"CBT head trimming tool"

G

GeorgeH

Guest
While surfing the web I found a UK article about a head trimming tool (a metplate trimmer) that emulates the Eley Tenex EPS bullet. Does anyone know about this tool?
 
Cicognani Bullet Trimmer

That's it.

Interesting tool. Lets you use Eley Club but enhance its performance to simulate Match or Tenex.

The science is sound; high power shooters have recently begun cutting a metplate to tighten groups. While cutting the metplate increases drag and reduces velocity, it eliminates a lot of yaw which increases group tightness.

But the real value of this gizmo is limited to people who shoot Eley Tenex, Match, and Team. It gives them the ability to practice with cheaper Eley ammo.
 
Tenex dimple

Save your money and buy ammo. Research has shown that the dimple on Eley has no positive effect on accuracy. If it did it would be a simple addition for any mfgr. It however seems to make a great sales tool.
 
The dimple

Hi Charles:

The dimple has nothing to do with it. There is a basic principle of fluid mechanics known as Bernoulli Effect. The principle simply states that a faster moving fluid creates lower pressure.

The curve of the bullet is longer than the length of the bullet's axis. That gives rise to lift. (Lift is not a factor with a bullet because its velocity declines with distance and the effect of gravity.) But because the bullet is spinning, when a defect in the curve is encountered, air peels off and applies force against the bullet like a little bump in the road.

I suspect the dimple has value, but I don't know what it is.
 
GeorgeH said:
That's it.

Interesting tool. Lets you use Eley Club but enhance its performance to simulate Match or Tenex.

The science is sound; high power shooters have recently begun cutting a metplate to tighten groups. While cutting the metplate increases drag and reduces velocity, it eliminates a lot of yaw which increases group tightness.

But the real value of this gizmo is limited to people who shoot Eley Tenex, Match, and Team. It gives them the ability to practice with cheaper Eley ammo.
Click to expand...

Could you be kind enough to point to any body of reference at all that indicates the EPS bullet has anything what so ever to do with yaw?
 
EPS Bullet

Hi Tim:

Cutting a metplate to tighten groups have been going on for a while with high power shooters. My post was to (i) try and find out who made the cutter, and (ii) to find out if anyone on this side of the Atlantic has any experience with this 22LR cutter. It has found some acceptance with bench rest shooters in Europe, but I haven't met anyone who has used it here.

Quality control on match grade ammunition has gotten so good in recent years that gizmo's like this now have some utility where 10 years ago, no one would have noticed.
 
GeorgeH

I started a thread on this subject some weeks back and my results was the same as yours. I could not find anyone that thought there was any value to these things. But I do know shooters in the UK and Italy think these things work.:confused:
 
GeorgeH said:
Hi Tim:

Cutting a metplate to tighten groups have been going on for a while with high power shooters. My post was to (i) try and find out who made the cutter, and (ii) to find out if anyone on this side of the Atlantic has any experience with this 22LR cutter. It has found some acceptance with bench rest shooters in Europe, but I haven't met anyone who has used it here.

Quality control on match grade ammunition has gotten so good in recent years that gizmo's like this now have some utility where 10 years ago, no one would have noticed.
Click to expand...

Well yes and know. Your high power-group example is a bit deceptive. Short range BR guys [up to 300yards] don't do it much if at all. Very long range shooters deal with the fact that out that far the bullets are on the ragged edge of stability. The question was posed because the EPS slug was not developed with stability in mind but wind related issues, real or percieved.
 
The question was posed because the EPS slug was not developed with stability in mind but wind related issues, real or percieved.
Click to expand...

Hi Tim:

Wind--that's what this is all about. Eley's Tenex is the most wildly used match ammo for 50 meter competition. That's about 165 feet. Air is considered in science as a fluid. It is how the air/wind acts on the bullet that is affected by cutting the metplate.

My interest is: how does this gizmo work in real life.
 
George, you have homework to do, wind effects everything, yaw develops for any of several reasons. Ask any number of people exactly what twist to shoot a long 30cal bullet. The theoretical meplat issue is uniform metal on the bullet, the comparison between it and the EPS bullet has, I believe been made nowhere but your post.
I think you missed the point that if it was used in real life we'd hear about it.... it isn't.
 
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Hi Tim:

I don't understand what you are saying. Have you used this tool? If so, what has your experience been?

I have used a similar gizmo for high power, but its cut is far, far shallower (and a lot cheaper too) than the rimfire tool. I find the concept interesting. But I'm not here to debate you, I'm here to learn from the experience of others as to this tool.
 
The Paco Tool

Hi Singleshotom:

I am familiar with the Paco style tool. It is a great device to enhance a small game hunting bullet or to turn a 22 LR into a clean cutting wad cutter.

The tool that I'm trying to learn more about is made in Italy and is used by European smallbore bench rest shooters. That is what fascinates me. A tool that can uniformly alter the performance of a smallbore bullet so precisely to interest benchrest shooters.

I want to understand how do you use the tool so to produce uniform results? How does the group size of a modified Eley Club bullet compare to the performance of black box Match or red box Tenex? At what range does any advantage disappear? Is it worth the money (it sells for 180 Euros which is over $200 USD)?

US benchrest shooters have greater access to long range facilities. Maybe this tool doesn't have practical benefit for US benchrest shooters, but could it be of value to 3/4P and prone smallbore shooters?

For example, at my son's junior rifle program the average kid (who is serious about practicing) shoots a minimum 5,000+ rounds a year. For practice, they shoot RWS target, T-22, what is now green box Eley Target, SK, and Wolf Match. But when they go to Camp Perry, out comes Eley Tenex, Match, the other high end ammunition. But if you can alter a bullet's profile and give it grouping charactics similar to the high-end stuff, then you have dialed-up the quality of your practice time.
 
It is illegal for US Bench shooters to modify the ammo at all. Not sure about NRA but I suspect the same there. That being the case, it is somewhat of a mute point. Also, it would be illegal for the Europeans to use that ammo at the worlds using the RBA rules. As an academic discussion, if there was a clearly defined advantage, all bullets, not just the good stuff, would use that profile.
 
Hi Don:

The gizmo is to make practice more effective. I know that Europeans who use Eley ammo seems to like it. The tool is now in its second generation. Unfortunately, whatever discussion that I have found on the web is not in the English language. So, I assumed that someone here, who posts on the web, may have had some experience with it. Heck, it was a pain to just to find out who made the gizmo over there.
 
George, nobody uses one. Your believe that the "top" shooters all use the EPS bullet might be a tough sell to the guys that won several national matches this year with round bullets. Somewhere down the road you got convinced the main component to better is a flat bullet.
 
Your believe that the "top" shooters all use the EPS bullet might be a tough sell to the guys that won several national matches this year with round bullets.
Click to expand...

Hi Tim:

I don't know where you are coming from.

I can care less what the "top shooters" use. I'm just interested in learning about whether or not this gizmo works. That's it.

Eley is a very popular manufacturer of ammunition. If you use Tenex, Match, or Team there is no cheap source of practice ammo with a similar bullet profile. All I want to know about is if this gizmo allows a person to use another Eley product and give it the grouping characteristics of its more expensive cousin.

Tenex wasn't developed for benchrest. It was developed to enhance grouping characteristics in 50 meter 3P rifle competition. But this gizmo was developed by an Italian company to be marketed to European benchrest community.

I don't want to endorse or condemn a product before I learn about. I understand the science behind the idea, and I have been doing something similar to 223 ammo in high power service rifle shooting.

But there has to be a reason why the product is popular in Europe but not in the US. My guess is price and effective range.

Eley developed its EPS bullet profile to enhance its percentage of 5 shoot grouping within a 15mm diameter. They spent a fortune in R&D and the end result turned into a rifle only product.

In 3/P ISSF competition Eley controls the lion share of the ammunition market. The US marketplace pales in comparison to the European market. In German speaking countries alone, there are over 15,000 small bore shooting clubs.

So, if this gizmo reduces the cost of practice ammo for Tenex, Match, or Team shooters, I'd like to learn why.
 
In wrote an article in the UK on the CBT a few years ago. This was via a lot of testing with a number of ammo types and prices ranges so I was paid to do it. Whilst it had minor affect on top of the range ammunition (although in high winds it helped present a more stable group) the trimmer did help to achieve better consistency on the lower brand ammunition. I still have some of the test cards somewhere and I know a few others who did try test themselves.

It is an expensive product and may offer nothing to you apart from the fact that it is enjoyable testing and comparing. As stated in other posts I would seriously doubt this would ever be allowed in international matches and could be illegal in some countries - modifying rimfire ammunition is classed as unsafe in a few places.

I used this tool quite a bit with cheaper ammunition but have not used it since moving to R50 and then Eley EPS over the last two years.

By the way trimming hundreds of rounds is not a job for the sane. Cheers
 
George, I think your right, it must be cost. I think that the guys, rightly so, that need $6000 in rifles for a season and shoot about $3000 worth of ammo just ain't gonna spring for that last hundered bucks. As to your thoughts on the bullet development, go find the several articles written by Frank Tirrell about this type bullet well before ELEY, then reference all the published Calfee data and his work with ELEY. When done, you might want to do a search here in the archives for any posts on the subject. Don't you think you'd have heard something here after asking the same question 8 different ways?
 
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