So I am having some issued with loading for Suzy (the 6.5 creedmoor that I just recently got). I bought a set of RCBS dies to load for this rifle. I am using Nosler virgin brass (not factory seconds). Bullets I am using are Nosler 120 gr ballistic tips. As I am doing load development I like to try and obviously have the same seating depth for each round. After I load my first round I continue to load the rest in my test batch. For some reason after I seat the first one and then go to the 2nd, 3rd, and 4th round the seating depths do not stay the same. Sometimes the jumps are as much as .0010 sometimes as small .0001. I am using a Hornady CBTO gauge to try and give me the most exact measurement possible, instead of just measuring cartridge overall length. Anyone have any guess as to why this is? I have never experienced this before with any other round I reload for.
Trouble getting consistent seating depth
- Thread starter ReloadKy
- Start date
Not compressed loads I am assuming? That plastic tip on a BT should be pretty consistent. Take a cartridge that you are showing a .010 difference with using the comparator, and see if you are seeing the same difference measuring the overall length from that cartridge base to tip of bullet.
If you are seeing no difference measuring base to tip, then just to make sure measure 10-15 bullets only, using your comparator just in case you got a batch of bullets with varying ogive measurements. I've never ran into it from the same box, but I have seen significant differences of the same brand and weight of bullet from 1 box or lot to another.
The last thing is concurring with what Scotty is saying. If you are noticing some seating harder than others, it can throw your lengths off.
If you are seeing no difference measuring base to tip, then just to make sure measure 10-15 bullets only, using your comparator just in case you got a batch of bullets with varying ogive measurements. I've never ran into it from the same box, but I have seen significant differences of the same brand and weight of bullet from 1 box or lot to another.
The last thing is concurring with what Scotty is saying. If you are noticing some seating harder than others, it can throw your lengths off.
hunter24605
Handloader
- Apr 30, 2016
- 2,533
- 4,177
Something often overlooked is cleaning the shell holder. A build of of gunk or case lube can cause inconsistencies, too.
hunter24605
Handloader
- Apr 30, 2016
- 2,533
- 4,177
Yep, and I’d also measure the base to datum line on a sampling of cases. There’s usually inconsistencies to be found there, too. I’d imagine that also would cause varying OAL’s..so many things to consider
- Thread starter
- #8
truck driver
Ammo Smith
- Mar 11, 2013
- 7,319
- 880
The Reading Micrometer seating dies are the way to go for consistency in seat since they seat off the o-give and not the tip of the bullet. Annealing the necks of your brass helps also.
Brad, get yourself a Frankford Arsenal Universal Micrometer seating die, and it will fix that problem for you. I get very consistent results, usually within .001" or so. It's about $70 and will handle everything from .22 to .33 caliber. Or you can spend a lot more money and get a micrometer die for each cartridge that you load for, but I see no need for non-competition loading.
Charlie-NY
Handloader
- Mar 11, 2005
- 1,420
- 855
A variation of .010" is a lot. This can easily be caused by bulky powder charges that are contacted by the bullet base when seating. That would be the first place I'd look. Excessively tight necks tend to cause a similar variation, IME.
TackDriver284
Handloader
- Feb 13, 2016
- 2,534
- 2,056
Checking seating stem and exchange it to a VLD seating stem to ensure the seating cup engages the ogive, not the bullet tip, I have changed from RCBS to I use Redding dies years ago. Not saying RCBS are not good dies, but its my preference since I had a few issues with RCBS dies. Deburr the necks with a VLD chamfer tool. When powder charges are close to 100% or more, you will have a powder crunch and readings will be off. I have had a few thousands off when using 46 + grains of Varget in the .308 until I used a drop tube to minimize powder crunch. I remove the button from all my dies and use a carbide steel mandrel which is .001" or .002" under bullet diameter for optimal neck tension. If the cases have been fired several times, it will harden and I anneal for those reasons where case necks have different seating pressures, but in your case .010" is a lot of variation. I would start with the seating stem inspection and use a VLD seating stem, powder overfill ( if any ) and neck tension.
What brass are you using?
What brass are you using?
pharmseller
Handloader
- Feb 13, 2012
- 554
- 88
“Sometimes the jumps are as much as .0010 sometimes as small .0001.”
Zero point zero zero one? I don’t find that significant. Granted, I don’t shoot past 600 yards, but 0.001” to me is nothing. Differences in shooting form will have more impact on precision than 0.001” variation in seating depth.
Speaking of which, how do your loads shoot?
P
Zero point zero zero one? I don’t find that significant. Granted, I don’t shoot past 600 yards, but 0.001” to me is nothing. Differences in shooting form will have more impact on precision than 0.001” variation in seating depth.
Speaking of which, how do your loads shoot?
P
TackDriver284
Handloader
- Feb 13, 2016
- 2,534
- 2,056
Was it was .001" or .010" ? I read your post and Shadetree's comment about .010" then wrote my reply on it, thought it was .010" but the OP mentioned .001". Sorry.
If its .001" its not much, but .010" is.
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Charlie-NY
Handloader
- Mar 11, 2005
- 1,420
- 855
What he typed was "Sometimes the jumps are as much as .0010 sometimes as small .0001." Since I doubt that he was measuring OAL to the 10/thousandths of an inch; I assumed that he just added an extra 0 by mistake. I could be wrong.
RL338
Handloader
- Mar 23, 2017
- 3,290
- 5,320
There could be several reason for a variance. Neck tension , bullet tip bottoming out in the seater before making full contact on bullet , and at what precision is Hornady’s comparator cut. If I read your post right 0.0001”-0.001” variance is nothing to be ashamed of.
TXbaldhunter
Handloader
- May 12, 2007
- 404
- 331
Seat depth variation used to drive me crazy.Depths were all over the place.Then I bought a Hornady comparator that clamps on my calipers and measures off the bullet ogive instead of the bullet tip.I think it cost around $30,comes with inserts for different calibers.You will soon find way more consistency in the comparator length.
pharmseller
Handloader
- Feb 13, 2012
- 554
- 88
