Chrony Christmas

[CrossHairs]

I bought myself a Chronograph for christmas this year (Chrony Gamma with a the printer) and hit the range this morning with a few loads to see what was what.

It was actually very interesting to see the effect of muzzle velocity over impact point. I know that a lesser velocity will mean a lower strike point, but it was nice to see it in action.

Anyways, here is a picture of a ten shot group with my savage 12 VLP in .223.....guess which shots have the highest and lowest velocity of the ten!? And yes, there are eight shots all through that nice little hole.

I'd found in the past that my Savage likes to use a lighter load for the 55 gr bullets (V-Max) I was actually quite surprised at how slow they were going! Might have to try something at the other end of the spectrum for fun too!

I was also quite surprised at how effective the IMR 4064 powder was too...with the general shortage that we've had, I grabbed some to see how effective it was for a .223 round.

With a real lack of information on the 4064 for the v-max I extrapolated a load from other loads I had used and some other information that I had available. Worked out pretty well, and the actual muzzle velocity is about 100 fps lower than I had predicted...now I need to test my comparative load to see how fast it was....it too may have been this slow!

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[rebelcop121]

Lucky you, You get to go out and shoot. I may have to wait until Spring. I did get out for a short time just after Christmas when we had a warm spell above zero. Back down to minus 14 today. Hard to use the Chrony in that type of cold and the powder doesn't burn at a consistent rate below about 20 degrees Faren.
On the flip side, your observation about slower bullets going lower isn't always the case, especially in heavy magnum handguns. Slower moving heavier bullets often print much higher...I'm guessing Muzzle Flip/Recoil has more time to affect the path of the bullet.

Greeting from the Interior of Alaska...LOL

 

[Gunner3456]

You nailed the reason I wouldn't reload without a chrony. Even a new batch of the same brand and type of powder will vary.

You are also right. That's really slow for a .223 which means you're almost defeating the purpose of the design of the round.

 

[Collateral]

That looks a little slow.
My Speer 13 shows a loading for IMR 4064 with a 55 grn bullet.

26.5 grns = 3143 fps
24.5 grns = 2843

 

[CrossHairs]

That looks a little slow.
My Speer 13 shows a loading for IMR 4064 with a 55 grn bullet.

26.5 grns = 3143 fps
24.5 grns = 2843

Interesting.....that's quite a bit higher load for sure.

 

[Collateral]

The IMR powder site shows:
55 GR. SPR SP IMR 4064 .224"dia. 2.200" COL
23.0 2867 40,300 PSI
25.7C 3201 52,600 PSI
all from a 24" barrel.


Accurate Shooter site shows:
IMR-4064
24.8grn = 2700
25.3grn = 2800
25.8 = 2900
from a 20" AR
http://accurateshooter.net/Downloads/sierra223ar.pdf

 

[Gunner3456]

I forgot to say contrats on the chrony! At least you get a reading on how you're doing.

How many guys happily load along and have no idea what they are producing?

Now you have the chance to dial it in.

 

[CrossHairs]

I forgot to say contrats on the chrony! At least you get a reading on how you're doing.

How many guys happily load along and have no idea what they are producing?

Now you have the chance to dial it in.

Which is why I bought it.....I like the intrinsic value of absolutes!

 

[bugeye]

That one big hole is impressive.
One of the debates online about Savage 223's is that they have a 1-9 twist rate, so light bullets end up spinning at about 250,000 rpm, near the max rate the bullet can stand and stay together. This seems to be the reason for using slower - heavier 67 - 69 gr. bullets in a fast spin barrel. Less powder makes for slower speeds and is another way to avoid the uber spin.

I know nothing myself, just saying what I've read. My new 223 is shooting about 2.5 moa so far, I hope it's only the POS scope I have on it.

 

[CrossHairs]

That one big hole is impressive.
One of the debates online about Savage 223's is that they have a 1-9 twist rate, so light bullets end up spinning at about 250,000 rpm, near the max rate the bullet can stand and stay together. This seems to be the reason for using slower - heavier 67 - 69 gr. bullets in a fast spin barrel. Less powder makes for slower speeds and is another way to avoid the uber spin.

I know nothing myself, just saying what I've read. My new 223 is shooting about 2.5 moa so far, I hope it's only the POS scope I have on it.

I have some 60 and 69 grains to try out as well. I'll be interested to see how they perform. I did find that 50 grain Speer's did not do well in my Savage at all, spin rate may be part of the problem there. That said, I shot some 50 grain v-max's at 200 yards this week and was really surprised at how well they did...certainly getting m.o.a or better at that range! I've replicated the load to see how fast they were travelling!

This is part of what I like about handloading and shooting, there are quite a few variables to consider, and that's before you even get your finger on the trigger! So when it comes together, life is good!

 

[Gunner3456]

Most AR-15's ship with 1:9. They shoot the 55 - 62 grain bullets just fine. It's when you get over about 75 grains that you need a tighter 1:7 twist. That's not due to the weight of the bullet but rather the length, or the aspect ratio.

The really light (short) bullets would prefer a 1:12 twist, but 1:9 is the overall best compromise if you can have just one. My 1:9 twist AR's will shoot MOA or better with 55 and 62 gr bullets. I push 55 gr fmj (most of what I shoot) at 3150 fps. I wouldn't worry much about the 50 gr.

It might be time to check overall length of the bullet. You want about .020 gap before the bullet contacts the riflings. I do this manually with a dummy round (no primer or powder) until the riflings mark the bullet, and then set the die to seat the bullet down another .020. (measure OAL when touching, then reduce OAL .020.)

This setting varies with different brands and shapes of bullets; and is another great reason to buy components in the largest lots you can afford.

$.02