300 Win Mag loading

[Hobbit]

Hi

I am about to work up a load for a new 300WM 30" bartlein that Mik put on my AI AXMC

planning to use 225gr ELD-Ms and N165 (gets to where I need it with the 30" tube and not too savage on the barrel)

I have Peterson brass that sorted very uniform indeed 

I was wondering about primers - should I use a magnum primer or not - will be aiming for a stiff if not actually hot load

I have a redding competition die set but suspect I will actually use the lee collet die over the neck bushing die or at least do a comparison

I understand that magnum primers are more about pressure resistance that any ignition effects - is this correct??

any suggestions on the primer front or any other aspect of this small project 

thank you 

[duey]

Use magnum primers, there is a large column of powder to ignite 

not saying none Magnum primers won't work but may not give the consistency of ignition required 

[Hobbit]

Duey

Thank you - does that mean magnum primers have 'more oomph' and help with ignition rather than just being harder and able to cope with higher pressures without flattening etc??

[Incisor]

I used to use magnums with my 300 win mag under 70ish grains of RS70.  Been using ‘standard’ LR Muroms for last few years as they gave lower ES than either CCI or Federal magnums and never had one fail or delay in conditions from -20 to +30 degrees C  

regards

[duey]

Hobbit 

to be honest I've never looked into the difference but I believe that there is a bigger bang from the magnum primers, I'm sure that Laurie would be able to give a more definitive answer 

also I was happy with my load so wasn't going to waste barrel life searching for a little bit extra 

[Andrew]

Non magnum primers.~Andrew

[Hobbit]

Andrew 

Whilst I applaud you economy of words I would like to clarify your position ?

for the avoidance of doubt your are suggesting, like Incisor, that non magnum primers are the way to go??

Duey

I completely get it - if it works crack on with the shooting - my barrel was not cheap and it s a lot more finite that a 308 so agree

hence my aim to get a solid steer and go with that

I have seen a lot of love for the federal 215 magnum primers from the US

Cheers

[Andrew]

Better grouping and lower ES/SD. I once used magnums but a long range shooter friend told me he never uses them so I tried straight Match Primers with excellent results on the chrono and target.~Andrew

[Laurie]

N165 is a very easily ignited powder grade and even though you'll be running charges around the 70gn mark, it doesn't need a magnum primer for match use. In fact as Andrew and others say, some LRMs will most likely increase groups, ES/SDs. LRMs are routinely specified for cartridges like this in US manuals and sources as their primary use is 'hunting' often in (low) temperature extremes we would never see in the UK, and certainly not in range use. A primer that is perefectly adequate at say a low 5 or 10-deg C, can struggle at minus 20 or 30 and even if the cartridge goes 'bang' OK may see such a large MV reduction that anything other than very short distance shots strike low as well as producing reduced terminal energies and bullet expansion.

LR Primers though are a really mixed bunch. My tests have shown some standard LRs (eg Remington 9 1/2) as being 'hotter' than other makes of LRM (eg the Russian KVB-7M that works very well in match use in much smaller cartridges). The Federal 215 and 215M alongside both versions of Remington are the ones to be wary of.

I'd try CCI-BR2s and Fed 210Ms, both match jobs if you can find any, plus the Murom KVB-7 / PMC LR. The S&B primer gave very good consistency for me in 308 tests and would likely do so even in this larger cartridge.

Ball powders in the 70gn plus charge range may be a different matter as some older types need a more vigorous primer to provide consistency in all temperatures. It's difficult to be prescriptive in this matter as many manufacturers have made great strides in making this type of propellant easier to ignite and cleaner burning in recent years given that their main clients are military ammunition suppliers and the military become ever more demanding on reliability, reduced bore fouling, wanting anti-coppering agents, and most demanding of all temperature stability. P B Clermont's Ramshot powders seem to have few or even none of the traditional ball type downsides other than a narrower efficient chamber pressure band. Conversely, although a recent introduction, I found that Hodgdon's CFE223 simply doesn't ignite properly with the reduced primer power of Lapua 308 SR primed 'Palma' cases.

[Hobbit]

Laurie

Very helpful as ever - I'll look up some of the match primers you suggest

Thanks

[Catch-22]

Sorry to hijack, but what about even larger magnums, like the .300 and .338 Norma Mag, .338 Lapua Mag etc.

Would a standard LR match primer do the job or does the additional powder (20+ grains more than a .300wm) necessitate a LR Magnum, like the Fed 215m?

thanks

[gyr]

Laurie

is 170 as easily ignited?

txs