Choosing a primer

[COLT45SA]

If I were to load a number of rounds with small rifle primers and an equal number with small BR rifle primers, should I expect to see a significant difference in accuracy~?

 

[No manches"]

The difference will be on SD's, not in accuracy".

 

[Shooter13]

Ther are many that know a lot more about this than me but my answer would be no. You said significant, you would see possibly some (if you are using BR primers, using standard there might be more of a difference

 

[cem]

Define significant. Define number. Statistically distinguishable? Big enough to matter in game fields? How good a shot are you? Do you routinely use wind flags when load testing? How many shots for each test group?

Shooting in a warehouse in Texas will make it easier to see real differences.

Any two populations are very likely to differ. It is very unlikely even for two populations that are in fact the same to sample exactly the same in two different samples. The same population fired different days may well differ. Differences that might be attributed to any one factor can easily be lost in the noise even when real. Larger sample sizes will typically give larger groups than smaller sample sizes - ten shot groups will be larger than three shot groups.

Fired successive days I'd expect differences. Unless the groups are consistently very small - true bug holes - I'd expect distinguishing the effect of primers from other influences will be difficult.

My own belief is that there are real differences and the BR from CCI or Gold Medal Match contribute to uniformity. I'm not interested in the field to go to the effort to make the statistically significant differences significant (matter) to me.

 

[JFrank]

At short range maybe not so much but as distance increases the differences become more obvious.

 

[762willdo]

If I were to load a number of rounds with small rifle primers and an equal number with small BR rifle primers, should I expect to see a significant difference in accuracy~?

I can tell you that I went from cci450 to br2 in a dasher and had a noticeable increase in accuracy, but that’s just me…….

 

[NZ_Fclass]

I went to every local gun shop and bought 1 box of every primer in stock to test the accuracy and SD of my BR loads.

I have 1 packet of RWS SR primers.

 

[Laurie]

The difference will be on SD's, not in accuracy".

Try it - you might (in fact, I'd predict will be) surprised as to how much difference primer change makes to 100 yard group sizes. That is 'change' between any makes/types of primer as choosing a 'BR' version may not in itself make an improvement, possibly even the reverse.

Unfortunately, the OP doesn't quote a cartridge, or this may just be a blank sheet of paper theoretical exercise, but I've seen considerable differences in precision from custom or good factory rifles in most small cartridges using SR primers - 223 Rem, 6BR, 6.5 Grendel. Mentioning the Grendel, Bill Alexander gives the advice that once a reasonably functioning load combination is achieved, then try every primer you can lay hands on as the Grendel is (in his words) very sensitive to primer choice. I'd widen that to all such cartridges using 22-28gn powder charges.

 

[6bra1k]

If I were to load a number of rounds with small rifle primers and an equal number with small BR rifle primers, should I expect to see a significant difference in accuracy~?

not if shot in a production rifle, maybe in a custom br rifle

 

[tom]

How I approach it, right or wrong...

I load powder ladders through a range of powder I know is working. Each ladder has a different primer. One ladder will usually stand out as "best", as it will group smaller off of peak tune. Sometimes a couple will look good at peak tune, and I go with the one that is grouping better coming and going.

Tom

 

[spudgun]

Last year I did a test of the primers I had on the shelf.

The load was for my 6.5 CM, and the brass, powder, bullet was the same for all the tests.
5 shots at 1000.

WINCHESTER
CCI 450 MAG
CCI 400
CCI #41
FED 205M

Sorry but my spread sheet won't format correctly.

My data showed 29 FPS difference at 1000 yds. Accuracy was 1.1 - 1.9 MOA.

 

[K22]

Maybe, maybe not. Any time you change components there is a chance that it may affect both precision and / or point of impact.

However, in my many years of reloading and shooting, the most influential factor I found was the bullet selected provided you are using a suitable powder for that cartridge. Second, I would say is the powder charge.

 

[257ack]

Most Group BR shooters (at one time) used Federal SR. The consensus was there was no difference between the match and SR. Billy Stevens shot his way into the hall of fame, sometimes using WSR. Of course, were talking small primers with a small flashole. Sometimes, I used Wolf primers (no longer avail.) and could not tell any difference. The real test is the tune and bullet seating is the most important part of tune.

 

[257ack]

The secretes of the Huston warehouse were not the Gospel. I have sat and talked to Don Graci, a few times about this. He said he did not fare as well in the warehouse as some of who shot there. but it was not real life conditions. He tuned at the match for conditions. BTW. Don is a hall of fame shooter and a darn good smith

 

[257ack]

and his wife a good cook

 

[Ned Ludd]

I've compared various small rifle primers (205s, BR4s, 450s) in head-to-head tests with the exact same load on a number of occasions. Sometimes, there appears to be little obvious difference between them. At other times, even different Lot#s of the exact same primer showed obvious differences in group size and/or velocity outputs. When you have the right primer for a given load, it shows. Exactly what characteristic(s) make one primer the best with a given load over another, I don't know with any certainty, but's it's likely a brisance thing.

I guess what I'm really trying to say is that I have no idea whatsoever how to precisely answer your question, or even if there is a "correct" answer. If there was some way to accurately predict in advance which primer would work best with a given cartridge/powder/bullet weight (other than a SWAG) without having to actually test several different primers, then everyone could just buy only the primer they know is best for their chosen components. Unfortunately, it doesn't work that way, so you have to test/compare primers to reach an informed conclusion.

 

[338 dude]

If I were to load a number of rounds with small rifle primers and an equal number with small BR rifle primers, should I expect to see a significant difference in accuracy~?

Probably not

 

[JPB4BAMA]

Try it - you might (in fact, I'd predict will be) surprised as to how much difference primer change makes to 100 yard group sizes. That is 'change' between any makes/types of primer as choosing a 'BR' version may not in itself make an improvement, possibly even the reverse.

Unfortunately, the OP doesn't quote a cartridge, or this may just be a blank sheet of paper theoretical exercise, but I've seen considerable differences in precision from custom or good factory rifles in most small cartridges using SR primers - 223 Rem, 6BR, 6.5 Grendel. Mentioning the Grendel, Bill Alexander gives the advice that once a reasonably functioning load combination is achieved, then try every primer you can lay hands on as the Grendel is (in his words) very sensitive to primer choice. I'd widen that to all such cartridges using 22-28gn powder charges.

Out of curiosity, why do you make this statement about cartridges in the 22 to 28 grain range? I'm sure there is a sound internal ballistics reason, just wondering what that might be. And on that note in your opinion would primer choice trump "extreme" precision in powder charge weight? I currently shoot a 223 AI and struggle to get my velocity SD's below the low to mid teens (this is with a regular RCBS chargemaster), but I can routinely print in the low 3's to mid 2's at 100 and keep it < 1 MOA at 600, often in the 3" -4" range. So I wonder if an investment in a better scale would benefit my choice of cartridge, or is this simply something inherent to that class of cartridge that I accept and go on enjoying what I can shoot with low component cost and consumption.

Thanks

 

[Laurie]

Out of curiosity, why do you make this statement about cartridges in the 22 to 28 grain range?

The key words are 'small cartridges'. It's a reflection of the size of powder charge that sees different primers produce different outcomes. It presumably affects other calibres too with small enough charges and cases, eg 30BR, but I've no experience here.

The other thing to note is that while a straight primer substitution may (usually does) affect short-distance precision that still doesn't in itself prove that one model is better or worse than another as subsequently refining the powder charge weight often compensates. The important issue is not to regard primers as interchangeable so far as precision goes, and ideally once a good load is worked up stick with that primer, better still the original primer production lot, if consistently producing small groups is the shooter's primary concern. (I have also on occasions found that a single primer model is head and shoulders above the rest of the pack with a good-performing bullet/powder combination in these small cartridges, and the obvious conclusion is to get hold of enough of that primer model to last the rifle's barrel out. I imagine that this effect is what Bill Alexander is referring to in his Grendel primer choice advice.)

ES/SD values are often affected too by primer substitution, but at short distances don't in themselves affect short-distance group size, or if there is a direct relationship it's one I've never encountered. In fact, there almost seems to be a perverse link in that the number of times the powder charge that gives the smallest group also gives the largest ES (or it produces small groups and ES values but at 150fps too low MV). In an ideal world, one wants the 'Goldilocks' combination that gives all things for longer distance shooting - high enough MVs, low SDs, and superb precision.

The 223, and I don't suppose the AI variant is any different, is a sod to get small spreads out of. There is at least one live thread running on the forum as to why this should be so. Look up @Ned Ludd 's posts on this as well as other issues of making 223 shoot well at long distances with heavy bullets. In my case, any ES below 20 fps is regarded as acceptable with this cartridge and that involves powder charge variations smaller than plus or minus 0.1gn. (As 0.1gn changes 223 MVs by typically 10-12 fps with 80gn and heavier bullets, sometimes more depending on powder, a 0.2gn charge weight range induces at least 20-25 fps ES before any other effects kick in as they do with any cartridge. Whether you need to have charge consistency down to the single powder kernel, ie ~0.02gn, depends on the combination of needed precision and distance involved - 1,000 yard F/TR shooting on targets with a MOA 10-ring and half-MOA X-ring is a very demanding application for the 223 even with 90/95gn bullets. 100 or 200 yards, even with out and out precision needed, much less so at least in this respect.

 

[JimPag]

If I were to load a number of rounds with small rifle primers and an equal number with small BR rifle primers, should I expect to see a significant difference in accuracy~s

When I bought all of Boyer's stuff there were cases of regular Federal 205's and not one 205M anywhere. He had a couple of bricks of BR4's but that's it.