Primers do degrade

[rep308]

I loaded up at test batch of 21.5 gns of H110 with a 270 gn speer gold dot .44 mag using 15 year old Winchester Large Primers. My last load of these 10 years ago averaged 1620 fps using the same components, but this batch averaged only 1550.

The powder was new, it was the primers that were 15 years old. I'm figuring that they must have lost some of their zing over time. I'm off to get a new sleeve this week and will repost when I have results.

(I did check the chrony with other loads and it is fine)

 

[EddieCoyle]

It could also be that the powder formulation has changed in 10 years.

 

[Rob Boudrie]

It's tough to limit changes to one variable over a decade - are you sure the bullets where the identical hardness, thickness of jacket, etc? Did you leave the test gun unfired for a decade so you wouldn't have 10 years of barrel wear (which typically results in loss of velocity). Your upcoming comparison of loads from the same batch that vary only in new vs. old primers will be interesting, but still not enough to conclusively conclude that it was age that did it.

 

[EddieCoyle]

From Hodgdon's site (note the velocity of 1421fps:

This is the latest data, I'd be interested to see their data from 10 years ago.

 

[rep308]

More Details:

The firearm in question is a Ruger .44 mag Deerfield rifle with a 16" barrel, which I bought for Deer hunting. I sighted in the gun with Remmington Core Loc 275 gns which chrony out at about 1530 fps. I then started to reload as the Core Loc was hard to find and I could get a little more zip out of handloads. I settled on Speer 270 gn jacketed soft point, bought 200 of them and 500 pieces of Starline brass. Ten years ago I worked up a load with 21.5 gns of H110 and used Winchester Large Primers. This got me about 1610 FPS with a real tight velocity grouping in a 5 shot group. I loaded up about 75 rounds. The velocity was consistent with the Speer reloading guide for rifles.

I'd fire 5 or so rounds to check the point of aim prior to season and maybe a couple of rounds before going out in the field. Some years I went out, some I didn't and the 75 rounds lasted me to today.

I loaded up 10 rounds yesterday using the same bullets, same new brass, same, now 15 year old Winchester Large Primers that I used before. I used the same Dillon 550 with the same dies and settings.

I used a new can of H110 and fired out of the same Ruger Deerfield that has about 100 total rounds through it. The 10 shot string ranged from 1535 to 1578 with an average of about 1560 fps. (It was about 1220 out of my 6" 629). The Remmington Cor Loct that I had left over went out at 1540 so I do not think the problem is my trusty of Shooting Chrony. I also checked the powder level very carefully during the reloading process

The only variables that have change is a new can of H110 and the primers were 5 years old the first time and 15 years old the second. That is why I'm thinking the primers are the cause of the 50 fps drop and increase in velocity spread. I will buy a new sleeve of primers and get back to the range next week.

Thanks for any insight, you guys have got me back into reloading

 

[rep308]

I finally found some new Winchester Large Primers. Here is the data comparing the 15 year old primers and the brand new primers. The new primer results is similar to my 10 year old data when the now 15 year old primers were 5 years old. The primers were stored in my dehumidified basement

Results:

Firearm: Ruger Deerfield .44 mag 18" barrel
Shooting Star Brass, 270 gn Speer semi jacketed soft point
21.5 gns H110 (same powder batch for both groups)
shooting chrony in FPS

15 year old WLP primers:
1584,1578,1548,1576,1555, 1535,1533. 1566 - 1559 AVE, 51 spread - std dev 19.7

New WLP Primers:
1608,1591,1608,1612,1609,1587,1617 1604 AVE, 30 spread -std dev 11.1

I only had 3 rounds left of the 10 year old ammo that I loaded with the old primers and they were in at 1600 fps, I didn't write down the exact results. I now believe that the bare primers degraded while the loaded ammo did not change over 10 years. I'm going to load up another 250 round, which will be another 10 year supply for my deer hunting rifle, I only wish more rounds were actually aimed at deer!

 

[BIG GUN]

The difference in velocity is of no concern unless you are shooting benchrest. The variation could be caused by the primer mix in the last batch.
Powder burn rates vary with every batch. That is why you are supposed to drop amounts by 10% and work back up, every time you use a new lot.

 

[rep308]

The difference in velocity is of no concern unless you are shooting benchrest. The variation could be caused by the primer mix in the last batch.
Powder burn rates vary with every batch. That is why you are supposed to drop amounts by 10% and work back up, every time you use a new lot.

The velocity of the loads with the same batch of primers went down by 50 fps between loads done 10 years ago and this summer. Moreover the standard deviation of the loads doubled. Would the primers still make a bullet go bang, yes, but primers change over time

 

[Scrivener]

How were the primers stored?

I take mine out of the cases and put them in surplus ammo cans as the cans becom available.

 

[doobie]

Experiment: take the rounds from 10 years ago, pop the bullet, pour out the powder. Reload the round with new powder and a new bullet.

 

[BIG GUN]

The velocity of the loads with the same batch of primers went down by 50 fps between loads done 10 years ago and this summer. Moreover the standard deviation of the loads doubled. Would the primers still make a bullet go bang, yes, but primers change over time

The question is how badly did the change in velocity impact accuracy? For the average shooter it is a moot point.
I went to the range today and fired my Ruger #1 in 300 Win. Mag @ 300 yds. with ammo I loaded in 1988 using old CCI mag primers I bought back in the late 70's when a shop in Bedford was going out of business. I got a 1.47" group, I should worry about degradeing?