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Eg. kist loaded up 83 rounds of 7mm saum, all brass was resaized the same, annealed etc. loaded to 57.86mm with the 7mm comparator, and half of them went between 57.78 and 57.9 mm, the other half were bang on.
what would cause this ? Seems to happen with whatever cartridge im reloading. could it be my hornady calipers ? Additionally, if you were aiming for 57.86mm, what tolerance would you call safe ? I can hit a tartet at 460 with this, 2 rounds less that 13mm apart centre to centre.
Projectiles consistent in length?
havent actually checked those. Id imagine that would cause a small discrepency ? berger projectiles, or hornady though.. im assuming that they are all different lengths to a degree, but seating them pushes down on the ogive also ?
Seating stem doesn't contact the bullet ogive. It contacts somewhere above it. Any variation in projectile shape means the seating stem isn't contacting in the same place each time. This is further complicated by the fact your Hornady comparator isn't measuring to the ogive either.
I now also use a Short Action Customs comparator which is the correct diameter for the given projectile diameter and all the variances I used to experience is eliminated (for Bergers).
interesting.... might have to look into the SACC ,
I’ve measured several boxes of Hornady and Sierra with a comparator. A box of Hornady projectiles have a variance of 0.13mm and Sierra 0.08mm. As for what’s safe for seating depth tolerance it would be beat to test it.
As said, the seating stem doesn't contact the ogive, it pushes not far below the plastic tip on my dies.
I have noticed a difference in projectile length between batches of Hornady ELD-X, but haven't noticed it within a box.
I literally spend the time, pulling and seating them all to the perfect depth. But that would definatly cause my discrepancy
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Everything mentioned above including Neck tension variances
There is a fix regardless of the cause
Don’t load to final length first time
Load 5 or 10 thou short on them all
Then measure and micrometer adjust the seating stem for the last measured thou for each one
IE. this one only needs 2 thou, this one needs 4 thou, this one needs 8 thou and this one needs 2 thou
Problem solved
@Larskramer ....you need a good comparator which measures in a similar spot to where the seating stem contacts, then you can measure from base to ojive on your bullets. You will see a difference in length even with the bullets from the same batch.
Never mix different batches as they will be streets apart at that point on the ojive.
You might also consider lapping the projectile to the seating stem and your comparator if you want to be really fussy.....the witness mark should be at least 0.040" wide....a narrow ring contact tends to dig in and give erratic performance as you are experiencing.
The measurements you are quoting are not relevant when measuring with a comparator....they are designed to provide a comparison between the items you are measuring. You should be finding at what point the bullet touches the lands then determine where you want your projectile to sit compared to that datum...ie either jammed or jumped......!
Get yourself a kit, comes with two bodies and your choice of inserts for headspace or base to ogive.Quote:
Originally Posted by Larskramer
https://ozarkoutdoorsnz.co.nz/reload...omparator-kit/
That's hugely tedious. Best for the OP to find the cause and go from there. If I got a variation of 2 to 8 thou I'd be mortified.Quote:
Originally Posted by 7mmsaum
Sac make a very nice product but you don't need to spend those sort of dollars.Quote:
Originally Posted by gqhoon
I've got the original Stoney Point set (Now Hornady) and have added to it Sinclair shoulder bushes and ogive bushes which do a slightly better job of measuring than the Hornady.
Where could one obtain said Sinclair ogive inserts ? sorry can't google from work :(Quote:
Originally Posted by zimmer
Loading ELDMs in 7mm and the projectile length is different from what hornady states, then there is variation of up to +/- 2-3 thou. Annoying but you can batch them for group shooting.
Greetings,
I have noted some distinct changes in the ogive position and shape, enough to be detected by eye. Additionally the projectiles in a box are not all made in the same die so they will vary in shape slightly. I just start with 1mm jump where I can which works for me.
GPM.
So that is 0.08mm over target and 0.04mm under target
or to translate into imperial... 0.003" under and 0.0015" over
My sense of proportion has to ask what is the problem?
no problem, just asking what the cauyse can be, aswell as what should be considered too high and too low from the targetQuote:
Originally Posted by LBD
https://www.brtshooterssupply.com.au.../sinclair-int/Quote:
Originally Posted by dannyb
Haven't bought anything from Sinclairs/Brownells for yonks.
Haven't checked stock levels though.
It might be interesting to now look at the bullet OAL and compare with the comparator OAL... if there is no common theme then you have a pretty good indication that the projectile shapes vary (ie ogive to tip) even if the weights are exactly the same.Quote:
Originally Posted by Larskramer
Another thing to have a look at , would be to measure the projectile length with the comparator and see how they vary.
No one has mentioned pressure, and consistency of caliper use.
We all tink we can repeatably apply the same force and therefore get the same measurement on the same object. Try it with your eyes closed or the caliper held so you can watch the dial. Measure the same thing 5 times and see if you stay within .001 " because that is the +/- measurement
that is giving the issue. ( +/- 1 gives a range of 3)
Use a wibbly wobbly bullet not a flat piece of steel.
I am surprised that none of the reloading companies have come up with a hydraulic device to take the human error out and give consistent pressure...... maybe if they did we wouldnt need to measure anymore.
I think also you need to take out your seating stem and check it fits your orgive and isn't bottoming out on the tip of the projectile.
Yeah definitely can manipulate the calipers a little to give you that range. It is the same when seating the bullet to make sure the ram pressure is consistent. AMP guys came up with an electric bullet seater and lots of interesting guff on seating pressure. Not cheap though.
I’ve found variable neck tension causes “spring back” when loading. I had this real bad in the last batch of 7mm rem mag I loaded. I could feel it in the press when projectiles were harder or softer to seat then the “normal”. The observation always aligned with my measurements immediately afterwards. Soft to seat were seated further in the case (a real prick when it goes beyond what you want) and hard to seat were seated too long and need an adjustment and pushed further.