Reloading 223, powders & filling ratios


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HisDivineShadow
March 22, 2013, 04:09 PM
I'm going to start reloading .223 with my own cast bullets pretty soon, I got a 65gr and 75gr design I am going to work on, I think the 75gr one will be more suited to my needs though, easier to work with heavier bullets and slower velocities.

I am limited to VV powders where I am so I was looking at VV loads on lapuas website:
http://www.lapua.com/en/products/reloading/vihtavuori-reloading-data/relodata/5/44

The 77gr Scenar with N135 looks like an interesting candidate for load substitution, I checked it out in QL and then replaced with my own bullet (the 75gr) and got velocities just where I was hoping, 2150-2200fps.

Now the cast bullet is shorter by a lot since it's all lead with a gas check so that leaves more empty space in the chamber, starting load is an 89.5% fill ratio, vs 94% for the original bullet. This is the crux of my question, having heard of the phenomenon of detonation and one of it's primary causes (slow rifle powders and low filling rations) I'm being a bit paranoid about this.

I'm wondering if there's some kind of accepted limit or existing data for certain powders that indicate what's an acceptable minimum filling ratio? Gut feeling says 89.5% filling ratio is just fine and anything above 80% should be fine too, but it'd be my face and not my gut who took the risk.

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rcmodel
March 23, 2013, 11:55 AM
This is the crux of my question, having heard of the phenomenon of detonation and one of it's primary causes (slow rifle powders and low filling rations) That seems to be a phenomena limited to very over-bore magnum calibers and reduced charges of very slow magnum rifle powders.

I don't think it applies to standard calibers like .223, .308, 30-06, etc.

Here is my take on it.
http://www.thehighroad.org/showthread.php?p=6976324#post6976324

I also believe that a powder with a burn rate closer or faster then H-4895 would be your best choice for lead bullets.
Perhaps N130?

See this for another angle on powder burn rate suitable for reduced loads.
http://www.hodgdon.com/PDF/H4895%20Reduced%20Rifle%20Loads.pdf


rc

HisDivineShadow
March 24, 2013, 12:03 PM
Thanks for your answer. It is something of a mystery right now what will work best, I was going for using real load data as a base, N135 and bullets in the 75gr area seems to provide the numbers I am looking for in "simulation". Been feeding it into QL and testing the various powders.

N135 got me the velocities I wanted (2100-2400fps) while the others seemed to ramp up to 2600+ easily, N135 provided good filling ratio (start load is 90% filling) and the burn should be slow enough to cycle the gun. I have been considering faster powders of course, N120 is another prospect I am looking at, less filling though for the speeds I desire, but I might be giving filling ratios too much importance.

Once I get some missing parts for my 223 setup I will continue some experiments I've been doing using N110. I was able to try a few shots last night and found that 14gr of N110 would eject the brass, not sure if it would cycle though as I had only one of each charge I tested, the others where 10,11,12,13 grains. It hit the plate I was shooting at 70 yards-ish at least. Maybe there's a load in the 14-15 range that will work....

Walkalong
March 24, 2013, 05:03 PM
I really like N130 in .223 with 55 Gr jacketed stuff. I bet it works well with heavier lead.

Mule
March 24, 2013, 05:41 PM
HisDivineShadow,

Two questions for you;
You indicate you are using a semi-auto rifle. I have been reluctant to use cast bullets in my AR because I have been led to believe the lead will foul the gas port. Are you concerned about lead fouling?

Are loading components hard to find in Finland? Availability of components is at crisis level in the States.

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