Can changing primer lot change group size

[AussieWriter]

The answer is sometimes.
It can also change both the size and shape of the groups.

You need to shoot several groups and average out the results watching for a trend. A single group represents nothing.

 

[Mike Matteson]

Over the years I have had great luck with Fef-210 primers. It didn't make much differents in changes with loads and groups. All the reading about primers here has made me wonder about primers and maybe I was missing something. I have found that Fed-215 primers wasn't needed in powder loads about 75 gr. I don't really have a rifle that holds much more than 75grs anyway. I tried them in the pass and those 215 open up my groups, and velocity was about the same. Group sizes open up. At that time it was being done using a chronograph for velocity.
Presently I now have several different primer made by other manufacture or brand names. i will give them run in my reloading of case to see what if there anything different in the primers. I believe there is, and I'll do a lot more documenting this time going forward, plus recorder it.
Did you change powders during that time?

 

[AussieWriter]

Setting an arbitrary powder charge as your personal cut off point to switch from standard to magnum primers is common. Most of us do it and my cut off is "about" 70 grains.

I say "about" because when approaching that powder charge I load cartridges with both to see if the load is favoring one over the other and also to qualify the adequacy or otherwise of the std large rifle primer.

To reduce the cost of consumables you can also load with magnum primers when you hit 70ish grains and where you find best accuracy, qualify it with equal loads using the std primer.

Its all range time with determined interest in fine shooting, so there are no real losses from the practice.

 

[emp1953]

I have been developing a load for a 7RM using Norma brass, H4831, Nosler 150BT and CCI #34. I had a consistant velocity of 2974 with single diget ES and SD and group of 3/4 MOA. I ran out of the CCI #34 and opend a new brick of CCI #34 (differnt lot) and my group went to 1 1/2 MOA, velocity remained around the same (2985) but ES was 29 and SD 13.5.

I am fairly new to percission reloading, so I don't know if the different lot of primer caused this, or should I look for some other problme.

Help please.

I've seen POI/group changes when changing from brand to brand or from LR to LR magnum. Very little or no perceptible change in primer lot numbers. But then I got into exclusively using CCI #200. I guess my skills at the range were never precise enough for me to see differences from lot to lot. I would suspect that something else "additional" also contributed to the change you see. What was the sample size that gave you the 3/4MOA and the sample size that gave you the 1 1/2MOA. I was always able to buy my primers in cases of 5000 so I usually got same lot numbers.

 

[Mike Matteson]

I've seen POI/group changes when changing from brand to brand or from LR to LR magnum. Very little or no perceptible change in primer lot numbers. But then I got into exclusively using CCI #200. I guess my skills at the range were never precise enough for me to see differences from lot to lot. I would suspect that something else "additional" also contributed to the change you see. What was the sample size that gave you the 3/4MOA and the sample size that gave you the 1 1/2MOA. I was always able to buy my primers in cases of 5000 so I usually got same lot numbers.

That works, if you can get them in 5000 lots. Remember you can only store 10000 primers in your reloading area. In a car you can have as many as you want. ATF rules. Don't ask me why. Especially now with it being almost impossible to get LRP in more than single brick at one time. Just getting getting one brick in different primers can take up the 10,000 prmers in just LRP, now get into Shotgun, and SRP, and Pistol primers.
"STUPID IS, STUPID DOES" ATF

 

[emp1953]

That works, if you can get them in 5000 lots. Remember you can only store 10000 primers in your reloading area. In a car you can have as many as you want. ATF rules. Don't ask me why. Especially now with it being almost impossible to get LRP in more than single brick at one time. Just getting getting one brick in different primers can take up the 10,000 prmers in just LRP, now get into Shotgun, and SRP, and Pistol primers.
"STUPID IS, STUPID DOES" ATF

Right, as if supply challenges aren't enough to deal with. Coloring within the ATF guidelines adds to the complexity. I got lucky recently while on a trip to a relative in Central Pennsylvania. An LGS up there had Remington 9 1/2's on the shelf at $74 per brick, 5 brick limit. I got my five, should last me for as long as I need primers. All my original loadings were with CCI200's. My new loads with the Remington s shoot to a different POI, 1" lower. Since I zero at 2" high at 100yds I'm completely happy with the results. I'll take luck every time.

 

[cajun]

So how many rounds had you fired with the other primers and that load? Any time you change lot numbers you may see some difference but that is a lot.

 

[buckbrush]

How many shots generated the data pre and post primer change?

 

[emp1953]

So how many rounds had you fired with the other primers and that load? Any time you change lot numbers you may see some difference but that is a lot.

If you are questioning me, the original CCI200 load consisted probably of 240 rounds. The load with the Remington primers stands currently at 90.

 

[Mike Matteson]

TAG

 

[Pdyson]

There are many factors that make a rifle fall out of tune but I've never seen a giant swing like that, not even between brands. In my experience bad primers have more severe indicators like hang fire. It's definitely worth it to try a different brand or lot# and see.

 

[Rflshootr]

Re-chrono the load. If it is the same, look elsewhere. If lower, bump the powder up, if higher drop the powder down.

 

[cajun]

If you are questioning me, the original CCI200 load consisted probably of 240 rounds. The load with the Remington primers stands currently at 90.

The question was for the OP.

 

[Frank in the Laurels]

...since everything in reloading is a variable the answer is yes, but in a hunting big game rifle I don't think enough to make a huge change in the impact area. With a target vital area at least the size of a volleyball up to a beachball a primer change would never account for that big of a change...now benchrest or competition shooting at a distance you might have a concern because of the size of the score area..but those shooting at that level would make sure they had enough of each charitable before starting.