T
This is what I do.. Feel it bottom out then press firmly again 2-3 times to be sure...
How Much Primer Crush?
- Thread starter Kyle Schultz
- Start date
Okay, that is making sense...here is what happened to me...somewhere around 1991 I built a pre-64 Model 70 with a Kreiger AMU contour barrel, McMillan A-2 stock and I had a Mark 4 M1 scope. The rifle shot fantastic...like 3/8" at 100. Best group ever with it was an incredible {for me} 1/2" at 200 yards.
I put the rifle away, used the scope on something else and it sat in the safe until a few months back. I get it out, load up some rounds and go to the range for a go at it. I was lucky to keep it around an inch. Several groups were a little over an inch.
I started looking for a problem. I have a borescope and made certain the bore was clean. I tried several different loads thinking something may have changed with the powder. Played with seating depth, even bought a new benchrest. Got looking at the cases...primers were a little bit high. Didn't notice it before. I was priming with a Lee tool I have had since the late 80's. It was wore out. I also noticed that brass these days seems to be very inconsistent with primer pocket depth...most being too shallow. I have a new priming tool and pocket uniforming tool on the way...we will see. I don't know of anything else it could be. With fresh annealed cases I used to sometimes get 5 fps ES with this rifle. Never more than 10-12.
The cup, to my knowledge, never contacts the base of the pocket. The legs of the anvil are what "bottoms" in the pocket. This is essential, as the anvil must remain fixed when the firing pin hits the cup, smashing the primer compound between them.
Reloaders must push on the cup, though, in order to seat the primer. This must be done without damaging the dried pellet of primer compound. So yes, it is possible to push too hard, deform the pellet severely, and cause erratic performance.
I seat by feel, trying to feel the anvil legs bottoming in the pocket, which feels like a sudden increase in resistance to seating force. In other words, as I continue to push the primer stops moving further. Then I feel each one to determine the surface of the cup is just slightly below flush with the case head.
Reloaders must push on the cup, though, in order to seat the primer. This must be done without damaging the dried pellet of primer compound. So yes, it is possible to push too hard, deform the pellet severely, and cause erratic performance.
I seat by feel, trying to feel the anvil legs bottoming in the pocket, which feels like a sudden increase in resistance to seating force. In other words, as I continue to push the primer stops moving further. Then I feel each one to determine the surface of the cup is just slightly below flush with the case head.
I never liked the "feel" thing. I use an RCBS ram primer. It is trial and error to find and then lock down the die at the proper depth for seating the primer, but once done, it will not vary. It is a lot slower process than with any hand tool, but it works for me.
CJ6
Silver $$ Contributor
I asked this on another forum and came up with the same conclusions. I tried to get .003 crush and never could get a consistent readings, .002 was where I was and ended up (using Tula LRPs),less gave me irregular ignition (higher ESs)
Brians356
Gold $$ Contributor
I've only ever used the Lee Autoprime hand primer. Cheap, but effective. And I also uniform the primer pockets using the Sinclair (nee Whitetail?) tool, so the pockets are all the same depth, and nicely squared at the the bottom corners.
With the way the camming action works on the Lee (and probably other similar ones), by the time you feel the anvil bottom out, any additional compression of the handle yields very little movement of the cup, so what feels like a lot of compression is really just a couple of thousandths. And in that position you have maximum cam action leverage.
Some chaps are fixated on an exact repeatable amount of compression, but I tend to believe some of the best-known BR shooters who have stated "just a bit of compression after it bottoms out" is all the matters, and you can feel that with a tool like the Lee. I seriously doubt the difference between, say, .002" and .004" of "crush" (assuming you can ever really measure it accurately enough) will make any difference in your groups sizes. It's well down in the noise floor, dwarfed by many more significant variables.
Just my opinion, about which I am the world's foremost expert (thanks, Bruce Williams.)
With the way the camming action works on the Lee (and probably other similar ones), by the time you feel the anvil bottom out, any additional compression of the handle yields very little movement of the cup, so what feels like a lot of compression is really just a couple of thousandths. And in that position you have maximum cam action leverage.
Some chaps are fixated on an exact repeatable amount of compression, but I tend to believe some of the best-known BR shooters who have stated "just a bit of compression after it bottoms out" is all the matters, and you can feel that with a tool like the Lee. I seriously doubt the difference between, say, .002" and .004" of "crush" (assuming you can ever really measure it accurately enough) will make any difference in your groups sizes. It's well down in the noise floor, dwarfed by many more significant variables.
Just my opinion, about which I am the world's foremost expert (thanks, Bruce Williams.)
swd
Silver $$ Contributor
It's actually completely opposite. When you seat a primer the anvil it is pushed up into the cup and compound. A correctly seated primer will have the bottom of the anvil seated flush with the bottom of the cup with everything bottomed out in the primer pocket.
swd
Silver $$ Contributor
I forgot to mention the reason the anvil does not come seated is to reduce their sensitivity and make them safer to ship.
Factory loaded ammo has a different process.
When large ammunition manufactures like Winchester, Remington, Federal etc. that make their own primers, they seat the anvils all the way in while the compound while it is still wet and then prime the brass while the compound is still wet.
The primers we get for reloading are not exactly the same as what goes into loaded ammo from large manufactures.
This is all from 15 or so years ago. Now that lead styphnate is being phased out the process may or may not be exactly the same
Factory loaded ammo has a different process.
When large ammunition manufactures like Winchester, Remington, Federal etc. that make their own primers, they seat the anvils all the way in while the compound while it is still wet and then prime the brass while the compound is still wet.
The primers we get for reloading are not exactly the same as what goes into loaded ammo from large manufactures.
This is all from 15 or so years ago. Now that lead styphnate is being phased out the process may or may not be exactly the same
Upgrades & Donations
This Forum's expenses are primarily paid by member contributions. You can upgrade your Forum membership in seconds. Gold and Silver members get unlimited FREE classifieds for one year. Gold members can upload custom avatars.
Click Upgrade Membership Button ABOVE to get Gold or Silver Status.
You can also donate any amount, large or small, with the button below. Include your Forum Name in the PayPal Notes field.
To DONATE by CHECK, or make a recurring donation, CLICK HERE to learn how.
Click Upgrade Membership Button ABOVE to get Gold or Silver Status.
You can also donate any amount, large or small, with the button below. Include your Forum Name in the PayPal Notes field.
To DONATE by CHECK, or make a recurring donation, CLICK HERE to learn how.