some interesting developments sometimes, but can also lead to some dead ends. In any case, that's why he's responsible for som many cartridge/firearm/equipment developments over the years, and I guess that's a good thing.
For what it's worth, He's had several runs of this brass, and they've been of varying quality; some quite good, others . . . not so much. As to the capacity issue, there definately is a limit, but I suspect that it's actually a bit more than the XC. As you may be aware, we are now offering a 308 Palma case, which utilizes the small primer. We had some concerns for this one, but so long as it's used within the parameters that it was intended, it's working quite well. AGiven a very slow burning or dificult to ignite powder, or very cold temperatures, I can definately see a potential for problems. In any case (no pun intended) it's not going to be a set capacity or charge weight that becomes a problem, but a combination of factors. Charge weight, powder type and speed, ambient air temp, etc.. Little common sense and some preliminary testing with your particular component combination should go a long way towards heading off any surprises here.
Interesting Kevin, I shot 308 Cases with a small primer pocket back in the early eighties. It was called URBR Brass and was made at the request of Jim Stekl and used to form his first 6BR cases. The brass was thin walled and not of the best quality IMHO, but once neck turned and fire formed in my Shilen barreled, hunter class rifle it managed to out shoot all of my 308 brass with large rifle primers. Even managed to win the N.J. States with it. Problem was Nobody was making a lightweight quality match bullet back then so when I the 308 re-barreled to a 30X44, I was stuck shooting 150 Gr.Sierras, even at that I managed a 250-18X in a match at Sulpher springs when the record was either 19 or 20X. That was a pretty good score in the early eighties but I'm rambling, Sorry. Didn't mean to hijack the thread. To the original Question, I have shot 6X47 cases drilled and untouched and for me the untouched shot much better and the chrono doesn't lie, E.S. ans S.D. was much lower with the untouched cases.
Years ago when flash hole uniforming became the vogue I came across some older Winchester 220 Swift factory loaded rounds at a cheap price and when they were fired I began the process of reloading when to my surprise the flash holes on these cases were found to be considerably smaller. A friend with more experience told me the original factory loads were loaded this way to keep the primers from piercing due to the high pressures. I opened a few of the older cases to the same size as the later versions and the primers came out the same as the newer ones when fired but when I used the older cases with the original hole it took another grain and a half to get the same pressure signs. I never used those loads but do remember those factory loads were stout, how stout?, I don't know, that was before I had the money for a chronograph. When it comes to flash hole diameters I use them at the size they came and only uniform them hopefully leaving another variable behind.
John, you are correct, and with the FL 308 case that worked fine. Thanks for pointing that out. As a side note Rem 7 1/2 primers were the only ones that I didn't get hang fires with. Never tried CCI-450's back then. Not sure they were available then, tough to remember that far back.
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