Primers for 338 Lapua Magnum

[werew]

Using Federal 215M primers i've been getting flat primers using 300SMK bullets, from 88gr. to 91gr. of H1000. This is using virgin Lapua brass, seated off the lands by .010.

88gr. seemed like a very safe starting point to me yet 88-91 grains all produced identical results on the 215M primers.

There's also some slight printing of the firing pin's hole on all of the primers.

There are no other pressure signs and brass looks great.

I've been reading the CCI 250 primer cups are a harder steel and thinking I should try these?

Any thoughts on this appreciated and welcome.

 

[CanSniper]

Re: Primers for 338 Lapua Magnum

Any idea how fast they are running? I am running 92grns of H1000 w/ 215M's @ 2800 fps and almost no sign of pressure.

 

[werew]

Re: Primers for 338 Lapua Magnum

My chrono's battery was dead, i'll clock some next time and see what I get.

 

[CanSniper]

Re: Primers for 338 Lapua Magnum

Usually not very concerned with just a flat primer if it is not acompanied by other pressure signs. The Federals do seem to be softer to me also. What rifle are you running?

 

[ChadTRG42]

Re: Primers for 338 Lapua Magnum

The Federal 215M primers have a thinner cup, and will flatten a little easier than others. So, I never look at the primer as a pressure sign (except your obvious issues, like a pierced primer). Shiny spots on the case head stamp, ejector marks, and sticky bolt lift will appear for pressure signs. If you switch to a CCI #250 mag primer, this problem should go away. Otherwise just keep loading em up.

 

[werew]

Re: Primers for 338 Lapua Magnum

Thanks,
Im using a Savage 110fcp. I get consistent/identical primer flattening as well as firing pin hole "print" on the primer thru-out the 88-91gr. powder wgts, so I strongly felt these were "misread" pressure signs due to the 215M's thinner/softer cup. Never had this issue with 215M and 7mm Mag, then again the 7mm mag doesnt cook up to 60,000 of pressure. I bought some CCI250 primers today and will give them a whirl.

Im very happy with a 5-shot group/node in 1 ragged hole, well under 1/2" at 100yds using 300smk (.010 jump) and H1000 at 89.5 - 90.5 grains. My 300 Hybrid Bergers haven't gotten much testing yet as it got dark quick that day. I'm looking forward to seeing what I can print @ +300yds which is where this round is supposed to stabilize.

Thanks, and i'll update with results and pics if possible.

 

[JimGnitecki]

Re: Primers for 338 Lapua Magnum

I am starting to think priemrs are being made now with aofter skins.

I say that because although I am running only 41.5 grains of Varget in my 308 175g Sierra Matchking loads, the primers look a bit "flatter" than I am used to seeing in the past. In fact, the last 2 times I have been at the range, I've asked several other shotoers present to look at them and tell me what they think, and they all said exactly the same thing: yes, they look a bit flat, but there are absolutely no other signs of pressure (no extractor marks, no firing pin hole marking, no swipe marks, etc).

Adding further credibility to the primer "softer shell" idea, the priemrs looked dientical during my recent ladder tests, all the way from 40.5g of Varget through 42.5, and all the way from 40.0 grains of IMR 4895 through 42.5 grains.

I think this is the new "normal".

Jim G

 

[werew]

Re: Primers for 338 Lapua Magnum

Jim,
I think you're right. If this is the case with Federal Primers, i'm going to be switching over to CCI250's for my 338LM if they work like I think they will.

Ill try some of these new fed215m's in some 7mm mag loads, if they handle my 7mm pet loads like my 6-7yr old 215m's, then ill have 200 extra for that rifle.

 

[Harpy]

Re: Primers for 338 Lapua Magnum

werew,
Did you get a chance to try the CCI250's in your 338LM FCP yet?

 

[werew]

Re: Primers for 338 Lapua Magnum

Harpy,
I've got them loaded and ready, havent had chance to get to range yet on my days off. I've been distracted by a female of the blonde hair, blue green eyes sort. Damnit I think i'm in trouble! lol

Will keep ya updated and post pics of my results of the 2 primer types.

 

[Harpy]

Re: Primers for 338 Lapua Magnum

werew,
I shot a five shot group with "your load" over my chrono the other day with my Savage 110FCP:

Lapua Brass,F215M,90.0grs of H1000, 300SMK,.010 off.

ES 22.80
SD 9.59
Ave 2768fps
Group .568
Temp 38 F
Ele 1900'

Harpy

 

[werew]

Re: Primers for 338 Lapua Magnum

Harpy, nice shooting. What is your most accurate load currently?

Here are my results. Hottest load tried was 91.5gr of H1000/300SMK, primer was a little flat, slight firing pin hole print and no cratering. Very noticeable difference between the primers. I'm switching to CCI250mag.

I did get ONE 285HORN load chrono'd, 89gr. H1000, cci250mag and .015 jump gave a AVG 2750 fps. I went up to 90 grains with this bullet and saw no high pressure signs... this new bullet might be a winner for me. Had many hits on a 1000yd tombstone and I played around at 1500 with my last 3 rounds and i'm impressed.

Compared to 300SMK and 300BERG, Hornady 285 bullet has a larger surface bearing area, slightly "chubbier" nose profile than the 300BERG and almost the same length as the 300SMK. 285HORN EASILY fits inside my magazine with a custom OAL .015 jump.