Discussion in 'Rimfire & Smallbore' started by Dubya, Feb 5, 2012.
What is a fairly good rimfire thickness gage and where can I buy one.
Gary (aka dubya)
The RCBS master case gaging tool comes (or had available as an optional extra) 2 blocks that are for rim thickness measurements for .22RF and .22 Magnum cartridges; that was the deal when I got mine, but I don't know if it's still that way or not.
After using the RCBS master case gaging tool for that purpose, I purchased a Bald Eagle Rimfire Cartridge Gage from Bill Gebhardt at Bald Eagle Precision Machine Company in Lock Haven, PA (570-748-6772). The Bald Eagle rim thickness gage is just as accurate as the RCBS, and because it is designed specifically for the purpose (it falls into that general class of gages referred to as "snap gages"), rather than having the function being an add on among several that the gage accomplishes, it is MUCH faster. I definitely prefer the Bald Eagle gage to any other I've ever used. Fast and accurate is good.
I will sell you a Bale Eagle rim guage for $100.00 shipped... Email me at firstname.lastname@example.org for pictures and mailing info...LT
Thanks all, I appreciate the info.
Buy the Sinclair Guage for about $35.00, very fast and plenty accurate, I just don't think there is enough of a difference in accuracy to warrent spending $100.00 on a RF thickness guage.
It may be a little faster, I don't know, but you'll never see the difference on the target.
Just my 2 cents, John
How about this one? Trim a spent .243 case to make sure the mouth is square. Measure the length. Insert a .22 round, measure the o/a length then subtract the "case only" length. Result? Rim thickness.
Price? Varies with whether not you already have a .243 case, trimmer and caliper. Or know somebody who does. ;D
Not quite as cheap as Lesloan, and maybe not as quick as a dedicated tool, but if you have one of those Sinclair Hex Style Bullet Comparators, just stick the 22 cartridge in the .24" hole and measure it. Total inches - comparator thickness = rim thickness.
I could be mistaken, but I think the rimfire accuracy guys quit doing that sometime back. Bob Gebhardt sold Bald Eagle a few years ago. Don't know if the new owners are doing anything or not.
Don't know if Bill sold the business or not - I know it was on the market, and he offered it to me in one of our more humorous telephone conversations, but I lack the ability to step into his shoes. But he still advertises the thickness gage in RIFLE magazine, as late as the March, 2012 issue, and the address in the ad is still on Allison Street in Lock Haven, PA.
Other's results may differ; I've had better (and more consistant) results shrinking groups measuring rim thickness than weighing cartridges, so I quit weighing and switched to measuring rim thickness some years ago.
Is there a possibility that a specific range of headspace lends itself to improved grouping by sorting rim thicknesses? I have read numerous claims indicating that properly chambered rifles that leave little room for the casing to get tilted, combined with a chamber length that grabs or engraves the bullet, negates the effects that sorting rims gives other less ideal rifles. I have sorted rims for my accurized 10/22 and there is a bit of improvement. My CZ 455 on th other hand shows no improvement from rim sorting. Same pretty well goes for the sorting ammo by weight.
I'm sure even going into the lands, that going in the same distance every time could only help.
What I have found is that the brand and type of ammo make the difference, the $18.00 a box ammo, I've seen very little difference in checking rim thickness, I tried doing some CCI SV the other day, the rims were all withing 1/2 tho of what the majority of them were, it's not going to help much there.
But on Wolf MT, I have had great results, far fewer fliers and more consistant grouping, so I think the ammo itself will tell you which benefits from sorting rim thickness and which does not.
In the case of the Wolf MT, I usually end up with 3 or 4 different batches, I go by the half thou. and 4 to 6 that are way out from the others.
Anything outside of the norm is used for seasoning the barrel.
I'll do a brick at a time so I can fill the boxes and not have too many left over that are the odd man out. One or two boxes is just marked for seasoning the barrel, so there really is no waste.
If I'm going for the best groups possible, I will weigh the ammo and segregate it that way also, but most of the time just do the rims.
It is something that works, no matter what anyone says, thing is, it works much better on some than on others depending on the QC of the rounds. Only way to know for sure is to try it on the ammo you shoot. That way you are not wasting time sorting ammo where there is really no difference in groups, but others, it makes a huge difference.
My Best, John K
To add to the above post, with ammo brands that respond to rim thickness sorting, we have found that just grouping by thickness numbers has resulted in smaller groups, with a general tendency for group size to further improve as rim thickness increases, UP TO A POINT. Once that point is reached, groups with greater rim thickness don't show any increase in accuracy and sometimes fall off a bit. Generally, this spot has been reached about 0.040" if memory serves. To get much of any gain you have to sort a brick at a time to get significant quantities of each thickness, and in the few brands we have sorted, the biggest number has been in the 0.038", +/- portion of the range with a marked drop off in quantity of 0.040" or larger out of a 500 round brick - the number of cartridges in each 0.001" increment batch between 0.035" and 0.041" is pretty much a bell shaped curve in quantities of one or more 500 round bricks with the same lot number in our experience. For the ammo we shoot and the rifles we shoot it in, anything 0.035" or under, or over 0.041" becomes barrel foulers for serious shooting or plinkers for our fun shooting. As before, your experience may vary. Like anything to do with rimfire shooting, each rifle has its preference for optimum rim thickness, just as for ammo brand.
I linked this thread to Rimfire Accuracy. You might check their experiences. Bear in mind they are serious competition shooters.
It may be the quality of their ammo is better than yours.
Thanks for the link. It certainly looks like their experience runs parallel to mine. Sorting by rim thickness does essentially nothing for higher priced high quality match ammo - very little variation to begin with there. But it works wonders with the cheap, bulk pack ammos that, as the guy over there said, would give serious precision shooters hives - I thought that was a great description of the ammo I mostly sort by rim thickness. ;D
Very good post, I have found your results to mirror mine. Some people think sorting will make a $5.00 box of ammo as good as a $15.00 a box ammo, considering your rifle likes both types, but it will not.
The Wolf MT has responded the best to sorting. It shoots very good in my Savage. Sorting gets rid of a good portion of the fliers and tightens groups, but it still will not shoot as smll as the expensive ammo.
I one time shot a perfect 5 shot group, 5 @ 50 yds. The hole measured .222" across.
It was a one time thing, never repeated, I've come close, but never another.
The point is not that I shot a perfect group, the point is tha it was Wolf MT, rim sized, 38.5" and weighed, I'd bet there would have been no way to have shot a perfect group had I not sorted the ammo, one would have been out.
It makes for better, more consistant groups, but it's no substitute for expensive ammo.
Rim sorting on ammo that you have seen that it makes a difference on is worth the effort to me.
My Best, John
You can find Rim Thickness gages in Sinclair's Catalog.
I have used the one made by G3. It clamps onto a caliper and is simple & fast to use.
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