WANTED: Info on BEST 22 rim thickness gauge

[saskatoon]

Greetings,

I am getting competitive in SB and need rim thickness gauge to improve groups.

What are your recommendations on easy to read, FAST gauges that are NOT caliper based. Calipers give precise measurements and I've seen one gauge that has numerals, ie, 3,4, 5,... for ammo separation.

Regards and Merry Christmas,

Blackie

[Guest]

That's an interesting statement Saskatoon:

I am getting competitive in SB and need rim thickness gauge to improve groups.

It moves me to ask the question, will checking rim thickness really help you achieve your objective? I presume that you already do a thorough batch test of the ammunition you already use? If you do so and select your batches by their performance over 40-50 shot groups then maybe, just maybe rim thickness measuring might be beneficial. However, consider the following; if the ammunition you are using is high grade then it is reasonable to assume that it's manufacturing tolerances are small; after all you are happy with its performance in the testing process. Although the rim thickness may (will) vary the absolute figure should be low and you could expect 90% of the rounds to fall within "acceptable" tolerance. Lower grade ammunition may well not achieve these figures and even though you eliminate the "rogue" rims you still have to contend with variation in other parameters.

I know of a test carried out in the UK with 1000 rounds of Tenex. 500 rounds were batch tested from the box using 2 barrels. The other 500 were measured for rim thickness and sorted. These were then tested with the same 2 barrels and note kept of the groups produced by each thickness. You know what?, there was no significant statistical difference in performance between the unsorted batch and the measurement graded batches. Now as I said above, this may not be the case if you used lower grade ammunition with wider manufacturing tolerances, but then again it might.

I fear that we sometimes measure things because we can and assume that consistency in size must guarantee performance. But this is not necessarily true as we should take all the parameters into account. A round may have a thicker rim, but is it due to thicker metal or a different shape? Does it more primer? Is there less propellant in the case? I would rather put my trust in the groups that I have seen a batch produce rather than measuring every round in the hope that it might do some good.

If you are looking for a good Rim Gauge then try this one http://www.intershoot.co.uk/acatalog/To ... ories.html the Gehmann 138. It is much better than the eccentric wheel devices.

My thoughts,

Merry Christmas everyone
Rutty

[jrmcdaniel]

I have never shot .22 competitively but from what I have read, I thought that concentricity was more critical than flange thickness?

[saskatoon]

Greetings again.

Good points in above responses. Palma ammo (bullets, powder, case,etc ) are built with VERY close tolerances; the only factors I can control on .22LR is manufacturer OR rim thickness since powder/primer are beyond my control.

I am using Lapua Club Standard at less than $4.00/50 for practice and competition; beats VERY expensive Ten-X or comparable. Mostly interested in cheaper ammo for practice sessions and have found substantial rim thicknesses from force needed to turn down bolt handle on Anschutz 1813.

Never heard that concentricity was a factor, though.

Regards,

Blackie

[Fred Mannis]

The only time I ever resorted to measuring rim thickness was in a situation similar to what you describe: difficulty with closing the action on my Toz 35 Free Pistol. I was using inexpensive B&S ammo for practice. Sorting allowed me to set aside the very thin (light hits) and the very thick (hard to close the action).

Looking at the Gehmann device, I doubt it is any faster than caliper based units, as the time consuming step is inserting/removing the cartridge. I used a G-3 Gauge with digital readout calipers: http://www.sinclairintl.com/cgi-bin/cat ... type=store
It was reasonably fast.

Hope this helps.

[Guest]

the price of ammo dosen't necessarily give you a gauge of quality. in my experience, certain guns seem to 'like' a certain type of ammo better than others. i have an Anschutz 1912 and have tested lots of different brands of ammo in it. I've found that Federal Gold Medal Target at $2.99 a box shoots just as good if not better then any eley. just a thought

[Spencer]

.

Never heard that concentricity was a factor, though.

Regards,

Blackie

a search on this site for 'concentricity' will throw up some threads around March 2006 that discuss the topic.

Spencer

[GOVTMODEL]

Greetings,

I am getting competitive in SB and need rim thickness gauge to improve groups.

Regards and Merry Christmas,

Blackie

I'm curious as to how you made that determination? What is the headspace of your rifle? Have you found a relationship between headspace and rim thickness?

My recollection is that the rim thickness of Eley products is 0.039" and that the standard deviation is quite small. Many Eley shooters have the headspace adjusted on their rifle to 0.041 inches.

Your mileage may vary:-)

Richard

[1813benny]

.

Never heard that concentricity was a factor, though.

Regards,

Blackie

a search on this site for 'concentricity' will throw up some threads around March 2006 that discuss the topic.

Spencer

Most of the hype was from the manufacturer of the gage.....this has pretty much been dismissed by the benchrest crowd and they are the most demanding when it comes to toys like that one.

[saskatoon]

Greetings to all,

The purpose of getting a thickness gauge was to categorize my "cheaper" ammo (<$4/50) in reasonable groups to at least provide consistency in head space while competitive shooting. I figured that if ALL the ammo used was too thick OR too thin OR somewhere inbetween, at least it would shoot more evenly; I'd shoot this ammo in groups and NOT mix them. Of course, the "cheaper" ammo may have greater variances in powder or bullet weight which could easily defeat my one variable (rim thickness) control endeavor.

I would guess and expect that $100/brick ammo would be more consistent due to price and reputation, but I have not come to the conclusion that high end ammos accuracy is worth the $$$. This opinion is subject to change, of course. :-)

Happy Holidays to all,

Blackie

[Tony C.]

If your goal is to find the best shooting .22 ammo for your rifle, I would suggest you save the money you are willing to paid for a thickness gauge and put them towards better quality ammo.

After 20+ yrs of small bore rifle competetive shooting I came to the conclusion after a shooter has acquired the best quality rifle him/her can affort with stiff action; good trigger; barrel etc... the only way to make that rifle to shoot up to its full potential is to feed it with good ammo, there just no getting around of it.

Fact is, there are very little aspects of a round of match grade .22 ammo, that as a consumer can improve by means of inpecting and sorting, the most important factor will affect the accuracy of the ammo are beyond the control of the shooter, such as the quality of the bullet; brass casing; consistancy of the powder and priming charge and so on, perhaps the most imprtant factor in determine how accurate a case of ammo will shoot is how consistant the crimping is applied, and there are just nothing you can do about it except pulling every round of ammo.

You may of course, from time to time, found a case of cheaper ammo shot vey well, almost as good as top grade stuff, however, the reason the top grade are much more expensive is because they are much more consistant. For years I pratice with second grade ammo such as Lapua Master and shoot match with top grade ammo like Midas or RWS R50 and its equivalent, lots of time the mid grade ammo shoot almost or at times better than top grade ammo, but in every case, 1 or 2 round out of a 100 or so just won't go into the 10 ring, to ensure every single round will have 10 ring accuracy, you need to pay more for the ammo maker to do the sorting for you.

Lots of shooter has gone down the road you wants to go; checking and sorting the ammo and so on, most have given up, they found out life is much easier if they just buy the best ammo they can affort and spend the rest of thier time shooting. However, if you are going to a important match, then it may worth the effort to weight evrey round of ammo you selected for that match, I know 1 shooter loss a medal in the final due to what we suspect the round has insufficient powder charge; it score a 6 at 6 O'clock and the discharge sound is quite different.

One more thing, keep an eye for when an ammo maker introduce a new line of products, very often, the quality are much better, I recall when Lapua introduce Master, the first few batches were so good, I gave up on Eley 10X, other makers such as RWS; Wolfe etc.. all done the same thing, this is of course to get you hook onto thier product.

The bottom line is, there's very little you can do to transform so so quality ammo to top grade ammo, consider this: lets say after you done your sorting of $4/100 rds ammo, you end up with 50 rds of good shooting ammo (I'm not so sure that will be the case) you are in fact paying $8/100 rds plus the time you spent sorting, is it worth it? Only you can decide.

Happy New Year.

Tony

[Jim Morrison]

I agree with Tony all the way.
I would like to add something.

I feel a person should collate their shooting ability with their ammunition. Many years ago before I switched to air guns, when a parent came to me and asked what ammunition I was starting them out on, I’d replied “Wildcats”.

When they could keep them in the black at 50 feet, I switched them to what ever the DCM provided.

Kind of the same way now . But instead of Wildcats, I start the new shooters, who now are adults, on 711B.

And when they feel they can shot a better score with better ammunition, I say “have at it”.

But if with the better ammunition, they can’t, then it’s back to the 711B.


Jim

[metermatch]

I know you asked a simple question here, and mostly got related info, so I will throw out some more:

First, let me point out I have never used a rim guage. In fact, I don't think I have seen one in person.

Second, I am not so sure I believe the claims being made.

That said:

I have to ask: when you say getting competitive, do you mean you are just getting into competition (beginner), or are you getting very good (master level)?

If you are a beginner, you are big-time wasting your time. You will never see the difference. Your training time is much better spent doing other things.

If you are a master, good luck, give it a try, and please let me know if it works.

But I do not believe it will hurt anything, either. So if you have a few extra bucks, and spare time on your hands, go for it. But if you are hoping it will turn a sharpshooter into a master, not a chance.

By the way, someone here mentioned headspace at .041". If I recall correctly, acceptable headspace is considered to be .041" to .045", and Karl Kenyon set mine at .042", which is considered a bit tight, but I never had any problems with over 100,000 rounds of Eley Tenex.

Jeff

[Guest]

Here is my $0.02 on the subject. I also use a rim guage to separate my less expensive ammunition. I currently use Eley Club Extra (sorted of course) for practice a generally use Eley Tenex EPS for big outdoor matches although Eley Match EPS works great indoors.

In addition to using a rim guage I also weigh my ammunition and have found that these two variables seem to work quite well in "creating" a consistent batch of practice ammunition. After i sort the ammo I keep all of the same parameter rounds in separate batches so I do not "throw away" the rounds that are not the same, i simply put them in a different batch and when that batch fills up I use it.

As far as the other shooters comments on consistency vs. price I agree for the most part. However, with that said, I also need to candidly express my disappointment with Eley Tenex EPS! I batch tested 100 rounds, indoors, with a scope to check on the accuracy and consistency of this ammo. What I found was that in 100 rounds (out of the box) there were 6 that cut the 9-ring at 50-feet indoors! That should NEVER happen when you consider that they are charging over $16.00 per box of 50. Imagine what would happen outdoors when the rifle is not secured and the weather starts to be a factor. I am sceptical now because you do pay for the "extra quality control" and with the batch I tested "out of the box" it simply was not there.

Anyway, I hope this helps answer your question. Have a great one! Good shooting!

[metermatch]

While I agree with the above, that when spending the big bucks for the top ammo, you expect the best.

But the real world is very different, for many reasons.

1) No one said that every batch of top ammo is going to shoot top scores in every gun. Too many variables. If there was a simple answer, it would have been done long ago.

2) You don't know how the ammo was treated. I'm not saying your ammo is bad, but what if your ammo sat on a hot loading dock for a day or so?

3) have you tried other lots of ammo?

4) did you get this ammo just off-the shelf, or direct from distributor?

Let me relay a story that happened to me:

About 20 years a go I wanted to buy some more ammo. I ordered 100 rounds of Eley Tenex in about 10 different lot numbers from a very reputable mail order house, and tested it. It was all junk. Every last lot number. It shot worse than my Eley Club. And I know there was nothing wrong with my gun.

What I learned from this test and from asking around was that by the time I got to test my different lot numbers, the ammo had already been picked through, and the best lots long sold out. Argue with me all you want, but if you want the best ammo, you better be prepared for a trip to England to test there, or you better be friends with one of the big importers in this country to test ammo lots when it come in, or forget making it to the elite level.

My having 1987 Eley Tenex lot number WJ1001 made all the difference between my setting a number of national records, and just being a good club shooter. Period.

And I also know that same ammo lot number was tested in Billy Meeks' rifle (member of 2 US Olympic teams) and Steve Dembers' rifle. Both of their guns did pretty good with it, but they found other ammo lots that did better in their guns, but did not do so good in my gun. So every gun is a law unto itself.

And if anybody has any Eley Tenex WJ1001 for sale, let me know.

Jeff

[Guest]

Jeff,

I agree with your statements 100%. My grumble with the Eley that I tested is this...if you are being charged over $16.00 for a box of 50 (true you can get a discount for large orders) you and I (and everyone else) as consumers have a right to expect a consistency that matches the prices being charged.

I think you are right on the head when it comes to the fact that different lots perform differently. My rifle loves Eley and that is why I started taking the extra time to do thickness tests, weight comparisons, and visual inspections myself. I can buy a less expensive lot, do the above testing, and get a good batch of ammo, at least for my rifle.

[GOVTMODEL]

Every barrel is unique, and every lot of ammunition is unique; that's why Eley has a Customer Range and a full time person to run it. IIRC, Eley shoots ~500 rounds from each lot through four barrels during QA testing.

For a shooter to test ten rounds of ammunition from one particular lot and come to any conclusion about that particular brand of ammunition is simply not warranted, and is unsound from a statistical viewpoint.

As for pricing, no one in Birmingham is glad to see the value of the US$ decline:-(

Richard Ashmore

[Guest]

Richard,

Thanks for the comments but I think you missed something in my original post. I did not conclude anything with just 10 rounds. I shot 100 rounds out of a vice to conduct my testing. You can argue that Eley using 500 rounds is a better indicator but statistically that is not a true statement. In fact, with a 95% confidence interval and using the following equation n = ((z x s)/E)^2 to determine the minimum size for n, my sample size is well over the minimum size required.

I undersatnd your concern about statistical significance...as a coincidence, I am a university professor with a Ph.D. in Mathematics and one of my concentrations is in Statistics, as such I would never conduct such a test without having a well defined and sufficient sample size. Based upon my test, my conclusions are warranted, at least for that particular lot. The data had a small standard deviation overall, but when you have mulitiple outliers as I had you begin to wonder how that can happen (6% outliers in a sample of 100 rounds is statistically significant in its own right).

I am concerned beacuse it seems the price of Eley is on the rise and the quality may be questionable for recent lots. Maybe it is just the result of massive hand-picking of lots and what is left are the less desired ones. My rifle has always loved Eley and it is just recently (the past 8 months or so) that it is resisting this brand. I had my rifle thoroughly inspected and the barrel is still in great shape. Anyway, enough of this topic :-)

By the way, I see you are from Rhode Island! Where abouts? I grew up in Newport and shot Juniors at Rogers High School (Henry Fletcher was my coach).

[GOVTMODEL]

Richard,



By the way, I see you are from Rhode Island! Where abouts? I grew up in Newport and shot Juniors at Rogers High School (Henry Fletcher was my coach).

I live in Portsmouth and am a member of the Newport Rifle Club from 1992 onward. I know Henry Fletcher well, though he's not as active as he once was.

It is entirely possible that I misunderstood your methodology. When Eley tests QA tests ammunition, about four rifles fire about 125 rounds each from the lot being tested, and the results determine what label that lot gets, i.e., TENEX or Match.

At th Customer Range, you fire, from your barrel, a forty shot group from each batch being tested. Eley's test fixture, while far superior to my Ransom Rest, is still subject to operator error affecting the outcome. Regrettably, I have proven this.

I heard, anecdotally, that right after the move to the new facility that there were some difficulties in getting TENEX to come out of the machines. My stash was big enough to tide me over:-)

Where do you shoot now?

Richard Ashmore

[Rutty]

Another poster on the Stirton board came up with the following:

After a recent batch testing visit to Eley I was surprised at how difficult it was to make a decision on which batch to select. There was a whole load of different information including gun score, absolute group size, average group size of the four constituent groups, a score distribution histogram and also graphic representations of 40 shot groups and the constituent 10 shot groups. Much of this data was conflicting, e.g. the smallest groups didn’t necessarily have the highest gun score etc.. This got me wondering if there was a way that I could evaluate the data in such a way that I could iron out some of the statistical spikes caused by the relatively small sample size (i.e. 40 shots per batch) and come up with a single number which would represent how well a particular batch would shoot. We know that the distribution of shots fired will be a circular normal distribution which means that, given some sample data, we should be able to calculate the probability of where shots will land. Knowing this I’d like to find answers to questions like: What percentage of shots can I expect to score 10.4 or better? or What percentage of shots can I expect to score less than 10?

It turns out that this is very similar to a problem which the scientist Sir John Herschel had written about in 1830:-


'. . . let us imagine a person firing with a pistol at a wafer on a wall ten yards distant: we might, in a general way, take it for granted, that he would hit the wall, but not the wafer, at the first shot; but if we would form any thing like a probable conjecture of how near he would come to it, we must first have an idea of his skill. No better way of judging could be devised than by letting him fire a hundred shots at it, and marking where they all struck. Suppose this done,-suppose the wafer has been hit once or twice, that a certain number of balls have hit the wall within an inch of it, a certain number between one and two inches, and so on, and that one or two have been some feet wide of the mark. Still the question arises, what estimate are we thence to form of his skill? how near (or nearer) may we, after this experience, safely, or at least not unfairly, bet that he will come to the mark the next subsequent shot. This the laws of probability enable us on such data to say.'


After a couple of attempts Herschel came up with a formula which can be used to predict the probabilities of how far a shot would land from the center of the target:

p ( R > r) = exp (- (r ^2)(log 2) / (a ^2))

Where R is the distance for the center of the target and a is an inverse measure of the shooters skill chosen such that p (R > a) = 0.5.

In the case of our ammunition batch testing instead of “a” representing the skill of the shooter it represents the accuracy of the batch and we can calculate it using the following formula:

a = r * sqrt(- (log 2) / (log (1 – H)))

Not only that, but he provided a link to a page to allow us to calculate it ourselves by simply inputting the shot values: http://www.bagpus.com/batch_test.html

This is in effect a Circular Error Probability calculation, which once again according to the original poster:

According to wikipedia the CEP is "a simple measure of a weapon system's precision. It is defined as the radius of a circle into which a warhead, missile, bomb, or projectile will land at least 50% of the time". This is exactly what the calculated value of "a" is above - the radius of the circle which we expect 50% of shots to land in. The reason it's useful is that it remains the same irrespective of the number of shots fired, whereas the absolute group size increases with the number of shots fired. I believe that it's a far more useful measure of ammunition performance than group size.

I really must get out more!

Rutty