Understanding Primer Seating Depth, How much "crush" is good.

[RegionRat]

Just FYI.
There have been design standards for military primers and ammunition for a long time.
When primer performance is measured in the test stand or in the closed bomb, they are inserted to specifications for the test to meet standards.

Below is a clip of the Remington and Olin primer designs.
I have seen others go as little as 0.002" - 0.004", but most are 0.002" to 0.006" reconsolidation, or what is being called "crush" on the forums.

 

[jghoghunter]

Czkid
If you're happy with what you are doing. You're getting good results from your testing then by all means keep doing it. 3/4 of this sport is mental.

 

[Richard Jones]

Pretty good info right here. >>> Dusty Stevens Post

 

[TheCZKid]

That post was good, thanks for sharing it. I think I'm no the right track now. I'm hoping Sunday or Monday, (a couple warm days here) whichever day has lower wind, will go shoot some tests. All my load development has been with flush primers, and I'll use that as my Control group, then go .005, .008 and .011 and .014 seating depth from the case head. I think my "0" crush will happen at .008, and I'll be about 3 thousandths crush at .011, and 7 thousandths crush at .014, if I'm doing my math right. I'll check when it's not 2:18 am!

 

[jimmymac]

Dear Heavenly Father. I pray to you today this simple prayer. Thank you Lord for continuing to bless me with great hand feel when using my hand held Lee Autoprime tool. The wonders of it still amaze me to this day. I know I haven’t been cleaning my primer pockets either, but through your grace it hasn’t mattered one iota on my targets. May I also ask that you intercede and vanquish the demons that plague my beloved brotherhood so they may see the light and not concern themselves with picking the fly poop out of the pepper. With you, all things are possible. Amen.

 

[r bose]

I only seat by feel. Not some adjustable device. An adjustable seating tool would only work properly IF you knew that every piece of brass has the EXACT same primer pocket depth. They don't.

But be careful if you uniform primer pockets depth. Too deep might cause light firing pin strikes and ignition problems. Some shooters tend to create more problems than they solve.

 

[Dimner]

For this post, crush is that feeling after you feel the primer hit the bottom of the pocket and then adding more pressure to seat the anvil:

I did a test once, of a tiny crush, normal crush, and alotta crush.

My results were: I was not good enough of a shot to find any difference. That's when I learned the phrase 'can I shoot the difference?' Well the answer is I couldn't, not at .7" groups @100 yards. (this was a couple years ago). Now I wont try these types of tests anymore until I can get below .4" consistently. I can tell it is me, the shooter, that is the limiting factor. And that I'm shooing heavy sporter type rifles. I just don't have the shot to shot consistency and the ability to read wind as of yet.

 

[TheCZKid]

From my last test target with my 20 Vartarg, which was a ladder test on N120 powder, I had a couple nice groups at 17.6 and 17.7 grains, .24" and .12" respectively. So, the accuracy of my shooting, and my rifle, appear to be good enough to fiddle with the question of how deep I'm going to seat 1000 primers in 1000 pieces of brass, that I am prepping for loading this winter, for this rifle. Though obviously, there are some believers, and nay sayers, amongst the brethren here. Hallelujah!



I'm trying to remove the flyers I get when testing my loads, and when trying to hit a sage rat in the head (only part showing) at 220 yards. The flyers, which I don't think are related to wind or my shooting, or charge weight, seating depth of bullets, brass prep, primer selection or the precision of my loading process. It's just one of the "variables" which might cause a smaller or larger group, or hit or miss at distance. And, like I've said here, up to now I've always just seated the primers flush, which I see is not a good idea. And it's a variable I'd like to know if it makes a difference or not. If you don't think it matters, then Glory and Amen!

 

[justinp61]

If a person has a load that shoots well in his rifle, let's say with the primer seated flush, what is he going to gain by changing the seating depth? I'm speaking of a varmint rifle that'll shoot 1/2 or so moa, not someone's bench gun.

I think picking the fly poop out of the pepper is a good analogy.

 

[TheCZKid]

If a person has a load that shoots well in his rifle, let's say with the primer seated flush, what is he going to gain by changing the seating depth? I'm speaking of a varmint rifle that'll shoot 1/2 or so moa, not someone's bench gun.

I think picking the fly poop out of the pepper is a good analogy.

What is he going to lose by checking, if it will shoot in the 1's and 2's?

My rifle is a varmint gun, bring out to the fields to shoot rats. If someone has a rifle that's only capable or .5 MOA, or their shooting skills are not at a place where it would make a difference, as other variables would have more of an impact, then yes, primer seating depth is not important in that situation.

As Shakespeare said, "The lady protesteth too much!"

 

[gunsandgunsmithing]

From my last test target with my 20 Vartarg, which was a ladder test on N120 powder, I had a couple nice groups at 17.6 and 17.7 grains, .24" and .12" respectively. So, the accuracy of my shooting, and my rifle, appear to be good enough to fiddle with the question of how deep I'm going to seat 1000 primers in 1000 pieces of brass, that I am prepping for loading this winter, for this rifle. Though obviously, there are some believers, and nay sayers, amongst the brethren here. Hallelujah!

View attachment 1516564

I'm trying to remove the flyers I get when testing my loads, and when trying to hit a sage rat in the head (only part showing) at 220 yards. The flyers, which I don't think are related to wind or my shooting, or charge weight, seating depth of bullets, brass prep, primer selection or the precision of my loading process. It's just one of the "variables" which might cause a smaller or larger group, or hit or miss at distance. And, like I've said here, up to now I've always just seated the primers flush, which I see is not a good idea. And it's a variable I'd like to know if it makes a difference or not. If you don't think it matters, then Glory and Amen!

Just trying to be helpful here but that's a huge difference for .1gr of powder. Even the 17.6-17.7 show something else going on for you to have that much different POI at that distance.

 

[TheCZKid]

I think on that day, wind was an changing directions and affecting POI between groups, but yeah, I see your point.

 

[gunsandgunsmithing]

I think on that day, wind was an changing directions and affecting POI between groups, but yeah, I see your point.

Yep, it coulda been wind. Coulda been wind on some of the bigger groups too, though.

 

[TheCZKid]

Hard to know, I rarely have calm days here when I try to do testing. I go out to a spot in the woods close to my home, and drag my stuff out there.

 

[gunsandgunsmithing]

Hard to know, I rarely have calm days here when I try to do testing. I go out to a spot in the woods close to my home, and drag my stuff out there.

Flags? I mean, people get tired of hearing that but there's a reason for them. You're 18.0gr load was not wind. I'd guess it to be .3-.4 off on powder which puts you on a sweet spot at 17.6-17.7.

 

[TheCZKid]

Wind flags are also new to me, but I totally agree are important. In the last year or so, as I realized how much wind was messing with my testing. I ended up getting 3 MTM flags, and setting up light stands with posts on top which hold them, as that's all I can afford currently. On that day I might have had one sitting next to my table, but not sure, as I didn't have much time to do everything.

 

[gunsandgunsmithing]

Wind flags are also new to me, but I totally agree are important. In the last year or so, as I realized how much wind was messing with my testing. I ended up getting 3 MTM flags, and setting up light stands with posts on top which hold them, as that's all I can afford currently. On that day I might have had one sitting next to my table, but not sure, as I didn't have much time to do everything.

They don't have to be expensive. Anything beats nothing. Even surveyor tape on a few bent coat hangers will tell you when NOT to shoot. I bet you'll get a lot more of those small groups and you can explain them to all the other range shooters who will ooh and ahh over your shooting expertise and small groups!

 

[mr45man]

For this post, crush is that feeling after you feel the primer hit the bottom of the pocket and then adding more pressure to seat the anvil:

I did a test once, of a tiny crush, normal crush, and alotta crush.

My results were: I was not good enough of a shot to find any difference. That's when I learned the phrase 'can I shoot the difference?' Well the answer is I couldn't, not at .7" groups @100 yards. (this was a couple years ago). Now I wont try these types of tests anymore until I can get below .4" consistently. I can tell it is me, the shooter, that is the limiting factor. And that I'm shooing heavy sporter type rifles. I just don't have the shot to shot consistency and the ability to read wind as of yet.

Just a couple of quality wind flags will help a LOT.

 

[TheCZKid]

I doubt that I'll impress anyone! I don't see anyone locally who shoots, as I just go shoot by myself when I test, in the woods. I was not trying to convince anyone about the importance of primer seating depth either, I'm just trying to understand if it's worth it being important to me.

Reloading is a hobby that I enjoy, keeps my mind occupied, and gives me a goal, to shoot tiny groups of holes on pieces of paper, which will hopefully translate to hitting more sage rats, or coyotes, rock chucks, etc. Keeps me out of trouble and gives me something to do.

I enjoy learning, and in this hobby / craft, is seems there's a rabbit hole waiting all over the place!

PS: yeah, I should get a couple good quality flags, a good investment for sure. I was thinking of trying to make some, but I don't have the shop to do that right now, so it's what's available to buy, and something was better than nothing.

 

[K22]

I doubt that I'll impress anyone! I don't see anyone locally who shoots, as I just go shoot by myself when I test, in the woods. I was not trying to convince anyone about the importance of primer seating depth either, I'm just trying to understand if it's worth it being important to me.

Reloading is a hobby that I enjoy, keeps my mind occupied, and gives me a goal, to shoot tiny groups of holes on pieces of paper, which will hopefully translate to hitting more sage rats, or coyotes, rock chucks, etc. Keeps me out of trouble and gives me something to do.

I enjoy learning, and in this hobby / craft, is seems there's a rabbit hole waiting all over the place!

PS: yeah, I should get a couple good quality flags, a good investment for sure. I was thinking of trying to make some, but I don't have the shop to do that right now, so it's what's available to buy, and something was better than nothing.

Wind issue:
I use surveyor's tape; it works ok and it's cheap. I place at the various locations using wood stakes, pretty simple.

If you go to the various ballistic calculators and plug in just a slight wind at various angles you will be amazed how it can affect shot dispersion.