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Gene Beggs
12-27-2007, 10:50 AM
We benchresters tend to be nit-picky perfectionists and are always looking for ways to improve the quality of our loaded rounds. Some feel it is beneficial to sort cases by weight while others (myself included) feel it is a waste of time. Same goes for weighing each and every powder charge. Try the following experiment and I think you will agree. In addition to your normal loading equipment, you will need a good chronograph and powder scale.

For this experiment, use only one case; one that has been fired two or three times. Load and fire the case ten times with carefully weighed charges, chronographing each shot. Note the extreme spread.

Now, go back to the loading block from which you took the one case and load ten of those cases with thrown charges from your measure using your favorite technique and fire those ten over the chronograph. I'm betting you will see little or no difference between the extreme spreads; sometimes, it will actually be less than with the weighed charges! This is an eye-opening experiment; try it, I think you will be surprised.

So,,, if it's not the cases or variations in powder charge that causes one round to be faster than another, what is it?? You tell me. Some say it is variations in neck tension, but I don't think so. Several times during the past few years, I have loaded twenty 6ppc rounds and every one of them felt the same when I seated the bullets, but the extreme spread of those twenty rounds might be 43 or 38 or whatever, sometimes as much as 53 fps. What's going on? The only explanation I can offer is it is the primers. That is the one variable over which we have no control other than switching to a different brand or lot number.

What do you think?

Gene Beggs

JohnVm
12-27-2007, 11:49 AM
Gene, I think that you are correct on primers. The primers have a certain amount of energy released and the more this varys the more variance you will have in ignition and total energy produced and that is why the hotter loads are quite often the one that is more accurate. The more powder, the more energy, and the less effect the varience of the primer energy will have on the total output. I hope this makes sense.

Duane(Pa)
12-27-2007, 12:07 PM
I think some of the 1000 yd. guys weigh their primers? Maybe there's something to it. I don't like weighing anythying, but I do buy my 220R brass from Hoen sales already weighed. I shoot outside and blame everything on the wind:)

Gene Beggs
12-27-2007, 12:19 PM
Gene, I think that you are correct on primers. The primers have a certain amount of energy released and the more this varys the more variance you will have in ignition and total energy produced and that is why the hotter loads are quite often the one that is more accurate. The more powder, the more energy, and the less effect the varience of the primer energy will have on the total output. I hope this makes sense.

Yes John, your suggestion makes perfect sense. The times in which I have observed single digit extreme spreads were when I was shooting hot loads. Here, I'm speaking of the 6PPC cartridge. Strangely enough, I experienced my best match results ever at the 2003 NBRSA Nationals in Phoenix winning the HV Grand shooting light loads of 8208 in the 26.9 to 27.7 grain range. Go figure. :rolleyes: There is still much we do not know.

Later,

Gene Beggs

Tony C
12-27-2007, 01:48 PM
Gene

Just brainstorming. Is it possible that Calfee's thoughts on "relaxing" could provide some insight? Or does that just apply to rimfire???

Tony

Tom Rose
12-27-2007, 02:00 PM
Gene,
Could that spread in fps be within the standard error tolerence of the chronograph? The spread is about 1/10th or .01 of the velocity if my math is correct. :)

bryan
12-27-2007, 03:35 PM
Gene: I am a proponent of weighing charges, even if I don't always do it:rolleyes:
While getting ready for my 6mmBeggs, I spent some time with the powder measure throttled down to the level I expect charges to be, so I could build a referrence chart for my powder bottle. I use a Neil Jones measure, and set it to drop 25.0gr H4198 (or close). In 20 drops, the measure gave me a range of loads from 24.9 to 25.2 with no rhyme or reason. I did this twice. Then I dropped ten loads into the pan and it weighed 251.2gr. A second ten weighed 251.1gr, and a 3rd ten weighed 251.2 gr again. SO, the ten drop average is EXTREMELY close, yet individual drops vary by as much a 3 tenths. A Harrels I had a while back did the same thing.
I just don't like the idea of getting that 24.9gr load into the same group as a 25.2gr load. At least nobody has pointed to the advantage of doing that on purpose.
Second, I can't help thinking about barrel heat (even with a few fouling shots) and how that may bear on the velocity readings. Did you allow the same time between shots with 10 cases as with the single case reloaded 10 times?
By the way, that 25gr H4198 load was a "for instance", and was used as an example.
Keep up the good work!
Bryan

jackie schmidt
12-27-2007, 04:09 PM
One thing we have noticed with our 30PPC's is we are getting very good ES and SD numbers when shooting over my 35-P Chrono. Almost always in single digits. Much better than what I normally get with my 6PPC's.
I have no explanation for this.........jackie

Nader
12-27-2007, 06:50 PM
Hey guys, the primer thing is real interesting. Has any body come up with a way to measure primer energy without powder involved.I seem to remember an article in PS a couple years back where somebody(sorry, I can't remember what I had for lunch)had photos of different brands of primers going off,and some seemed to burn hotter than others,but was any one brand tested for consistency, Hmmmmmm?
Joel

abintx
12-27-2007, 06:52 PM
Gene: Here is an outstanding article I read yesterday that might shed some light on another aspect of what you've found: http://www.6mmbr.com/medlerTUBBBSC.html. Bottom Line: Sorting bullets by bearing surface/body/shank length can improve Extreme Velocity Spreads (ES) and improve accuracy. Why? As the article points out, variances in bearing surface creates variances in friction which leads to variances in pressures which in turn leads to inaccuracy.

I sorted a box of Sierra MatchKing 69 grain HPBT's and ended up with two groups. One group's bullets measured .507 to .508 and the other .502 to .503. Not a bad difference within each group. Only .001 difference but .005 between them. Needless to say I'll shoot them as segregated groups.

I spoke to a Sierra ballistician today and asked if the difference was because they may have come from different dies and mixed into a box. He said no, they know that they have a problem and are working on it. He said what they found was that the lube they use and the way it's used causes bullets in the morning to have shorter shanks and the bullets later in the day to have longer shanks.

I'm not bullet smart enough to comment on what he told me but I certainly understand now that if I use Sierra bullets or others, sorting by shank length or bearing surface, might improve my results.

Gene Beggs
12-27-2007, 07:27 PM
Bryan,

You bring up a good point when you asked if I waited the same amount of time between the ten shots. No I'm sure I did not. When I loaded the same case ten times, it surely took more time between shots even though the loading room is right next to the firing room.

Dave Short
12-27-2007, 07:29 PM
I've noticed (sometimes, but not always) that a .003 to .005 seating depth change will increase or decrease the ES by a considerable amount. The first time I ever noticed it I changed the depth back and shot another string over the chrono just to verify what I thought I'd observed.......sure enough, it was for real...that time.

I have tried to chrono those loads that shoot noticably better in the wind than most, in hopes of identifying something unique that I could look for during load development. It seems that there is no real magic charactaristic (aside from velocity) to watch for. In fact, some of the best loads exibit the scariest spreads.

I remember a PS article in the mid 90's about thrown vs. weighed charges. The conclusion was that thrown charges out-shot weighed charges. The (assumed) reason was that the powder orientation within the case was more consistant than when dumped through a funnel. The powder, in theory, burned at a more consistant rate because of this orientation. Opinions?

-Dave-:)

Charles E
12-27-2007, 07:46 PM
I remember a PS article in the mid 90's about thrown vs. weighed charges. The conclusion was that thrown charges out-shot weighed charges. The (assumed) reason was that the powder orientation within the case was more consistant than when dumped through a funnel. The powder, in theory, burned at a more consistant rate because of this orientation. Opinions?If that's the article I'm thinking of, it was by McPherson & was all over the map. It included things like velocity variations with about 6 grains of powder in a .38-40 case, depending on how the powder was oriented (all at the front vs. all at the back, etc.). The particular thing you mention was, as I remember, some variations where how you charged a case could give a compressed load done one way, and just a full case done another. Best I remember, McPherson speculated there would be more variation when using a powder funnel (i.e., weighing), unless maybe you used his swirling technique? Typical McPherson BS.

Gene Beggs
12-27-2007, 07:50 PM
One thing we have noticed with our 30PPC's is we are getting very good ES and SD numbers when shooting over my 35-P Chrono. Almost always in single digits. Much better than what I normally get with my 6PPC's.
I have no explanation for this.........jackie

Most interesting Jackie. The first time I experienced this phenomena was when Shelley Davidson and a couple of other shooters brought their 30 BR's to the tunnel. Their extreme spreads were always amazingly low. My gut feeling is that it has something to do with case capacity versus bore diameter and bullet weight. The Russian 7.62 X 39 cartridge is a classic example of this; it generates velocities all out of proportion to its size.

Later,

Gene Beggs

Dave Short
12-27-2007, 08:02 PM
If that's the article I'm thinking of, it was by McPherson & was all over the map. It included things like velocity variations with about 6 grains of powder in a .38-40 case, depending on how the powder was oriented (all at the front vs. all at the back, etc.). The particular thing you mention was, as I remember, some variations where how you charged a case could give a compressed load done one way, and just a full case done another. Best I remember, McPherson speculated there would be more variation when using a powder funnel (i.e., weighing), unless maybe you used his swirling technique? Typical McPherson BS.

I don't remember the article in detail, but it was not a small charge of fast burning powder in a big black powder case. It was a modern case, using a case full of powder. It was actually fairly well written, but the conclusions were not very well supported.

-Dave-:)

Gene Beggs
12-27-2007, 08:09 PM
Hey guys, the primer thing is real interesting. Has any body come up with a way to measure primer energy without powder involved.I seem to remember an article in PS a couple years back where somebody(sorry, I can't remember what I had for lunch)had photos of different brands of primers going off,and some seemed to burn hotter than others,but was any one brand tested for consistency, Hmmmmmm?
Joel

Joel, I remember seeing two such articles where photos were used to show the flash that each primer produced. What I would like to do is devise some way of measuring the energy/pressure produced by each individual primer. Could we use a recording pressure gauge hooked up to a barrel stub installed in an action? A ball in a clear tube? or whatever? Think about it.

GeneBeggs

abintx
12-27-2007, 09:19 PM
Primers are the topic of two discussions in "The Benchrest Shooting Primer." Probably the two you're talking about. One is "Primer Tests" by Steve Chernicky, December 1985, pages 131 through 135. It covers the tests and equipment used. Quite comprehensive. The other one, "More on Primers" is covered on pages 8 through 10. Both show flash photos. Hope this helps.

Gene Beggs
12-27-2007, 09:46 PM
Primers are the topic of two discussions in "The Benchrest Shooting Primer." Probably the two you're talking about. One is "Primer Tests" by Steve Chernicky, December 1985, pages 131 through 135. It covers the tests and equipment used. Quite comprehensive. The other one, "More on Primers" is covered on pages 8 through 10. Both show flash photos. Hope this helps.

Thank you Art. It's most appreciated.

Gene Beggs

pbike
12-27-2007, 09:50 PM
Gene,

a few points here, I am surrprised that nobody has mentioned it. In the first scenario you speak of 1 case (fireformed a few times) then loaded ten times for an extreme spread, standard deviation test. In the second scenario you speak of ten cases, all very close fired for a string to find extreme spread, standard deviation etc.

My question is what is going on with the barrel all this time? In the first scenario how long between shots to load the cases and fire them, has the barrel cooled? was it warmed up before the string started? was it timed fire so that the temperature of the barrel was kept constant?

In the second scenario, would you keep the same barrel temp as the first scenario? how long in the warm chamber would a case be allowed to sit (and possibly warm)?

To get results from a test like this you have to have a standard method so that the test results show you what you were looking for, with respect to brass, not barrel temp.

Does this add any helpfull information to your test?

Paul

Gene Beggs
12-27-2007, 11:27 PM
Gene,

a few points here, I am surrprised that nobody has mentioned it. In the first scenario you speak of 1 case (fireformed a few times) then loaded ten times for an extreme spread, standard deviation test. In the second scenario you speak of ten cases, all very close fired for a string to find extreme spread, standard deviation etc.

My question is what is going on with the barrel all this time? In the first scenario how long between shots to load the cases and fire them, has the barrel cooled? was it warmed up before the string started? was it timed fire so that the temperature of the barrel was kept constant?

In the second scenario, would you keep the same barrel temp as the first scenario? how long in the warm chamber would a case be allowed to sit (and possibly warm)?

To get results from a test like this you have to have a standard method so that the test results show you what you were looking for, with respect to brass, not barrel temp.

Does this add any helpfull information to your test?

Paul

All good points Paul. No, I made no effort to time the shots or maintain the same barrel temp. My "tests" tend to be quick and dirty and my experiments more like what one would encounter during match conditions.

GeneBeggs

pbike
12-27-2007, 11:41 PM
Exactly Gene.

In match conditions I (think) it may be better to have 10 really good cases, than to try to load one case ten times and shoot it in 7 minutes time for record!

As you say about the primers, all we can do is buy what works and buy all we can within the same lot. All other variables that you change at the match would be the seating depth, amount of powder, neck tension (via sizing button), or primer brand, that is if you think one brand works better in humid or dry whatever you need.

Paul

ShelleyDavidson
12-28-2007, 06:47 AM
took photos and did a write up of lots of different primers while being fired from a stub barrel. Maybe German will chime in.

Shelley

GS Arizona
12-28-2007, 08:19 AM
Shelley, yes, I'm working on a larger project involving that and have been in touch with Gene since this thread began. Hopefully something interesting will develop.

brickeyee
12-28-2007, 11:56 AM
Gene,
Could that spread in fps be within the standard error tolerence of the chronograph? The spread is about 1/10th or .01 of the velocity if my math is correct. :)


A typical 'run of the mill' crystal oscillator is 100 ppm (part per million) or 0.01 percent.
1/10 would be 10%, or 0.1.

A bigger issue with chronographs is the interaction between the sensor spacing and the oscillator frequency.
At some point a single count of the oscillator starts corresponding to a 1 ft/s change in the velocity and the accuracy goes down for higher velocities.

Tom Rose
12-28-2007, 12:08 PM
Brickeyee,

What I was trying to point out is that an error of .01, which is the tolerance of the chronograph, would produce a variance of +/- 35fps at 3500 fps. Just because the machine says something, don't take the reading as an absolute. The real fps just might be closer than one would think. It would seem to me the possibility of this deviation should be taken in account.

GS Arizona
12-28-2007, 12:13 PM
Tom, 35 fps is much more variance than a good chrono will deliver. In fact, if we could only rely on them to that level, they would be of little value except for the grossest of measurements. My experience with a few different consumer grade systems and with the Oehler 43 which is sort of in-between consumer and commercial grade is that you can rely on them to a far closer level than 30 or 35 fps.

pacecil
12-28-2007, 12:48 PM
Well, how close can you rely on them? A tenth per cent accuracy is pretty good. Are you saying they are much better than this, or just a little bit better?

BLUEKNOB
12-28-2007, 01:38 PM
Just a thought experement.

To test the consistancy of the primers. Could you take an old barrel,thread the muzzle and screw in a pressure transducer, hook it up to an o-scope, and fire primed cases in it to measure the variation in pressure. Would that blow something? If so maybe a small hole drilled into the transducer connector would bleed off enough pressure to make it safe.

Allan

Gene Beggs
12-28-2007, 06:23 PM
Just a thought experement.

To test the consistancy of the primers. Could you take an old barrel,thread the muzzle and screw in a pressure transducer, hook it up to an o-scope, and fire primed cases in it to measure the variation in pressure. Would that blow something? If so maybe a small hole drilled into the transducer connector would bleed off enough pressure to make it safe.

Allan

Allan, that's a good suggestion. I have thought of something along that line with installing a threaded connector into an old barrel, either leave it full length or maybe shorten it to a stub, I don't know. I thought about using a pressure gauge that had a resetable needle on it; one that would record the highest pressure reached for each shot. I didn't think about using a transducer and an oscilloscope because I'm not too savy about such things.

Tell us more.

Gene Beggs

BLUEKNOB
12-28-2007, 06:56 PM
Gene:

I'm not a tech wiz. I have some training and background in electronics,(But that was 30 years ago. I'm sure there are others on this forum who are more tech savey than me.
I did do some research on the transducer. www.omega.com has transducers with a 1/4" pipe thread that I'm sure could be screwed into an adapter in the end of the barrel. I may try talking to someone at omega to see what model they think would work best. For all I know you may be able to connect the output to a computer to record the results. I think it would be best to start with a long barrel to avoid building pressures to high till you can get an idea of how much pressure is produced. Wouldn"t want to blow it up. The wife gets upset when I do that!:)

Allan

Don
12-28-2007, 07:07 PM
Allan, that's a good suggestion. I have thought of something along that line with installing a threaded connector into an old barrel, either leave it full length or maybe shorten it to a stub, I don't know. I thought about using a pressure gauge that had a resetable needle on it; one that would record the highest pressure reached for each shot. I didn't think about using a transducer and an oscilloscope because I'm not too savy about such things.

Tell us more.

Gene Beggs

Gene, a pressure gauge should work just fine and have the advantage of recording in psi which most everybody can relate to vs. voltage levels for the
transducer/scope method which is obtuse for many.

Make sure to clean the barrel of primer residue periodically or the pressure gauge valve may malfunction from said trapped residue..........Don

J. Pendergraft
12-28-2007, 07:41 PM
I don't think it's the primers causing extreme spread. I have used the same primers for example in a 338-404 and got consistent single digit velocity deviation where with another case for a smaller bore size would run over 25 fps deviation. Weighing primers is fruitless. Look at the sealer sometime, it's obvious the amount of sealer varies. I expect the process that puts the mixture in the cup is much more precise than the sealing process.

Gene Beggs
12-28-2007, 09:05 PM
Yeah, something like that might be just what we need. I could install it in a barrel, but from that point on, someone smarter than I am would have to figure out what to do with it from there. Let us know what you find.

GeneBeggs

Gene Beggs
12-28-2007, 09:23 PM
I don't think it's the primers causing extreme spread. I have used the same primers for example in a 338-404 and got consistent single digit velocity deviation where with another case for a smaller bore size would run over 25 fps deviation. Weighing primers is fruitless. Look at the sealer sometime, it's obvious the amount of sealer varies. I expect the process that puts the mixture in the cup is much more precise than the sealing process.

J., I know what you mean; there seems to be something that relates to case capacity vs., bore size/bullet weight. My gut feeling is the more you choke the cartridge down, i.e., big case/small bore, the more finicky it becomes and the greater the extreme spreads. Two cartridges that come to mind as prime examples of this are the 6PPC vs., the 30 PPC. Every 6PPC I have ever had showed anywhere from 35 to as much as 53 fps extreme spreads, while Jackie Schmidt reports consistently low extreme spreads with his 30PPC. I have observed the same thing with many different 30 BR's.

GeneBeggs

Don
12-28-2007, 10:25 PM
J., I know what you mean; there seems to be something that relates to case capacity vs., bore size/bullet weight. My gut feeling is the more you choke the cartridge down, i.e., big case/small bore, the more finicky it becomes and the greater the extreme spreads. Two cartridges that come to mind as prime examples of this are the 6PPC vs., the 30 PPC. Every 6PPC I have ever had showed anywhere from 35 to as much as 53 fps extreme spreads, while Jackie Schmidt reports consistently low extreme spreads with his 30PPC. I have observed the same thing with many different 30 BR's.

GeneBeggs

I wonder if that isnt the product of; a twice as heavy 30 caliber bullet, greater mass, less percentage relative bore surface contact, than a comparable 6mm caliber bullet in the same size case capacity range and how it all relates to barrel bore variations, textures, and bullet jacket/bullet core hardness variations that ultimately influence the velocity differences? Along this line of thought, do the .22 Beggs/Russian velocity variations exceed both the 6PPC and 30PPC?.........Don

melkapule
12-28-2007, 10:32 PM
Decades ago I read an article, so long ago I only think it was written by Creighton Audette.
While looking for a good highpower rifle load he loaded ammo with increasing amounts of powder. The load chosen was one whose velocity varied least with slight differences in weight of powder. I think a load was chosen because if the powder charge varied slightly but accuracy stayed high, the load would perform in competition. As powder charges were lessened or increased, the accuracy quickly deteriorated.
Does this method make sense in BR?
If this question belongs somewhere else please move it. Thanks.

Dave Short
12-28-2007, 10:35 PM
I'm inclined to believe the relatively high velocities, the low ES, and the ease of tuning the 30's provide is related to the large volume of the bore. I picture the effective "chamber" to be the volume of the space from the inside of the case head and the bullet at any given point in the barrel......the volume increases at a much greater rate than the 6mm or .22, and is ultimately much greater by the time the bullet clears the muzzle.

-Dave-:)

Lynn
12-28-2007, 10:36 PM
I think in Glenn Newicks book is a section saying Allie Euber was getting zero fps extreme spreads in his 6PPC but the groups weren't real good.Maybe someone can ask him?

On the extreme spreads it seems you have to reach a certain pressure point and when you do everything comes together.On a 6BR you can't reach that point with Fed 205M's because they pop when you reach 25 fps extreme spreads due too the pressure.A simple switch to the CCI 450 Magnum will keep the primer from popping and cut the extreme spreads down to around 8fps.

I know most 100 yard benchrest shooters take there bullets out of the box and shoot them without checking there weight.I think if you have a 0.7 gr difference in weight there is a very simple formula that will tell you how this affects both the velocity and the bullets bc number.It isn't a large number but at 1000 yards it matters.
Lynn

Pete Wass
12-30-2007, 09:08 PM
for a few years now and have decided that the ES is not very important. What is more important is to have exact charges and to have all of one's bullets positioned in the cases exactly the same where they will engage the lands.

I have seen, time after time, how a tenth of a grain can change the shape of a group or where the bullet prints on the paper. I have also seen, time after time how rounds loaded to the same OAL, measured where they will touch the lands, will change the shape of groups.

One can not always find a tiny round hole simply by changing seating depth and will need to increase or decrease the load but those are the two things that matter most, from my experience.

I have never seen any relevence to case size or weight. I have seen some relevence to the weight of bullets though. Light or heavy ones will print in a difference place on the paper.

I also found one summer that ES could be changed with primer make. That year, I found that Winchester Small Rifle primers gave the smallest ES's. I found that Fedearl LR primers gave the best ES's. I have used both since.

I don't have a tunnel to shoot in but I use to have close to it; a very sheltered slot through some Conifers into a pit. Flags never moved when I did the testing.

Anyway, I haven't exactly set the world on fire shooting but I think I show up with some of the best tuned rifles on the field. Others , better at condition reading than I, have shot very well with my gear.

In short I think I would say that it's what appears on paper that matters, not on the crono screne. ;)

Gene Beggs
12-30-2007, 09:14 PM
I'm inclined to believe the relatively high velocities, the low ES, and the ease of tuning the 30's provide is related to the large volume of the bore. I picture the effective "chamber" to be the volume of the space from the inside of the case head and the bullet at any given point in the barrel......the volume increases at a much greater rate than the 6mm or .22, and is ultimately much greater by the time the bullet clears the muzzle.

-Dave-:)

Well said Dave. I agree completely.

Gene Beggs

rudedog
12-31-2007, 12:35 AM
Has anyone ever weighed cases and taken ten cases that weighed the same,and then filled them with water to check the internal volume of the case, both in weight and the amount of water it takes to fill it.Just a rookie thought
Rudy Manuel

Gene Beggs
12-31-2007, 04:21 AM
Has anyone ever weighed cases and taken ten cases that weighed the same,and then filled them with water to check the internal volume of the case, both in weight and the amount of water it takes to fill it.Just a rookie thought
Rudy Manuel

Yes, I have done exactly that several years ago and was surprised to find there was no correlation between case weight and water volume. I know it doesn't make sense, but that is what I found and the reason I quit weight sorting cases.

Gene Beggs

Pete Wass
12-31-2007, 09:26 AM
Yes, I have done exactly that several years ago and was surprised to find there was no correlation between case weight and water volume. I know it doesn't make sense, but that is what I found and the reason I quit weight sorting cases.

Gene Beggs

I have always felt that cases are just a container to hold the things that matter most, Period. They only need to be sized properly so that the bolt operates easily and I like the idea of limiting their growth but I have never seen that they were the cause of bad shots.

J. Pendergraft
12-31-2007, 09:33 AM
I had a Highwall .45-70 once that yielded incredibly low velocity ES. This was shooting 500 gr cast bullets with smokeless powder. I have read that the black powder shooters get low single digit spreads consistently with these big bore guns. Low ES is definitely easier to acheive in cartridges that are not overbore. For short range BR it's just not as important as the longer range games. I guess it could give one extra confidence if his loads exibit low velocity ES.

Gene Beggs
12-31-2007, 10:52 AM
Don, in answer to your question,

"Along this line of thought, do the .22 Beggs/Russian velocity variations exceed both the 6PPC and 30PPC?"

I can't speak for the 30ppc because I have never owned one, but the 6mm Beggs compared to the 6ppc averages about half the extreme spreads in muzzle velocity. I attribute this to the smaller case capacity relative to bore size.

It would take much more experimentation to prove it, but I have stumbled on to something I believe is significant as it relates to extreme spreads and that is flash hole diameter. The flash holes in the Lapua 220 Russian case, out of the box are drilled .059. Since this is too small to accept most decapping pins, I have always drilled them out to .063 with a Sinclair tool while the case is in the lathe during neck turning. In some cases, I have even drilled them out as big as .073. I now believe that is a mistake and that we should leave the flash holes exactly as they are; .059. With my 6mm Beggs NT, I usually see extreme spreads of around 20 to 30 fps with excellent accuracy. I have tried many different powders but I always come back to good ol' H4198.

Gene Beggs