Small rifle primer 308 case

[johara1]

I have read here that the 6.5x47 was the largest case that the small rifle primer would work with. Now Lapua has a SRP. 308 case,I know it was out a long time ago but everybody said it wouldn't work and it disappeared. now did everything change?.....jim

 

[Laurie]

It was always said .308W was the maximum that would work with a small primer and the 0.060" flash-hole in combination, and that was certainly the case with the old thin-walled Remington UBBR design with some powders and in some conditions. Some people reamed the flash-holes out to the standard 0.081" to cure hangfire problems. Ball powders that are harder to ignite could be a particular problem.

Times - and powders + primers - change it seems. It was the US Palma team that asked Lapua to have a go and team members report good results after a full season of testing. Ammunition was even kept overnight in the freezer and taken to the range in cool boxes and still peformed well. These cases may still cause problems in the depths of the Canadian winter or suchlike, but there doesn't appear to be one with the powders normally used in .308W match ammo with 155gn bullets, primarily Varget, H4895, Reloder 15, and Vihtavuori N140/150/540.

The aim is to reduce MV spreads, and the Palma Team says you can expect at least 30% reduction in the size of the spreads compared to standard large primer / flash-hole brass based loads. This reduces vertical spread on the target at extreme ranges, which Palma is shot at. The team also says its tests found that trying various makes and batches of off the shelf Small Rifle Magnum primers (which should be used at all times) produced less variation from lot to lot than they've found with previously used Large Rifle models.

It'll be interesting to see how this brass works out. I imagine it won't be cheap as it'll be a special production item, most Lapua 308W cases continuing as now. It's said there will be no other changes to case weights and dimensions unlike the old Remington brass that was designed to be a starting point for reforming into BR cases or similar.

Laurie

 

[1000yardstare]

In an attempt to stay semi-sane in the long Canadian Winter (I saw that swipe, Laurie, old buddy) I shoot cast bullets at 50 metres in various calibers. Have my own moulds, lubrisizer and furnace. A far cry from Summer F Class but I just got my ORA annual dues renewal in the mail so there is light at the end of the tunnel.

But I digress........

One rifle used is a Ruger .308 Target rifle. This small primer Lapua .308 case sounds interesting. Typical cast bullet loads use small charges of faster burning powders like 4759, RL7, 3031. I am averaging 3/4 inch 5 shot groups at 50 metres with a 170 gr gas check Lyman bullet sized .309 using regular Win cases and LR primers. I am wondering if the smaller flash of the SR primer would provide benefit in this situation.

So I will contemplate this scenario while watching a TV news cast showing Brits up to their ying yangs in snow and frozen iguanas falling out of trees in Florida. And I don`t even have to stick my loads into a freezer to evaluate the usefullness of SR primers. I just place the ammo box on the shooting bench while walking up to the target board.

 

[JERRYHM]

I had no problem storing the ammo in my freezer for a day, but NO way would I go in the freezer to shoot them. MOVE where it is warm in the winter to shoot!

Actually the MV average was only reduced by 10 fps on the frozen loads and the ES was a little better compared to the loads at 65 degrees.

Jerry

 

[johara1]

Now here is the reason i wanted to know,necking down the 308 case to 6mm will also reduce vertical in the 6mm superx or the 6cm ?........jim

 

[Laurie]

In effect a small primer .243W or variation thereof?

I'd think you'd only know if you tried it once the brass is available. Most such cartridges use slower burning powders than .308W depending on what bullet weight you had in mind. It could be the small primer and flash-hole turn out to give marginal ignition with powders in the 4350-4831 class given thicker deterrent coatings.

................ or then again, they might perform brilliantly.

Suck it and see as we say on our side of the Atlantic.

 

[Rust]

Well, if Jerry and Robert say the stuff is good to go then I guess that's good enough for me.

By the way Jerry, what was the basic load you froze, powder and primer combination?

 

[JERRYHM]

Rust,

One of the five shot frozen loads. Chambered with the new Palma team's reamer.

July 20, 2009 Sacramento 100 yard chronograph

Varget – Primer -----MV---- ES --- SD --- Comments
4X.2 --- F205M --- 3003 --- 08 --- 03 ---- 5 shots --- Frozen load

Jerry

 

[rfair]

Small rifle primed cases are all I shoot from my 308's and they shoot great with varget or RL 15 but my brass is remington BR that I got a long time ago. I can reload it and reload it and have only discarded about 5-6 cases. someone told me to sell it and buy some Lapua brass but this stuff shoots better than Federal or winchester brass that I have.





l

 

[wapiti25]

I have some old rem 308 UBR brass and mine has the .081 flash holes. I used to make 7mmBR out of it for my XP100. I also read about some Tubb brass 6mm that did not work with the small primer. Just thought that I would pass that on. I would still try it for my self.