Small rifle primers in Lap Palma case

David B · Post by **David B** » Tue May 20, 2014 6:01 pm

Most 308 shooters I know have better ES SD etc with these cases, put down to the small primer, is this generally the case? Does any one know why?
Could it be some thing as simple as grains of powder finding their was into the pocket and effecting the flash
:?:

johnk · Post by **johnk** » Tue May 20, 2014 9:41 pm

The theory (promoted by German Salazar for some thime now) but endorsed since by quite a number of effective shooters is that the best consistency occurs when using just enough primer to light the powder being used. That might mean using a less brisant primer like the PMC Russian LR than for example, the RWS in standard cases, or as you suggest, going to a case with a smaller primer. I've found that with AR 2206, I do get better extreme spreads & a tad better velocity out of the Lapua Palma case than the standard; other shooters using different powders have not achieved the same results, eh Matt.

The break even point can be subtle & not necessarily immediately evident. My 30-284 seems to like with the PMC primers at the moment, but I've stuck with AR 2209 to date. Were I to try a slower powder, or a double based one which I would expect to use a sugnificant surface coating, the results might be different.

williada · Post by **williada** » Tue May 20, 2014 10:44 pm

My initial thinking is that the smaller primer allows you to use a denser load which probably burns more efficiently with higher pressures to move the peak of the pressure curve towards the breach. Reduce the air gap and you tend to get reduced SD’s. German Salazar did some testing and debunked the claim that the small primer flash produced a jet like flash to ignite the powder more efficiently. Like John said, the theory is you just need enough to get the candle lit. If 5000 psi comes from a primer then it might be possible the initial explosion can blow powder forward if there is an air gap, who knows and lead to a less efficient burn. Salazar saw little difference in the flash between large and small primers in the end. Now I am inclined to think it was a Palma team tactic to come up with something different which incidentally to sold more Lapua brass. There is certainly nothing wrong with the results using the .308W small primer but small SD’s don’t guarantee tight results at long range. Other factors come into play such as compensation. Also consider that some people get excellent results in calibres such as the Long Dasher using magnum small primers. So it depends on the powder and coatings used. If anyone has another slant it would make interesting reading. Like John said , a faster burning powder such as 2206 can achieve the same result. It will move the peak of the pressure curve back towards the breach and yet the load will still will have an air gap in a .308 and be hot enough to overcome the argument to increase load density for an efficient burn. Any combination of components, still need tuning.

BRETT B · Post by **BRETT B** » Wed May 21, 2014 1:27 pm

I have formed 243AI and 260 AI out of the palmer brass and found them to work very well. In testing i found the small primer was NOT a cure for a bad tune as i had bad vert in the 243 and the small primer did nothing to help it!! it still had to be tuned with powder/seating depth to get rid of the Vertical. I like how the primer pockets don"t loosen as fast as Large rifle do but they are not as easy to read pressure signs on primer shape compared to large primers. Velocity and SD/ES seem to be on par with LRPrimers in my testing and definately no loss of accuracy!! I can not say for certain yet but i think if there is an advantage it is not the small primer but rather the smaller 60 thou flash hole which is similar to a PPC case. This is only a theory i have but i believe the more concentrated flame through the smaller flash hole may help accuracy slightly but it is hard to test this theory but my gut is telling me there may be something there so i am going to continue to use them and gather as much Data as i can !! I have used some very slow burning powders ( 2217-R22 etc) and up to 50 gns and have had no issues with bad ignition with the CCI450 so far so lighting up a fair stack of powder seems no problem .

David B · Post by **David B** » Wed May 21, 2014 5:03 pm

Wearing the appropriate PPE I recently deprimed some live primers, large rifle
What triggered my thinking was there was plenty of room in the primer for grains of powder, some had up to three others had none. Could they effect the flame for better or worse was my thinking.
The last standard cases I perchased just were not as good quality as the cardboard box cases perchased some time ago. The Palma cases are better quality so this should give them a head start..

Steve N · Post by **Steve N** » Wed May 21, 2014 9:09 pm

What size decapping pin do I need to remove primers if using Palma brass? If the flash hole is smaller do you need a smaller pin? I use Redding and Lee dies.

Aubrey · Post by **Aubrey** » Thu May 22, 2014 11:37 am

Footsore wrote:What size decapping pin do I need to remove primers if using Palma brass? If the flash hole is smaller do you need a smaller pin? I use Redding and Lee dies.

You need 0.6 pins - same as for 6BR.

johnk · Post by **johnk** » Thu May 22, 2014 12:13 pm

Actually the .06 can be too large for the current Lapua 6BR brass. You'll need to dress a pin down to fit: http://www.6mmbr.com/6brfaq.html#37828

Razer · Post by **Razer** » Thu May 22, 2014 3:35 pm

Footsore wrote:What size decapping pin do I need to remove primers if using Palma brass? If the flash hole is smaller do you need a smaller pin? I use Redding and Lee dies.

I only neck size, so, I use the Lee Collet neck sizer.

When I started using Palma Brass sometime ago, I ordered another Lee 308W neck sizer, took out the mandrel/decapper, put it in the chuck of a cordless drill and, on slow speed, ran the decapping pin backwards and forwards along an oilstone until it fitted snugly in the small primer pocket flash hole.
I use CCI 450 primers with the Palma Brass, no complaints from me.

Enlarging the flash hole defeats the purpose of using the small primer.
I was lead to believe, by what I have read, that the small flash hole concentrates the flame through the centre of the propellant thereby giving a more even/consistent ignition.
Brett B alluded to this when he wrote;
I can not say for certain yet but I think if there is an advantage it is not the small primer but rather the smaller 60 thou flash hole which is similar to a PPC case.
This is what started Lapua thinking and, ultimately, producing Palma 308W cases.

Using a large rifle primer through a small hole would not work for lots of reasons, but, if it did, then all the brass that we use would 'only' have the need for a small flash hole.

Longranger · Post by **Longranger** » Thu May 22, 2014 8:13 pm

And yet I know someone who very successfully uses Palma cases with the flashhole enlarged to the LR size. Go figure?

plumbs7 · Post by **plumbs7** » Thu May 22, 2014 9:14 pm

Longranger wrote:And yet I know someone who very successfully uses Palma cases with the flashhole enlarged to the LR size. Go figure?

Hmmm ..... Me too!

Razer · Post by **Razer** » Thu May 22, 2014 9:14 pm

Longranger wrote:And yet I know someone who very successfully uses Palma cases with the flash hole enlarged to the LR size. Go figure?

So do I.
Does that someone comes from North Queensland?

Mind you, paying extra for Lapua Palma Brass and then enlarging the flash hole to LR size is not very cost affective, but, when the LR Lapua cases are unavailable, it may have been the only option. :wink: