switching primers

N

nnn66

Sergeant
Full Member
Minuteman
Dec 6, 2006
194
2
Texas
#1
I'm fairly new to reloading and have just recently been putting a lot of effort into working on loads for my .308 Win. I've only worked with 2 different powders so far, Accur 2520 and Varget, and have mainly focused my efforts on Varget. I'm using Lapua brass, FL sizing it for first loading and then neck sizing after that. I've worked my way, in .1 grain increments, from 43gr up to 45.4gr of Varget, using 168gr AMAX bullets. It seems that my best accuracy results have been between 45.0 and 45.2gr Varget, with group sizes consistently 1 inch or less. This was while using Remington Large Rifle primers.

My question concerns switching to a different primer. A friend of mine gave me some CCI BR-2 primers and suggested that I try them to see if they made any difference. I loaded up 10 identical rounds with 45.2gr of Varget, with the only difference being that five of them had Remington primers and the other 5 had CCI BR-2 primers. I went out to the range and fired them at 100 yards. The results were that the Remington primered rounds grouped at about 1.25 inch and the CCI rounds grouped at under 1/2 inch. Could this be a result of switching primers or just a fluke? I haven't tried it again yet, but intend to do so in order to see if I get similar results.

If it is the primers that make that much difference, I would really like to understand why, so I would much appreciate feedback from those of you who are knowledgeable on this subject. Also, when switching primers like this, should I also start over and run through all of the different powder increments again or am I ok to just stick around the sweet spot that I've already determined while using the Remington primers? Anything else I might need to be aware of regarding safety in switching between these two primers?
 
#2
Re: switching primers

I've used both WLR and BR2 primers, but I've never tried a side-by-side like that. I think the BR2s are better and more consistent, but I wouldn't think you'd see that kind of spread. I would be more concerned that you are close to the edge of a node with your powder charge and one primer or the other is pushing you out of that node. How did you work you're load up? If you followed OCW or ladder methods and you picked 45.2, then I'd have to wonder since that is close to your max from the data above.
 
#3
Re: switching primers

Gene: thanks for your reply. As I mentioned before, I'm quite new at all of this, so I'm not even sure how to properly work up a load. I've read about ladder method, but am not familiar with OCW. Perhaps I need to try another method than what I've done.

I simply load 20 cartridges at a time, 5 each of 4 different loads and then shoot them in groups of 5 to see how they close I can get them to group. I sort of randomly chose my initial loads and then worked from there, tweaking a tenth of a grain at a time and retrying loads that looked good to me. I spent numerous days over a three weeks period, shooting 20 rounds a day and then going home and loading 20 more for the next day. I've definitely seen the tightest groups in the 45 to 45.2 range.

Is there a better way of doing this? I'll do some searches and read more about ladder method and OCW. Anything else I might need to try?
 
#4
Re: switching primers

It all comes down to barrel harmonics. Your barrel whips and flops as the powder ignites and the bullet moves down the tube. It's a very small amount of movement, but enough to change the POI if the bullet leaves the barrel at a different angle than it is at rest. See this site for some cool (exaggerated) animations of these harmonics:

http://www.varmintal.com/amode.htm

Basically, if you could duplicate everything exactly, it wouldn't matter because the barrel would always be at the exact shape when the bullet left the end, but this is impossible in practice. The best you can hope for is to find a "node" where the timing of the burn and the speed of the bullet down the barrel are such that the barrel is as close as possible to it's at-rest condition. When you hit the node, then small variations in powder charge, barrel temperature, etc. all contribute very little to the overall equation and you get consistent results.

Dan Newberry developed the OCW method to make it easier to figure out where the node is for a particular load. You can read all about it at his site:

http://optimalchargeweight.embarqspace.com/

He has a pretty good way of shooting and measuring the results so it's easy to find your node. Once you do, you can fine-tune it for tightest groups with different primers (changes the burn rate a little) or seating depths of the bullets (changes the exact timing of the bullet leaving the barrel).
 
#5
Re: switching primers

Thanks for your help, Gene. I have just spent some time reading everything on Dan Newberry's site and it has got me thinking that I want to start all over and see what results I can get using this method. The concept of the round robin method, as opposed to what I've been doing, makes perfect sense. I'm not sure I totally understand all of it yet, but I get the general gist of it for sure and will read over it again and will surely get a better grasp of it once I start trying it at the range. I've been shooting rifles for over 35 years, but have never reloaded until about 2 months ago and I'm really having a lot of fun with it! I know I still have a lot to learn, but I'm eager to keep at it, so I expect that I will find my load quite soon. Thanks again!
 
#6
Re: switching primers

I know nothing about the concepts above. But I have my procedures. Developing a load should start with primer selection and go from there.

I think it is questionable to take your load development and once arriving at optimum velocity and accuracy, to begin switching any component. You certainly wouldn't work up a load with 44.0 grains of IMR4350 and decide to substitute H4831 the same weight. Or switch different brands of the same 180 grain bullet....at least I wouldn't.

I don't think the above is a valid or fair comparison. I don't know if this is true, but I heard a long time ago that (for instance) the difference between the 210 LR primer and the 210M is they run the assembly lines at half speed for more control and assumed accuracy? If that is the case, then it could just be (above example) the happy coincidence that a CCI primer and it's intensity performed with better accuracy than the Remington? But, as far as I am concerned, that is not the way to develop a load. BB
 
#7
Re: switching primers

You're certainly entitled to your opinion BB, but you're in the minority. Dan Newberry has a pretty solid and popular methodology, and you're the first I've heard of to have any disagreement with him.
 
#8
Re: switching primers

Okay, fair enough. I'm okay with the BB as well as the Dan Newberry school of load development. And, in my first sentence above, I admitted my ignorance. It's a wonder, over forty years, yet I have stumbled on a few loads that performed to my satisfaction without benefit of the Dan Newberry's solid and popular methodology. Sheer luck, I suspect? BB

edit: I have always found comfort in minority thought, by the way. Popular is for beauty contests.
 
#9
Re: switching primers

Well, I certainly don't know much about developing a load and am simply learning from reading whatever I can find on the subject and from trial and error. I just came home from work and loaded 20 more rounds, 5 of each in 4 different .2 increments. I thought I would try that and see where it gets me. Won't get a chance to shoot them until Saturday morning, but hopefully the results will somehow be meaningful. I'm keeping good records of everything I do and have a stack of paper targets stacking up in my collection, so I think I will eventually figure it out. I'm sure there are better, faster and more efficient ways of doing it, but I'm certainly having fun with it anyway. So far, I've only worked with my .308 but once I get the hang of it, I intend to start working on loads for some of my other calibers. This reloading business is quite entertaining to me, so I don't mind all of the trial and error that I'm going through in trying to figure out the best way to work up a load, but I definitely would like to eventually learn the best methods for getting it done more efficiently. This time I have used only CCI BR-2 primers. I have already tested all of these same loads with Remington primers, so perhaps I'll be able to see if there seems to be any real difference and will report back here on what I find.
 
#10
Re: switching primers

From a safety standpoint, I would not switch primers with >45 gr of Varget and a 168 grain bullet, but you are still here, so that aside... Some primers might give you more consistency than others. I have found that BR-4's work better for me than Remington Small Rifle Match... but this does change where you are on your velocity, which might be part of what makes it work.

I would do a little more side-by-side testing, but it sounds like it works for you and if one set of primers works better than the other, then go for it.
 
#11
Re: switching primers

Thanks Carter. I was kinda wondering if switching primers like that might present some safety concerns. My friend, who gave me the CCI primers, has been reloading for decades and I'm certain that he is very safety conscious, so when he suggested that I try that load with a CCI primer, I assumed it was something safe to do. He did, however, say that I should be careful about signs of pressure, but he didn't seem to think the gun was going to blow up on me. Is this something I should be concerned about? I just loaded some with CCI primers and 45.4gr Varget. I didn't have a problem with them at 45.2gr, but 45.4 is getting on up close to the max of 46 for this bullet with Varget. I guess I really don't understand the difference between the Remington large rifle primers and the CCI BR-2. Is there really enough difference to present safety issues. I've shot 45.4gr Varget with Remington primers, but I'm a little reluctant to do it with the CCI if there's a danger of blowing up my gun!
 
#12
Re: switching primers

I have tested using all the same components with the exception of the primer (but not with maximum charges) in the past and the results are far less sterling than the difference in your groups. If anything at all, I saw only slight changes in velocity variation shot to shot and nothing in accuracy. Newberry's OCW method is a good program to follow but must be followed exactly for best results. I, as Buzz says, have come up with a lot of very accurate loads without it though. Maybe it was just luck
smile.gif
.
 
#13
Re: switching primers

I did fail to mention in my original post to this thread that I had shot 45.2 grains of Varget in a previous shooting session, using Remington primers, and had a much smaller group...closer to 3/4 in, so it could be that it was me who caused the big variation in group size on the day that I compared the two primers, side by side. The concept of shooting a round robin method rather than firing all five shots of one load and then all 5 of another, really makes a lot of sense to me. I'm definitely going to try that this weekend. I think it will certainly cut down on the possibility of some factor other than the cartridge itself causing discrepancies in my groups.
 
#14
Re: switching primers

One group isn't going to say anything. Do 3 - 5 groups and look at the average. Not the smallest group produced, but the average if you are testing two loads against each other. Obviously, in developing a load, it is impractical to shoot this many groups, but load development is more art than science.

When comparing different bullets or different powders, you really have to go through the task of developing the best load for a given set of components, but primers, I would say you could switch out and just compare A to B without developing a whole new load.

ALSO... if you are a new reloader, know your pressure signs:

Copy this or print it out and keep it.
 
#15
Re: switching primers

thanks! I'll print it out. I have been shooting some of the same loads over and over in order to assess consistency. Between 43 and 44.5, I was not happy with results, but when I stick somewhere near 45, I've been getting good groups. I just loaded 5 rounds each of 44.8, 45.0, 45.2 and 45.4. Is this a good enough spread that it could give me any meaningful data or should I be doing something completely different?
 
#16
Re: switching primers

You'll probably only catch one node with that spread, and only if it happens to center near 45.1 gn. I'd do a 6 shot test with 0.3 gn between loads. If you consider 45.4 your max (not unreasonable) then I'd go 43.9, 44.2, 44.5, 44.8, 45.1, and 45.4. Load 5 or 6 of each (3 for the test with a couple of spares for possible called fliers). Always start with the lowest load and check each shot for pressure signs. If your aim is true (use a sled if possible) you should see a clear trend. Once you find your node, then you may want to tighten the load spread to 0.2 or 0.1 gn around your node and shoot another test for verification.
 
#17
Re: switching primers

Let me get this straight. This method talked about (above) starts with selecting a primer at random and working up a load in two tenth grain increments, arriving at a max load and subsequently a "node" load that is safe and accurate......then, the advice is; to switch primers? BB
 
#18
Re: switching primers

Personally, I've never messed with the primers. I've worked up my loads with the OCW method, then worked on seating depths to tighten my groups. Supposedly you get the same effect (changing the timing of the bullet leaving the barrel) by using a faster or slower primers, but I've never heard of anyone actually doing that. Seating depth is far easier to control and fine-tune assuming no constraints such as magazine dimensions.
 
#19
Re: switching primers

Yes, BB, you got it straight...sort of. I didn't really select a primer at random; I selected Remington because they are the only primers on the shelf at my local store. I started working on the load and was stopping by a friend's house on the way home from the range to share my results and ask some questions of him. One day, he just handed me a box of CCI BR-2 primers and said, "here, try these". This is how it all came about. I tried the primers with the load I was shooting and I thought the results were interesting since, on that particular day, the rounds fired with the CCI primers gave me far better results than the Remington primers....thus this thread was started. However, I do realize that these two 5 shot groups, on a single day, can't possibly be very meaningful and that there could be any number of other reasons for the differences. Haven't tried it again, but was curious to know if anyone thought the primers could have had a part in it. I know it all probably sounds pretty silly to you, but I'm quite new at reloading and am learning as I go, so just seeking advice and opinions. Thanks for all of the feedback.
 
#20
Re: switching primers

I do not consider it silly, at all. But, you are right. You can almost expect different results on different days due to obscure as well as obvious factors.

There has been some mention of larger sample size, which they call an aggregate over on the benchrest forums. Statistically, two separate groups don't tell you a heck of a lot, but you can see trends and cut the learning curve with a program such as the one mentioned, and about which I am still uninformed and ignorant. Hey, it could be a great method? But, it's not the only way to come up with acceptably accurate loads.

I will tell you one thing I am pretty sure of; premium barrels are consistently accurate and others can be very hard to understand what you are seeing, on paper. While there could be a specific combination of components that works well with your harmonics, etc. Finding it is like a needle in a haystack, whereas accurate barrels seem to have a lot of options and many accurate groups to choose from, which is when you have to get out the calipers rather than the ruler. Meaning, (unfortunately) there is no magical load or seating depth that will turn your crummy barrel into a one holer. BB
 
#21
Re: switching primers

Primers are not created all equal. The brisance of the primer can/will vary from manufacturer to manufacturer. The brisance determines how and to what extent the powder is ignited. While changing primers can change the pressure profile and pressure peak, if you are well below maximum, it is generally safe to do so. However, if you are within 5% of maximum, then the load should be worked up if any component is changed.
 
#22
Re: switching primers

I'm going to try to get to the range early in the morning and shoot these 20 rounds that I've loaded and will report back here anything of interest.

I think I understand what you're saying, BB, about a quality barrel being easier to find an accurate load with. However, I've got a feeling that I'm going to have some good results with mine even though it isn't a high end barrel. So far, I've been pleased with what its been able to do.

It is a completely stock CZ550 Varmint rifle with a hammer forged heavy barrel in .308. On a good day, I have been able to get some pretty tight groups, with several going through the same hole. This is with an inexpensive fixed power 6x scope at 100 yards.

I'm currently within a few days of ordering a much better scope for this rifle. After looking at some of my groups, I have thought that I probably can't possibly get any tighter than that with the optics I have. I have excellent eyesight and shooting form, but that scope simply doesn't allow me to see my aimpoint with enough precision to know that I'm aiming at exactly the same spot each time. I think that being off by a quarter inch or so could be the result of not being able to see any better than that through this scope.

I'm learning a lot by reading through posts on this forum and I intend to keep working on it until I can put them all through the same hole. I appreciate all of the good feedback I get from you guys.
 
#23
Re: switching primers

The target you use can work against you. With some scopes, instead of trying to aim at the center of a round dot, it is a lot more precise to lay your crosshairs exactly into a corner of a square. Align so that you eliminate all daylight on the side and bottom edge, for instance, and you are aiming at the exact same place every time. I like it a lot more than attempting to judge exactly when you are bisecting a circle, unless you are using a dot reticle. BB
 
#24
Re: switching primers

OK, I just got home from the range and I'm not sure quite what to think about my results. It certainly wasn't what I expected as my "pet loads" did not perform so well. Of course, I did use only CCI primers this time and have been using Remington primers in the past. However, the 45.2gr of Varget with CCI primer that performed so well for me last time, did not live up to expectations today.

First thing that went wrong was that my local store was out of the targets that I've been using, so I had to get a completely different type of target this morning. Then, when at the range, I noticed that I was experiencing what must have been parallax because as I would move my eye position, the red dot on the bullseye would move around within it's circle...quite irritating!

I set up four targets at 100 yards, one for each of my loads and shot at them in round robin fashion, one shot into each before moving to the next target. I cleaned the barrel beforehand and fired one fouling shot before getting started. I fired 5 rounds of each load. I allowed the barrel to cool for a couple of minutes between each shot.

All four loads impacted the same general area of the target, a little high and to the left of my point of aim. In fact, I can stack the four targets on top of each other and see daylight through them.

Surprisingly to me, the 44.8gr load performed the best, creating one jagged hole measuring .675 inches at it's widest point. All three of the other loads, 45.0, 45.2 and 45.4 performed similarly to each other, all creating groups about 1.3 inches at their widest point. That surprised me because I've done much better with these same loads in the past using Remington primers and with CCI primers on the 45.2gr load.

Despite the problem with parallax, I feel like this was a pretty fair assessment as I did my best to maintain consistent form on every shot.

Another variable that I haven't mentioned yet is that this was brand new, never fired Lapua brass that I full length sized before loading. I think that I will now neck size them and load these same loads and perform the same exact test again.

Any suggestions on something I should be doing differently, other than purchasing new glass?

note to BB: I have been using Leupold 100 yard targets with the squares, but they weren't available today. Instead, I got round targets with red-dot centers this time. I do like your suggestion to line up with the edges of a square though. I've been shooting between the 4 squares, but will try your suggestion soon.
 
#27
Re: switching primers

I'm guessing parallax may be your enemy now. Bad optics can really screw with load development.

If you don't have a focus adjustment on your scope, you really need to get a new scope. If you do have a focus adj., don't trust any numbers on it. Forget they are there and just adjust until there is no apparent movement between your reticle and target picture when you move your eye side-to-side or up-and-down. If the focus is off when you get zero movement, you need to adjust the eyepiece.
 
#28
Re: switching primers

Yes, I'm seriously looking at a Vortex PST 6-24 with FFP. In fact, if it wasn't the weekend, I would be making some phone calls to check on availability to place an order. I'm almost certain that I'll have one ordered sometime Monday. I'm using an old Springfield Armory Gov model 6x40 right now. Its ok, but it always leaves me wishing for more and feeling like its a handicap. I have to have better glass asap! I think a better scope will be an enormous help in getting my groups to tighten up.
 
#30
Re: switching primers

I realize this may not be "tactical" enough on this board, but. The Zeiss Conquest scopes have just terrific optics, for the money. I have a 4.5X14X44 on a 243 set up for prairie dogs and it's about the best $700/800 scope on the market, in my opinion. To get a <span style="text-decoration: underline"> little </span> better, you have to pay a <span style="text-decoration: underline">lot</span> more. BB
 
#31
Re: switching primers

Thanks for the recommendation BB, but I've about driven myself nuts reading reviews and specs on scopes for the past few weeks and I finally settled on the Vortex PST. It wasn't an easy decision and I went back and forth between several different models before I was able to make up my mind that I want to go with this one. I did consider the Zeiss Conquest at one point and I'm sure it is a great scope. However, there has been a sort of peace that has settled over me after making this decision and I just can't go back into that state of uncertainty again...the Vortex it is!
 
#32
Re: switching primers

Well, it "looks" bad ass, and it sure has a kool name, and I have never seen one, or know anything about them? I hope your peace continues. Fighting obvious parallax in a scope without the means to correct it other than shooting at the distance for which it is supposed to be parallax free, is very frustrating. BB

edit: the Leupold 40X benchrest will certainly help tighten groups. (just a thought)
 
#33
Re: switching primers

I've read lots of reviews and compared its specs to many other options I was considering and it seems to be just what I'm looking for at a reasonable price. Another consideration is that it seems to be a very popular scope, so if I end up not liking it for some reason, I'm pretty sure it would sell in a hurry. Now if I just knew for certain what rings to get for it. My CZ550 has very limited options for optics mounting, but I'm thinking I will try the high rings that Leupold makes for CZ. US Optics makes a 20moa rail for CZ, so that's another option I'm looking into. I guess that's what I get for shooting a rifle that's not very popular...not many people to ask for advice on it.
 
#34
Re: switching primers

CZ makes a very nice looking rifle but I have never owned one. I was thinking of one in 19/223Calhoon for a while, but drifted to other stuff. I like a blind magazine, dislike removable ones, especially those that stick out below the stock. It's a good thing we have choices and opinions. BB
 
#35
Re: switching primers

I really like my CZ a lot. In fact, I like it so much that I'm planning to get another one in .338 Lapua. CZ uses a single set trigger that I really like. The downside is that they have dovetails milled into the receiver and rings will only fit in one spot. I had to go with high rings with a 40mm scope because my bolt handle would scrape against the scope when I had medium rings. I know US Optics makes a rail for it, so might see how that works.
 
#36
Re: switching primers

I know this thread kinda got off track from the originsl subject of switching primers, but I just thought I'd check in in let you guys know that I got that Vortex PST ffp 6-24 ordered today and it is on its way. Tracking says I should have it next Monday. Not sure how soon I'll get to go test it out, but will definitely check back in here with results once I've tried it at the range. My plan is to shoot those same loads with the new scope and see what happens.
 
#37
Re: switching primers

A good scope can make a huge difference. Switching back to primers, I have found that the BR-2's are not quite as "hot" as the Win LR primers I use. Velocity is down a bit when using them side by side with the same powder charge.
 
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