Meplat trimming & bullet tipping?

[gt40]

The reason I started this thread is because I have shot 5 shot groups at 400 yds as small as 1.5" and 1.75" but not consistent, but my average the other day was larger. I shot five 5 shot groups which measures 2.0", 2.375", 2.375" 2.25" and another one that was 1" for four shots and one flier which gave the group a total measurement of 2.25".

I was hoping that if I did trim the meplat and tipped the bullets I could get more consistent groups down under 2 inches. For me that is a lot of $$$ if it probably won't help. http://www.bullettipping.com/

What do you think?

gt40

PS: I am shooting a 6mm Norma BR. with 105 gr. Berger VLDs, CCI BR4s and Varget just touching the lands.

I am also using my new Vortex PST 6-24x50mm FFP MOA scope with the Vortex custom turret. I had it on 24 power when shooting these groups.

[J. Valentine]

It is very hard to say if it would improve anything. The Meplat diameter of a Berger 6mm 105 VLD is .050 . That is fairly small already . A lot of the things people do to improve accuracy are trail and error in the beginning anyway and they throw out the things that don't work.
Closing a meplat can demonstrate a higher BC in most cases so that may translate to a better accuracy potential from flatter trajectory and maybe better wind fighting ability . How much you could accurately close a .050 Meplat and see a measurable improvement is debatable . How much of you group spread at 400 is related to wind not intrinsic accuracy. Although higher BC can help wind issues.
Trimming is another issue and if the meplats are very out of square it can show results if that is the case then you need to trim first before closing a meplat to close it square to the axis of the bullet. Trimming can throw up burrs to the side of the meplat that can cause closing problems . Trimming , then hand deburring and then tumbling to smooth up the meplat then closing could work.
However a lot of work goes into the Berger VLD bullet and I can't see that the work is warranted , from the samples I have seen I wish I could make as good a bullet at home.
Some of the bullets I have made could definately gain from such work but a Berger VLD I am not so sure. You really have to try it and see if you like the whole process and the results.
I suggest that if you do , start with a small batch of bullets first and see how they go before altering hundreds.
I still think that jacket thickness precision is the most important factor to group accuarcy and we can't control that with factory bullets some reloaders have ultrasonic measuring devices to check made bullets . I am not sure how precise they can be in gaging the thickness of a jacket .

[Charles E]

The problem with your question is it assumes that a general answer fits, where I don't believe it does. I got interested in this phenomena when I saw the raw data Larry Bartholemew and Dr. Oehler got when testing the model 43 chronograph with a bunch of long-range chamberings and bullets. One thing stood out: the BC of some bullets varied as much as .020, whereas other bullets had a low SD for BC (drag). Typically, the low SD bullets were the tipped ones -- by tipped, I mean the plastic inserts, as in the A-max.

Aside from the A-maxes, I didn't see any clear pattern by manufacturer.

Dave Tooley got a model 43 and began some testing of his own. You could always get a lower SD of BC variation by trimming the meplats. Sometimes that lowering was a fair bit, some times insignificant.

Raising BC by repointing the bullets is another matter. It won't take out any vertical over trimmed meplats, but you might get slightly less horizontal dispersion because of less wind drift. How much? Depends. And whether or not the slight rise in BC will show up on the target depends on how much increase you get. I'd agree that the small amount gained by closing an .050 meplat isn't world-shattering.

So the way to answer your question is to shoot your set-up over a Oehler model 43 chronograph with an acoustic target and get actual data. Problem is, that costs far more than the meplat closing and trimming devices.

As for me, since I own both a meplat trimmer and point closing die, I use them on my bullets. Done right, it can't hurt, even if it doesn't help much, esp. with the 6mms.

[Cheechako]

gt40

.6 MOA groups at 400 yards certainly leave a lot of room for improvement. But, before resorting to exotic and expensive things like meplat trimmers and pointers I'd take a good look at the usual suspects. Barrel, bedding, load, etc. You should be shooting 1/4MOA or better at 100 yards with a good 6MM BR. If not . . .

JMHO

Ray

[Law Dawg]

GT40:

Try to find the archive thread where Jason Baney posted pictures of his testing of the 6mm Clinch River 106 shot in his 6BR at the 1000 yard club in PA. a few years ago. In a round robin test with closed meplats vs. unmodified meplates the difference in the vertical was about 18" in favor of the closed meplats. His 5 shot groups were 2.xxx with the closed meplats and 5.xxx with the unmodified meplats. Jason went on to win the Heavy Gun class that year in the World Open with the closed 6mm meplats -- in his 6BR Light Gun of 15.xxx pounds. I think you will find that this test and the threads associated with it turned Mr. Litz onto the closed meplats. In my opinion, the Litz analysis of that testing brought real credibility to meplat closing.

As to the Berger 105s, John Whidden closes the meplats on his and they have worked rather well. In vertical at Camp Perry in the shootoffs in 2010, a huge majority of his shots were waterline -- from the prone with sling.

It is all about uniform BC. A nice trim will help a lot on your vertical, but so will a simple closing because it "merges" the junk on the meplat into a uniform point. You can trim to uniform and close to recapture the BC -- and several other combinations. Of course, you can usutally close J4 jackets to a smaller meplat than you can Sierra jackets because the Sierras are thicker -- a few tricks will fix this as well. As for the time to close the meplats, I can close 15 per minute after I get my ORIGINAL PINDELL die set up. I can't keep up that pace for too long (and don't try), but I can cycle at that rate with little effort.

As an aside, all the testing has been done over many thousands of rounds. Many World Records have been set in 1000 yd BR, F-Class, and Long Range prone and many Championships have been won with the closed meplats. It is a no-brainer for your best long range load.

Good luck,
Jim Hardy

[John Kielly]

I've found with the commercial projectiles that I use in my 1200 yard gun (shooting off the elbows), I can do a pretty effective sort by pointing them up, then meplatting using the Whidden system which trims relative to the base of the projectile, then pointing them up another thousanth or two after cleaning up the cut.

Trimming the meplat that way goes damn close to doing a sort on base to ogive length with this type of projectile. The only hassle is setting up for a new batch. It takes a little time to trim the minimum amount. There have been instances when the factory batching is less than desirable that I have had to do a second cut on the point. I'm figuiring that in that instance, I have more than a single run of projectile, in which case I batch accordingly. Otherwise, I sort by eyeing in how closed the meplat is.

Admittedly I take more care with my 1000 yard benchrest projectiles.

[Charles E]

GT40:

Try to find the archive thread where Jason Baney posted pictures of his testing of the 6mm Clinch River 106 shot in his 6BR at the 1000 yard club in PA. a few years ago. In a round robin test with closed meplats vs. unmodified meplates the difference in the vertical was about 18" in favor of the closed meplats.
Jim Hardy

Jim. That's passing odd. As it happened, I was shooting 106 Clinch River bullets in my 6 Ackley when Dave Tooley got interested in bullet front ends. He took some of mine, and put in plastic tips, like in the A-max (though they weren't A-max). Done right (it's Dave, remember) on a lathe, indicated in, and bored.

Shooting side by side, the 106 CR tipped bullets struck at the same elevation. The groups were similar, but as I remember, the tipped bullets had a touch larger group. Usually, with other bullets, the tipped ones did shoot much higher.

Now my 106 CRs had very. very good meplats. Obviously, I didn't see Jason Baney's. So we're left with a couple choices, given the reported 18-inch difference.

Just one more instance of anecdotal evidence. Not saying either of us is wrong, but it shows a different kind of testing is needed.

When it gets down to it, given possible variations in shooting, the only data is a side by side comparison over a chronograph like the model 43, which shows both time of flight (letting the program compute ballistic coefficient) and variations in BC (ES, SD).

Charles

[gt40]

Unless I am mistaken I have two different instructions in which you do first. Whidden's instructions say to point the bullet first and then trim the meplat and others say the opposite. "Extensive testing has also shown that light meplat trimmer after pointing produces the maximum possible BC consistency. " OR do you trim the meplat then point the tip then slightly trim the meplat again?

http://www.sinclairintl.com/.aspx/pi...ing_Die_System

gt40

[Cheechako]

gt40

Anecdotal evidence is what keeps many of the "gun & shooting" gizmo manufacturers in business. Not that there's anything wrong with that.

Take my advice - get that 6mmBR shooting tiny groups at point-blank distances first. Then extend yourself out to the mid ranges.

JMHO

Ray

[Law Dawg]

gt40:

You can trim and point. You can point and trim. You can trim, point, and trim. You can trim, point, trim and repoint. You can just close the meplats. And, you can just trim. Your choice.

John sorts within a certain criteria, closes the meplats and then takes a very light trim off the tip -- no repoint. He also shoots moly Berger 105s and that serves as a lube for a very nice looking bullet when it comes out of the meplat closing die.

Jim Hardy

[Law Dawg]

Charles:

"Anecodotal evidence" -- outch my old friend and mentor. Please send me your 6mm VLDs and let me do what I do to them. I will ship them back at my cost. You can test them and post it here. I already know the results -- just like when I shipped the bullets to Jason Baney to test.

I don't know how to find that thread in the Archives, but I bet you do. Don't make me remind you of when you borrowed my 300 WSM Light Gun for a shootoff in which you shot a screamer group with 210 JLKs (closed and tricked meplats) out of a 12" Twist 5C Broughton. Not that your marksmanship on that occasion means anything other than that -- but I had to remind you of it -- maybe the only time you have shot my closed meplats and they worked mighty fine indeed.

I think you have my address. Send those 6mm bad boys to me. I have been trying to convince you to go closed meplats since 2002 and now is my chance! Remember the ones I prepped for Joel for his 338 Light Gun -- first time out he goes 4.xxx with that cannon and 300 grain SMK. Let me make you a believer with your own testing.

Regards,
Jim

[Charles E]

Jim, we're talking past each other. You convinced me long ago, in the sense that I now have a Whidden repoint die, and I've always had meplat trimers -- actually, it was Dave's work that convinced me of the meplat trimmer, but you who got me to fork over the $300 or so for essentially the tiny little cylinder.

Now these are tools. Where I'm coming from is that the lot of 106 CRs that I had were darn near perfect. And they had tiny meplats, as small as one can get & still not lose knock-out pins in the point-up die -- about .050. I don't remember if you were still shooting 1K-BR when I had that rifle, but for a year, it won at least a relay every match out. A Hawk's Ridge relay, 10-11 people on the line, and most of them with good equipment. (Yup, that's anecdotal evidence.)

Based on the test with the tips Dave put in and the bullet strike, what I find hard to accept is the other CR-106 bullets printed 18-inches higher due to a change in drag (BC) alone. The plastic tips have essentially the same mepat diameter. And not much lead is taken out to put them in, they still weigh 104 or so. So I can't say what happened, but what I or anybody should accept as data would be firing these against the stock bullets over a 43, where velocity and BC (time of flight), plus the variations, are all available.

Moreover, I have two .30 caliber bullets made on the die R.G. and I came up with, the one used for the 187. OK, a .30 has a slightly larger meplat -- usually .062 is about as good as anyone will try -- and J-4 jackets usually give fuzzy points.

Now, one weight of those bullets, an experimental 187, prints significantly higher than the unmodified, fired the same day with the same load at Butner. The other one, a bit heavier, does not. I can't explain it, but there we are. Sample size a fair number of bullets, but just one rifle. And not shot over an Oehler 43.

For giggles some time, use your ballistics program to get a time of flight (or total drop) for the CR 106. Let's say they have a BC of .520. See how much you have to increase the BC to get a drop 18 inches less. If it is an unreasonable amount, something else must be going on.

Now it never hurts to have these tools. Often they'll help. It seemed to me the original poster kind of wanted a guarantee that they would always help, and that has not been my experience. Lord, he could try A-Max bullets and get the benefits for the cost of the bullet. If the new A-max shoots in his rifle, that'd end it.

Charles

Edit:

Another test, aside from the ballistics program, would be to run the bullets numbers in the JBM drag-twist program. Make no change to the bullet numbers except meplat diameter. Change it to .001 if you want. See what the program gives for the new B.C. Does it agree with the number from the ballistics program?

Now I understand this is modeling only, that real-world results must stand. But the models too have been proven to accurately predict. What I'm suggesting is that a change in the print of the bullet print alone is not the only test. That's where a 43 is helpful.

[Joe Salt]

Charles Tell me this, if I'm shooting over a chronograph and getting single digit readings and they shoot like crap. And then the ones I played with on paper with double digit readings shot much better. which way would you go. I think you rely too much on these reading from the chrono, all I want to know is how fast there going so when I change lot# on powder I get back were I was. i've seen better results with the 30 cal than with 6.5 and 6mm. pointing. Ask 4Mesh how much difference there was with his reloads and mine out of the same rifle, he doesen't point. He told me he wouldn't have believed it if he didn't do the shooting. Charles as long as I'm politically correct, most of this is ballistics Masturbation to me.

Joe Salt

[Charles E]

Joe, were talking past each other too. Obviously I'd go with the single-digit groups, whatever the ES -- as I posted on the ES thread.

But what people are talking about in this thread is that using certain tools ALWAYS increased BC, and a lot. That's the beginning of old wives tale number 6,745. Now there is a good way to test this, since BC is just a simple way to get at drag, and drag, in this case, is essentially a time-of-flight phenomena. The only thing pulling a bullet down is gravity, so if everything else is the same, if it hits higher, it just gets there faster.

How to check the claim? Simple. Measure the time of flight, showing up as computed BC. Now, if it turns out that the computed BC doesn't explain how much higher the bullet hits, we know there something else going on as well. Do we use the tool? Certainly. But we stop the old wives tale and begin looking for just what that something else is, maybe it will help us more when we understand it.

As long as we're left with "mine hit higher" we also have to allow "mine didn't. And not all of mine do.

[Law Dawg]

Charles:

In testing closed vs. unmodified meplats at John Whidden's range, Butner, and Ft. Benning, we never had ANY unmodified bullet equal a closed meplat. That is from the old Palma 155 (2155) to the 300 grain 338 SMK. The bullets that benefited the most were the .224 and 6mm bullets (because the percentage of closure was more of the total dia of the bullet). No matter how small the meplats out of the box, you could still get a lot of difference in the vertical and often the accuracy. The Pa boys know of Jason's testing and the pictures are in the archives. It was right on the money with my 6BR load shot out of my prone gun. Jason was shooting about the exact load as my prone gun with the difference being my 31.5" barrel, i.e., about 3000 fps for me and something like 2975 for Jason with RL-15.

What got Bryan Litz' attention was his calculated wind deflection from the 18" of vertical difference. Charles you are correct. I am saying that there is NO bullet you can send me that will not benefit from MY MEPLAT CLOSING DIE at 1000 yards. Some more than others. For example, a 6mm Secant ogive bullet made on J4 jackets will show more improvement than a similar bullet made with Sierra jackets because the J4 allows a smaller meplat closure (without a bunch of tricks). As a real world example of just a change in bullet design, the new Sierra Palma (2156) will shoot about 3 minutes higher at 1000 than the old Palma (2155) -- that is about an off-the-paper difference -- with unmodified tips and the same exact load.

Jim