I have just wasted two hours trying to figure out how to use a Stoney Point Bullet Comparator to set cartridge OAL. Using the measurements from my Sinclair Seating Depth Guage and the bullet comparator, I come up with lengths which are way too long! For example, in my .270, I measure 2.069 with the Sinclair tool, 1.229 bullet length (140gr hornady), and .693 with the bullet ogave seated in the comparator. None of these combos seem to make sense when I put the cartridge in the caliper with the comparator attached. The case either hits the comparator, or if I add 1" to the measurement to take into account the length of the comparator the cartridge is too long to chamber in my savage.
When I measure using the dowel method, I come up with an OAl of 3.315, which is pretty close to 3.298!

Anyone have an easy way to explain how to use a comparator?

Mount the proper sized blank case on the device. Drop a bullet into the case, and insert the case/bullet combo into the chamber and push the inner rod up, thus pushing the bullet into the lands. Lock the rod at this point with the lock screw. With the comparator attached to your caliper, take a measurement. Let's say that the measurement is 2.645". If you wish to load your rounds,lets say, so that the "jump" is 0.010", then adjust your seating die so that the loaded round, when measured off the same comparator, measures 2.635". Note that with each different brand/weight bullet in a given caliber will require a new measurement. Hope this helps.

Geronimo

I meant to add that COL means very little because bullet tips get bent and peened and the overall variation in a given lot of bullets is often greater than the length of bullet jump desired.

Geronimo

Hey Wes

Don't know how you're using the Stoney Point. Sounds like you're using it to measure to the ogive of the bullet and using other methods to measure the case and OAL. Do you have the modified case for the caliber you are trying to reload? If so, then slip the bullet in the modifed case and follow instructions and the Stoney Point is the only thing you'll need to gauge distance to the lands (or at least an approximation thereof).


A government big enough to give you everything you want is strong enough to take everything you have

I will try and help here, I have the same set up your using, at least i think i do, so here is how I get my OAL for a given bullet/cartridge combo.

I use the stony point COL gauge first, the red handled stick that you screw the modified cartridge too and stick in your chamber forcing the bullet forward to the lands then you lock the rod so you can take it out and measure at your leisure.

thats the first half of the procedure, next you need your bullet comparator, the NUT looking thing with all the holes drilled in it for various caliber bullets, (i clamp the calipers onto it and set them to ZERO, since i cant measure off the ogive its self, this basicly does not add the comparator to the measurement.)

with the bullet seated in the modified case attached to the stonypoint COL tool and the bullet inserted into the appropriate hole for the caliber on the comparator (nut shaped thing so we are still on the same page), I measure the whole thing, from the bottom of the brass case to the top of the comparator (which I zeroed my calipers on so they wont add it to the measurement) which will give you the measurement with no extra math or frustration..
I do admit that balancing the comparator on the bullet and holding the OAL gauge and calipers all together at once can be frustrating to take 1000ths of an inch measurements, but I believe this is what you are trying to achieve. atleast thats how I do it with the above mentioned tools.

quote:

Originally posted by Westernmassman:
I have just wasted two hours trying to figure out how to use a Stoney Point Bullet Comparator to set cartridge OAL.

And the more you use it, the more time you will waste.

quote:

...the cartridge is too long to chamber in my savage. When I measure using the dowel method, I come up with an OAl of 3.315,

You probably got this dimension correct since the method is easy to do and is repeatable.

So, your "cartridge is too long to chamber in my savage" is probably due to something else.

1. I'd suspect you either did not get the case "Resized" enough. Just take another empty case, lube it, Resize it, wipe the lube off and see if the empty resized case will chamber. If it does not, you need to re-adjust your Full Length Resizing Die or trim the case length. If it does chamber, move on to #2.

2. It could be that during the Seating process you have the Seating Die too low in the press which will cause it to begin "crimping" the Bullet as you near the end of the stroke. This can cause the case to "widen" near the shoulder and prevent the case from going in your chamber.

With the Seating Die out of the press, place an empty case in the Shellholder and raise the ram. Screw the Seating Die into the press until you feel it touch the case and then un-screw it 1/2 turn and set the Lock Ring. Seat the exact same Bullet you used to measure the Kiss-the-Lands distance with the dowel - without a Primer or Powder in the case. Try chambering it in your rifle and it should work just fine.

If not, let us know.

quote:

Anyone have an easy way to explain how to use a comparator?

Give this contraption to someone you really don't consider a friend.

Hot Core: My resized cases fitted fine. I don't set up my bullet seater to crimp. I think I just messed up with the calculations.

I spoke with Sinclair and think I found out why I had problems. I will try one more time, and if it doesn't work I'm going back to my dowel!

Thanks for the link Bill.

quote:

Originally posted by Westernmassman:
Hot Core: My resized cases fitted fine. I don't set up my bullet seater to crimp. I think I just messed up with the calculations.

I spoke with Sinclair and think I found out why I had problems. I will try one more time, and if it doesn't work I'm going back to my dowel!

Hey WMM, I sincerely wish you the very best of luck with the Stoney Point - thing. Lots of folks recommend them, so they apparently work well for a lot of people.

But, just in case:

1. Close the bolt on an empty chamber and slide the Dowel(or a Cleaning Rod with a Flat Tip Jag) down the Bore until it contacts the Boltface.
2. Getting as close to the muzzle as possible, wrap a piece of Paper Tape around the Dowel and remove it from the Bore.
3. Select one Bullet from a box and think of it as the Set-Up Bullet(S-UB).
4. Remove the Bolt from the receiver and drop the S-UB into the Chamber.
5. Place something against the S-UB's base to hold it in place.(Even a loaded cartridge works fine.)
6. Run the Dowel back into the Bore until it makes contact with the S-UB. (Make sure it does not slip by holding pressure against the S-UB's base.)
7. With your 0.001" capable Caliper, measure from the muzzle to the Leading edge of the Paper Tape. That is the Kiss-the-Lands distance for that exact S-UB and is the Overall Cartridge Length(OCL).

Take the S-UB and Seat it to the OCL. Then remove the Seating Die from the press and measure across it's entire length which will give you the Overall Die Length(ODL) and write it on the Bullet Box.

Let's say the ODL is 3.330" and you want to Seat the bullets from that box 0.030" Off-the-Lands. Adjust the ODL to 3.300",screw it into the press and begin Seating bullets. The OCL may vary slightly due to the position of the Ogive changing a bit from bullet to bullet, but the Ogive-to-Lead distance will be right on the nose and that is what is important to great accuracy, not OCL.

Best of luck to you.

Hot Core: That's exactly how I set up my .358 BLR. Works great in that leveraction, and will work great in my savage I'm sure. Just trying a different method. (since i already spent the dough)