Small primer 6.5cm vs large

[T3_tinker]

So, I've got some hornady brass which have the large primers and I've worked up a load for them that works well but I'm getting some lapua brass that has small primers. Will this make a massive amount of difference if using the same recipe?

[Scotch_egg]

Yes it will.  From the research I have done as long as you aren’t Pushing the top end load data large primers will work and the average man won’t ever see an advantage over small primer primer brass. 

 

With that look at the star line brass that Henry Kranks sell at £58/100 or there abouts. You can then try your current load data. It may need minor adjustment due to case capacity but far less of a difference than changing to small primers. 

[Long Gun]

I can't speak as to the accuracy gains of the small vs large rifle primer brass, but I can say that if you buy the Lapua brass you need to ensure your dies have pins small enough to fit in the flash holes. Not a big deal by any stretch, but can be a pain if you don't ensure it's sorted. 

Scotch egg: you have any experience of the quality of the starline stuff compared with Lapua? 

 

 

[phaedra1106uk]

I've been using Starline SRP for about 8-9 months now, the one's I shot on Sunday and Monday are on their 6th and 7th firings with 1 anneal at 5 firings. 

No difference in accuracy to first firing, biggest limitation in the equation is me not being physically able to hold anything steady enough to better than 1MOA on a good day!.

Current loads are 42gr N140 with Lapua 100gr Scenar or 38gr of N150 with Nosler 140gr Custom Competition, both using Murom KVB-223M small rifle magnum primers.

[chaz]

Has anyone tried magnum and non magnum primers, and found what the real world difference is?

Cheers.

[phaedra1106uk]

Yes, not a lot to be honest.  The Murom magnums produce a slightly lower speed than standard Federal or Magtech.

There's another thread on here about it where Laurie explains that the Muroms are not really "magnum" in power but do have thicker cups to withstand the pressure better.

Laurie also has an excellent series of articles in Target Shooter, this is the one on small rifle primers,

http://www.targetshooter.co.uk/?p=2662

[VarmLR]

SRP brass using small rifle primers/small flash-hole seems to produce lower ignition energy than LRP brass hence lower MVs.  With my 6.5 CM, I've found MVs some 100 to 150fps down on equivalent LRP loads.  TAKE NOTE:  DO NOT try and replicate SRP loads in LRP brass as chances are you could end up way over safe pressures, especially if loading moderate to hot in SRP.  It may be safe the other way around, but never from SRP to LRP where recipes should not be replicated.

The main difference with magnum SR primers AFAIK is that on many, cup thickness is greater to allow for higher pressures.  Some, like the Remingtom 7.5,  may be hotter than "standard" SRP.  Muroms are the same IME be that KVB-223 or KVB-223M but I've found that even in 223 I prefer using the magnum primers as I've had a few standard ones blow on me.  No difference between Murom magnum or std on velocities from my own experience but I've only used them ion 223 and 6.5CM.

[phaedra1106uk]

At the moment I'm only pushing the Nosler 140's with 36gr of N150, I did a ladder test from 35.0 to up to 43gr with no obvious signs of pressure, best nodes were at 35.6 to 36.4 and 38.0 to 38.4.

36gr will do what I need it to, as I've posted elsewhere my days of consistently shooting sub-moa groups with anything are long gone due to disabilities.  Even sat with an MTM High-Low shooting table I can just about manage 1moa! at 100m.  No problem dropping Sarts falling targets at 800-900m with that load though

I'll stick with the Murom KVB-223M primers as I still have about 9,000 of them to get through!!.

[VarmLR]

They're ok phaedra

sorry to hear about your disabilities...I have some sympathy there as I have a worsening back condition and everything creaks these days when shooting prone!