?

Alf wrote:

quote:

One sees clearly that the rifling engraved the shank, hence my question as to what the specifics are in terms of the relationship between the bullets claimed diamter relationship to the CIP/SAAMI spec.

This picture is the opposite side of that same bullet Alf is referring to -


Clearly on this side of the bullet the rifling didn't engraved the shank!

So it seems that the same rifle can cause different engravings on the different sides of the same bullet!

Isn't it now, based on this example, rather a question of how barrel riflings differ within one barrel rather than the bullet conforming/not conforming to certain standards like CIP/SAAMI or whatever?

Jagter,

quote:

So it seems that the same rifle can cause different engravings on the different sides of the same bullet!

Does this mean that the rifling in a barrel could be thinnner on one side than the other ?
I'm sorry but I cannot think why it would be this way. Maybe it is but it doesnt make sense to me. Dont you have another fired bullet for another example ? Maybe this is just a bad example to use.

Of course the lands could be a different height (radius) in the barrel.

If anything the shank diameter of the bullet must be no larger than the smallest diameter of the lands.

And the bands must be far enough apart for all the deformed band material to have some place to go.

As long as the bullet shank diameter is smaller than the land diameter(s) and the band diameter is not significantly(!) larger than the groove diameter then all should be acceptable.

But these variations are an inherent problem with monolithic solids, and could require specially made bullets for any particular barrel.

As to the question of pressure, it seems intuitive that to drive a given weight bullet at a specified velocity the banded bullet with less potential resistance would require a lower pressure. I have not the faintest as to what the magnitude of that reduction in pressure might be.

quote:

I e-mailed Ty Herring at Barnes and he stated that this was indeed so but refused to state how much or what the actual reduction is claiming it to be some important critical trade secret ?????

I would say that Ty doesn't know. It would be a pretty easy thing to measure if it was that important. I think the main reason Barnes bullets are grooved is to decrease barrel fouling.

The only thing I need to know as a handloader is that, per my testing in a couple of .308 caliber rifles is that the Barnes TSX, Barnes banded spitzer solids and Nosler match bullets of the same weights impact about the same place with the same powder charges at 100 yards and the velocities are fairly similar.

You will be surprised at the number of oval barrels out there. It is not uncommon for rifling depth to differ from groove to groove. If a bore is bowed through the outer profile of a barrel, lands will wear more on one side than the other. Bad cleaning habits with a cheap cleaning rod and no bore guide will cause measurable and visible anomalies in time. The picture below is of the engraving made by the four lands of a 30-06 barrel. The opposing lands differed by a considerable amount as can be seen. The bullets were fired into a water tank at about 800fps.



Alf,

quote:

exactly what does conform mean?

con·form (kn-fôrm)
v. con·formed, con·form·ing, con·forms
v.intr.
1. To correspond in form or character; be similar.
To bring into agreement or correspondence; make similar.

sim·i·lar (sm-lr)
adj.
1. Related in appearance or nature; alike though not identical.

spec·i·fi·ca·tion (sps-f-kshn)
n.
1. The act of specifying.
a. specifications A detailed, exact statement of particulars, especially a statement prescribing materials, dimensions, and quality of work for something to be built, installed, or manufactured.
b. A single item or article that has been specified.
3. An exact written description of an invention by an applicant for a patent.

quote:

This means that when shot from an original Mauser the barrel rifling would engrave no only the bands but also the shank of the GSC bullet.

You should make the distinction between engraving and scraping. Correctly, the drive bands are engraved as material is displaced. The shaft of an HV is scraped and there is a big difference.

en·grave (n-grv)
tr.v. en·graved, en·grav·ing, en·graves
To carve, cut, or etch into a material: engraved the champion's name on the trophy.
To carve, cut, or etch a design or letters into: engraved the silver watch with my monogram.
To carve, cut, or etch into a block or surface used for printing.
To impress deeply as if by carving or etching

scrape (skrp)
v. scraped, scrap·ing, scrapes
v.tr.
To abrade or smooth by rubbing with a sharp or rough instrument.
To rub (a surface) with considerable pressure, as with an edged instrument or a hard object.
To draw (a hard or abrasive object) forcefully over a surface: scraped my fingernails down the blackboard.
To injure the surface of by rubbing against something rough or sharp

quote:

This 375 GSC bullet as posted by Jagter illustrates exactly what I'm refferring to.One sees clearly that the rifling engraved the shank

Look at the illustration again. At A you see that material is displaced where the drive band is. This material is displaced to the side as well as partially scraped over the shaft surface behind the drive band. There is a distinct area where the shaft surface has not been touched by the lands and could therefore not be engraved as it is not even scraped. Moving further down to B and C, the displaced material increases because the drive band width increases. What you see as engraving is the displaced material that is scraped across the shaft surface. This is clearer on the oblique view at D. The tops of the drive bands, as seen at E, has touched the bottom of the rifling grooves, effecting a good seal against gas blowing past the bullet.

Comparing only the length of the engraved portion of a smooth or grooved bullet to that of a drive band bullet is simplistic. Given a barrel that is on spec and bullets that are not under size, this is what happens: With a land width of 2mm and a 4 groove barrel in caliber 9.3, the displaced material on the grooved bullet you measured amounts to about 30.6 cubic mm. On our 9.3 HV bullet, the total volume of material that is displaced is less than 9 cubic mm. I say less than 9 because the drive bands taper towards the top and I am not going to calculate the volume precisely. Then there is still the matter of where the displaced material goes. On a smooth or grooved bullet, the majority of it is compressed into the shaft. This causes the bullet to lengthen. That is why it takes approximately 12 000 p.s.i. to engrave a smooth or grooved bullet. On a drive band bullet, the material is displaced to the side, where there is space for it and the engraving pressure is in the region of 1 200 p.s.i.



Take a look at this and then tell me again that the difference between a grooved bullet and a drive band bullet is open to debate. There is no comparison.

In the picture below, the engraving of the drive bands are quite clear while the scraping of the shaft is so light, it is only visible towards the rear of the bullet.


On this HV bullet, one of our older designs, the alternating engraving and scraping is highly visible in the alternating dark and light sections down the shaft of the bullet.

Gerard,

Are you able to measure any overall lenghting of the fired bullet in the first photo (the one shot a 800fps) as compaired to an unfired bullet.

The reason I ask is because I frequently read words like engrave or cut when referring to how the rifling puts its mark on a bullet.

I think cold forgeing or swaging would be a more accurate description of the process.

To me engraving or cutting implies bullet metal is being removed like when a milling machine tool spues chips of metal from a work piece.

I think the bullet is forged into the rifling and therefore looses virtually no weight by having the rifling pressed into the bullet shank. Yes a negligable amount of copper is scuffed of the bullet and left in the bore as bullet metal fouling but it take lots of shots to build up in the bore.
It believe it would take a very sensitive laboratory grade scale to measure the copper lost to scuffing off in the bore on firing.

The same grade of measurement tools would probably be needed to see how much the bulet has grown in length by having the rifling squeezed into the shank. The displaced metal has to flow to some ware and solids are not compressable, but they can be made to flow which is why we have to re size our fired brass.

The lengthing by squeezing process may account for the irregular position of the rifling marks as the bullet is forced longer the shank probably bends (wriggles) slightly as it is force to lengthen. Know doubt the bullet tip even wriggles in a small circle during this whole procces.
What are the odds of the bullet tip remaining in the exact centre postion in the bore on exiting the muzzle after this process.

Hi Guys
Here is the answer to the Barnes v. std bullet question.
http://www.dtic.mil/ndia/2004arms/session9/siewert.ppt
It stands to reason that the lower the friction in the barrel the lower the breach pressure for the same bullet weight/powder charge
The engraving force is greatly reduced in a truely banded bullet compared to a TSX. THe Barnes TSX bullet has a reduced bearing surface compared to standard Barnes X but there is still more pressure required to engrave the shank than either a GS custom or LM-KJG.

Mark

Greenjoy,
I doubt that the lengthening of a drive band bullet would be measurable, if it lengthens at all. The displaced driveband material is pushed aside, rather than impacted into the body of the bullet. The material that is displaced on a smooth or grooved bullet and the logically resultant lengthening may be measurable but I have not done so.

You are right about the terminology we use. "Engrave" in the sense of a smooth bullet should rather be "cold forge".

?

Gerard,

Your Std 7 English lesson was a splendid one, but seeing that Alf passed Std 10, makes it hilarious to say the least. Alf raised a very valid question, so we can all understand better what we are seeing. One simplistic explanation could have been .... some barrels do not conform to the bullet's dimensions, so engraving is sometimes uneven and scraping may also occur, as barrels have a tolerance spec (some barrels are tighter than others). This explanation presupposes then that your bullet is actually more precision made than a barrel.

Warrior

As per usual the Alf vs. Gerard discussion degenerates into semantics and mumbo jumbo.

ALF
This is easily solved in relation to the barnes x/tsx proj...just run both through a pressre gun and you will have your results/answer...i will tell you now the barnes x will run at a much higher pressure, than the same weight tsx proj...
if you like i can put a few loads through the pressure gun with the 200 gn barnes x nd the 200 gn tsx
i can do the same with the 180 tsx ,but dont have any 180 barnes x on hand for comparison , if you have a few barnes x send them down and i will get them pressure tested
regards daniel
Daniel

Alf,

quote:

exactly what does conform mean?

You ask, I answer and now you complain. I never know when to take you seriously.

quote:

So a rifle with bore/cal dimension of say 9.3mm + 0.04mm only "scrapes" a bullet with shank diameter of 9.286mm ?

BTW that spec of 9.3 is not correct. Current CIP states 9.00mm and 9.28mm + .02mm. So, yes, a 9.286mm diameter shaft is scraped by a 9.28mm diameter groove dimension and the lands will forge the shaft to a depth of 0.28mm.

quote:

unless one has knowledge of exactly what a specific rifle's particular barrel dimension it is it is not necessarily "safe" to choose a mono bullet with grooves and or bands?

What we can say with absolute certainty is that a drive band bullet will always require less force to engrave than a smooth or grooved bullet in a particular rifle. No matter what combination of sizes you try, the lower engraving pressure of a drive band bullet can never be approached by any smooth or grooved bullet. If a rifle will be damaged by mono drive band bullet, it will be damaged easier/sooner by a smooth or grooved bullet regardless of construction. A possible exception would be a copper jacket filled with marshmallow.

quote:

What is the fundamental difference betweeen say a Barnes TSX and say a GSCHV or a Lutz or any other ? In terms of how they are derived??? Both /all or all start of as a rod with particular diameter, both / all are then subjected to a milling proccess

Barnes cold forge/swage/turn their TSX bullets. We only turn. Milling is different from turning. ( Milling Machine / Lathe) Swaging/forging is radically different from turning. In turning there is no work hardening of the copper. In swaging/cold forging there is. Turning is far more precise and there is greater repeatability of form from batch to batch.

quote:

Gerhard claims his is not randomly chosen, it is done conforming to CIP/SAAMI spec, again without the sarcastic reference to the dictionary I ask conforming to what spec?

Alf, what is the problem here? I stated that GSC bullets conform to the CIP/SAAMI spec. The spec includes the tolerance. So if you buy a GSC .284 bullet today, it will have a particular size in a particular place on the bullet. If you buy another GSC .284 in two years time, it will still measure the same dimension in the same place. We have a standard of manufacturing that we adhere to and everything we make conforms to that standard. The standard is in a specific relationship to the CIP/SAAMI spec.

When all is said and done, the bottom line remains here.
We still claim a unique first into the market and we have a ten year head start on those who copy.

?

Alf,

I guess I'm pimping my own mumbo-jumbo.

Instead of arguing about banded mono bullets it seems that some data would be nice!

But even with published reloading data, it is only a ball-park estimate as ever gun, rifle, brass, barrel, etc. are different.

Banded bullets are a great idea, and so much better idea than the old mono solids like the Barnes. Flat nose bullets are even a better idea.

Even without the instrumentation to prove it, it seems that if one shot typical jacketed solids and some banded mon solids with the same charge of powder, which bullet flies out of the barrel faster?

I'm guessing the banded bullet would have a higher velocity but that wouldn't mean the pressure is less as I would guess that the pressures are about the same.

The pressure with the same charge of powder couldn't be less unless the bullet velocity and therefore residence time of a bullet would be much less than the other. In the limit the pressure would be less with no bullet at all!!

The other approach would be to load different amounts of powder so that the two different bullets had the same muzzle velocity. If the banded bullet came out as needing less powder to achieve the same velocity as the jacketed bullet, then one could guess that the pressure is less, but it doesn't answer your question of how much less!

At least in my book, the minutia could save an elephant hunter's life! If they don't die of boredom first.

Alf

Speak to Lutz Moeller if you dont believe Gerard or PM him. I'm sure he will know the exact data you are looking for.
On the other hand just believe me banded bullets are better for heavy doubles than standed monolithic or TSX bullets.

Mark

?

Alf

We are looking at about 30% if I remember rightly compared to standard bullets but as I said you need to get someone like Lutz involved. Nothing better than a phyicist that make banded bullets. I'll try and get him to post you an answer.

Regards

Mark

We tested today a brass 12ga slug
with shaft diameter smaller than
land diameter and it does it at same loads
and low pressure as 12ga hardened lead slugs.
A slug that Greg Sappington designed, with
four bands that take up 40% of the sides.
Four bands are same as groove size.
Other banded 12ga brass slugs with shaft dia
same as lands we had to cut back a little
on the loads to have same pressures.Ed

North Fork Solids and Cup Points...
Their shank does not normally touch the barrel.

I say "Normally" as individual barrels can vary a great deal.

quote:

This means that when shot from an original Mauser the barrel rifling would engrave no only the bands but also the shank of the GSC bullet. Something incidently seen with all GSC bullets recovered over many calibers shot from my rifles

Alf,

1) Which calibers are involved? Would it only be metric calibers?

2) based on the measurement given on your .366/230 grain bullets, it seems the driving bands do not fill the difference between groove diameter and the bore diameter:

----------- CIP Std ---- HV bullet
Groove = 9.28 mm .... 9.234 ----> driving bands smaller by 0.046
Bore .. = 9.00 mm ..... 9.086 ----> shaft of bullet bigger than bore size (0.086)
Diff .... = 0.28 mm ..... 0.148 ----> bands do not neatly fill the gap

Tolerance of .02 mm

It seems then that Alf's original question of conformity & specific relationship in fact has something to it.

Gerard,

Please advise if the above is correct and your comments on what it means?
bigger by 0.086 mm
smaller by (0.046)mm
Diff is 0.040 mm

So, the lands will cut into the bullet's shank.
Would the gap of 0.046 mm induce flame-cutting?

Warrior

Alf,

quote:

The shank of the bullet crudely measures out to 9.286mm actually smaller than the 9.3's Zug diameter of 9.5mm+0.05mm

Alf, the 9.5 should obviously be 9.3, just a typo, I am sure. Also, please measure your 9.3 HVs again on the rear drive band. We revised the 9.3 drive bands in 2004, in accordance with the CIP revision of middle of 2002. What are you measuring with, a vernier caliper or a micrometer?

Will,

quote:

But these variations are an inherent problem with monolithic solids, and could require specially made bullets for any particular barrel.

The variation in CIP/SAAMI spec as well as wear within reason is accommodated in our design spec. Where a barrel deviates significantly from spec and it is not practical or desirable to replace it, we will gladly make special run bullets for it. No extra cost but they will not be stock items.

quote:

If the banded bullet came out as needing less powder to achieve the same velocity as the jacketed bullet, then one could guess that the pressure is less,

It is the other way around. Because the drive band bullet offers less resistance through the freebore/leade, more powder is needed to get to the same speed as a jacketed bullet. This will result in lower peak and/or average pressure. Further increasing the charge to equal the pressure of the jacketed bullet will result in higher speed with the drive band bullet.

Chris,

quote:

It seems then that Alf's original question of conformity & specific relationship in fact has something to it.

And the Troll continues to question that of which he has no understanding. The agenda remains foremost though: Find fault with GSC Bullets.

Here is an idea - Contact some of these people and tell them GSC bullets do not give accuracy. Or talk to some of these guys and convince them they are using badly designed bullets. Pick one, any one, I will put you in contact.

You should stop fretting about the dimensional specifics of our drive band bullets. I will not give you exact design parameters or specs. That information represents an ongoing evolution of design that spans ten years and remains the reason why GSC bullets are different from even those that appear to be exact copies.

Hi Guys

I am posting this intersting link on behalf of Lutz which should answer Alfs questions. I would however recommend reading the whole page which should answer a lot of secondary questions about the benefits of truly banded bullets.

http://www.lima-wiederladetechnik.de/Englisch/7-mm-Bull...mparing_Measurements

Below are pics of 9.5mm and 7mm with no engraving on the shanks




Mark

Gerard,

This is not about finding fault with your bullets. It is about dimensions and how they relate to CIP, that is all. I have not referred once to accuracy or the lack thereof. In previous postings I have said many a time that your bullets are precision made and accurate as many people attest to. Did I not compliment you umpteen times on the innovation of your products?

Gerard, your paranioa creates a lot of clutter. Rather stay focussed on the topic of dimensions and why they differ and what the consequesnces might be. For example if a copper jacketed lead-core bullet is slightly undersized that it would still seal/obturate properly, whereas with solids it might not be, etc.

There is no state secret in dimensions Gerard, they can be measured, as you well know. Just guide us through with facts and I assure you that will be appreciated by one and all. If you did change the drive band specs in 2004 of your 9.3 bullets then it is certainly no sin; in fact that is commendable.

I think most 9,3 users would like to hear about the changes in CIP specs during 2002. What were the specs and what are they now? Just think about it this way ... you may have adjusted, but many other manufacturers may not have adjusted to the new specs and that puts you in lead of all drive band derivative manufacturers.

Remember this is for fun and to learn from one another.

Warrior

?

?

quote:

I think most 9,3 users would like to hear about the changes in CIP specs during 2002. What were the specs and what are they now?

Gerard,

I am curious to know about the circumstances leading to and necessitating changes in specs for the 9,3 after all the years. Did they make the groove to groove distance bigger? Conversely, have we been shooting bullets that were over size for bore/groove dimensions?

Warrior

Gerard,

Why would CIP have changed the spec after all these years? It just does not make any sense. As Alf stated, I take it that those dimensional standards always applied. I am truely baffled, or are you spinning us a yarn here?

Warrior

quote:

Why would CIP have changed the spec after all these years?

Beats me. Why don't you harrass them for an answer and then argue with them about it. I am sure you could easily dream up several imaginary reasons why they should not have done what they did or should have done what they did not do.

quote:

I am truely baffled, or are you spinning us a yarn here?

I think we have had this discussion before. As you baffle so easily, you should find a baffle support group. They could help you through the ordeal of accusing CIP of lies and deception when you have your arguments with them.

?

Thanks Alf,
It should measure between 9.285 and 9.295, depending on how cold it is there. I don't think it is as cold as 9.234. That would put a crimp on a lot of things.

three honest questions

what is the percent BEARING surface area reduction in a grooved bullet?

what is the percent BEARING surface area increase with increasing twist from 18 to 10?

Do these cancel out?

Lutz Möller low Friction Drive band Bullet “KJGâ€, that obviously seals, but keeps the Lands off the Shaft



Lutz Möller low Friction Drive band Bullet “KJGâ€close View to show how the Band seal the Groves. Photograph Norma in Amotfors /Sweden, after the 7,62 mm KJG penetrated 60 cm Gelatine



Lutz Möller plastic tipped low Friction Drive band Bullet “KJG spitzâ€, after it hit the Watertank with 1.100 m/s (and after 70 cm Water the Steel bottom too)



Same Bullets from above hitting Water with different Speeds



Engraving Force of a jacketed M80 Lead Bullet in to a M240 Machine gun throat



Engraving Force of a low Friction in to a M240 Machine gun throat. While the Force carries no Units, both were measured by the Order of Arrowtech Associates with the same Scale. Shown are the Averages of each 40 Bullets

Note: KJG Peak force is 38% below the jacketed Lead Bullet.
Note. The Standard Deviation “Sigmaâ€of the KJG is about an Order of Magnitude lower, than the Full metal Jacket Bullet



Three Samples to measure the Force to leave Case mouth



Brake forces of three Bullets to leave the Case mouth.

Fact:

A well done Drive Band bullet is able to reduce Engraving Force into the Barrel throat and Friction in the Barrel below that of jacketed Lead Bullets. Numbers are given.

Benefit:

A well done Low Engraving Force and low Friction Bullet shall be uploaded and will deliver higher Speed, than comparative Designs of the same Weight an Length (others cannot be compared on even PLayground), the Barrel will keep cooler and more consecuteive Shots can be placed with given Accuracy

Regards Lutz M
p.s. I have a new Identity, as I moved my Website and first replies from AR captured my Spamfilter, without me noticing that, but You will know who talks.

quote:

As you baffle so easily, you should find a baffle support group. They could help you through the ordeal of accusing CIP of lies and deception when you have your arguments with them.

Gerard,

Since you brought up the change by CIP in 2002, I think the onus is one you to state the changes for the greater good of AR readers. I do not need to accuse or argue with CIP; we just need a statement of fact from you, that is all. If there were changes to groove/bore dimensions, what are the problems then to publish them here? Knowing that CIP made changes in 2002, why did you then only make the changes to your bullets in 2004? Something does not quite gell, unless you had no 9.3 orders between 2002 and 2004!

Warrior

This is way over my head. Has a new double owner what I need to know Is A) why when I shoot 500 gr norfork cup points I have little rings showing up on case necks. B) What mono's can I shoot in my Merkel 470. Why is it ok for the cup point's and the CSN's but considered a problem with the TSX's.

JD

Chris,
So much ignorance, so little time!

quote:

Since you brought up the change by CIP in 2002, I think the onus is one you to state the changes for the greater good of AR readers.

CIP makes revisions on an ongoing basis. Only you would suggest that I keep AR abreast of these changes which would be close to a full time job. Your vast lack of knowledge / grip on reality is showing once again.

quote:

Knowing that CIP made changes in 2002, why did you then only make the changes to your bullets in 2004?

Because that is when we started seeing the changes trickle down to the manufactured products coming through the market. You were up in arms about the twist change CZ made recently so you are obviously unaware of the evolution of the industry that is an ongoing living thing. You should catch a wake up and realise how little you actually know before starting a scrap that shows you up for the ignoramus that you are.

quote:

Something does not quite gell, unless you had no 9.3 orders between 2002 and 2004!

And you are the one who constantly harps about paranoia! What a joke. But of course there has to be the obligatory snide comment about GSC products. Every time you deny your agenda of slander, you confirm the fact that you lie like a sack. Go on, tell us again what your favourite bullet is, you have not done it for a while.

quote:

Because that is when we started seeing the changes trickle down to the manufactured products coming through the market.

What a statement ... "changes trickle down" ?
They trickle from 2002 down sloooowly to 2004?
They trickle like powder granuals, hey?
What a profound statement.
At this rate, something seems retarded to me.

Gerard, we just want to know how the groove and the bore diameter changed, that is all.

Warrior

quote:

At this rate, something seems retarded to me.

You are beginning to understand. Well done! Remember, you cannot change what you do not acknowledge.