Small primer benefits ?

[Hammer]

.

Most of the "accuracy" cartridges use small primers as opposed to large primers.

Some basic cases are available with both primer sizes.

Have y'all tested cartridges that are available with both small and large primers and concluded that the small primers are in fact a material improvement to accuracy ?

.

 

[tenring]

There was discussion on this a good while ago. Forget the details, but believe a test of the SR prlimers produced a more controlled flame.


Google German Salazar. He has written several good primer tests.

 

[varminthunter1]

Small primers and small flash holes as in the ppc (220 Russian) cases are a plus for accuracy. I would think the same would be true for other small capacity cases.

 

[Grimstod]

Very interesting. Would a magnum case suffer if it had a smaller primer?

 

[Laurie]

Very interesting. Would a magnum case suffer if it had a smaller primer?

Yes, it's generally agreed that .308 Win charge weights are about as large as the small primer / small flash-hole ignite reliably, ie up to just under 50gn. Lapua says that its 308 Win Palma brass shouldn't be used for hunting - a temperature issue mainly as many powders are harder to ignite reliably if they're very cold.

It's not just the primer, but the smaller flash-hole too (1.5mm v 2.0mm) as it affects the primer flame and how it penetrates the powder charge.

The rationale is that large primers are over-powerful for smaller cartridges and greater consistency is obtained by reducing the primer 'power'. Pre 308 Win Lapua Palma brass, the main way of improving this was to use a very 'mild' LR primer - some production lots of German RWS were particularly favoured by long-range sling shooters. The Russian Muroc manufactured LR primer (PMC at one time, more recently Wolf) is likewise often favoured nowadays for this reason, and not just in 308 Win, but in long-range .284 Win loads and similar that use around 55gn powder. By keeping the primer as 'mild' as reliably ignites the charge in all normal target shooting weather conditions, velocity extreme spreads are reduced which reduces 'elevations' on the target at 800 yards and longer ranges. US Palma Team managers reported a third reduction in velocity spreads in .308 Win loaded with the new 155gn Sierra Palma MK over H. VarGet compared to equivalent velocity loads using standard Lapua brass and match LR primers such as the Fed 210M.

What it also does where you can compare both types in the same rifle is to reduce velocities slightly, so .308 Win loads need to have charges of powders like Varget and H4895 increased by 0.3-0.5gn to return to the previous MV.

For more run of the mill cartridges / uses, the changes / benefits are small. One of the few such designs around is 6.8mm Rem SPC where Remington brass is LR and Hornady is SR (but with the standard 2mm flash-hole dia. not the 1.5mm of the small accuracy cartridges and Lapua .308 Win Palma brass). With this being a small cartridge (25-30gn charges), you'd think that the small primer brass would be noticeably superior. I couldn't see any difference in that sense between them. (What it will do here though is increase case life as the LR version hasn't got a lot of metal around the primer pocket which loosens in five or six firings with warm loads.)

 

[Grimstod]

Good explanation Laurie.

 

[jden]

Back in the early 90's during the .220 Russian brass shortage a few of us tried the IMI 7.62x39 necked down to 6mm and fire formed in our 6 ppc chambers. This brass had large primers and after roughly 10 reloads the brass separated about 1/3 of the way up the case. After this became a common occurrence we made the determination that the large primer was actually melting the brass at the separation point. We purchased some small primer sleeves. Problem solved but the sleeves did leak enough to be another problem. Our conclusion was that the large primer in a small high velocity case such as the 6mm ppc would not work. We were using Fed 210M primers and H-322 powder.

 

[Michael Courtney]

Some interesting results:

http://arxiv.org/ftp/arxiv/papers/1102/1102.1644.pdf

We've also seen single digit velocity variations with Lapua Palma brass, Berger 155.5 bullets, Fed 205m primers, and Varget. Also with the Murom DDNP based primers. These primers are very weak and often produce significant ignition delays, so you need great hold and follow through to produce good groups, but weak ignition does produce minimal velocity variations, especially with Varget (and likely other cylinder powders).

We have not seen good consistency in velocity with weak primers and ball powders.

 

[Mr. Ten-X]

US Palma Team managers reported a third reduction in velocity spreads in .308 Win loaded with the new 155gn Sierra Palma MK over H. VarGet compared to equivalent velocity loads using standard Lapua brass and match LR primers such as the Fed 210M.

And as soon as they put 10X as much effort into L-R as the up/down excuse, they may finally get somewhere, LOL.

 

[TonyR]

And as soon as they put 10X as much effort into L-R as the up/down excuse, they may finally get somewhere, LOL.

What is the "up/down excuse"? I need something like that.

 

[XTR]

The biggest thing I like about SR verses LR is brass life....
By having a SR primer pocket leaves more "meat" (brass) in the case head, which yields tighter primer pockets and extended pressure tolerance.

Donovan

I would advise folks trying the SR brass to be careful as to how you interpret this. I'm confident that for a given load that the SR version of the brass will last longer than the LR version. It makes sense, there is more metal around the pocket; however, do not interpret this to mean that you can push velocities up to the next node. I tried that last yr. I will tell you that you can in fact smoke a Lapua SR case in one shot and it doesn't really show it the way that LR brass does.

I was experimenting with heavy bullets and powders with no published load data (215s and N550) and was running pressures that were beyond where they should be.

The point is you should take this to mean that at the pressures we shoot in F-TR you'll get more effective life from your brass with a similar load, not that you can run 150FPS faster than you are currently running. Maybe you get 12 reloads out of your brass instead of starting to lose pockets at six or eight. Pay attention and if you are playing with SR brass and you are losing pockets in two or three firings (or less) you're too hot.

 

[Laurie]

And as soon as they put 10X as much effort into L-R as the up/down excuse, they may finally get somewhere, LOL.

What is the "up/down excuse"? I need something like that.

Tony,

you obviously need a copy of "The Diggle Dolloper's Book of F-Class Excuses" subtitled: "How I'm regularly cheated out of First Place"

Happy New Year my friend - Paul Crosbie is rerunning our 2011 Blair Atholl four-day event in June finishing up on the Monday with a Celtic Challenge team match for Scotland, Ireland, and Wales with both F/TR and F/O teams this time.

 

[TonyR]

And as soon as they put 10X as much effort into L-R as the up/down excuse, they may finally get somewhere, LOL.

What is the "up/down excuse"? I need something like that.

Tony,

you obviously need a copy of "The Diggle Dolloper's Book of F-Class Excuses" subtitled: "How I'm regularly cheated out of First Place"

Happy New Year my friend - Paul Crosbie is rerunning our 2011 Blair Atholl four-day event in June finishing up on the Monday with a Celtic Challenge team match for Scotland, Ireland, and Wales with both F/TR and F/O teams this time.

Hi Laurie
I wish I could be there for that event. I may get over there later this year, maybe for the Murray Cup. Give my best to everyone.
Tony

 

[tdking]

Very interesting. Would a magnum case suffer if it had a smaller primer?

Yes, it's generally agreed that .308 Win charge weights are about as large as the small primer / small flash-hole ignite reliably, ie up to just under 50gn. Lapua says that its 308 Win Palma brass shouldn't be used for hunting - a temperature issue mainly as many powders are harder to ignite reliably if they're very cold.

Having tried some Remington BR cases in my 708 years ago (1991-1993) I can tell you that the small rifle primer will not reliably ignite a 38-40 grain powder charge if the temperature is less than 40 degrees F. I used to use 38.5 grains of 4895 behind a 130 Sierra in my 708 and it would cause hang-fires routinely below 40 degrees F. You should try shooting rapid fire with a load like this. You will find out how good your follow through is! Click..............BOOM!, Click.............BOOM! The delay was about 1/2 second to a full second. It was like shooting a flint-lock!

TDK

 

[BradY]

I use the SR cases in a 260improved here in Aus with 43.2gr 2209 (H4350) and 140gr bullets around 2860fps. Our temps shooting can be anywhere from 10 to 40 degrees celsius. The CCI450 magnum primers do not have any issue sparking off that powder charge and hold very good vertical at 1000yds. I know of others using similar burn rate powders in true 260AI's with the same cases doing fine and running at 3000fps. The case head in these cases are very strong and primer pockets just dont seem to go loose. In a 308W with 155gr bullets shooters now use almost nothing but the small primer cases. But occasionally people find better results with the LR cases in different rifles. Each rifle, shooter, ammo, powder lot, primer lot, bullet lot, barrel etc are different. Some find a very good tune with SR some use LR. You need to test it for yourself to see what you prefer. But most come back to the CCI450 as the primer of choice, with a few using BR4 and FGMM's.

 

[Hombre0321]

Very interesting. Would a magnum case suffer if it had a smaller primer?

Yes, it's generally agreed that .308 Win charge weights are about as large as the small primer / small flash-hole ignite reliably, ie up to just under 50gn. Lapua says that its 308 Win Palma brass shouldn't be used for hunting - a temperature issue mainly as many powders are harder to ignite reliably if they're very cold.

Having tried some Remington BR cases in my 708 years ago (1991-1993) I can tell you that the small rifle primer will not reliably ignite a 38-40 grain powder charge if the temperature is less than 40 degrees F. I used to use 38.5 grains of 4895 behind a 130 Sierra in my 708 and it would cause hang-fires routinely below 40 degrees F. You should try shooting rapid fire with a load like this. You will find out how good your follow through is! Click..............BOOM!, Click.............BOOM! The delay was about 1/2 second to a full second. It was like shooting a flint-lock!

TDK

You speak in an absolute, that doesn't seem to work on a regular basis, at least not for me. My load for my 6.5x47 Lapua uses in excess of 40 grains of powder( maybe not by a lot but it is in excess of your quoted 38-40 grains) I have shot 1,800 rounds this winter in practice in temps as low as 15 degrees and have not had a single misfire.

I am not saying your results are wrong and maybe you are having some misfires, but maybe it is something other than the primers---Maybe...

RS

 

[Laurie]

If you look this subject up on the US Rifle Teams Long Range Forum, there was a great deal of discussion on this issue insofar as its use in .308 Win was concerned at the time when the US Palma teams were working with Lapua with prototype production batches. (The driver for its introduction was a request by the Palma Teams' managers to Lapua rather than the other way round.)

Many of the 'old hands' on the forum have hands-on experience of using Remington UBBR brass, a 308 Win case with the small primer pocket, 1.5mm flash-hole diameter and thin walls designed for reforming to whatever calibre BR case you fancied before 6mm and 7mm brass became available from the factories. There were various tales of woe with some users saying that the only way they could be made reliable was to drill the flash-holes out to the larger 2mm size used in most cartridges.

However, it seems that SRM primers and most powders have changed over the last 25, 30 years as the Palma case has worked out very well indeed. My initial tests showed that some powders seem to be temperature sensitive in them with 308 size charges. Viht N140 and N550 performance was degraded in temperatures just over freezing and restored in different conditions when it was a few degrees warmer, so I'm personally wary of using Palma brass in temperatures under 5-deg C (40 F), but I know people who use it in the UK all year round with 210s and hefty charges of N550 with good results.

6.5X47L and the BRs use considerably smaller charges than .308 Win, so should have a greater safety margin. Nevertheless, I'd still expect some types of powder to prove 'iffy' in very cold conditions. There are many well documented cases of magnum revolvers barely producing enough pressure to get bullets out of the barrel with full case loads of ball powders like H110 with standard Large Pistol primers in very cold days in places like Montana and Wyoming for holster carried revolvers amongst 'working users', the same loads proving completely reliable in normal conditions.

 

[BradY]

Shot everything from 2206H (H4895) up to 2213sc (H4831sc) in it and they all fired fine. This was in 308 and 260 improved. Others have done the same in anything from 243AI up to 260AI and 308. Again, CCI450's used in all. Wouldnt recommend it with anything thats not a magnum primer and colder than the 10-15 degrees C. Some have had good luck with FGMM in the 308 with 2208 (varget) but most use a magnum primer to burn the larger body of powder. The only time I ever got click.... bang was when my firing pin was dragging on the bolt body. 1 in every 10 wouldnt go off and got a couple that took a split second. That was fixed and the gun has never done it again in hot or cold weather.

 

[Laurie]

Shot everything from 2206H (H4895) up to 2213sc (H4831sc) in it and they all fired fine. This was in 308 and 260 improved. Others have done the same in anything from 243AI up to 260AI and 308. [BY1983]

It's interesting that you've tried small primer brass successfully in the .260AI. Several people have asked on this forum and others about experience with reformed small primer brass in .260 and 7mm-08, but you're the first person I've heard of who's actually tried it. On the face of it, if the concept works OK in 308, it should do equally well in this pair. The only reservation I had was that .260 tends to use slower burners than 308 and this might affect performance on the margins, but obviously not. So, many thanks for contributing this bit of information.

FWIW, I did side by side tests with the 185gn Berger Juggernaut in 308 over H414 in both types of Lapua brass with CCI-BR4 v Fed 210M primers. Temperatures weren't freezing, but a cool spring day 1,000 ft ASL in northern England - ie frigid by Oz standards! I expected the LRP brass to give far superior results to the Palma variety given ball powder's legendary harder to ignite status, but actually found the SRP brass better by a considerable margin - groups, velocity ES and SD values. As always, MVs were slightly down with the Palma brass loads, but you just factor that into your load development.

 

[BradY]

We too were skeptical to start with as we can be shooting 15 degrees one day 30 the next. But still everything holds up well with the loads. Primers included.

I havent checked my spread or SD since a rechamber, but I know the waterline in my load is good enough to shoot 60.10 (100.10 for the US viewers) at all ranges, its just the wind calls that arent right way too often :-\ We also shoot very close to sea level too, not sure if that will make an impact.