Inconsistant loaded round COL?
- Thread starter Chopaka81
- Start date
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I am using the Hornady Lock and Load.
Case Gauges & Headspace Tools - Hornady Lock-N-Load HeadspaceTool Set w/Bushings
Interesting about the seating depth... > .030" hummm.
woods
Well-Known Member
If you are using the Hornady OAL gauge and a modified case then in all likelihood you are seating farther from the lands than you think anyway. When you insert the bullet into the modified case and push the modified case into the chamber, you push it all the way forward until the modified case shoulder is against the chamber shoulder. When the modified case is fully forward the case head of the modifed case is farther forward than a fire formed and chambered loaded round case head will be.
IOW, you have to allow for the headspace of the modified case. If you have a Hornady Headspace Gauge then you can take measurements to the shoulder on the modified case and on a fire formed case and see what the difference is, if there is any (probably will be). You have to add this to your measurement for how far you are loading away from the lands. So if the difference on the shoulder measurement was .010" between the modified and fire formed cases, and you were loading .003" from the lands according to your measurement on the modified case, then you would add the .010" and you would actually be loading .013" off.
Now there are some extenuating circumstances such if you were FL resizing and you would then subtract the distance you are moving the shoulder back. IOW if you were pushing the shoulder back .003" or if your case still had .003" to expand before being fully fire formed so it would contact at the shoulder, then the firing pin would move the case that .003" forward during firing and that would also affect the distance you are loading from the lands.
Best to back off a reasonable distance and work up a load where this minutiae will not cause problems.
I did not make that mistake. I am using twice fired neck sized brass that has been sorted by weight, trimed to length, necks turned, primer holes uniformed, and flash holes deburred.
Bare in mind I am not bumping the shoulder of the brass, therefore in my little brain the differences in individual ogives of the bullets and slight variances in case length should influence the "overall" measurement of a seated bullet since the distance between the ram and the bullet seating die is fixed.
I provided the link to the lock and load from Hornady since it was the 1st link I came to. I apologize that some did not know I was using an ogive measurement insert. My bad.
Basically we used the lock and load to eastablish the location of the lands, then used an 30 cal ogive measuring insert with the lock and load to deterime the overall length.
Sounds like the +/- 0.003" deviation is just the way it goes and I will have the live with it.
Regarding the suggestion that I pay close attention when seating the bullets and using a consistant stroke, I have been doing that and it has helped.
FWIW, The reloads are not compressed.
Thanks for the input guys, I was mainly worried about my press being out of whack, sounds like for "utility grade" reloading the old rockchucker is fine. However, for percision bullet seating I may need to upgrade to a Wilson Arber Press. I guess that is the price one will have to pay to get from 0.5 moa to 0.25 moa. In my world of engineering I refer to it as dB $$. the price is now going up expotentially.
Bare in mind I am not bumping the shoulder of the brass, therefore in my little brain the differences in individual ogives of the bullets and slight variances in case length should influence the "overall" measurement of a seated bullet since the distance between the ram and the bullet seating die is fixed.
I provided the link to the lock and load from Hornady since it was the 1st link I came to. I apologize that some did not know I was using an ogive measurement insert. My bad.
Basically we used the lock and load to eastablish the location of the lands, then used an 30 cal ogive measuring insert with the lock and load to deterime the overall length.
Sounds like the +/- 0.003" deviation is just the way it goes and I will have the live with it.
Regarding the suggestion that I pay close attention when seating the bullets and using a consistant stroke, I have been doing that and it has helped.
FWIW, The reloads are not compressed.
Thanks for the input guys, I was mainly worried about my press being out of whack, sounds like for "utility grade" reloading the old rockchucker is fine. However, for percision bullet seating I may need to upgrade to a Wilson Arber Press. I guess that is the price one will have to pay to get from 0.5 moa to 0.25 moa. In my world of engineering I refer to it as dB $$. the price is now going up expotentially.
Chopaka81
This might be a long shot. Are you using a pre-done store bought case, like from Stoney now Hornady? I make my own cases from a fired case, from the chamber/ barrel of the rifle I'm working with... If it's a factory fired case; one needs to knock a few thousands off the length to get the crimp line off the case; which helps the bullet move in and out of the case mouth freely, other wise it's not a issue on none crimped cases… chamfer & chafe the case just a little, and you've got a case that reads the chamber nut's on.
436
This might be a long shot. Are you using a pre-done store bought case, like from Stoney now Hornady? I make my own cases from a fired case, from the chamber/ barrel of the rifle I'm working with... If it's a factory fired case; one needs to knock a few thousands off the length to get the crimp line off the case; which helps the bullet move in and out of the case mouth freely, other wise it's not a issue on none crimped cases… chamfer & chafe the case just a little, and you've got a case that reads the chamber nut's on.
436
No.
I am using Rem Brass. I bought empty cases, fire formed the brass (and broke in my new barrel) using 150gr loads.
From there, I full lengthed sized the brass, turned the necks, tirmed to uniform length, de-burred the flash holes, did first time load development. Now I am on the 3rd reload of the "selected" brass.
Chopaka81,
I may have gotten a little off the thread of your first post… What I was asking was; how you determine your "jump" before you start load your ammo. That's where a Hornady OAL Gauges & Modified Cases would have come in… I understand your using a Bullet Comparator Inserts with Calipers to measure off the ogive of bullet in on a loaded cartridge.
I was just curious as to how you calculated the chamber and free bore to the lands and groves.
436
We inserted a lock & load device with a 300 RUM dummy case and a 208gr A-Max bullet, carefully pushing the bullet forward until it contacted the lands. We then locked the device removed all from the chamber and then measured the ogive.
woods
Well-Known Member
That "300 RUM dummy case" will be smaller than your fireformed case in the case-head-to-shoulder measurement and that will throw your measurement off. That dummy case is what 436 was talking about where he makes his own from fire-formed brass in his chamber.
OK, I see your points, however I am thinking that if the dummy round is shorter than a fully fireformed case, the end result would be a loaded round coming with the bullet being seat deeper (the delta of the two). Not sure of this, I will have to think about it.
