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Old July 6, 2012, 08:11 AM   #1
rebs
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looking for a factory duplicate load

Does anyone know how much H335 powder would be a factory duplicate load for a 223 55 gr bullet ? In my loading manual it only gives one factory duplicat load in one powder and its not H335.
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Old July 6, 2012, 08:43 AM   #2
Brian Pfleuger
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How many fps is factory ammo? What is the fps range of h335 loads? Do they overlap? If so, extrapolate the appropriate charge and work up to it if it's above minimum. If not, you can't.

Why the duplicating factory ammo? it's not special.
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Old July 6, 2012, 11:18 AM   #3
rebs
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I shot a box of remington 223 55 gr and they were really accurate so I figured I should be able to duplicate their load.
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Old July 6, 2012, 12:08 PM   #4
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Start with 23.5 grains and the RP 55 grain bullet and work up 1/2 grain at a time until the desired accuracy is achieved.
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Old July 6, 2012, 06:13 PM   #5
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Accuracy, in my experience, is usually VERY strongly related to a particular velocity in a particular rifle ... and it seems pretty rare that fastest is best. The best thing to do is run a couple of the known accurate loads across a Chrony and then work your load up to match THAT velocity in YOUR rifle ... given, of course, as Brian mentioned, that the target velocity is reasonable for your new powder.

Personally, I cannot imagine trying to load accurate and safe ammo without a Chrony ... but then I haven't stuck to reloading manual loads in a LOOOOONG time ... I tend to go with QuickLoad simulations and Chrony data and use the manuals as a safety check for what should be reasonable.

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Old July 6, 2012, 08:11 PM   #6
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I wonder which factory the loading manual claims to duplicate? If it's a Hornady or Speer manual I suppose they could give their recipe. But since factories use different bullets and/or powders for their particular loadings, "factory load" is a pretty vague term.

Are you using Remington bullets? That would be a good start.
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Old July 6, 2012, 08:46 PM   #7
rebs
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I am using Hornady bullets
I'll do as suggested and start at 23.5 and work up from there
thanks for the replies
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Old July 6, 2012, 11:44 PM   #8
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The last lot of Remington UMC I shot through my chronograph showed 3110-3125 fps from a 20" barreled AR. To duplicate similiar velocity with H335 powder you'd need in the range of 24.6 to 25 grains. Start just a little lower in the 24 grain range and work up to the above charges. The most often said accurate 55 fmj bullet is the Hornady 55 fmj. Use a recommended primer for semi-automatic rifles. Don't use RP 6 1/2 primers in .223 loads. I use RP 7 1/2 primers in .223 loading with the above charges. Overall lengths using 55 fmj bullets range from 2.200 up to a maximum oal of 2.250". It depends on which bullet you use. Some are long sharp pointed and 2.250" would be correct while others have blunter rounded tips and they usually end up from 2.200-2.230". It's sometimes hard to duplicate factory load accuracy but experimenting can duplicate or better factory load accuracy. H335 is the perfect powder for 55 grain .223 loads. I seat Hornady 55 fmj's at 2.220" oal and they work in my AR's from 2.215 to 2.230".
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Old July 7, 2012, 03:49 PM   #9
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Quote:
Originally Posted by rebs
I shot a box of remington 223 55 gr and they were really accurate so I figured I should be able to duplicate their load.
As I understand it, barrel harmonics tend to support your idea, but the vagaries of internal ballistics trip that up a little. How fast the bullet accelerates inside the length of the barrel may cause your barrel to flex (or "whip") differently.

You are on the right track, but will probably still need to do some "tweaking" of the load to achieve the tightest groups and/or the same point of impact.

Do get a chronograph. It will help tremendously.

Good luck.

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Old July 7, 2012, 05:16 PM   #10
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I my experience, accuracy tends to be related to bands of barrel times in a particular gun. For a given muzzle velocity, a faster powder will produce a shorter barrel time, and a slower powder a longer barrel time, so just matching velocity isn't necessarily enough. You also need powders whose pressure profiles tend to result in similar barrel times.

Since Remington will have used a bulk grade powder that doesn't necessarily match anything available to handloaders exactly, you may never duplicate what they did exactly. It is not safe to simply load to the same velocity they got unless you know your powder burns no more quickly than theirs did at the pressures their ammo produced. If you try to do it with a faster powder, you will be at higher peak pressure by the time velocity matches, and your barrel time will be shorter, to boot. Also, you have to be using the same brass (to get matching powder capacity) and the same primers they did. The brass is usually less critical in .223 than in some other chamberings, as they little cases seem to vary less from headstamp to headstamp than most, but I've seen primer change alone raise pressure enough to increase velocity almost 5%, so that's a critical factor.

So, go ahead and start development with your powder choice at a minimum load and work up, as advised, but be prepared to stop at the best accuracy load and realize it might be producing either less or more velocity when you do.

Also, with H335, being one of the older spherical propellants (it is canister grade WC844) you will likely get more consistent ignition from magnum primers. CCI, in particular, reformulated their magnum primers in 1989 specifically for these military type spherical propellants from St. Marks Powders (the OEM maker Hodgdon buys it from). If you look at the CCI primer application chart, you'll see they refer to their small rifle magnum primer as the 450 Mag for spherical propellants. Their #41 is the same primer with a differently shaped anvil to reduce sensitivity for military style rifles with floating firing pins, thus to mitigate slamfire risk to some extent. I've also had excellent ignition consistency with these powders using the inexpensive Russian made TulAmmo KVB-556M NATO spec primers. The Russians have a strong target shooting culture, and in my guns and in some other tests already published on the board, they have produced about half the velocity spread of others.
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Last edited by Unclenick; July 7, 2012 at 05:21 PM.
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