Small Vs Large primer pockets ?

[BillyBoy 57]

I bought a 6.5 creedmor ruger hawkeye. No ammo available, been looking for 2 months or more . Finally found some in stock brass at midsouth , it is winchester brand. I see the brass for this cartridge is made in small and large primer pockets depending on the manufacturer . Why ? I see this on 308 win. as well . Not new to reloading , just never saw this before .

[Bart B.]

Small primers often produce better accuracy in 308 or smaller cases. But only with stick powders in warm weather temperatures above 60 degrees F.

[RC20]

The small primer in theory is more accurate.

By how much and how the other factors or reloading might affect that?

Might see it in match grade factory ammo where the tolerances are not just tight but controlled to a degree most reloaders will not achieve.

That said I have shot a bit of match ammo and mine loads were better though I never tested to see if the average was better, just best groups were by far.

Mostly I think its theoretical and maybe a real top rated shooter might see the difference (of which I am not one).

I think its a gimmicky thing for most. Its amazing what they come up with that we just can't live without like the new RCBS powder dispenser that weights out to a millionth of a grain.

[BillyBoy 57]

The Wiinchester brass does not say large or small , I will find out when it gets here . I will be happy just to get it . Thanks for the info .

[kilotanker22]

Winchester brass will be large primer. I am not aware of them making standard cases with small primers

[RC20]

You are welcome.

I put together a 6.5 Lapua rifle on a Savage Target action and missed that only Lapua makes the brass and its small primer. I lucked out and got 200 cases on sale, that will last me a long time.

Given that I would have gone with the 6.5 CM.

Good news is I have a couple thousand small rifle primes from the 223 days and my brother sold me another couple thousand so I am good for some time.

I can shoot around 1/2 MOA and even less on a good day, but I totally doubt I can begin to see a difference in a large primer pocket and a small one.

I have been impressed with the small Extreme Spread and Standard Deviation but I suspect 6.5 CM is so close to the same as not to see the difference.

I do like shooting it and I lead in with it for settling down as well as seeing what I can do (again 6.5 CM would be the same in my opinion).

6.5 is a fun round, more so as I am just bench rest setup with a bull barrel, not much recoil.

6.5 CM has a lot more choices brass and pocket wise and unless you are bench rest expert, that is what I would go with.

[BillyBoy 57]

The Hornady Reloading manual says the initial factory ammo for this caliber (6.5 creedmoor ) had the load printed on the box. It says the bullets were hornady A-max in 120 and 140 grain but thats it, no powder info . Anyone know anything more on the factory ammo ?

[kilotanker22]

Originally Posted by BillyBoy 57

The Hornady Reloading manual says the initial factory ammo for this caliber (6.5 creedmoor ) had the load printed on the box. It says the bullets were hornady A-max in 120 and 140 grain but thats it, no powder info . Anyone know anything more on the factory ammo ?

I used to have a couple boxes of this stuff. Memory may be failing me now, but I seem to remember 41.5 grains of Hodgdon 4350 being listed on the box of 140 grain Amax ammunition I had with my first Creedmoor rifle. To be clear, I am not 100% certain that is what the box said, only what I seem to remember it saying. 41.5 grains of H-4350 also happens to be the maximum listed Powder charge for 140 grain bullets in the Hornady ninth, tenth and eleventh edition manual.

I have shot a fair amount of ammo in this load range and it generally shoot MOA or better in all barrel lengths that I have owned.

[101combatvet]

This reminds me of the old adage - you can't outshoot your rifle. Note: In 2021, you can't outshoot your primer.

Enough matches have been won with large match primers for competitions in .308. Why change now? Answer: no need.

[Unclenick]

It's another variable in a game where we generally try to control as many variables as we can.

Knowing that when loading density is lower, magnum primers sometimes produce the lowest velocity variation, but that when load density of the same powder is high a standard primer will often do better, I suspect going to small primers to reduce velocity variation is most likely to work out with 100% to slightly compressed loads. If you are using a powder that only fills the case 85%, there's a good chance the large primer or even a larger magnum primer will do better. This will likely vary by the cartridge and powder and bullet combination, but that's my very generalized expectation. In your gun with your bullets and powder, YMMV. All you can do to be sure one way or the other is test.

[BillyBoy 57]

Originally Posted by kilotanker22

I used to have a couple boxes of this stuff. Memory may be failing me now, but I seem to remember 41.5 grains of Hodgdon 4350 being listed on the box of 140 grain Amax ammunition I had with my first Creedmoor rifle. To be clear, I am not 100% certain that is what the box said, only what I seem to remember it saying. 41.5 grains of H-4350 also happens to be the maximum listed Powder charge for 140 grain bullets in the Hornady ninth, tenth and eleventh edition manual.

I have shot a fair amount of ammo in this load range and it generally shoot MOA or better in all barrel lengths that I have owned.

Thanks for the info !

[hounddawg]

technically the reasoning behind small primer pockets is that they have less surface area so will withstand higher pressures. Personal experience is that the large primers function better with ball and flake powders and small better with extruded. Just my personal experience, no studies to quote

[RC20]

All you can do to be sure one way or the other is test.

And hope the noise levels are low enough to see the difference (if any)

[Unclenick]

Yep. And if they aren't, then congratulations are in order; your system isn't picky and you can use anything.

[Don Fischer]

Something I wonder about is accuracy. How much accuracy do we really need in a hunting rifle? I've got several hunting rifles that will give me right at 1/2" @ 100yds, how much more than that is needed to hit the vitals of a big game animal?

[kilotanker22]

Originally Posted by Don Fischer

Something I wonder about is accuracy. How much accuracy do we really need in a hunting rifle? I've got several hunting rifles that will give me right at 1/2" @ 100yds, how much more than that is needed to hit the vitals of a big game animal?

I think that "need" might not be the appropriate term. Obviously, to me anyway, 1/2 moa is more than sufficient for hunting as you have also implied. I think that 1.5 moa is acceptable for a hunting rifle used to moderate ranges (400 yards). Half the fun is learning what works. Why not figure out what works the best while we are at it?

[hounddawg]

How much accuracy do we really need in a hunting rifle? I've got several hunting rifles that will give me right at 1/2" @ 100yds, how much more than that is needed to hit the vitals of a big game animal

Now if you are asking what the difference between a 1/2and a 1/4 I'd say not much however

inaccuracy's are cumulative. Rarely will you get a animal that stands perfectly still, a wind gust can come from any direction at any time, unless you are hunting from a stand you will rarely have any more support than a shooting stick at best. Any one of those or all could be the difference between a clean kill or having to track a blood trail. The difference between a 1/2 MOA rifle and a 2 MOA rife is that the 1/2 gives you 1 and 1/2 inches of insurance for all the other things than can go wrong and cause that bullet to hit outside the kill zone.

[Bfglowkey]

Factory ammo from Hornady info: They rarely list the powders they use anymore in factory ammo. Most of the time it is a proprietary blend. Take one apart and see if you can visually match it to another? Rumor has it that if the box is of the Superformance line they use their Superformance powder but I cannot verify or deny that rumor so take it for what it is.
Accuracy is one of those things shooters like to use to feel better about themselves lol. Opinion only: Those who tout how accurate their gun is are newer shooters and searching for validation that they are capable, while older shooters saying 1 MOA is plenty good dont spend much time honing skills and downplay the MOA size and offer game results for validation.
Me, I have been guilty of both example extremes depending on if I am able to get a load and gun to shoot to a self imposed standard of .75 MOA out to 300yds ( just at 100 is not always the full picture) but then again I have time to burn being retired.

[Unclenick]

My understanding is that Hornady has more than one Superformance powder because the ranges of cartridges and bullet weights they make available in that line are too great for just one powder to be optimal for them all. The powder Hodgdon sells is just one of them, and we can't copy all of Hornady's loads with just one of the powders.

Blending in powders is not normally of different powder types, but rather of different lots of the same type that came out of the base process with different burn rates. The blending is to adjust the net burn rate of the blend toward a nominal value. Exceptions may exist.