I am considering the purchase of this tool but have a concern. With the RCBS Precision Mic that I have been using the device is actually chambered into the gun by the bolt and a dimension is obtained from the bolt face to the ogive. But with the Stoney Point the case is held in place by hand.
My question: When using the Stoney Point gauge, is the case pushed into the chamber as far as it will be when the completed cartridge is chambered (with the power of the camming action)? Since the overall measurement is taken from the base of the cartridge, this is an important factor.
Maybe this is not a factor and I could be off base but any comments would be appreciated.
Considering the same purchase, I have another related point of confusion. In order to have an accurate overall length with the Stoney Point device, is it not logical that you would have to use a case that was been fire formed to fit your chamber? Would the use of a standard Stoney Point case that was not fire formed lead to an error in the reading? Would some additional measuring and simple arithmetic clear this up?
quote:Originally posted by TERMINATOR: In order to have an accurate overall length with the Stoney Point device, is it not logical that you would have to use a case that was been fire formed to fit your chamber? Would the use of a standard Stoney Point case that was not fire formed lead to an error in the reading?
I wouldn't think that would matter. The fit of the case isn't critical in this instance. The back of the case & the end of the bullet (or the point on the ogive that touches the rifling) will be the same, regardless of case forming.
I imagine that you could use a 222 case & get a very good number in a 223 chamber, etc.
Gents - The Stony Point gage uses a SAAMI spec fired case for each given cartridge. If you have a non-SAAMI spec or wildcat cartridge, simply forward two fired cases to Stony Point. They will tap the case for the gage. This ensures that you will maintain accurate measurements.
I have not had any problems using this gage. There are a lot of methods out there, but the Chamber-All is the most accurate tool I have found.
Z
Posts: 10780 | Location: Test Tube | Registered: 27 February 2001
Thanks for the feedback. I think you are telling me that unless I buy other tools to measure my chamber against standard dimensions, it would be wise to mail in two cases to get a custom set up for each gun.
Terminator, it's true that unless you use a fire formed case from your chamber that you are going to have a small error due to the headspace. How much error depends upon how much headspace your rifle has, but it really isn't enough to worry about, in my opinion. I bought a tap that fits the threads on the stoney point tool and tap my own fireformed cases. I'm not that worried about the headspace error, but when you use this tool for more than a couple of rifles the tap pays for itself. You can send the cases to them to have them tapped but it takes me about ten minutes in my garage to drill out the primer pocket and run the tap through it. Putting the case in the chamber by hand doesn't apply the camming force of the bolt, but you'll find after using the tool that there is a definate stop in the chamber. I don't think the bolt would push it in any farther.
I've done exactly the same as Boltman, using a tap and a once fired case. The problem is that in introducing the tapped case and bullet into the chamber on the Stoney Point tool, you are relying on the shoulder for the measurement whereas the distance you are trying to determine is the boltface to the lands. You'll have at least a .004" difference with an unfire case, and it could be more depending on the headspace of the rifle in question.
Even when measuring the lands with a threaded, fired case you should seat a bullet in the cases to be used, seat the bullet out about .010" further, mark it with either Dykem or Marksalot and chamber it to determine if you have land marks on the bullet. Once you determine exactly where the lands are you can set your bullet seater with the dummy round and know exactly where you are in relation to the lands. Bob
Posts: 1261 | Location: Placerville, CA, US of A | Registered: 07 January 2001
Thanks for the insight. I'll probably get my own tap too. Had not thought of it. Seems to me nothing is perfect but the fire formed case is the best way to go. The question is how close is close enough. My bet is the tool would get me about as close to my goals as anything else available and further perfidity would probably not make a signifigant difference.
If you're worried about it not being 'fit' to your chamber, you need only worry about it being too long. Headspace, fireformed, ect is not a problem with the tapped cases they sell. I always put the cases they sell in my chamber and 'cycle' it a few times to be sure it fits smoothly and that it's not too long. As stated above, if you want it to your chamber or they don't have your brass in stock (ex. the 50 BMG) just send them 2 fireformed cases and $10.75 for labor & return postage.
quote:Originally posted by ARshooter: I am considering the purchase of this tool but have a concern. With the RCBS Precision Mic that I have been using the device is actually chambered into the gun by the bolt and a dimension is obtained from the bolt face to the ogive. But with the Stoney Point the case is held in place by hand. I don't know what type of action you are using your RCBS precision mic shell in but if it is a Remington and anything like mine you are not getting a correct measurement with it either, the ejector plunger pushing the fake shell/bullet requires that the "bullet" be so tight in the fake shell setup that it pushes the fake bullet into the lands and gives false readings in my guns with the Remington spring plunger ejector type, as the other post states the fireformed case is the best, but all of them are just starting places and as long as it is consistant any way will work to measure with a good comparator,imo, good luck and good shooting!!! My question: When using the Stoney Point gauge, is the case pushed into the chamber as far as it will be when the completed cartridge is chambered (with the power of the camming action)? Since the overall measurement is taken from the base of the cartridge, this is an important factor.
Maybe this is not a factor and I could be off base but any comments would be appreciated.
Posts: 687 | Location: Jackson/Tenn/Madison | Registered: 07 March 2001
