Primer testing for load development

[KMart]

We all have our favorite primers and usually we start our load development with that primer. At what point, do you start switching primers to see if groups get better with brand x, y, or z?

Do you pick a powder and bullet and test all the primers up front?
If your load is not working out, do you test then?
Do you test at the end when you have a pretty good load and want to tighten the group a bit?

 

[JBT47]

I am interested in this as well.

 

[dmoran]

My own input: after the seating is nailed down. The charges should be fine tuned to each primer, especially when there is a change in velocity from one to another.
Donovan

 

[gotcha]

Do you test at the end when you have a pretty good load and want to tighten the group a bit?

That's when I do the primer test. Sometimes very noticeable improvements, sometimes accuracy gets worse, sometimes no change at all. You'll never know unless you test

 

[KMart]

My own input: after the seating is nailed down. The charges should be fine tuned to each primer, especially when there is a change in velocity from one to another.
Donovan

I have always been of the opinion that you can tune a load to the primer you are using, but sometimes it doesn't work out that way.

 

[dmoran]

I have always been of the opinion that you can tune a load to the primer you are using, but sometimes it doesn't work out that way.

Which can be said for bullets and powders as well.....
Also have noticed how some powders seem to like a specific primer more.
Donovan

 

[.22gongzilla]

An article in Hodgdon's Annual Reloading Manual "The Role of the Primer" a couple of years ago (author: 'Pearce', I think) did a good job explaining primer selection for .223/.308 with various propellants. As a result I generally use regular primers with stick powders and mag primers with ball powders. I've tried using mag primers simply for pressure reasons, but the benefits are dubious: a standard .223 case head can mushroom severely and affix itself firmly to one's bolt face even as the mag primer remains intact, I found that out.

 

[mikecr]

I would go after primer potential after load development, because I know of no way to do it earlier.
Primer changing is a bit of a setback, leading to further adjustments.
Shouldn't be much, but I've seen primer changes shift grouping size more than I would pursue.
The problem IMO, is that we don't know why each primer is changing things. Any of them should provide sufficient powder ignition, and they do.
The difference for us is in how consistently they provide that ignition.

I once had a firing pin under setscrew control slip in it's cocking piece. This was very difficult to conclude, as all primers still fired, there was no feeling of timing change, just a step change (for the worst) in both accuracy and precision. ES/SD increased taking me in/out of my tune.
Given that nothing about my ammo had changed, it had to be the gun. The barrel was young, so it had to be in the action. Stabbing in the dark, I changed primers, and it happened to shoot better, which in my mind meant something else had changed, so I went back to load developed & offending primers. I disassembled the bolt, no problems with lube or changes to sear engagement/pin fall(assumed correct), but where should the firing pin be? While the pin seemed secure, maybe it had somehow shifted..

On this suspicion, I ran a 3sht grouping test with 10thou increments of released firing pin protrusion from bolt face. The groups opened and closed twice, in nodes, and I suppose this was my load reacting.
This whole mess turned out a blessing as best pin setting here gained me a full 1/8moa better results than my original load development had. I was used to solid 3/8moa at 300yds, that dropped to 1/4moa with this effort. Same Fed205s. It's a factory Cooper, 223Rem.

I've wanted to further explore this but haven't.. All I know now is that there is potential here.
I suspect that we could use any primer of our choosing, and recover performance by optimizing striking of it.
The testing would have to establish standards in pocket depths, primer seating preload/crush, and headspacing. Easy enough.
Not so easy is proper amount of pin fall to begin, pin weight, and optimum spring force. These would have to be established as well, and I can't find answers there to act on.
Just a pile of abstracts, that I think is the reason we use every kind of primer in every cartridge & powder.. None ever rise to be considered best for everyone.

 

[370bc]

I just finished an OCW powder bullet test @ 200 yards, then confirmed at 500. Then did a primer test @ 200 with 3 different primers, then confirmed @ 500. My group Went from 3 inches vertical to 1 7/8 inches vertical. Ackeyman suggested the primer test. He is the man and my thanks to him sharing his knowledge and suggestions!

 

[Ned Ludd]

If you have some idea of the approximate charge weight where you will likely end up, I would test the primers as the first step (or at least an early step) in the process. I've seem different primers make as much as a 25 fps difference in MV with a set load. I'd personally prefer to know about that before carrying out charge weight optimization. Otherwise, you might have to redo the charge weight testing with the new primer, even if only a "streamlined" test, in order to find the center of the optimal charge weight window. The main benefit of choosing one primer over another IMO is usually lower ES/SD, as opposed to grouping, although that can certainly change as well. I can usually tune grouping sufficiently well for my purposes using seating depth adjustment. If you wait until near the end of the process to try out different primers, the possibility exists (although not a certainty) that you may be almost all the way back to square one in the process if the final primer choice gives results that are dramatically different than the one used to work the load up in the first place.

 

[hogan]

Own a Sierra or Berger loading manual? I don't own the Berger book, and the Sierra is about 15yrs old; but... IF you start with the load parameters the premier accuracy bulletmakers recommend, IE use their recommended primer and their bullet, you will not have to sacrifice a good barrel trying to reinvent the wheel.

How much "testing" you gonna do?
Got a new barrel from a new barrelmaker?

Do you see where I'm going with this?
If you were shooting lead boolits, then you got minimal throat wear, but you're not... So you're gonna test several primers and vary your loads by fractions of a grain to see what delivers the opitimum. How many primers? What weights of how many powders? Gonna stay with one bullet?

If this is how you get your jollies; by all means... Yet, if you're shooting enhanced velocity loads, small diameter bullets, using slow burn rate powders and testing 5 or 10 rds (maybe more?) to determine which powder, weight, and primer; you're looking at hundreds of rounds fired.

Barrel life might be 1200-3000rds on average for decent precision. Optimum precision likely ends about 800rds with a 6mm or 6.5mm Whizzer. Shooting a large magnum? Lots less, if you got a brake and don't let your barrel cool between shots.

Why reinvent the wheel? If you've shot-out your throat getting that one ideal load, will the next barrel work as well?

Probably buy the Berger book and shoot their optimum load for the bullet you like. Try a couple and see which bullet your rifle likes. If you stay with the "accuracy load" you've eliminated a lot of variables. Because you are asking questions of this sort, probably best advice is to shoot the "accuracy load" until you can't improve. If the bulletmaker's accuracy/optimum load won't perform for you; it's either you or the rifle, presuming you can load good ammunition.

 

[KMart]

Own a Sierra or Berger loading manual? I don't own the Berger book, and the Sierra is about 15yrs old; but... IF you start with the load parameters the premier accuracy bulletmakers recommend, IE use their recommended primer and their bullet, you will not have to sacrifice a good barrel trying to reinvent the wheel.

How much "testing" you gonna do?
Got a new barrel from a new barrelmaker?

Do you see where I'm going with this?
If you were shooting lead boolits, then you got minimal throat wear, but you're not... So you're gonna test several primers and vary your loads by fractions of a grain to see what delivers the opitimum. How many primers? What weights of how many powders? Gonna stay with one bullet?

If this is how you get your jollies; by all means... Yet, if you're shooting enhanced velocity loads, small diameter bullets, using slow burn rate powders and testing 5 or 10 rds (maybe more?) to determine which powder, weight, and primer; you're looking at hundreds of rounds fired.

Barrel life might be 1200-3000rds on average for decent precision. Optimum precision likely ends about 800rds with a 6mm or 6.5mm Whizzer. Shooting a large magnum? Lots less, if you got a brake and don't let your barrel cool between shots.

Why reinvent the wheel? If you've shot-out your throat getting that one ideal load, will the next barrel work as well?

Probably buy the Berger book and shoot their optimum load for the bullet you like. Try a couple and see which bullet your rifle likes. If you stay with the "accuracy load" you've eliminated a lot of variables. Because you are asking questions of this sort, probably best advice is to shoot the "accuracy load" until you can't improve. If the bulletmaker's accuracy/optimum load won't perform for you; it's either you or the rifle, presuming you can load good ammunition.

I only asked, at what stage of load development do YOU do your primer testing? I didn't ask for a lecture about wearing out my barrel. You still didn't answer my question.

 

[Titan]

I just sort my primers into milligram lots works better for me rather then switching brands for reducing es and sd, in my experience with federal and wolf LR primers.

 

[mikecr]

Kmart, I guess hogan is suggesting that primer testing isn't worth it, because we can just lookup our best loads in a book!
It would amaze me if anyone else, here, believes that...

 

[hogan]

If you start at a known and trusted beginning point, you isolate many variables.

Have you ever fired consistent good groups? Ever fired them with this particular rifle? Ever gotten great results with whatever the load is you're now questioning? Not like you gave any information about why you are wondering about primers, much less say which ctg you shoot or which primer you load...

Of course, if you are just ruminating aloud about the tribulations of dialing-in that last variable that might gain you the three ten-thousandths you need to win the super shoot; then please pardon my failure to grasp the situation. Yet, I doubt that is the actual situation. Just know it wasn't my intention to give offense. happy shooting!

Oh, and anyone who thinks you can evaluate anything in the precision world with results from 3rd groups is really flying blind.

 

[Thumb]

I did a lot of testing with powders, bullets, seatings and finally got my goto load at around .234" groups of 10 at 100 yards. I just today tested out 4 other primers using my goto load and what a difference. Here are the results of those primers. It seems my groups got better as I shot but letting the barrel cool down 5 minutes or more between primers. My goto load used a Remington 7 1/2. I would say my best group here was the WSR primers with a .590" 5 shot group. BTW, these were shot at 100 yards.


CCI 450


CCI 400


CCI BR4


WSR

 

[trailrider121]

Very interesting post on primer swap. I like to see pictures of targets with different primers used.

 

[pacificman]

The last thing I do is test primers after finding my optimal charge weight. With the OCW test I find that trying different primers at the end of my testing will normally keep things in the accuracy node that you started with.

 

[savagedasher]

Primers are the same thing as spark plugs to a engine . Their a ignition source .
Its not un common to see 25 HP change on a engine . And it not un. common to see 30 Fps change on a bullet . Larry

 

[KMart]

The last primer test I did was with small rifle Win, Rem, CCI 450, RWS and Fed 205. Variation was a high of 2917 and low of 2885 fps.