Seating depth variations

[fivehundredlimited]

I measeure 10 projectiles from base to tip and the shortest was 0.704 and the longest was 0.715 , so there was a difference of 0.011 from shortest to longest and the average was 0.7113. So I definetly need an ogive comparator.

Just wondering....I can sometimes see a faint line left on the bullet from the seating die and it looks to be roughly half way between the tip and where I would assume the ogive to be. So I'm wondering even if I get an ogive comparator will my seating die still seat the projectiles to different col (measured to the ogive) the same way that measuring to the tip is not accurate?

 

[charles69]

I am measuring from the tip....how would I accurately measure to the ogive?

You take one of the bullets that you measured out COL to the 2.264 and measure it to the ogive.

Yes the difference in measurements comes from the differences in bullet measurements. I hand load match ammo using berger match bullets and there is even a few thousands of an inch differences in them. I sort all my bullets by length and load one group at a time and I have to change the seating die a bit between groups

 

[Alpheus]

You take one of the bullets that you measured out COL to the 2.264 and measure it to the ogive.

Yes the difference in measurements comes from the differences in bullet measurements. I hand load match ammo using berger match bullets and there is even a few thousands of an inch differences in them. I sort all my bullets by length and load one group at a time and I have to change the seating die a bit between groups

What length are you measuring? Overall, base to ogive or bearing surface length? Overall length is a useless number unless you are pointing/trimming your meplets. Adjusting your seating die to keep the same overall length will do nothing to improve accuracy, heck, it will probably make your jump/jam variations worse.

If you really want to make seating depth a none-issue, here's what you do:
-buy two sets of bullet comparator inserts.
-sort your bullets by bearing surface length.
-use a modified case to determine your length to lands
-use a quality sliding sleeve seating die that seats off the ogive eg Redding, Forster, Whidden etc.
-adjust die to achieve desired jump/jam.

Hell, you could even forget about sorting by bearing surface length. All you really need is the modified case, comparator and quality seating die.
Using a match bullet will help too. I know Sierra's at least tend to have very irregular meplets.

 

[charles69]

What length are you measuring? Overall, base to ogive or bearing surface length? Overall length is a useless number unless you are pointing/trimming your meplets. Adjusting your seating die to keep the same overall length will do nothing to improve accuracy, heck, it will probably make your jump/jam variations worse.
If you really want to make seating depth a none-issue, here's what you do:
-buy two sets of bullet comparator inserts.
-sort your bullets by bearing surface length.
-use a modified case to determine your length to lands
-use a quality sliding sleeve seating die that seats off the ogive eg Redding, Forster, Whidden etc.
-adjust die to achieve desired jump/jam.

Hell, you could even forget about sorting by bearing surface length. All you really need is the modified case, comparator and quality seating die.

I sort the bullets by length measuring from base to ogive. And then when seating I measure from base of brass to ogive and with the bullets being different lengths you have to adjust your seating stem to make the same measurement for each round so that you have the same amount of jump

 

[fivehundredlimited]

What length are you measuring? Overall, base to ogive or bearing surface length? Overall length is a useless number unless you are pointing/trimming your meplets. Adjusting your seating die to keep the same overall length will do nothing to improve accuracy, heck, it will probably make your jump/jam variations worse.

If you really want to make seating depth a none-issue, here's what you do:
-buy two sets of bullet comparator inserts.
-sort your bullets by bearing surface length.
-use a modified case to determine your length to lands
-use a quality sliding sleeve seating die that seats off the ogive eg Redding, Forster, Whidden etc.
-adjust die to achieve desired jump/jam.

Hell, you could even forget about sorting by bearing surface length. All you really need is the modified case, comparator and quality seating die.
Using a match bullet will help too. I know Sierra's at least tend to have very irregular meplets.

I am new to reloading and kinda wishing I hadn't bought the RCBS die set now after learning about the Redding / Forrester seating dies that seat using the ogive.
My main purpose for reloading at this point is to close up my groups at 100yds to around an inch. With Winchester white box I'm getting around 1.7 - 2 " groups. If I'm able to get 1" or less at 100yds then I will move out to 200yds as a max.

Assuming I stick with the RCBS seating die and get an ogive comparator and don't sort my projectiles into groups, can I expect to achieve 1" groups or smaller at 100yds with my cz 527 in 223?

 

[cosmic]

You're overthinking this. COAL is a minor variable compared to other parameters such as bullet weight, and powder type/charge. This is particularly true if you are reloading for a hunting rifle. Moreover, reloading to such a tight COAL can cause you problems in the field, just ask canoeptr on this board.
I reload to 30 thou jump for all my guns. Accordingly, I don't have to worry about bullet ogive variance from bullet to bullet, and box to box of the same bullet brand (very common). I find the most important accuracy parameter is bullet weight. Guns will naturally tune to a given weight, and that will show "right out of the gate" Conversely, some bullets just wont give good results, no matter what you do.
BTW - You can achieve what you want without all the fancy comparators. Measure a few bullets in a given box. Pick one with a typical OAL, and use it for your COAL to rifling trial. Mark the bullet with magic marker, and make it your reference bullet. Use the same bullet every time you are setting up your dies when reloading new batches. Pull the bullet from the case and put it back in the box for future setups. This way you are using your die bearing surface as the comparator. Simple...

 

[Alpheus]

I sort the bullets by length measuring from base to ogive. And then when seating I measure from base of brass to ogive and with the bullets being different lengths you have to adjust your seating stem to make the same measurement for each round so that you have the same amount of jump

The base to ogive length of a bullet doesn't affect the base of case to ogive length. What die are you using?

Assuming I stick with the RCBS seating die and get an ogive comparator and don't sort my projectiles into groups, can I expect to achieve 1" groups or smaller at 100yds with my cz 527 in 223?

I really can't say, there are simply too many variables in addition to seating that affect precision.
How do you weigh your charges?
What brass, bullets, powder and primers are you using?
How much brass prep do you do? Trim, chamfer, flash-hole uniforming, primer pocket uniforming, neck turning, sorting brass by volume or weight, annealing etc etc etc.
How good of a shooter are you? Don't intend to insult you, but it makes a huge difference. Positioning, breathing, trigger technique, sight alignment, the list is long.
What scope/bipod/rear bag are you using? How does you rig fit you? Is you barrel free-floating? Is the action bedded?

Good quality reloads are the good place to start. You want each round to be as identical to the next as you can make them.

Brass prep is important. Start with using brass from the same lot, this will help minimize differences without having to go OCD on it. Trim to the same length, doesn't have to be minimum for that caliber, just the same for each case. Use cases with the same number of firings for your groups, this minimizes differences caused by fireforming to the chamber and work hardening of the neck.
Generally, only neck sizing will get you the best results and longest brass life, not to mention make things quicker at the bench.
Get a high quality beam or electronic scale and weigh each charge.
Use quality bullets, Berger and Lapua are widely considered top of the line, other then some very expensive boutique manufacturers. Sierra and Hornady are the next ones down. These are not set in stone rules, people can get amazing results with cheaper bullets, it all depends on what your rifle likes.
When someone says X product is the best, take with a small grain of salt. What they mean to say is X product has worked the best in their experience. Experimentation is a big part of precision shooting and reloading. Testing with what a lot of other shooters have had a lot of success with is a good way to go.
Learn how to do proper load development, ladder tests and optimum charge weight tests are a good place to start.
Start keeping good records. Time, place, weather, group sizes, what range, other factors etc. Don't need to go overboard with taking down every tiny minutiae, but you need a way to tell what works and what doesn't. Also to see if you are improving.

There is a hell of a lot to this, so I will end with one last thing. Be ready to do a lot of readng. Find quality books and online resources. Books like The ABC's of reloading are an excellent place to begin. Forums like this one, accurateshooter.com, snipers hide, YouTube channels like 8541 tactical, and tiborasaurus rex.

Good luck.

 

[Bigturk]

These are some of my first reloads for my 223. I have loaded these bullets to the longest OAL that will fit in my magazine. Using the Hornady Comparator and headspace gauges the V-Max will have a longer jump to the rifling than the Calhoon HP. The V-max bullet is pointed more and the ogive is located further back on the bullet. Both are further from the rifling than I would like but I am limited by magazine length. I am please with my purchase of the Hornady Comparator set.

 

[charles69]

The base to ogive length of a bullet doesn't affect the base of case to ogive length. What die are you using?

I am using the RCBS competition seating die which seats off above the ogive, I am considering getting the forester seating die, I believe these seat off the ogive which will solve all my problems.

 

[fivehundredlimited]

Thanks guys, just wondering, I did the marker and bullet test and got a col of 2.264" touching the lands...so I reduced that by 0.02" so I am thinking that should atleast provide a margin of safety so that none of the bullets are jammed.