The Primer Effect

[South Pender]

We all know that variations in powder, bullet, and even brass will be accompanied by differences in accuracy. But what about primers? I expect that the standard advice is to try several different primers in one's quest for accuracy, but can a change from, say, Federal 205Ms to CCI BR-4s (or Rem. 7½s) be expected to produce a difference in accuracy? Staying with the small rifle primers for a moment, are certain powders better ignited by one or another primer? And is there one front-runner among the small rifle primers for best accuracy with small-caliber cartridges?

 

[mikecr]

Changing primers, like anything else, is a change.
Something to work with.

 

[IdahoSharpshooter]

Friends tell me that there are two kinds of primers for serious accuracy work: Federal 205M, and everything else.

I had them on back order for two years, and finally got some.

 

[Sniper338]

Yes it can and it does change. Thats why you test primers... its obvious you probably havent shot a primer test before. Fo it for shits and giggles, same load, just change primers. Shoot out further than 100 yards too.

 

[Rsadams]

There is a flame test with pictures that shows the difference in primers on here somewhere.. Speaking of SR primers the use of magnum to light off ball powders seems to be the thing especially in .223 and the Speer reloading manual has some good info on the use of magnum primers in .223 that alot of other manuals don't..

The one major thing I have found with primers is in pistols like .38 spl some will not light off a round that's position sensitive... Like the use of S/B primers and win231... Simply changing to a Fed. Win. or CCI will light it no problem..The S/B won't and leave unburnt powder bad...

So as stated above I believe changing primers to me could make a difference. In the end its about fine tuneing a round.. Or maybe you run into problems like I have with CCI SR primers flattening for no other reason than being soft so I changed to the bench rest CCI with a thicker cup to stop it..

As far as being a front runner thats a loaded question becouse some like the Fed. Or CCI BR or even win. or remington.. Most will say stick with the Fed match primers or the CCI BR or even one of those two is clearly better but I think it's what ever shoots the best in your rifle or pistol... Testing is the key.

 

[ebb]

Yea, you might want to have a talk with your friends. I had been sold out on federal match primers and Tim North of Broughton barrels told me he had better luck with Winchester on big magnum cases. I tried it and he was right.

 

[243winxb]

http://www.shootingtimes.com/ammo/ammunition_st_mamotaip_200909/

 

[nicholst55]

Back in the late '80s or early '90s, American Rifleman ran an article about accuracy-testing primers. I think Ed Harrison wrote the article, but I'm old and have CRS. He was concentrating on the then relatively new AR-15 Service Rifle in .223. He devised a method of photographing the flame produced by a SR primer in a cutoff case head, and determined that the primer producing the smallest flame produced the best accuracy. At least, for his purposes at that time. Seems like he settled on Winchester primers, but like I said earlier, I'm old and have CRS. And, a lot has changed since that time. There are several different primers that weren't available at that time, and Winchester has changed the manufacture of their SR primer. The Winchester SR primer is generally not recommended for use in the AR-15 now due to a thinner cup.

 

[Mozella]

During some .223 load workup using CFE-223, which is a very fine ball powder, I had quite a few "pop-bang" type hang fires. In other words, I could hear the primer go off followed immediately by the main charge, but with enough delay to hear it. I was using CCI BR-4 primers and they were working fine with several short stick powders, but not so well with the CFE-223. The hang fire rounds produced a significant change in POI.

I changed to the CCI 450 "Magnum" primers because of the increased brisance and that solved the problem. Now my CFE-223 loads go off normally and produce good precision.

Other than situation, I'll have to say I haven't noticed an accuracy advantage between several of the well known quality primers. I HAVE noticed less than reliable results using some of the lower grade primers, specifically CCI 400 I use BR-4, Federal Premium Gold Medal Match (when available), and CCI 450's. The important part, for me, is to have a primer which produces reliable and consistent ignition.

Having said that, I would not change a primer type without doing a mini load work up because while I think there are several good choices, it is obvious that they aren't all identical.

 

[Shaggy357]

Primers are like powders in that they have different burn rates, and you likely have your favorites. Like mashed potatoes and gravy, fried potatoes and catsup, and boiled taters with mayo for salad, some powders go together a little better with certain primers. A buddy and I purchased DW revolvers on the same day. They are one serial number different. We split an order of brass and powder, then went together to order a bullet mold. We each worked up a load as time allowed and found what worked best in our gun. He offered to set up his chronograph one weekend and we were going to see how well our loads were doing. I was using Rem 7 1/2 primers with AA1680. He was using WSR primers with AA1680. Loads came out within 100 fps of each other. Same gun, same brass, same powder, same bullet.....but his load with WSR primer had 2.0 grains more powder than my load with Rem 7 1/2.

I have a different silhouette gun that would shoot inch groups all day. Was shooting with a different friend who was asking about the load due to flames coming out the end of the barrel. When we really got into the conversation, he asked how dirty the barrel got. We started talking components, load specifics, etc. He told me my powder and bullet were part way down the barrel before the complete ignition. That was powder coming down the barrel causing all the flames. He asked if I tried different primers. No. He suggest I try. Same load, just cooler primer. Took that gun from shooting inch groups to half inch groups, and from 2 foot of flames to negligible flames by using a cooler primer that ignited the powder better.

If you look in my primer vault, you will see WSR, Rem 7 1/2, Rem 6 1/2, CCI 400, CCI 450, Federal 205, and Federal 205Ms. These are just the small rifle primers. Each fills a niche in the quest to create the best load for each gun. My most used are WSR and Rem 7 1/2. I buy them by the sleeve. The others, by the box of 1000. Will most work in about anything? Yes. Is one best for every application? NO. Every one of them can take a load from MILD to WILD if you do not work up to your load safely. Read your loading manual. They list the primer used in their testing for a reason. Switch the primer and you HAVE to work up to your safe load.

What's on your taters?

 

[butchlambert]

I like Winchester best. Found them to be good during a previous shortage of 205 primers. I have about 5,000 205M in reserve if I get short on the Winchesters. Now my Winchesters are probably at least 20yrs old.

 

[Laurie]

I like Winchester best. ..... Now my Winchesters are probably at least 20yrs old.

These older ('silver' colour) are as I understand it, rated much higher by many than the current production (brass colour) model for both performance and cup strength.

 

[T-shooter]

Primers may make a slight difference unless it's a magnum primer. There are so may other things to be concerned with, I would put primers near the bottom of the list. I've had good luck with Federal Match primers and just stick with them.

Back in the late '80s or early '90s, American Rifleman ran an article about accuracy-testing primers. I think Ed Harrison wrote the article, but I'm old and have CRS. He was concentrating on the then relatively new AR-15 Service Rifle in .223. He devised a method of photographing the flame produced by a SR primer in a cutoff case head, and determined that the primer producing the smallest flame produced the best accuracy. At least, for his purposes at that time. Seems like he settled on Winchester primers, but like I said earlier, I'm old and have CRS. And, a lot has changed since that time. There are several different primers that weren't available at that time, and Winchester has changed the manufacture of their SR primer. The Winchester SR primer is generally not recommended for use in the AR-15 now due to a thinner cup.

Yes, you may have to be concerned with an AR-15. The firing pin is free floating and contacts the primer when you chamber a round. Here is a test with Federal primers. I chambered a few rounds letting the bolt slam as you normally would. I now use a titanium firing pin for an added measure of safety. It makes much less of an indentation compared to the stock steel pin. Rechambering the same round 5 times increased the size of the dent. Don't know if one could ever go off if somehow the same round was chambered and then taken out not fired and reused later. If the Winchester has a thinner cup, it may be possible.

 

[Laurie]

Yes, you may have to be concerned with an AR-15. The firing pin is free floating and contacts the primer when you chamber a round. Here is a test with Federal primers. I chambered a few rounds letting the bolt slam as you normally would. I now use a titanium firing pin for an added measure of safety. It makes much less of an indentation compared to the stock steel pin. Rechambering the same round 5 times increased the size of the dent. Don't know if one could ever go off if somehow the same round was chambered and then taken out not fired and reused later. If the Winchester has a thinner cup, it may be possible.

It can happen, at least with the very early M16. Many years back a retired British Army ordnance officer wrote a series of illustrated articles about his experiences of investigating firearms and ammunition blow-ups in the long defunct British 'Guns Review' magazine.

One case he investigated was somewhere in the far east where British soldiers patrolling an area for insurgents were issued with US M16s on a trial basis. On leaving camp one day, an experienced non-com had an inexplicable ND as he charged the weapon. This was found to be caused by chambering a round at the start of a patrol, unloading it at the end and replacing it in the magazine top position ... to have the same thing happen again and again on subsequent outings until finally there was a great enough indentation on chambering to cause the round to fire. The effect was replicated in controlled trials. After that an instruction was issued to ensure a fresh cartridge was always the first to be chambered and that the muzzle should be pointed at the ground on chambering it. I don't suppose this incident helped the Colt sales team much in trying to sell the rifle to the UK. (A later set of 'black marks for the M16A1 and its M193 55gn bullet ammunition was British Special Forces experience with them in the early 1980s Falklands war where several well aimed shots produced hits with minimal wounding / stopping effects on Argentinian defenders.)

 

[Mozella]

This post got me thinking about primers and I needed to do some load confirmation with Berger VLD 90's with Varget powder in my .223 so I loaded up 40 identical rounds except half used CCI BR-4 primers and the other half CCI 450 Magnum primers. Previous experience has shown me that the magnum primers work better for igniting CFE-223 which is a very fine ball powder, but I had not actually tested these two types of primers in a head-to-head test.

I scanned the targets and measured them using On Target software. The average results of the 8 different five-shot groups were very close. The Magnum primers had a 2.4% smaller MOA while the BR-4's had a 5% advantage in Mean Radius (Average To Center), a 0.4% smaller group height (Vertical), and a 0.4% higher Muzzle Velocity. In other words, considering the small test sample, I'd have to say these primers offer essentially identical performance.

The largest average difference was in Standard Deviation where the Magnum primers had a 32% smaller SD; however, because so many factors can effect SD and since my SD's frequently vary more than I would wish for reasons I can't fully explain, I wouldn't put too much value on the apparent better SD exhibited by the Magnum primers. The next test could very well produce opposite results.

The smallest group was shot using the Magnum primer but the second smallest was shot with the BR-4.

It should be noted that the group-to-group variation (same primer) was greater than the difference of the averages of the two different primer types.

Bottom line: This test was made with very carefully prepared ammo, identical in every respect except for the primers. Although 40 rounds is not a large sample, I think if there were significant differences in performance, it would have been obvious. In fact, the average results were nearly identical and showed less difference than one would usually see from one group to the next. Of course, different ammo, especially using a different powder, might produce entirely different results.