Newby to reloading question

[Jason shore]

Just received the modified case for the stoney point overall length guage from Rick 1970 for the 204.
This afternoon I used the guage to measure the oal
I found this
32 GR vmav 62.05 mm
34 GR Nosler Shots 60.20 mm
39GR sieera blitzkings 63.20 mm
I have about 130 of the 32gr vmaxs loaded long that need to be knocked down , 200 primed cases for the 39GR and i want to load up 10 34 Gr nosler shots to test .
My Questions is Harvey recommends to minus 1/16 inch of the oal which is -1.5875mm
So do I do:
32 Gr vmax 62.05mm -1.5875 which equals the ideal length to be 60.46 mm
34 Gr Nosler Shots 60.20 mm - 1.5875 ''''''''''''''''''''''''''''''''''''''''''''' to be 58.61mm
39GR sieera blitzkings 63.20 mm - 1.5875'''''''''''''''''''''''''''''''''''''''' to be 61.61 mm
Does this sound correct and am I on the right track ?
Any imput and help appreciated
Thanks Jason

[Model70]

Sounds like you have been measuring factory rounds mate. He means the OAL of your chamber. Measure that and knock 1/16 of an inch which is as you said 1.5mm.

[trevort]

and you need a comparitor to measure bullet length from the ogive. They should all be the same length where they engage the rifling, tip to tip length is irrelevant, as long as it fits the mag

[Rick1970]

+1 on what Trevor T said.

Measuring OAL to the bullet tip can give great variance in readings, a comparator is the go for setting up and leave the base to tip measurement for knowing what will/won't fit in the mag. The measurement from bullet tip to ogive can vary quite a bit from bullet to bullet of the same make/weight.

[Jason shore]

Sounds like you have been measuring factory rounds mate. He means the OAL of your chamber. Measure that and knock 1/16 of an inch which is as you said 1.5mm.

Not factory rounds I used the oal guage each time and put the differant projectiles in until they touched the lands.
What is the ideal way to measure the chamber ?
Sorry for the questions I am just trying to understand this
Jason

[Jason shore]

Guys purchased a comparator today.Can somebody please walk me through the correct way to find the best distance from the lands on the three mention projectiles. I am totally confused
Thanks Jason

[macca]

Hi Jason, If you have used the OAL guage to measure where each projectile engaged the lands(repeat several times so you are happy with your technique) then you take this measurement and take off 10/1000th's of an inch(I don't work in metric on rifles).From this point fire your groups and if necessary go closer or further away from the lands and see if your groups tighten up.Some will start by taking off 20 thou rather then 10 thou.

When checking the OAL i have a cleaning rod very carefully inserted from the muzzle to push the projectile back out after locking off the OAL guage.
Mate if this is as clear as mud then tell me and I'll try and do it clearer.(Just taken a couple of HD flu tablets,sorry.
cheers,
Macca

[Jason shore]

Hi Jason, If you have used the OAL guage to measure where each projectile engaged the lands(repeat several times so you are happy with your technique) then you take this measurement and take off 10/1000th's of an inch(I don't work in metric on rifles).From this point fire your groups and if necessary go closer or further away from the lands and see if your groups tighten up.Some will start by taking off 20 thou rather then 10 thou.

When checking the OAL i have a cleaning rod very carefully inserted from the muzzle to push the projectile back out after locking off the OAL guage.
Mate if this is as clear as mud then tell me and I'll try and do it clearer.(Just taken a couple of HD flu tablets,sorry.
cheers,
Macca

Macca
Thanks mate
That is what was doing , I just get mixed up with all the other ways it can be done.
Can you please explain how the comparator works and what is used for ?
Hope the tablets work
Jason

[macca]

Hi Jason, the comparator is placed on a vernier caliper and you place the point of the bullet in it(using the correct insert size for the projectile in question for the 204 that's 20cal)(remembering to zero the comparator and insert so your measurement will be only the projectile).
You place the base of the bullet on the opposite blade of the calipers keeping it all square and slide them together and you'll have the base to ogive measurement of the projectile.This is used to set seating depth etc,as its this point(the ogive) not the tip which you measured engaging the lands.
When you seat the bullet you can measure the completed round in the same way to verify how far off the lands you have seated the projectile.

cheers,
Macca

[Jason shore]

Hi Jason, the comparator is placed on a vernier caliper and you place the point of the bullet in it(using the correct insert size for the projectile in question for the 204 that's 20cal)(remembering to zero the comparator and insert so your measurement will be only the projectile).
You place the base of the bullet on the opposite blade of the calipers keeping it all square and slide them together and you'll have the base to ogive measurement of the projectile.This is used to set seating depth etc,as its this point(the ogive) not the tip which you measured engaging the lands.
When you seat the bullet you can measure the completed round in the same way to verify how far off the lands you have seated the projectile.

cheers,
Macca

Thanks mate for explaining , much appreciated
Jason

[Jason shore]

You place the base of the bullet on the opposite blade of the calipers keeping it all square and slide them together and you'll have the base to ogive measurement of the projectile.

Macca
When I do this the back of the projectiles that is sticking out of the inset just slides back into the mouth of the case. I must be doing something wrong. When I put the 32gr vmax into the insert and slide the other side of the caliper to the measured 62.05mm from the aol gauge the caliper does not touch the base of the case before the projectile and case comes appart.
Hope I am making sense at what I am trying to explain
Jason

[macca]

Mate you can't use the case unless the projectile is seated and ready to fire.So it won't fall apart.
You use the comparator to batch the projectiles .So you have an average length to use in the OAL guage etc.

Step one(which I think you are doing.)Measure the projectile seating depth with the OAL into the lands.
2.Subtract 20 thou(or what ever jump to the lands you wish to start with).
3.Assemble you bullet,powder,primer etc.
4.Place in seating die and seat(just turn the die up so it just seats the bullet).
5.Measure the whole bullet with the comparator,checking it's length against the distance you want to jump to the lands.This is part 2's measurement.
6.Adjust seating die down until this length is reached.Checking with the comparator.
7.Make up enough loads and test for accuracy.

Hope this helps.
Macca

[Jason shore]

Mate you can't use the case unless the projectile is seated and ready to fire.So it won't fall apart.
You use the comparator to batch the projectiles .So you have an average length to use in the OAL guage etc.

Step one(which I think you are doing.)Measure the projectile seating depth with the OAL into the lands.
2.Subtract 20 thou(or what ever jump to the lands you wish to start with).
3.Assemble you bullet,powder,primer etc.
4.Place in seating die and seat(just turn the die up so it just seats the bullet).
5.Measure the whole bullet with the comparator,checking it's length against the distance you want to jump to the lands.This is part 2's measurement.
6.Adjust seating die down until this length is reached.Checking with the comparator.
7.Make up enough loads and test for accuracy.

Hope this helps.
Macca

Thanks macca
I was thinking last night is the insert made up to resemble the size of the rifling ? I know were I am going wrong when I measured the overall I am measuring to the tip of the projectile and not the correct area where the ogive is touching the lands.the measurment should be taken at this point ,then minus the 1.5mm.
When the projectile is in the insert cant I measure the distance it is sticking out the back of insert then measure the total length of the projectile then minus the first measurement ?
This way of thinking will tell me how much of the projectile is past the point where the ogive is touching.
My way off thinking will mean you minus this from the overall length that I measured from the tip giving me the excact area the ogive is touching the lands
Hope I am making sense again
Jason

[macca]

No mate ,that will not be the same as getting the measurement from the OAL guage.This s due to differences in the way chambers,rifleing and the leade are cut in different barrels.You would get the difference to the tip but not specifically for the barrel in question.
When you get the OAL measurement keep a record of it and the date and projectile used.

After 500/1000 rounds revisit this data,it is often interesting to see the throat wear in your barrels.Then you can adjust your seating depth to maintain best accuracy.

cheers,
Macca

[juzz338]

Hi, Jason do you have or are you using a modified case on your oal gauge. if so you simply lock off the rod in the centre of your gauge when projectile is in lands then when you remove projectile from rifle place back into case mouth/neck with rod still locked off, cannot fall in now and with case still on oal gauge now measure with comparitor and replicate this length -however many thou you want off lands with your loaded ammo by adjusting your die. if you want to use your rifle as a repeater and not a single shot check to make sure your ammo fits into the mag, if not just load to mag length and be done with it