Primer seating depth

[L W P]

Do a search. This topic has been covered 10,000 times.

Is it really so hard for someone with experience in seating primers by feel to give around about measurement? Like in my case I have Lapua SR 6.5 Creedmoor brass and I've tried to SEAT BY FEEL. The numbers that I have come up with are .0095"-.011" below flush with the head. I used to just seat around .004"-.005" below flush with the head. I'm going to compare my best loads that are with .004"-.005" below flush ( which produce S/D's of 6-8 ) to the new seating depth of .0095"-.011" below flush to see if there is any improvement. The proof is in the pudding, never really understood that phrase. We'll just stick with the numbers.

 

[BoydAllen]

Is it really so hard for someone with experience in seating primers by feel to give around about measurement? Like in my case I have Lapua SR 6.5 Creedmoor brass and I've tried to SEAT BY FEEL. The numbers that I have come up with are .0095"-.011" below flush with the head. I used to just seat around .004"-.005" below flush with the head. I'm going to compare my best loads that are with .004"-.005" below flush ( which produce S/D's of 6-8 ) to the new seating depth of .0095"-.011" below flush to see if there is any improvement. The proof is in the pudding, never really understood that phrase. We'll just stick with the numbers.

What tool do you seat your primers with?

 

[L W P]

K&M

 

[L W P]

I screwed the head of the tool around 1/2 a turn or just slightly more, than I had be using it for the .004"-.005" seat. I felt the handle stop with a little resistance on 10 different cases and then measured the depths to come up with .0095"-.011" below flush, with no damage to the primer.

 

[Dusty Stevens]

Lets quit measuring primer depth. Lets seat them to a light crush and move on. I know of no serious competitor that measures primer depth. I know we like to obsess over details but this shouldnt be one that needs to be addressed. Way too many variables and seating by touch/feel is better even if there was a solid number

 

[L W P]

Really, with all do respect. And I mean that, I'm not blowing smoke. The primer being the key component here in making the cartridge go bang and know one is coming up with some new newfangled tool that electronically measures,shorts,and seats to an exact science. If I could invent such a mechanical electronic tool I would be rich. It does sound like something a lot of people would buy, doesn't it? Ok I'll let it go. Sorry

 

[Dusty Stevens]

Im not saying youre wrong all im saying is that you need to seat primers by feel not measurement. Those 3 components- cup, anvil and case is tolerance stacking at its finest. If it helps you to measure then by all means please do it. A digital graphing load cell primer seater where you could see the crush may be the ticket for your financial future (no need for measurement). Id buy one

 

[L W P]

Im not saying youre wrong all im saying is that you need to seat primers by feel not measurement. Those 3 components- cup, anvil and case is tolerance stacking at its finest. If it helps you to measure then by all means please do it. A digital graphing load cell primer seater where you could see the crush may be the ticket for your financial future (no need for measurement). Id buy one

OkI'll get to work on that. Thanks But don't tell my wife Please.
Seriously though I'll keep you guys informed to my testing at the range of the different primer seating depths. Good night, and my God Bless.

 

[retired]

so if you use the proper tool to uniform your primer pockets,
and then seat to the bottom( you will feel it) and then a small crush,
you have uniformity without measuring the primer seating depth.
if you insist on measuring something , measure your primer pocket uniforming tool.
is it cutting within the sammi spec for the pocket.

end of story.

Really, with all do respect. And I mean that, I'm not blowing smoke. The primer being the key component here in making the cartridge go bang and know one is coming up with some new newfangled tool that electronically measures,shorts,and seats to an exact science. If I could invent such a mechanical electronic tool I would be rich. It does sound like something a lot of people would buy, doesn't it? Ok I'll let it go. Sorry

 

[KenOath]

Is it really so hard for someone with experience in seating primers by feel to give around about measurement? Like in my case I have Lapua SR 6.5 Creedmoor brass and I've tried to SEAT BY FEEL. The numbers that I have come up with are .0095"-.011" below flush with the head. I used to just seat around .004"-.005" below flush with the head. I'm going to compare my best loads that are with .004"-.005" below flush ( which produce S/D's of 6-8 ) to the new seating depth of .0095"-.011" below flush to see if there is any improvement. The proof is in the pudding, never really understood that phrase. We'll just stick with the numbers.

In my own experience as long as you have the primer bottomed out in primer pocket you are good to go.. also in my experience it is fairly difficult to crush a primer with a hand priming tool, with a little practice you’ll know by feel when primer is bottomed out..no need for measuring.

Cheers Rushty

 

[jimmymac]

Since day one of reloading, I've always seated by feel. No one taught me. It's very intuitive. It's easy to tell when the primer bottoms out in the pocket with a nice solid stop. I obsess over many things in regards to precision shooting but this isn't one of them. This is a minor point IMO.

In the quest for ultimate precision, I concern myself with things like properly sized brass, powder charge window, bullet seating depth, good barrels, good bullets, good glass, proper bench technique, solid front rest with a good rear bag. Any and all of those things matter far more to me than wasting my time worrying about the primer in this case being seated .002 deeper than the the next case. If you can't read the wind, none of it matters anyhow.

 

[KenOath]

Since day one of reloading, I've always seated by feel. No one taught me. It's very intuitive. It's easy to tell when the primer bottoms out in the pocket with a nice solid stop. I obsess over many things in regards to precision shooting but this isn't one of them. This is a minor point IMO.

In the quest for ultimate precision, I concern myself with things like properly sized brass, powder charge window, bullet seating depth, good barrels, good bullets, good glass, proper bench technique, solid front rest with a good rear bag. Any and all of those things matter far more to me than wasting my time worrying about the primer in this case being seated .002 deeper than the the next case. If you can't read the wind, none of it matters anyhow.

^^^ This is all very good advice.

 

[Laurie]

One of the benefits of SRP brass IMHO is that it is much easier to seat SR primers and obtain good 'feel' on the tool than is sometimes the case with LR models. Prime both standard LRP 308 and Lapua 'Palma' brass together, and there can be a great difference in the ease of seating them.

Primer makes / lots vary too marginally in their dimensions as well as cup hardness, so it's sometimes quite difficult to be consistent but this seems to hardly ever be an issue with SRP. I really hate it these days when the brass / (LR) primer combination makes it hard work. When I did my Large Rifle primer tests five or so years ago, I'm at least half convinced that one reason the Sellier & Bellot product did so well was that it was the easiest model of the 15 tried to seat in the RWS brass used. Some makes / models had to be initially pressed hard, then once past a certain point dived in way too quickly over the remaining travel - forget 'feel' in these circumstances.

This makes for another 'plus' if there is a choice between LRP and SRP as increasingly applies with Peterson Cartridge offering SRP versions of of 6.5 Creedmoor, 260 Rem and 243 Win as well as 308 in addition to the usual LRP configurations. (I can see major confusion arising in the future though amongst handloaders who're not clued in on this wondering why primers either won't fit their new brass or once in the pocket fall out again, not to mention with the assistants in some gunshops! )

 

[JimSC]

I just make sure my primer pockets are clean and I double seat. I initially prime with my RCBS hand primer for speed but found some primers slightly proud of the case head so now I go back and reseat them on my press to make sure they are all bottomed out. I have noticed fewer flyers and a more consistent velocity by doing this and the double check only adds maybe 10 minutes for 50 cases. For match rounds the time is well spent

 

[seymour fish]

So if you are teaching a new reloader how to seat "by feel" how do you teach them what a proper seating depth feels like?

In a talent-free zone, consider over-intellectualization

 

[seymour fish]

Which is actually my point, you can't teach proper primer seating without some kind of dimensional data, you can't just tell a novice to simply press a primer in to the pocket until the anvil seats, they don't have any idea how that feels and with a press you wont even be able to feel the anvil seat. If you do some research you'll find that all primer manufacturers recommend that the primer cup be seated to at least .002" below flush and most use a range of depths of .002" to .004" with some recommending as deep as .008". The cup must be below flush in order to set the anvil at it's proper place, too shallow and the primers can be insensitive due to not enough energy being transferred to the mix, too deep and the primers can be insensitive due to the mix being crushed and pushed away from the anvil/cup contact area.

By this absurd logic it would be impossible to teach trigger squeeze without “dimensional data”. “If you do some research” is condescending.

 

[tenring]

I believe that primer residue left unattended can create variations in primer seating depth, and, perhaps, accuracy. I use this tool frequently:

http://www.pmatool.com/pma-lapua-sm...niformer-complete-w-handle-and-power-adapter/

 

[danny]

I seat till I feel the primer touch the bottom, then I keep going a lil farther. It ends up being in the neighbourhood of 0.004"- 0.006" below flush, depending on primers of course.

That is pretty much how simple it is. It is simple mathematics. Primer seated till it bottoms, then the depth of the primer pocket minus the height of primer indicates how far below the case head you are, NOT how far you want them seated beow flush, set with an adjustable (or even set depth) seating tool. This whole "how much do you want them seated below flush" argument/dimension is an improper approach which could yield you a primer seated insufficiently, just enough, or way too much, something you have no control over if you are just setting for a particular dimension.

Danny

 

[Rustytigwire]

Put bolt in hole
Turn bolt with fingers till it wont
Get wrench, tighten.
How much?
We hold these truths to be self evident.
Want same? Make same!

 

[msinc]

Someone once remarked on here that the primer was a critical component because that is where everything starts. They went on to say that because it's where it all begins very small minute differences will have a profound effect on accuracy. At the time I was chasing an accuracy issue with a particular rifle and it all sounded pretty good...like maybe something easy enough to test out.
I have always just used a Lee priming tool with the tray and seated by "feel". I did notice that I was starting to get some slightly high primers and careful inspection revealed some wear on the pot metal parts of the priming tool.
I had to call Forester for something unrelated and asked the guy if anyone made a priming tool that was positive seating. That is to say one that was adjustable and able to seat all primers to a given depth and force. He recommended the Lee Ram Prime. For $15.00 I got nothing much to loose but time, so I got one. They also sent me the repair parts for the auto prime tool. I played around with uniforming tools and both methods of seating primers and with the most accurate rifle I own {shoots around 3/8" groups at 100} I was unable to discern any difference for the shooting I do.
Early in this thread someone remarked that "primers were different thicknesses" or sizes...it is my understanding that so-called match or "benchrest" primers are stamped out of a sheet of metal that is held to tighter tolerances of thickness. In fact, I have read where this is the only difference. I've never been able to tell a difference accuracy wise {group size at 100} either way with match or other primers either.