uncharted territory

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spitballer

spitballer

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Frankly I'm astonished at the pressure and velocity I get with a barrel that's just 6" over the 24" test barrel used for .223 data, with the same 12" twist. With 55 grainers I can make use of the slowest powder, but not 64's without piercing a primer. Is useful data for target-length barrels available anywhere? Not asking anyone to go out on a limb here just need to know if others have had to use something slower like H414 for 64's thx
 
spitballer wrote:
uncharted territory
Click to expand...

Nice pun.

I have no experience with using something like H414 in a longer barrel, but following the uncharted territory metaphor, I will say in my best pirate immitation, "Arr! Caution, matey, there be Kabooms out there."
 
The velocity increase isn't surprising, generally speaking longer rifle barrels like to yield higher velocities.

Pierced primers is unlikely an effect of your longer barrel.
The pressure peaks within inches of the bullet beginning to move, not 30" away.
You would look at other causes of excess pressure.
Make sure you are measuring the powder correctly, check your
chamber dimensions, weigh your brass to see if it happens to be heavy
(heavier weight means less capacity within the case), weight your bullets
to make sure they are the weight you think, compare bullet and groove diameter,
etc. etc. etc.

If you cannot find any cause of the increased pressure, you can compensate for it.
Since you get extra velocity with the extended barrel, you can afford to
cut down on powder charge to reduce pressure (and barrel erosion).

Although it may be counter-intuitive, you can also shorten your OAL.
Like Weatherby cartridges, you give the bullet a longer jump to the lands
and it helps smooth out maximum pressure at the chamber.
I know common lore says it is more accurate to get the bullet closer to the lands,
but when your pressure is blowing primers you need to address pressure first.
And many rifles (like Weatherby) do not suffer from the jump. They are accurate.
 
What primers are you using also? Feds (if i remeber correctly) would pierce when ccis and wins looked fine.
 
That's very normal.

There are other barrel dimensions and ammo variables that make that happen all the time.

I've shot the same 308 Win ammo in half a dozen 24" barrels producing over 100 fps spread in average velocity.

You're using too much powder. Did you start with loads 10% below listed maximum charge weight?
 
Thanks for constructive input and sorry for the delay, I haven't had internet access for a couple of days.

The pierced primer was a CCI #400 using 26.1 grains of Varget with the 64's. Velocity for the first round was 3275, but the second round (pierced) was an astonishing 3375 fps! Admittedly the standard primer cup probably didn't help but the point is that the speed of the powder seemed to have a direct bearing on the speed of the projectile because when I switched to a slower powder the projectile slowed down as well. I found this to be counterintuitive: normally a faster powder with shorter pressure duration results in slower velocity, and this is what threw me off balance. But apparently the longer pressure duration (and I'm going to have to respectfully differ with Antz here, I suspect that a longer barrel does result in more effective pressure as a result of duration) of the longer barrel allows the projectile to begin to match the speed of the expanding plasma itself instead of relying on a leaky elasticity like a quicker powder - or at least this is my take on it. All I know for sure is that when I switched to the slower H414 I got a slower velocity, and the heavier cups of the CCI #450's seem to be more durable, too (LoonWulf your intuition correct here IMO). I'm still a little uncomfortable with the velocity but I can read primers so I'm thinking I should be okay at this point.

Again, thanks for all the helpful input. Also a word of thanks to Hodgdon for putting the venerable .222 Rem Mag back in the lineup this year: the pre-.223 data regarding H414 is of genuine value to target shooters IMHO.
 
Well I hit the range this morning with a slightly bigger charge of H414 and got better looking groups with the 64's. I've been keeping Ironworkerwill's advice in mind (from another thread) and focusing on reducing vertical spread, and this week's groups were definitely tighter in this regard so it would appear that I'm indeed headed in the right direction and still short of the optimum load. As an added bonus I seem to be getting a cleaner burn also.

But I could use some advice from an experienced reloader regarding an unnerving pressure sign:

I've gotten pretty good at reading primers and the CCI 450's are tough to flatten out, but obviously they do start to become flat at a certain point. So far I've only been getting one flattish one out of each batch of ten, generally on the third or fourth shot. Why the subsequent rounds don't produce flat primers is beyond me, but I'm guessing that it has to do with the fouling cycle. Anyway, my question is this: is there any reason why a safe max load can't have a flattish primer? I mean, obviously at some point I'm going to have more flat primers than round ones if accuracy requires an increasing charge - is this par for the course? Will safe max loads normally flatten them?

I'm withholding data regarding velocity and charge weight for the sake of clarity, because obviously I'm in uncharted territory here - I just need some input from an experienced reloader regarding what is normal with regard to safe max loads and flat(tish) primer cups. thx in advance
 
I've used h380 in .223 too. It was impressively concussive out of the 16" barrel. I can't remember where I found the data and don't really remember the groups. I'm sure if it worked well I would have remembered;). Although I love ball powder varget had done very well for me in 223.
 
Are you working with a compressed charge? I use H-335 exclusively in the 5.56 and a full charge is well up in the shoulder...so anything slower is going to normally take up even more room especially considering the 64 grain projectile. If it's being loaded to an over SAAMI OAL to make room for powder or get the projectile closer to the lands both could be helping with the pressure variable. How close to the lands are you now? And how much room under the projectile do you have for the powder?
 
...and I'm going to have to respectfully differ with Antz here, I suspect that a longer barrel does result in more effective pressure as a result of duration...
Click to expand...
That's not what he said. The pierced primer is not the result of a pressure curve of longer duration (longer barrel = longer pressure curve duration = collectively more effective pressure = more area under the pressure curve), The pierced primer is the result of a higher peak pressure.

A longer barrel will result in longer pressure duration and therefore higher velocity but it won't result in higher peak pressure because peak pressure occurs very early in the bullet travel--before there's any chance for a longer barrel length to have a significant effect.

If you are piercing primers, it is not because your barrel is longer, it's because your pressure peak is too high--you're loading the cartridges too hot.
 
JohnKSa said:
That's not what he said. The pierced primer is not the result of a pressure curve of longer duration (longer barrel = longer pressure curve duration = collectively more effective pressure = more area under the pressure curve), The pierced primer is the result of a higher peak pressure.

A longer barrel will result in longer pressure duration and therefore higher velocity but it won't result in higher peak pressure because peak pressure occurs very early in the bullet travel--before there's any chance for a longer barrel length to have a significant effect.

If you are piercing primers, it is not because your barrel is longer, it's because your pressure peak is too high--you're loading the cartridges too hot.
Click to expand...
I agree.

Although, I really don't like to use primers as a sole indicator of high pressure.
 
You asked: "Anyway, my question is this: is there any reason why a safe max load can't have a flattish primer?" The max charge you are referring to is only safe in the barrel they tested it in. That does not mean it will be safe in your barrel and obviously it's not. Every published data source tells you this.

If you are piercing primers the charge you are using is too high so don't keep using it just because it's printed in some book or site.

The only other reason might be, the 64gr bullet is longer than the 55gr bullet and if you are bumping up against the rifling that would increase the pressure, sometimes by a lot.
 
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