Digital Calipers
- Thread starter Druski
- Start date
Mount Sweetness
CGN Ultra frequent flyer
- Location
- Southern Ontario
Don't spend $30...go to Princess Auto or Canadian Tire...they go on sale for $10 to $15 and work excellent.
Agreed !! Even if there were much of a difference in the quality/accuracy of these things, the fact that you're only using em to check COL's of 45 ACP and 9's makes a larger $ investment just a waste. You could probably get away with a $2.00 plastic set from Prince Ass Auto.
Lucked out - Princess Auto in thier flyer - Digital set for $14.00
I had an order into Cabela's for other stuff so I figured I may as well throw in the Calipers on the order... but since Princess had em on sale..... I picked em up on the way home!
Thanks for the replies!
Im new to reloading, into shotgun not handguns. Now of the preciseness of the cartridge when assembled and/or being assembled, what are the typical variances allowed for these cartridges (as per the OP....9mm, .45acp)
The reason I ask, I have some experience with precision fitting devices and machines, and firearms is one of them. In the industries I have worked in, these calipers are not trusted at all for their accuracy is highly questioned. I have one of those digital calipers from the princess, and I have compared it to a known precise caliper and gauge block, I find it varying alot. I know that the major reloading companies offer a reasonably priced calipers looking very similar and possible the same but re-branded... but cant help to think that there is more to this than Im seeing here, is there room for a little error?
The reason I ask, I have some experience with precision fitting devices and machines, and firearms is one of them. In the industries I have worked in, these calipers are not trusted at all for their accuracy is highly questioned. I have one of those digital calipers from the princess, and I have compared it to a known precise caliper and gauge block, I find it varying alot. I know that the major reloading companies offer a reasonably priced calipers looking very similar and possible the same but re-branded... but cant help to think that there is more to this than Im seeing here, is there room for a little error?
For these cartridges, you generally want em somewhere between published COL (as minimum) and what will fit into the magazines without binding (as maximum), bearing in mind that they obviously must also chamber properly. Your greatest concern would be getting cartridges loaded at or near their max charge weight that were also seated more than 1/100 or so deeper than per the published (shortest) COL. This would give significantly higher than expected peak internal pressures.
If you were constantly dickin with real fast powder loadings at or near published maximums, in cartridges built near minimum COL, (hardly necessary for 9 & 45 ACP), there might be justification in spending $ for precision measuring gear. Other than this, if you're within say 10 or 12 thou you're plenty accurate enough. Just remember to work up loads starting at minimums, as you should, and you'll be quite OK.
...x2
One thing about the CT and PA digital callipers is that they come in 2 different accuracy ranges.
One reads to 0.0015" and the other only reads to 0.01" You don't really need the more accurate one if you are only doing COL, but you might want the more accurate one for bullet diameters and other finer measurements. Just a heads up as to what is on sale.
Just a quick note, the load/COL is based on the specified length of the bullet used in that load. If your bullet is say longer, then you need to increase the COL by the same amount. Otherwise you are seating the bullet too deep, the same as shortening the OAL.
One reads to 0.0015" and the other only reads to 0.01" You don't really need the more accurate one if you are only doing COL, but you might want the more accurate one for bullet diameters and other finer measurements. Just a heads up as to what is on sale.
Just a quick note, the load/COL is based on the specified length of the bullet used in that load. If your bullet is say longer, then you need to increase the COL by the same amount. Otherwise you are seating the bullet too deep, the same as shortening the OAL.
This is just my personal experience with digital calipers. It may or may not be common. Last year, I received a set of Busy Bee measuring tools for Christmas. They all looked very good. There was a small metal square, a 0-1inch micrometer a steel 6 inch x 15 cm rule and a 12 inch dial vernier caliper. Very pretty and practical set.
Now, I was curious. I took the set out to the shop and compared it against my other measuring instruments. The other stuff, is made by Mitutoyo and Starrett.
I zeroed the new instruments on the constants I have, 1/2in to 6in. A good set, made by Mitutoyo. The 0-1in micrometer was bang on. The dial vernier, was another story. As the caliper opened, the more it was out of spec. At 6in, it was out by .004. At 1 inch, it was out by .002. That may not seem like a lot, but when you are machining to relatively close tolerances, that is a lot. The Japanese and British instruments, were bang on, right up to 6 in. Not out by even a thousandth of an inch. Room temperature, was about 20C, which was constant for all of the tools.
I called BB in Burnaby, and they very graciously agreed to replace the set. They paid for shipping, both ways. Can't ask for better service than that. The only problem was that the next set they sent me, had the same problem. Exactly the same amount of discrepancy as the first set. Obviously, there is a flaw in their manufacturing. The calipers are a bit coarse but for the price, not bad. I kept the second set, because it was a gift from a person that didn't know better and it would hurt his feelings if I wasn't pleased. The calipers, will more than likely never be used. Not a great deal, as I have at least 4 others, both digital, manual dial and vernier style. The vernier style is getting harder to see, every day.
For general stuff, like measuring over all length or minor diameters, they are close enough. For precise work, I would check them out very closely. Especially, if they are the only accurate measuring tool you have. When it comes to measuring tapes, metre sticks and desktop rules, these discrepencies are common. Now, it appears that the same goes for the precise stuff. When you're set up for metric, converting existing machinery to produce inch style products, can be very tedious and difficult. In this case, close enough isn't.
Now, I was curious. I took the set out to the shop and compared it against my other measuring instruments. The other stuff, is made by Mitutoyo and Starrett.
I zeroed the new instruments on the constants I have, 1/2in to 6in. A good set, made by Mitutoyo. The 0-1in micrometer was bang on. The dial vernier, was another story. As the caliper opened, the more it was out of spec. At 6in, it was out by .004. At 1 inch, it was out by .002. That may not seem like a lot, but when you are machining to relatively close tolerances, that is a lot. The Japanese and British instruments, were bang on, right up to 6 in. Not out by even a thousandth of an inch. Room temperature, was about 20C, which was constant for all of the tools.
I called BB in Burnaby, and they very graciously agreed to replace the set. They paid for shipping, both ways. Can't ask for better service than that. The only problem was that the next set they sent me, had the same problem. Exactly the same amount of discrepancy as the first set. Obviously, there is a flaw in their manufacturing. The calipers are a bit coarse but for the price, not bad. I kept the second set, because it was a gift from a person that didn't know better and it would hurt his feelings if I wasn't pleased. The calipers, will more than likely never be used. Not a great deal, as I have at least 4 others, both digital, manual dial and vernier style. The vernier style is getting harder to see, every day.
For general stuff, like measuring over all length or minor diameters, they are close enough. For precise work, I would check them out very closely. Especially, if they are the only accurate measuring tool you have. When it comes to measuring tapes, metre sticks and desktop rules, these discrepencies are common. Now, it appears that the same goes for the precise stuff. When you're set up for metric, converting existing machinery to produce inch style products, can be very tedious and difficult. In this case, close enough isn't.
