Magnum Primer - not the results I expected

[Keith Herrington]

I've been regaling you all with tales of my quest to produce truly match grade ammo for the 30-40 Krag. To quickly recap:
a. Match grade collet bushing resizing die with .332" collet (.002" neck tension)
b. Brass trimmed to uniform length
c. Primer hole reamed
d. Necks cleaned inside and brass tumbled
e. Brass full length resized with no more than .002" runout
f. Powder charges all weighed to exactly 40 grains of IMR 4350
g. Hornady 220 grain JRN seated to uniform length with final runout between 0 and .004". By far the best results achieved to date.

I loaded 50 rounds of test ammo with 5 different primers:
a. Federal Large Rifle
b. Federal Large Rifle Magnum
c. Winchester Large Rifle
d. Winchester Large Rifle Magnum
e. CCI Large Rifle Magnum (250)

The results at 200 yards were startling:
a. All the Magnum primers shot considerably higher on the target, about 12" higher, than the standard primer loads.
b. Magnum primer groups were vertically strung as much as 10-12"
c. Standard primer loads were approximately 3-4" in size and fairly concentric. Using a 6 o'clock hold and a 300 yard setting the standard primer loads were clustered consistently around the X/10/9 rings.

The recoil of the Magnum primer loads was noticeably stiffer than with standard primers.

Based on the above I've decided to fore go any further testing of Magnum primers in my gun. They undoubtedly work for those that recommended I try them, but for me they are not the answer.

The next test loads will be 20 each of the Winchester Large Rifle primer, the CCI 200, CCI BR-2 and the Federal GM Match primer. 20 rounds each should give me sufficient data to make a solid choice or two for testing a larger sample.

[psteinmayer]

I couldn't speak to Federal primers in Krags, as there is no floating firing pin, and therefore no chance of slam-fire... but I have read about people having serious troubles using Federal primers in their Garand Rifle loads.

This year, I've obtained 2000 CCI 34 military-grade primers for loading my Garand ammo. I'm curious as to their comparison to CCI 200 and CCI 250 primers (I've been told that they are somewhere in between). I may switch to these in my Krag loads also.

Incidentally, the reason for my use of magnum primers with the IMR-4350 is purely from a burn prospective... being that 4350 is a slower burning powder and somewhat harder to ignite than say 4895 or 4064... and the hotter flame from the magnum ensures a complete burn with the 4350. That said, based on your results, I may revert to the standard CCI 200 for future matches if the military grade 34s don't pan out. With the shoulder problems I'm currently experiencing, it ain't gonna hurt any to reduce the recoil some!

[RichWIS]

Although your load is not a hot load remember that magnum primers can boost pressure. I don't know why you need them with 4350, it is not a hard powder to light and the Krag case is not a big case. I use magnum primers in my Garand with WIN 748, as there was an occasional noticeable delay with standard primers, but it is a ball powder. I have never had the problem with IMR series powder in any rifle, even in extremely cold weather. The CC! #34 from what I have gleaned from the CMP forum is a magnum power primer, as military ammo is loaded with either ball or extruded powder and it works even in extreme cold with either powder.

[Parashooter]

It may be worthwhile to understand that slow tubular powders achieve their burn rate mostly by kernel size and geometry - while slow spherical powders have to rely primarily on deterrent coatings. That's basically why most tubular numbers are relatively easy to ignite compared to "ball" powders of similar rate.

[psteinmayer]

Well, that makes pretty good sense to me. I do know that the CCI #34 is the military standard primer, and it has a slightly thicker primer cup which helps to prevent the slam-fire issue. That said, I may just switch back to using a standard CCI 200 for my Krag loads. We'll see.... I have all winter to contemplate this, as I'm out of commission for a few months (surgery to my shoulders).

[Parashooter]

The "thick cup" business circulated about the CCC #34 is apparently another bit of widespread misinformation. According to the manufacturer, a shorter anvil is the dimensional difference between the #34 and the #200, #250, and BR-2. Cup dimensions are virtually same for all.

[psteinmayer]

Ahhhh... Maybe that's it. The debate on thicker cups arose from discussions about slam fire in Garand Rifles due in part to the floating firing pin slamming against an overly sensitive primer with a thinner cup... as I recall - the discussion was that the Federal primers were the most susceptible to this, and the CCI primers were the safest. I might have mistaken or miss-quoted this... but that's how I recall it anyway. Either way, I'll be using the 34s in my Garand loads from here on out.

[Keith Herrington]

Did a followup 100 yard range session today to shoot up the rest of my test ammo. Shot ammo with WLR primers, Federal LR Magnum and CCI 250 magnum. As with this weekend, the Federal magnum load vertically strung the shots at 100 yards, but the CCI 250 primers did not. In fact, this load shot the tightest 5 shot group I've gotten to date.



Previously, the target below had been my best using the CCI 250 primer.



And the one below is the best to date with the CCI 200.



Now, 5 rounds does not a favorite load make. But what this tells me is the work that I did on the brass to make it more consistent and concentric, may well be paying off.

[psteinmayer]

So maybe I should hold off on dismissing my use of the CCI 250... I might just stick with it. To be honest, it has been working for me so far...

Keep at it Keith - your work is good for all of us, and your data will be invaluable!!!

Paul

[Keith Herrington]

So maybe I should hold off on dismissing my use of the CCI 250... I might just stick with it. To be honest, it has been working for me so far...

Keep at it Keith - your work is good for all of us, and your data will be invaluable!!!

Paul

Paul,
Keep in mind my barrel is a CMP tube with a .308" bore. I think an original Krag bore (which is often larger than that) may be (and here I'm guessing) less sensitive to the pressure spikes of magnum primers. I've already decided that magnum primers don't work well for me AT 200 YARDS. These tests confirm in my mind that loads that look good at 100 often don't translate well at 200. My next test will be with WLR, CCI BR-2, CCI 200 and GM210M. I'm not testing Remington or Russian primers simply because I don't have any and don't intend to buy any. From my research these four primers are all similar (though not identical) to each other in terms of heat and pressure, and most important will not string my groups vertically the way the magnum primers do.

What these latest test confirm most for me that match prepping the brass pays dividends. My efforts there were not wasted.