caliper measuring help.

[Nsghunter]

Before I knew better I bought a set of cheap digital calipers for handloading. I dont believe i can afford a nicer set now, so that is not really an option at this moment

When I use my comparator with my flsd my brass compared to a once fired from my chamber is .01-.02 different. The brass wiggles just a little in the comparator and if manipulate the brass a little the measurement varies by as much as .02-.04 but will usually fall into the same measurement as my once fired chamber brass. If I work to get the brass into a neutral position in the comparator but I have to hold the brass just right in my comparator.

I hope this is makes sense.

I'm not trying for competition accuracy but I need 1moa or better.
I'm suspicious that each round is correct and the variance is from the caliper or the wobbly comparator.

Will this completely kill my accuracy or most importantly will this in any way cause my round to be dangerous, well more than a normal load.

Are all the other comparators out there wobbly? Comparator is Hornaday, calipers are El cheapo from Northern tool and equipment.

All input is greatly appreciated. This will be my first ever batch of rounds I have handloaded.

Round is 30-06

 

[DaveB]

Nsg, need to know with which measurement are you experiencing the .02 --> .04 variance.

I also hope you mean .002 and .004.

 

[Nsghunter]

Nsg, need to know with which measurement are you experiencing the .02 --> .04 variance.

I also hope you mean .002 and .004.

I zeroed my calipers from the chamber fired round.. maybe the variance was in 1000ths not 100ths. .002 would be 1000ths and .02 would be 100ths correct?

I am away from my press right now and won't be back around it until late tonight or early am to make sure I give you the right info

I hopes to develop a 180gr load for the firar bear hunt in Oct nut that won't be happening until I'm sure I've got this figures out.

Thanks Dave.

 

[MUP]

You are correct Nsg. .001 is one thousandth, and .01 is one hundredth. .001-.002 is almost negligible in case length measurement imo. Some folks will take it to the extreme, but as long as you're not over max COAL I'd say you're good. Also, you do need to "wiggle" your brass to seat it between the two measuring surfaces of the calipers and the comparator face. With light pressure, wiggle the case until it seats nicely, then check your measurement.

 

[Rubberduck270]

Try spinning the brass as you measure it.

If you are measuring your fl sized brass as 1-2 thou shorter (from the shoulder datum) than the unsized once fired brass you're good. If it's 1-2 thou longer you're probably pulling the shoulder out when you pull the expander ball back through the neck. Polish the expander ball and make sure you lube inside the necks before you size them.

 

[DaveB]

Okay, a variance in the 1000, or .002--.004, those are okay. A variance in .02 -->.04 is different and could be not good depending upon what measurement is being taken.

Since you are using a comparator I believe the issue here is your assembled round length to the ogive, the point at which the bullet is in contact with the lands.

A variance of .002-4 would be of no concern. A difference of .02-4 means the bullet is seated too long out of or too deep into the case but even so, perhaps not long enough to be of concern.

Generally speaking, you do not want the bullet to engage the lands before you pull the trigger. You also do not want the bullet to "jump" a long way from the brass into the lands. When you do that, brass neck tension can have a huge effect on accuracy. Neck tension is abated by annealing which also tends to length case life. So, we want to control the jump through seating the bullet less deeply into the brass. Or, you can make your round be SAAMI length to the ogive. For starting-out accuracy lots of people do just that.

So the question here is
(1) can you chamber a round with no unnecessary effort?
(2) are your assembled rounds shorter than SAAMI specs?
(3) Your starting load is..Brass, primer, powder name and grains, bullet is 180.

 

[Nsghunter]

Okay, a variance in the 1000, or .002--.004, those are okay. A variance in .02 -->.04 is different and could be not good depending upon what measurement is being taken.

Since you are using a comparator I believe the issue here is your assembled round length to the ogive, the point at which the bullet is in contact with the lands.

A variance of .002-4 would be of no concern. A difference of .02-4 means the bullet is seated too long out of or too deep into the case but even so, perhaps not long enough to be of concern.

Generally speaking, you do not want the bullet to engage the lands before you pull the trigger. You also do not want the bullet to "jump" a long way from the brass into the lands. When you do that, brass neck tension can have a huge effect on accuracy. Neck tension is abated by annealing which also tends to length case life. So, we want to control the jump through seating the bullet less deeply into the brass. Or, you can make your round be SAAMI length to the ogive. For starting-out accuracy lots of people do just that.

So the question here is
(1) can you chamber a round with no unnecessary effort?
(2) are your assembled rounds shorter than SAAMI specs?
(3) Your starting load is..Brass, primer, powder name and grains, bullet is 180.

the brass is. Once fired, winchester and rp. Bullet selection is 180gr nosler partition. I believe the powder is hmr4350 but dont hold me to it it's tucked away in my gun safe (its never even been opened) and the primer is cci but like the powder im not sure on the number its pigeon holed away too. I've only gotten that far yet. I'll tell you for sure when I get home.

 

[Nsghunter]

Nsg, need to know with which measurement are you experiencing the .02 --> .04 variance.

I also hope you mean .002 and .004.

I zeroed my calipers from the chamber fired round.. maybe the variance was in 1000ths not 100ths. .002 would be 1000ths and .02 would be 100ths correct?

I am away from my press right now and won't be back around it until late tonight or early am to make sure I give you the right info

I hopes to develop a 180gr load for the firar bear hunt in Oct nut that won't be happening until I'm sure I've got this figures out.

Thanks Dave.

 

[Rackseeker]

.002 is 2 thousandths of a inch, .02 is 20 thousandths of a inch, .2 is two hundred thousandths of a inch. ,

 

[DaveB]

Nsg--
You are good, that variance is not going to affect your MOA quest.

Matter of fact, that small a variance is a good indicator of your progress.

When you are trying to get the same sight picture, the same breathing, the same squeeze on the trigger it is reassuring to know the bullets you assemble are as alike as they can be.

 

[Nsghunter]

Nsg--
You are good, that variance is not going to affect your MOA quest.

Matter of fact, that small a variance is a good indicator of your progress.

When you are trying to get the same sight picture, the same breathing, the same squeeze on the trigger it is reassuring to know the bullets you assemble are as alike as they can be.

Thanks!

I finally resized 15 cases to test load with but after getting a case stuck and successfully extracting it I called it quits for tonight.