Need some help - random seating depths

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Herk30

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Ok so I'm reloading 6.8 SPC w/ 110 Accubonds. Using a Dillon 550B press, Hornady New Dimension dies. I know it has to be something simple, but it's about to make me crazy. I have all the dies set, run one case thru to set OAL and it's dead on at 2.260". Run the next case thru and it's way deep at 2.254". Back it off a just a little and it's long at 2.273". Give it tiny turns until it's right at 2.260" again, run the next case thru and it's way deep again. So I back it off, run a case thru and it's long, give it a little turn and run a while new case thru, still long but closer. So I keep adjusting the die using a new case every time until it's dead on again. Run another case and it's way off again :banghead:

Please help me out with what I may be doing wrong.
 
+1

You need a bullet comparator to measure OAL off the ogive, not the bullet tip.

You can buy one of these for use with your dial caliper.

http://www.sinclairintl.com/reloadi...r-hex-style-bullet-comparators-prod34262.aspx

Or make one yourself by drilling out a proper size bolt nut to fit the ogive of your bullet about 2/3 way up the ogive so you have a flat nut surface to measure against with your caliper.

That's where you seating die is contacting the bullet.
Not on the tip where you are trying to measure it.

rc
 
My 550B will always make a single cartridge .005-.007" longer than when the entire shell plate is loaded. That may be some of it.

Secondly, you are pushing on the ogive to seat, but you are measuring to the tip for the OAL. That's a good part of it.

Additionally, if you are new to reloading, then you may not have your "stroke down". That is, you may not be seating each bullet at the same speed/ op handle force each time. Lube all the linkage parts, and then concentrate on slow/ steady op handle strokes. This typically goes away after 500 rounds.
 
Set the first one to the length you want, then load bullets. No use worrying about that small variation. It won't matter one whit. As noted, it is small variations in the bullets that cause this to happen.
 
I used to worry about the same when I first started until I got the Hornady bullet comparator. I now do all my measurements for my bullets, max ogive measurement, since that's the actual part that touches the lands.
 
I see what you're saying, but I'm still confused. So the ogive of the bullet is a more accurate place to measure, but how does measuring to the ogive give you your COAL, and how can you be sure you're not make a compressed load?

Especially if you set your die to the correct COAL on the first round and just run with it, that doesn't seem very safe to me if you're getting a variance like I'm seeing, anywhere from 2.540" to 2.780". Not to mention it seems like that would mess with your accuracy something fierce.

I should mention I ordered the Hornady Bullet Comparator kit, and I already have the Hornady Overall Length Gauge but it doesn't look like they have a modified case for 6.8 yet
 
Measuring to the ogive gives you a relative number, for a dummy round you load to the desired COL.

The way I understand it, for a subsequent reloading session where you want to load the same bullet / cartridge, you adjust the seating die in increments until you have the same relative number, measured to the ogive. This should be better than trying the same thing by measuring COL, as the bullet length varies more during manufacture than the diameter.

Depending on the quality control of the manufacturer, COL will still vary from round to round, but ogive to bullet base should be relatively consistent.

For the amount of variation you are seeing, is there any chance you have the die adjusted too far down and are fighting a crimp when you are trying to seat?
 
Jerk: exactly my situation, and I mean exactly,until I finally did what I read about and boarded the comparator train.

All aboard.
 
The only way to accurately measure oal is of the olgive. and since olgives vary by quite a bit you'll never get anything any better than what you are right now. This is why I either seat into the lands, so every round is making contact, or off the lands .010" so none will contact. Depending on what I'm going to be shooting them from and their purpose, hunting or printing groups, will dictate which route I go.

It drove me nuts when I first started reloading years ago until a BR shooter explained to me that even match grade bullets will still experience some olgive inconsistencies.

GS
 
and how can you be sure you're not make a compressed load?
Click to expand...

What are your concerns about compressed loads?

As to your OAL issue, Check the seating stem and see how your Plastic tipped Accubonds fit. If the stem makes contact with the plastic tip and not the bullet Ogive, you will have a lot of variations in OAL. Especially if the seating stem deforms the plastic tip.
 
The die is adjusted correctly, I double checked it just now hoping that was the problem. The seating die is seating off the ogive, I can see a faint ring where it touches.

I'll play with it some more tomorrow when the Hornady Bullet Comparator shows up. Maybe once I get it in hand it will explain itself, but I still don't understand how you actually use the measurement from the base of the case to the ogive to get your overall length. For example, how do I know what my ogive measurement is supposed to be for this caliber and bullet?

I'm sorry if I'm looking like an idiot here, but I just don't understand how it is supposed to come out. I've loaded quite a few different calibers and a variation of bullets and never had the OAL jump around like this. It's very discouraging, and I want to understand the right way to do it.

Maybe some videos on youtube will help by actually seeing it.
 
The entire shell plate should be loaded when setting the COL. Progressive units are know to have a variation as much as .010" Check out this company's kit. http://www.uniquetek.com/site/696296/product/T1230
Advantages
• Eliminates Loose Toolhead-to-Frame Fit
• Reduces OAL Variation*
• Improves Crimp Repeatibility
• Improves Bullet Conentricity from Seating Die
• Reduces Jams at Size/Decap Die
Click to expand...
Does it work? I have no idea. :confused:
 
I'm sorry if I'm looking like an idiot here,
Click to expand...

You are Not looking like an Idiot. Idiots do not ask question and learn from other's knowledge and experience.

You look like a handloader that has valid concerns and wants everything to be safe and accurate.

Carry on, you are doing great. Sorry it any of my comments made you feel uncomfortable.
 
I'll try it again with a full shell plate and see if that helps any. I guess I can see where it would torque the plate not having even pressure on all sides.

Thanks for the help and suggestions guys, it just gets aggravating trying to figure it out. I've always loaded v-max bullets in the past and never run into this issue. Maybe I've just been lucky.

The thing that still bugs me is, if I measure each cartridge with the bullet comparator, that will give me the measurement from the base to the ogive and tell me how consistently the bullets are being seated. But how does that relate to the OAL? What ogive measurement should I be looking for to hit my OAL? Or better yet, if bullets vary so much, why does all load data give you an OAL instead of a ogive length if that's more accurate?
 
Load a round to your desired OAL.

Check that OAL with your New Comparator.

That is your new Comparator OAL.

You are over thinking this a little. OAL is not that critical, it can have small variations from round to round without being dangerous or even inaccurate.

why does all load data give you an OAL instead of a ogive length if that's more accurate?
Click to expand...

Some load manuals do not even list the OAL tested it is that un-important. They instruct the handloader to find the best OAL for their rifle bullet combo.
 
6.8mm remington spc OAL

http://www.saami.org/PubResources/CC_Drawings/Rifle/6_8mm%20Remington%20SPC.pdf This SAAMI drawing lists minimum at 2.000" The maximum is 2.260" Longer than 2.260" and the round may not fit the magazine. The part of the bullet that will contact the rifling first is the ogive of the bullet, if seated to a OAL that is too long. The magazine in your rifle will not let you have a OAL that will let the bullets ogive make contact with the rifling. You would have to single load each round if longer than 2.260", a guess. http://www.brownells.com/.aspx/lid=12897/GunTechdetail/Gauging_Success___Minimum_Headspace_and_Maximum_COL Some cheap FMJ bullet are made on different machines. The ogive & crimping groove will not be the same, if you compare bullets from the same box.
 
Bullets out of the same box, made on different machines.

Walkalongs photo
attachment.php
Not only the weight of the Winchesters, but the cannelures are all over the place as well.
Click to expand...
http://www.thehighroad.org/showthread.php?t=634497 My bulk 5.56 Win. bullets were the same, but said to be seconds.
 
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