Primer difference

C

cdoc42

New member
Over the years I have read about differences in accuracy results with a primer change, but I always used CCI primers with satisfactory results so I had little interest in this topic. But when primers were in short supply I switched to Federal because I could buy some.

Recently I started an experiment with my 7mm Rem Mag. I always used Remington cases but several years ago I bought 500 Winchester cases and I arrived at the time when my Remington inventory was wearing out and it was time to switch. Would I have the same accuracy with Winchester cases?

It turned the answer was no. I was always under the impression that Winchester cases were more thick, giving less powder capacity, so I resized a Remington and Winchester case, replaced the dead primers,weighed them, filled them to a meniscus with water and weighed again. Then seated a Hornady 162 gr bullet in each (weighed) and all calculations revealed the displacement was 77 gr of water and the cases had the same internal
water /powder capacity.

I loaded 10 rounds in Winchester cases with the Hornady bullet and the same powder charge of H4831, and 10 more of each with H1000. The only difference between these was the primer. 5 in each powder with CCI250 and 5 in each powder with Fed 215.

Off to the range:

Results:

Win case, CCI 250, H4831 = 4 shot group 0966" with one flyer
Win Case, Fed 215, H4831 = 4 shot group 0.966" with one flyer

Win case, CCI 250, H1000 = 5 shots that spread over 2-3 inches
Win case, Fed215, H1000 = 3 shots, 0.6535"; 4 shots 1.091" with one flyer

So: with H4831, no difference with the primer

With H1000, big difference; but is the primer or the powder?
 
I would vote that the difference is in the powder.

Have had simular with Alliant and their RL25 and RL26.
The RL26 gives much better accuracy.
 
cdoc42 wrote:
The only difference between these was the primer.
...
With H1000, big difference; but is the primer or the powder?
Click to expand...

What did you do at the range to eliminate the shooter as a variable?
 
hdwhit, that is always a variable that enters the equation, for sure. But I use a sled-type rifle rest, being certain that it is in exactly the same position relative to the previous shots, and my home-made targets have 1/4-inch black vertical and horizontal lines surrounding the bull which is a 3/4 inch blaze orange dot, such that my crosshairs fit between the black lines and I can still see a small line of white between the vertical and horizontal lines if I hold it properly. I take a breath and slowly let the air out as I concentrate on the target so that as I end my expiration the trigger pressure is suffcient to fire the round. I fie three, change to the next rifle, fire three, etc, so that each rifle cools before firing again. If I'm still going to shoot after 20 rounds, I pass a wet swab of KG-1 through the bore just to remove excess carbon, then a swab of evaporating "scrub" cleaner to remove KG-1,then light oil, then dry it out with several swabs, and start shooting again, expecting the first shot may not count and just foul the bore (unless it is clearly where I expected it to be).
 
std7mag, why would you vote the powder? The cases, powder charge and bullets are the same - the only variable is the primers. Was that the same situation when you shot RL 25 and 26 - cases, primers and bullets were the same - just the powders differed?
 
The difference may be in the 'flyer' versus 'no flyer' that you identified.

All the groups but the worst one had flyers but the worst group with 'no flyers' probably had several flyers but in different directions.

With the data given, I would not begin to make any conclusions until I identified if the flyers were caused by the powder-bullet-primer combinations or the 'nut behind the trigger'.

In my experience, I always suspect 'the nut behind the trigger', namely me, until I can shoot groups that don't have flyers. And then, I don't make any conclusions until I shoot at least 10, and preferably 20 groups, to get a valid statistical sample. It the standard deviation in the group sizes is high, then 'the nut behind the trigger' still had too much influence.

To start with, you are shooting a high caliber round that has significant recoil. That kind of recoil forces the shooter to completely reset his position before he can be sure that it hasn't adjusted. If you don't, there is a very high probability that you have adjusted your set up position and if you do it only once during a group, you will probably see a 'flyer'.

There are too many variations that a shooter can introduce with set up, positioning, shoulder position, and trigger pull to cause groups sizes to grow that make it almost impossible to try and identify the variations caused by a primer or even a few tenths of a grain of powder. You also didn't say whether your case trim length and OAL were measured for each round and found to be +/- 0.001 or that the powder measures were within 0.1 grains. That is the kind of accuracy you would need to make conclusions about the variations caused by the slight difference caused by a change in primers.

Over the last two weeks, I have tried 3 different primers with my 6.5 mm Creedmoor (Federal 205M, CCI 400 and CCI BR-4) at 100 yards. The results were measured over 14 different loads with 6 groups per sample load. The 14 loads averaged 0.245 and two of the primers tested each had an exceptional load just under 0.2 inches.
CCI 400 primers averaged 0.224 with a best load of 0.152 and a worst load of 0.261.
CCI BR-4 primers averaged 0.222 with a best load of 0.193 with a worst load of 0.269.
Federal 205M averaged 0.293 with a best load of 0.251 and a worst load of 0.342.
That is a pretty big range to claim consistency even with group sizes that were small.

It would seem that the Federal 205M primers were not as good, but those groups were shot on a day with from 5-7 mph winds and the other two primers were shot in calm winds under 3 mph with no gusts.
The 205M primers were shot after a 2 week layoff caused by illness.
The 205M primers were shot with 4 different bullets with N150 powder.
The CCI BR-4 primers were shot with the same bullets and varying powder charges using IMR4350 powder.
The CCI 400 primers were shot using 3 different bullets also using IMR 4350 powder. One load, the best load, was shot at a significantly slower velocity and lower pressure.

The question to be answered is - was it the powder, the primer, the wind, or the 'nut behind the trigger' that caused the differences. Clue: The IMR 4350 powder has shown the best results over a variety of bullets and might be the main difference but the wind and the 'nut behind the trigger' probably had some influence..

Two years ago, I tested large rifle and large rifle magnum primers in my .30-06 to determine whether the magnum primers might produce better results in extreme cold. At 30 degrees, the magnum primers added only 12 fps to the muzzle velocity using a chronograph.

Using different manufacturers of primers (small rifle or large rifle) might cause a difference of up to 10 fps but probably much less. That is within the range of error that you might find in 20 rounds loaded to exacting loading standards. Most factory ammos won't provide that kind of consistency.
 
I shoot 308 cal bench rest only , 30 rounds per range trip , the two primers brands are CCI and Federal both are bench rest. Everything is exact except the primers 15 of each . I found no difference , both shoot the same .5 at 200 yards , 6 five shot groups.
 
"...7mm Rem Mag..." You do not need magnum primers for magnum named cartridges. Magnum primers are about the powder used and nothing else. Neither H4831 or H1000 require a magnum primer.
"...the primer or the powder?..." Only difference being the primer, it's the primer. However, the 1000 uses a bit more powder, roughly 5 grains, to produce just 92 FPS more velocity with 400 CUP more pressure.
And you're still getting more consistent and smaller groups with the 4831.
 
Win case, CCI 250, H4831 = 4 shot group 0966" with one flyer
Win Case, Fed 215, H4831 = 4 shot group 0.966" with one flyer

Win case, CCI 250, H1000 = 5 shots that spread over 2-3 inches
Win case, Fed215, H1000 = 3 shots, 0.6535"; 4 shots 1.091" with one flyer
Click to expand...
Do the groups "with one flyer" include the flyer in the group size or are they best 4 out of 5 shots? If the latter, how do the 5 shot groups compare with the over 2-3 inches group? And was that group over 2 inches or over 3 inches?
So: with H4831, no difference with the primer

With H1000, big difference; but is the primer or the powder?
Click to expand...
The first 2 groups' results would indicate that the second 2 groups' spread was not due to powder nor primer, considering the big spread between 3 and 4 shots in the last group. But you seem to have answered your own question in post #5, so maybe it's a moot point.
 
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cdoc42
I also use KG - 1 to clean the carbon but I never use oil in the barrel only if I wasn't shooting for months , then a light coat of Ballistol. I clean with KG - 1 dry patch , then Hoppe's # 9 bore solvent , let soak in the barrel for 15 minutes then tight dry patches to remove even more carbon , then I'm ready to shoot with no flyers, oil will cause flyers even when dry patched. Stop with the oil ,only when finished shooting for the season oil. Wash it out with Hoppe's then dry patch , you will group from the first shot. Give it a try.
 
Thanks, cw308, I will certainly try that.

Higgite, the group of 4 measures as listed; the flyer is the 5th shot outside that group in each case.

The 2-3 inch "group" I did not measure as a circle. There were 5 shots dispersed such that the longest distance between two of them was 3 inches, and the next longest was 2 inches. Lousy group in any case.
 
It would be interesting to superimpose the groups shot with like components, including flyers, by aligning their points of aim and see if there is a significant difference in group size between the two 10 shot groups. Comparing 10 shot groups, flyers and all, would be more statistically significant than comparing 3 and 4 shot groups which ignore flyers. One of the “good” shots could have been just as big of an accident as one of the flyers.
 
I happened to come across a series in Precision Shooting Magazine from late 1993 to early 1994 that discussed all areas that affect accuracy. It was quite detailed and I ended up with the impression that, despite all efforts, any small groups that are obtained are just as likely to have fallen to chance as to skill of the shooter. But I will not fail to continue...even a blind chicken finds corn.
 
As long as you can tell a flyer from a screw up . If everything goes right your on target light or no wind good trigger press an your shot goes 2" out of a tight group, mark that case , see if the flyer followed the case . May be a easy fix. Dump it.
 
Thanks for another good piece of advice. BTW, I just cleaned 3 rifles this evening, planning to test some rounds tomorrow. I skipped the oil.
 
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