Blunt Ogive 6mm bullets

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skeetlee

Active member
I havent posted much here lately or asked any questions here lately as i have been trying to learn this stuff on my own but today while shooting my 6ppc i noticed that my favorite bullet blowing around a little more than i thought it should have been. The bullet i like so well is a real blunt ogive bullet, probably close to a 6 ogive and this bullet is a short jacketed BT bullet. This is the first time i shot them in this new Krieger barrel as i have been waiting on my custom FL size die to be made. I still dont have the custom die and the only 6ppc die i currently have is a redding Small Base die. It sizes these cases way to much and i hate like heck to even use it but i wanted to see how this barrel was going to shoot, so i did. this darn die sizes the shoulder are .002, way to much. Anyway back to the topic. In General will a blunt ogive bullet be more wind sensitive compared to say a 8 or 9 ogive bullet? I had a shilen barrel last year that just loved these football bullets i have, but i didnt see to much today in this Krieger. I did shoot one Nice .190 group with XBR 8208 and the bullet .028 off full value JAM. Will a bad seating depth cause a bullet to be more wind sensitive? Whats the general thought on this? thanks Lee

One more thing i noticed today. On my brass there is a solid carbon ring all the way around the brass about 1/4th the way down or .110 down the neck.Looks like the tips are colored black. In Tony's book he says this is a sign of not enough neck clearance. I cant see were this would be true in my case. My brass is turned for a neck thickness of .0082 and my chamber is a .262. There should be plenty of clearance here. I can take a pic if needed. I have never seen this myself in person, just in tonys book. Maybe there is too much clearance??? Lee
 
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Here is a picture of my brass hopefully. Look at the tops of the necks. they are black. Like i said i have never experienced this before. What do you think? thanks Lee

normabrassring001.jpg
 
Lee
I have noticed the same thing in fresh brass, seems after a few firings you will end up with the normal sine wave. I can't explain why. You are very observant. Took me years to start noticing subtle differences in stuff. I am currently making bullets that are just as you described > blunt. They look like footballs > big mouth blunt boat tails. They are shooting real good so far, I'm not changing anything.
Be patient with the Kreigers, sometimes they take a few rounds to come in. Barrels are funny things. Everyone is different. Try Jam > .030 off of Jam > and .060 off of jam. Some BT like to run way off in some barrels, can't explain it > just is. I am a 133 guy, like it and shoot it a lot. Tried XBR just couldn't get it to work as well as 133.
I have a 1/2 thou clearance at the neck and chamber, still get the same carbon ring you are getting.
I use shims under my die to adjust for hardening of the brass. I've notice also that some of the Lapua brass cuts different. Sometimes it cuts like butter and other times it is a little brittle.
Every day may be a little different tune.
Good Luck

Marty
 
The answer to your question, at least, the one in the thread title, is a qualified yes. Qualified, because it doesn't matter much once you put the calculator and computer down and start shooting. I've shot Fowlers (6.5 ogive) and the 8.25 ogive BIB's at the same 300 yard match, the SE regional which use to be held at Charlotte, North Carolina. BTW, the meplat in the Fowler's is huge, which hurts the BC even more.

My aggregates were about the same with the different bullets. Reading the wind was much more important.

That isn't to say that individual barrels don't have a preference. They often do.

Just to put the matter into perspective, the 1,000 yard 10-shot HG group NBRSA record was shot by Dave Tooley. The 1,000 yard IBS 10-shot HG group record was shot by Joel Pendergaft. The 1,000 yard 10-shot HG group Australian record was shot by Jeff Rogers. All of them were shooting the 187 flat-base BIB bullet, with a calculated BC of around .540, and a real-world, doplar radar measured BC of .520. The final sanctioning body, Pennsylvania, got a new HG record late last year -- also the new world record, shot by Matt Kline. I believe he was using the 210 Berger. Prior to that, it was Joel Pendergraft's IBS record that held the "world" record.

Now, if the relatively low BC of those record holders -- close to or maybe lower than the usual 6mm 105 bullet -- wasn't a factor at 1,000 yards, how much a factor do you think BC is at point-blank range?

What the individual barrel likes is the "best" bullet. And since the life of a competition barrel is very limited from a large-match standpoint, you might be well advised to stock about 3-4 types of bullets. Pick your own, for me, it would be the old standby flatbase 6.5 ogive like the Fowlers, a flatbase with relatively sharp ogive around 8.5, a boattail like Barts on a .790 jacket, and a "fatty" with around a .2433-.2434 diameter ABOVE the pressure ring.

But pick your own styles.

You should be able to tell which of those a barrel likes, and be a significant way into load development, within 50 shots total. If it doesn't like any of them, it is always possible it might like another. But I think you'd be better off selling the barrel to a varmint hunter & getting another. If it takes 250 rounds to settle on a load, you've just given up half the big-match life of the barrel.
 
Lee, a good short range BR bullet is as good as the die set that made it AND the bullet makers capabilities... No matter what ogive.........

Concentric / strait.... Couple that with a "conservative" 6-7 ogive and the bullets go to "sleep" at the moment it leaves the crown.... No wiggles or "hunting for centerline" .... = Less wind sensitive @ 100/200 BR...

Still, to SEE the Superman bullet one MUST have the rifle, barrel, tune... Up to the task..... Shooter MUST be up to the task as well...

Make sure your reamer IS a .262nk......... With .0015 - .0020 total nk clearance, you should see the "sine-wave" pattern on the necks right after fireforming..... Check that your loaded rounds are bet .2600 - .2605 range.... .2610 or tighter will give ya a similar carbon ring on the necks your seeing.... "Fitted" necks are way more trouble than their worth... Can be quite dangerous...!

cale
 
Lee,
You ask good questions.To some of the "headier" questions there are no scientifically proven absolute answers. So you will get opionionated responses.At some point in time a competitor needs to quit wondering about things and " get some conviction" one way or another.What I believed last year has been adjusted to what I believe this year and will probably change somewhat to what I believe next year.You will probably experience the same conviction curve on your own.The proof is in the pudding,take your current belief base into competition this year and see how you fare.That's what I plan to do.
Hope these comments help,
Low ogive bullets have a wide tune window,high ogive bullets have a narrow tune window.
Low ogive bullets get moved around in the wind more so than high ogive bullets.
Bullets with big noses( meplats) lose velocity in a hurry.
Bullets with small noses are good.
Boat-tails are good( considering the current availibility of J-4 jackets)
Stay away from extreme profiles in bullet design.I plan to shoot a 7-3/4 boattail this year( The 8-1/2s are too fussy for me,I never shot one but the 6's gotta get manhandled in the wind)
Tune set-ups into the rifling "cut" conditions better than touch or jumped tunes.
A "really"tuned rifle will move half as much in the wind as a "kinda tuned" rifle
Information gained in temps under 50 degrees dosn't mean much in the competition of summer heat.
8208 xbr is " recycled little green army men" trash, get rid of it before you waste the competitive life of that new Krieger. Shoot 133 or 8208 pulldown.
Individual range terrain/atmosphere will influence tune performance. One needs to be aware of this. What worked in Toledo will not necessarily work in Midland.Your home range has it's own tune personality,don't get too hung up on it's tune performance results.
An over aggressive die will not hurt you as much as you have been led to believe,as long as shoulder bump is correct and your die/ bushing/press is producing straight ammo.
My boattails are .2430 diameter I turn necks to .0085 for a .260 loaded round in a .262 chamber. Tighter than that can be troublesome,looser than that( in a .262) makes for wimpy neck tension and shorter brass life.
Good shooting,Hope you have a good year.
Joel
 
Bullets

Cale, I am beginning to think that it is not the dies and skill of the bullet maker so much is it is the quality of the components. That is, when we are talking about bona-fide Benchrest Bullet Makers.

I have had bullets from the same reputable bullet maker, but different lot #, where one batch will shoot lights out, and the other batch mediocre at best.

Of course, there are dies that have born legends, The originol Euber, The Fowler, Ed Watson's, and a few others, but even those produced mediocre bullets from time to time.

I know this, when I do get a great lot of bullets, I'm not going to be shooting tin cans with them:)
 
Thanks fellas for the remarks. I guess its time to brake out the original Fowler bullets, and the 08 lot of N133, and get down to business!! I have said this before , and i will say it again. I would give almost anything to get away from having to use N133 for the 6ppc. One thing i notice at every single ppc shoot i attend is the large amount of competitors chasing there tune using N133. It also seems that most have no idea what needs to be done to get there rifle back in tune, and even more so they were never in tune to begin with. Tuning a rifle with N133 seems to be an elusive art, that most never get any kind of grasp on. I will admit that i am one of those that cant always seem to find mt tune in a timely manner. I can get a rifle in tune before a match, but keeping it there while shooting the match is very difficult at times. Most folks wont admit that, but it is the truth. I think its like anything else. Time and experience is a must to learn this art. We have some really good people giving us the basics but that's only a small part of it. Taking those basic sets of rules, and reading the target then making proper adjustments isnt easy. The good news is i am willing to put in that time, and i am willing to listen, when opportunity to learn presents itself. I guess we are all looking for that magic powder, if there is such a thing. I keep comparing my 6ppc to my 30BR and i really shouldn't. I can pre load for my 30BR and shoot well all day. Its very easy for me to at least wish for the same with the 6ppc.
My home range will be done before to much longer, and i will be able to spend the necessary time to learn and read targets then make proper adjustments. I will get there!!!

I just had never seen case necks like those in the pictures. That really had my attention. Lee
 
Lee like several have said,,,, measure a loaded round and make sure of the final size at the base.
 
I have .0025 clearance on my loaded rounds. I wil just about bet the black tips will go away after a couple more firings. Time will tell. the accuracy seems really good so far. I hope to make it out this weekend for a few shots but i may not. I am hauling dirt for my back stop on the new range. Woo Hoo!!!! I lucked out on the dirt too. I work for the city here and we have a hole yard full of mulch. Some of this mulch is several years old and it is now black dirt. I get it for free, as does anyone else. This stuff will work great for a back stop berm. Sure beats having to buy dirt at 200$ a load. Lee
 
skeetlee i have had bullets move more in a light wind from a 6ppc i had at 100 yards than what i would think is normal. i spoke to a BR shooter and he told me i need to chrony the loads and when i did i found the velocity was low and he was right, i tryed to up the powder to get the speed up on the bullets.
so chrony-n- the load can tell you alot about as you read pressure signs.
i have never shot 8208XBR in the ppc but i have shot it in a 14 twist 6BR and on cases that i shoot all the time it seemed to soot up my necks.
FJIM.
 
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