Home Forums Hunting & Shooting Ask The Gunwriters Small rifle v Small rifle bench rest primers

Anybody know what the difference is?
I can find Bench Rest primers on the shelf but not standard small rifle.

Ask Barsness, he explained it to me once or twice and I never remember what he said, but he did say it…

Absolutely nothing other than the most experienced and best compound spreaders make them. Not worth the cost diffrence.

Most of the benchrest shooters that I shot with used Fed 205's, most claimed no difference with the 205m's except extra cost.
There is a difference between Rem 61/2's and 71/2's though

Was got NBA say the same thing as above, I have a good friend in the Bench Rest HoF and he uses Fed 205s

What is that difference between the Rem primers?

Rem 6 1/2s are for lower pressure rounds like the Hornet and Bee. If you use them in high pressure rounds like 223 you are in danger of getting those cute little divits in your bolt face.

I believe the difference between standard and match primers is that the guys who have proven themselves to be the most consistent at spreading priming compound make the match primers.

I was also under the impression that Fed 205 M have a slightly thicker cup than Fed 205.

In CCI's the 450 is a closer replacement for the BR4 than the 400's are. The 400's have thinner cups.

The info about workers being the "most consistent spreading at spreading priming compound" was exactly what I was told while touring the Federal plant--but it wasn't "guys." A lot of the best primer-compound spreaders were women.

The 205Ms were also all made from the same lot/batch of brass, while standard 205s allowed changing the brass batch during that lot.

But otherwise there was no difference in priming compound, cup brass, or anything else. So no, the 205Ms do not have slightly thicker ups.

Have also toured the CCI primer-making department, and it was the same basic deal: The BR-4s are more consistently-made versions of 400s.

Nope. CCI 450s use a much hotter priming compound.

There's an interesting history there. The original 450s appeared in the 1960s, when higher-pressure cartridges using small-rifle primers appeared. Prior to the .221 Fireball and .223 Remington, no SR cartridge developed over around 50,000 PSI (in modern electronic terms), so all SR primers had relatively thin cups.

But those rounds required thicker cups to withstand the higher pressures, which was why CCI introduced the 450 and Remington the 7-1/2 primer. Both had thicker cups, but the priming compound was basically the same.

A while later CCI started using MORE of the same compound, to more consistently ignite powders in larger rounds, especially spherical powders.

In the early 1990s CCI changed the compound in 450s (and large-rifle 250 magnum primers) to a much hotter compound--which is why the 450 is not "a closer replacement " for the BR4.

I’ve shot CCI 400s and BR 4s side by side, same day, same rifle and they were within 5-10 fps. In some rifles, one or the other has shown better accuracy. In one of my hornets the BR 4s cut groups in half but you never know….

I forgot about that difference between the two. Thanks for reminding me!

Just to muddy the waters a bit, in my experience the Fed 205's and 205M's are exactly the same. they shoot the same numbers through the chronograph...............a few years ago Federal came out with an AR specific Match primer GM205MAR.
I have not measured to see if the cup is thicker or just made from a harder material but they are tougher than the regular 205 and 205M's

Then why, in the 21st century, do 400s seem so much easier to pierce than 450s & BRs?

I wasn't aware of that, but then have encountered VERY few "pierced" rifle primers in my half-century-plus of handloading.

I think you misunderstood MD. He was stating that 450's have a much hotter compound. MD also said that the cups on the 450's are thicker to handle the higher pressure


Trystan

I think the correct term is "blanking" primers not piercing. My experience with "blanking" was due to weak firing pin spring or excessive headspace.
No difference in 205 or 205m except a visual inspection according to a Federal employee at the Super Shoot 20yrs ago or so. Most BR shooters do not care if they are 205 or 205m, they just shoot what they have.

I understand exactly what he said. It's been my observation and the observation of many competitive shooters that the 400s not only have a lesser charge of compound, but also have thinner cups and that the CCI BR primers seem to have thicker cups, more like the 450s.

Interesting.... I built a 223AI on a new Rem 700 action and at 223 speeds it pierces the CCI400 primers. I tried the CCI450's and that seems to help.
I am thinking that Rem700 is a pos at this point. You would think something as basic as firing pin/hole dimension would be a no brainer?