Finally

[Tony Z]

someone has done a good proper test without any commercial agenda. Bids very well for CCI 450s and not much else in SRPs. I would have liked to see Rem 7 1/2s tried as i find them as good if not better than 450s.

http://alphamunitions.com/kaubers-corne ... e-primers/

[The Raven]

A great article, even for the unwashed like me.

I skipped a lot of the charts and numbers but the overall findings/conclusions make a lot of sense if you think of the basic physics of it all.

Alas I don't get to play with primer size choices...yet.

[Tony Z]

Then there is this. Sort of throws it all in the air again.

https://rifleshooter.com/2018/05/does-p ... mparisons/

[Tony Z]

Then to confuse it even more

https://rifleshooter.com/2018/07/does-p ... v-cci-400/

[The Raven]

Then there is this. Sort of throws it all in the air again.

https://rifleshooter.com/2018/05/does-p ... mparisons/

Just a quick skim of the tables appears to confirm (from the previous article) that smaller primers help accuracy. However, the MV contradicts larger=faster.

What is does show is that each rifle has it's own sweet spot. The challenge is discovering the exact combination that yields the sweet spot.

[Tony Z]

Of interest is the SDs Raven. A small SD never translated into flatter groups at ranges beyond 500 meters for me in any form of competition. Often the smallest groups had largest SDs. That was about the time i threw the chrono in the bin.
What i would have liked to see is the correlation between group size and SD. That is the one that tells the real story i think.
Either way, the data is interesting and in some instances contradictory.

When i get back from Narromine i am going to do 308 and 260 SR and LR in the HG. Testing with piles of crap like in the last two links is not testing. The human error in shooting groups needs removing because when i see those groups i see good groups destroyed by either spikes or poor technique. Also shooting groups at a 100 yards means jack shit. People buy these days to shoot well beyond that.

What was missing from the first link is the lead up to it. A shooter was using a 6.5 CM in 13 degrees F where they failed to fire or had severe hangfires. My experience with hangfires is one milli second away from shrapnel.

[Brad Y]

From experiences I have noted, the 260 improved versions (there are a few) can work with 2209 and CCI450’s and possibly rem 7.5’s (never tried them) as they appear to be the warmer SRP’s on the market. However some people I shoot with had problems and ended up going back to a larger primer and it helped them lose the odd weird fliers. They were of the opinion that their combination of action, barrel, powder and projectiles they were using at the time worked better with a stronger ignition. Certainly in the rifle I used at the time I could not get consistent results when I went to the slower 2213 using CCI450’s. Go back to 2209 and it would work again.

I’m a bit of a believer that the 308 size case is the upper limit a SRP can reliably spark off for both tight groups and high scores in LR benchrest or F class. And to go with that 2209 is about as slow as one can go in powder burn rate. Have seen some brilliant shoots with the faster BM8208 in 308 with 155’s and FGMM small primers.

JMHO

[dg]

g'day tony

thanks for Remington 7 1/2 memories.

I have been using original 2 anvil R 7 1/2 primers since the early 1970's for bush and range use.

since changing to the 6x 47 Lapua, 6mmBR and 6mmBR Imp for LRBR, CCI 450 and original R 7 1/2 are the only primers I trust.

Unfortunatley, the only batch of the new 3 anvil Rem 7 1/2's that I tried a few years ago in a 222 Improved, kept on leaking and pin holing on the edge of the cup at much less than maximum loads.

I still have approx. 4 boxes of the original 2 anvils, which are now only used for LRBR.



see you in a few weeks.

cheers
dave

[Camel]

G'day Dave, I use the new Rem 7 1/2 primers in all my rifles that take small primers, just noticed the bit about you having leaks, I was testing the 222 the other day, using 2207 R 7 1/2, Lap brass and 50gn Zmax I got just under 3500fps with them, think the powder charge was 22 gn, now this load is obviously way over book max, and I think just a tad hot for my rifle, I had to pluck the cases off the bolt face due to the primer going back around the firing pin and flowing into the hole, bolt lift and extraction was fine. Thing I am getting at is that none of the primers pierced nor were they excessively flattened with the edges still rounded.

I didn't know that they had changed the anvil in them, but then I dont take much notice of that stuff, I just keep using the same primer as they always seem to work well enough for my type shooting and are always available.

Accuracy wasn’t too bad either

[Tony Z]

Hi Dave Brad Mark. I too have a few thousand of the old 7 1/2s stashed. Plus a few others like the RWS Sinoxid. These as many would know were made specifically for the 5.6x50 RWS to ignite in 30 below zero chasing some deer that only the Euros would think a 22 cal was realistic for the task. They are the Hiroshima of small primers and like all things RWS built for strength.

The jury is still out for me on this small versus large rifle primer thing. There is no doubt that SRPs in larger cases have pockets that live longer and that in itself is appealing to me. It is the other stuff that has had me avoid the small primers in larger cases, right back to my first venture with a pair of 6x47 Laps quite a few years back.
Wherever you go on the interweb the stories are the same. Extraordinary claims in gains of low SDs and smaller groups etc. Then the other half say not so with poor consistency and errant flyers etc etc.
The errant flyer thing to 6.5s is nothing new and cannot in my opinion be attributed to SRPs alone. Another article i haven't linked claims SRPs in these larger cases makes them very temp sensitive aside and outside of other components like powders. This is exactly what i saw in my two failed attempts with a 6x47 at 1K. In the mornings it was different to what it was in the afternoon where we easily get a 15 to 20 degree C shift. Not good for group shooting. Fine for hitting steel plate and blood bags which is exactly where one of those barrels and cases are at now. It is quite apparent to me that DA numbers play here as they do with SR BR rifles with tuners on PPCs. Another area i have no patience for.

As i said, i will do a determined test in a few months of one verse the other. No interest in recording velocities, SDs or using chronographs of any sort as none of that leads to small groups, just worn out barrels. I will do accuracy specific development in my HG to determine which shoots the smaller aggregates in our local 600 yd IBS competition. No cherry picked one off fluke groups posted on forums.

[The Raven]

As someone who has ZERO experience with competition shooting and a relative newbie to reloading my logic is rather simple (and open to feedback from our local experts):

SRP means a smaller primer pocket, which means more brass in the head of the case and perhaps less ignition energy (compared to LRP). This may result in less stress on the brass and a slightly lower MV to LRP. As for accuracy, if the variance between same sized primers is (say) 1% of energy then SRPs should be relatively more consistent.

LRP suggests more ignition energy, into a larger primer pocket, which means less brass in the head. Hence, more ignition, perhaps slightly more MV and slightly more stress on the case head. As LRP is proportionally larger by volume than SRP then any variance (between LRP) would be much easier to detect.

As to which magic combination shoots better, however you want to measure it, that's dependent on too many factors (including the rifle, it's manufacture, and setup). Trial and error is probably the only way.

Perhaps overly simplistic...but if you consider theoretical extremes in primer size I think it'd bear out.

[Brad Y]

I enjoy discussions about this sort of stuff.

You won’t be the first person that I have heard from having trouble turning a 6x47 into a tight shooter. Those that did it wound them back to dasher speeds. A friend who used to run 243ai’s said more than once that he had no accuracy nodes above 3080 and below the high 3200’s with 105 class bullets in 8 twist barrels. Never did it myself.

With the 6.5x47 I had more luck and won a queens with 2208 and 130gr bullets.

I’m about to build an ftr rifle with 308 and 200gr bullets. Small rifle brass will be my first choice and will be going for cci450 first then br4’s with 2208. Bore dimensions ordered are .300/.308 and it has 5r rifling. Haven’t done much in the way of checking the action yet but I will be checking out firing pin fall and trying to time it to the trigger as best as possible (tikka action and trigger) from what I understand from discussions with Alex Wheeler it’s very important.

[Brad Y]

As someone who has ZERO experience with competition shooting and a relative newbie to reloading my logic is rather simple (and open to feedback from our local experts):

SRP means a smaller primer pocket, which means more brass in the head of the case and perhaps less ignition energy (compared to LRP). This may result in less stress on the brass and a slightly lower MV to LRP. As for accuracy, if the variance between same sized primers is (say) 1% of energy then SRPs should be relatively more consistent.

LRP suggests more ignition energy, into a larger primer pocket, which means less brass in the head. Hence, more ignition, perhaps slightly more MV and slightly more stress on the case head. As LRP is proportionally larger by volume than SRP then any variance (between LRP) would be much easier to detect.

As to which magic combination shoots better, however you want to measure it, that's dependent on too many factors (including the rifle, it's manufacture, and setup). Trial and error is probably the only way.

Perhaps overly simplistic...but if you consider theoretical extremes in primer size I think it'd bear out.

Raven your on the right track.
SRP small rifle primer
LRP large rifle primer

Yes larger primers have more mix so more ignition capability. The idea behind SRP brass especially in the 308 Palma situation as I believe was that smaller and gentler primers could still ignite the powder load and the smaller flash hole would improve ES/SD. If you ever get to measure the stats on 6br loads you will find it’s easy to get a load with small spread and deviation. But 6br is short and fat and by comparison the 6/6.5x47, creedmoor and 308 cases have a taller powder column. If you go to a 7mm RSAUM load it’s actually possible to get them to work very well without magnum primers. Powder choice is a key there. So back to say 308, it seems common a lot of shooters are using 2208 and cci450 magnum or in Tony’s case rem 7.5 primers as both have a bit more kick than regular or match primers. But I know of some getting away with gentler primers and still obtaining good ignition. A close friend has gone from 2208 which is the most common f class standard powder I would say, past 2206h which would be second in the list, to 8208. He is using federal gold medal primers, famous for use in the 6ppc which is a lot shorter and smaller case. He isn’t quite at the same velocity but accuracy is so consistent that losing 50-80fps isn’t bothering him one bit.

So many things come into play with it. Barrels, powder and primer and projectile lots, firing pin springs, brass uniformity, neck tension, seating depth, reamer design...

Tony is probably one of the best to discuss it with. I’m just an f classer and 1000yd benchrest shooter trying to learn from my experiences and don’t mind sharing what I have found and seen and been told.

[Tony Z]

Brad what i can tell you about magnum and standard small rifle primers came as a bit of a surprise late last year. It altered my perspective on magnum SRPs as i had specifically designed this case so that they were not necessary. I believed it would not be beneficial and would have a very distinct advantage by utilizing the FGMMs and BR 4s.

I chambered a slave barrel in the HG to gather load data on the 636 where it was used in 600 IBS matches with the idea that when i got around to fitting new barrels i could go directly to known data and short cut results and save barrel wear.

Midway through this development stage i did a multiple primer test at 600 yards during a match to see what group change and pressure effect may result. The exact load is not relevant but what is relevant and extremely important here is that all initial load development was done with non magnum primers, specifically CCI BR4s. I wanted a powder volume area first and primer and seating depth setting at a later stage. The CCI BR4s were hot but accuracy was very good so i stuck with it. The FGMMs were scary as pressure built the more shots were fired. All leaked badly. The bolt lift was heavy and brass had signs of stress and all were difficult to re-chamber. I distinctly recall telling Jeff H i might bail on the rest of the match because if the Federals did this, the remaining two primers may be catastrophic. The Rem 7 1/2s and CCI 450s with the exact same charge of Re15 had no pressure sign, tight groups and, wait for it, higher velocity. Bullet impact had climbed a minute at 600 yards. The 636 case can be loaded higher with magnum primers, show less case stress and have better results than other standard SRPs. Of course i could get great accuracy from the other primers, but at far lower powder volume and far less velocity.
For curiosity i took a 6 BR barrel and changed primers to see what results i would get there. Wood with FGMM was 30.8 grains of Re15 where bolt lift was just a little sticky. This is the exact load i had used over many matches at 1K in my old Diamondback and Krieger barrel i had sold a few years back. The working load in this barrel was slightly lower at 30.5 grains that resulted in some very tiny groups. Replace the FGMM with 450s and suddenly 31.7 grains became wood. 31.5 grains was a good working load for a velocity gain of over a minute at 300 yards and accuracy was at par.
The old story of magnum primers, back off a grain, is not relevant here. The hotter primers must alter the ignition in a way that contradicts previous learning through written verse from hundreds of articles and manuals.
A separate test i did was fire a CCI BR4 in a loaded 636 case with no powder. Then same with a 450. The BR4 flash was contained in the case. The bullet did not move. The 450 jammed the bullet well into the rifling and was difficult to remove. I think therein lies the reason for pressure drop. The chamber volume has increased immediately with the 450 and the bullet is moving with forward inertia. It may all be small but it seems it may be enough and appears beneficial. Very beneficial to the point i have changed my perception of what a magnum SRP actually does in smaller cases. I have just recently read about claims that a 450 has about the equivalent brisance as a standard LR primer. What that actual LRP was was not made clear but some believed it to be a 210. I think that is unlikely. A BR2? More likely.
The end result is that it will be highly unlikely i will deviate from magnum SRPs in smaller cases for LR rifles. In the 308 and 260 that remains to be seen but i do not expect it to be as clear cut. There actually may be an argument here to use 215s in both cases for more velocity gain.

[Brad Y]

Yes I think I got sucked in for the softest primers that should be nice and gentle and produce small groups. Powder likes to be lit. Mag primers do it. Even in the 284 I had probably my best barrel not perform for 500-600 rounds because I swore it would want br2’s. Change to fed golds and it came to life with a bit more velocity too.

I’m playing with my tikka 223 at the moment trying to get it semi competitive out of a factory barrel for ftr. Found the velocity I need, and two loads that have shown promise. Seating depth and primers when this horrible wind gives some chance for a testing day at 300.