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Discussion Starter · #1 ·
Just wondering if anyone has a favorite load for long range accuracy for the 223 with 1:7 twist. I worked up a load with Hornady 75BTHP and 26gns of BLC2 and went to the range today and tried it but I can't get it to group better than about 1.75 MOA. I'm shooting them from a White Oak Varmint upper which should be very accurate. I'm currently using Magtech primers as they are all I could find at the time and I think this might be part of the problem. Anyone else tested these and if so what were your results. I want to eliminate them from the load but I'll have to find some other small rifle primers first and we all know that can be a problem right now.

I checked the scope and the rings just to be sure and all is tight. Scope is brand new and I don't think it is a problem. I don't think I'm the problem either as I can usually easily shoot sub MOA as long as the rifle is accurate and I was really concentrating hard today but just couldn't make it group. I've got some Varget on hand so if anyone has a pet load developed with it and heavier bullets please share.
 

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Since BL-C(2) is a spherical powder, have you deburred your flash holes? I found AA 2520 to be surprisingly sensitive to that, and now do it to all cases I'm loading with a spherical propellant or any other fine grain powder.

Are you seating the bullets out long? At standard SAAMI length, QuickLOAD gives me about 58,000 to 68,000 psi from your load depending whether I use commercial or military case capacities, tight chamber or looser chamber. Potentially pretty warm. Groups opening up are a common pressure sign.

Take some of your fired, but not yet resized and decapped cases and weigh them to find an average one. Record its weight with the spent primer still in it. Fill it with water just flush with the mouth-no meniscus. Tap any air bubbles out, and with it level and gas-free, weigh it again. The difference is the fireformed case water capacity in grains, and that is what affects peak pressure. That's what the software needs to estimate pressure more accurately.

What is the length of the barrel on your gun?

I have run the 77 grain Sierra MK's in my 7 1/2" twist barrel with 23.8 grains of Varget with good success. Varget doesn't seem to care whether the flash hole is deburred or not. That is a compressed load. This is my service rifle match gun, so the barrel is 20". That stubby 77 grain bullet is seated to 2.260" for magazine feeding, which is why it is compressed. Winchester cases. Federal 205M primer. This has been a good 300 yard rapid fire load for me.
 

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Discussion Starter · #3 ·
Nick, thanks for the wisdom. Yes I did debur the flash holes since I thought the same as you. The 26gns is max per my manual and also from Hodgon's site. They estimate 49,500 CUP at a seating depth of 2.25. I worked up to that load with no pressures signs. In fact my primers hardly flatenned out at all even with the max load. The spent factory cases I have looked at have much flatter primers. I'm loading them as long as I can and still get them to feed in the magazine which is between 2.25 and 2.26". My barrel is 20" Wilson with a heavy contour. I don't know what their tolerances are but they state it is air gauged. Regardless, I think it should be a shooter and easily capable of sub MOA groups, thus my head scratching.

I have worked up some test loads with some Hodgon Varget and some Black Hills Match brass. I want to give the stick powder a try and see if maybe the ignition was a problem with the ball powder, plus its estimated pressures are lower with a higher velocity than BLC-2. I think the problem may be a combination of the ball powder and Magtech primers. Since I can't immediately eliminate the primer I'm going to eliminate the powder and give it another try. I'll let you know what the results are. If you have any other suggestions feel free to share them.
 

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If I do the pressure conversion by Bramwell's approximation I get 49.5 cup -> 56,000 psi, give or take. My power curve fit to Bramwell's data, which has a slightly better r² test result than Bramwell's puts it closer to 57,000. So, I'm guessing that the cases capacity used in developing the manual might be a grain of water greater than the one I used? That would still be normal. 55,000 psi is SAAMI's upper limit, but the CIP uses 4300 bar, which is 62,366 psi as an upper limit. You are likely inbetween the two.

I recall hearing the magtech primers have heavier cups than Winchester and Federal? Closer to the CCI #41. That may explain why your commercial rounds have flatter primers? In addition to cup hardness, difference in case headspace insertion length often affects primer appearance, too. In particular, if you put a brand new case in an RCBS Precision Mic or the case comparator on a Hornady (nee, Stoney Point) caliper adapter and measure it, then measure it again after firing and resizing, you find the sizing die never quite puts it all the way back. This means, when the brass is new and the firing pin shoves it forward and the firing primer backs out and pushes it firmly into the headspace determinant (the chamber shoulder in the .223), that primer has backed out further than it will firing that same case after resizing. This inflates the head of the primer more, making it flatter when the case stretches back and reseats it. Bottom line, new brass gets flatter primers, all else being equal. That and cup hardness differences are why primer appearance is not a very reliable pressure indicator by itself.

I have also heard of some folks having some largish MV extreme spread with Magtech primers. Others seem to have no problem. Have you got any chronograph results? I would beg borrow or steal some Federal 205 or 205M primers to compare. My local Gander Mountain had 205's on the shelf last time I looked. They are both mild and consistent. On another thread I recommended to a .221 Fireball shooter that he change from Remington 7 1/2 (a magnum BR primer) to the Federal 205M primer because he was having high extreme spreads. He did, and it cut both the ES and the group size roughly in half for him.

You hear people say Federal primers are too soft for floating firing pin gas guns, but I've never had an issue as long as they were the required 0.003" to 0.005" below flush with the face of the case head. The Sierra manual's section on loading for military gas guns says that was their experience, as well. They had put many thousands of 210M's through Garands and M14/M1A platforms without incident. Federal published a defense against complaints their primers were too sensitive in Precision Shooting in the early 90's, IIRC? They pointed out that while it was true their were more match reload slamfires reported using their primers than with others, it was also true that more match shooters reloaded with their primers than any others, so that was an inevitable consequence. Handloads with high primers are almost always the actual culprit in slamfires. Also, the AR bolt is inherently less prone to slamfires than the Garand and M14 designs, anyway. So I keep using 205M's for .223 reloads. I still use 210M's on the '06 and .308, too, but have gone to #34's where my load doesn't fill the case well. The magnum primer seems to help when there is empty space to pressurize.

Do you have a measured velocity for this load? What I have in mind here is to use Chris Long's optimum barrel time test. If I have your fired case water capacity and your average real velocity, I can tweak the powder burn rate to get a match to your lot. With that, the barrel time can be determined and compared to Long's projected sweet spot times. Might be worthwhile?

Also, have you been measuring the finished cartridge runout you are getting with these bullets? Their ogive shape might not like your seater die?
 

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Discussion Starter · #5 · (Edited)
Nick, I may be getting a little less pressure than suggested by the tables. I sized the cases just enough to make sure that they functioned properly in the gun. I know they are a little tighter in the chamber than a factory round would be. In fact the first few I did would not let the bolt lock into battery. I turned the die down just a little and resized them until they would reliably chamber and lock up the bolt. Thus I probably have a little more capacity than estimated, although I have not done the water measurement test yet. I'm going to check at my reloading supply shop (only one in my area) next week and see if they have any other small rifle primers but the last time I was in they had none. In the meantime I'm going to run some test loads of Varget through the rifle. I think it may give more consistent results with this Magtech primer. I don't have a chronograph yet (hoping Santa is bringing one). With my other calibers I usually just stay off max loadings by a grain or two and stick only to published data so I've not really worried about it too much. I'm not hung up on loading the fastest bullets possible and usually just load them hot enough to get the job done. With that being said, I intend to try and stretch this little 223 out to some fairly long ranges and wanted to get the velocity up a bit but not at the detriment of my appendages or face. I'm going to see if the Varget does any better and go from there. I'll let you know what my results are but it will be a few days before I get back to the range as it's been raining nonstop here for two days (7 inches in 48 hours) and is still pouring as I write this. Once the rain stops a cold front is coming and we are supposed to get snow. Gotta love the weather in Arkansas.

Oh and by the way. I think you are correct in your assessment of the primer cup on the Magtechs. They seem to have a pretty hard cup but I looked at hundreds of different once fired cases of various brands and everyone of them had flatter primers than my loads did. I'll get around to measuring the water capacity and give you that data in a while. Thanks for the help.
 

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Discussion Starter · #6 ·
Okay, here is the data. My average case weight is 97.7 grains. That is an average of ten fired cases. I took a case that weighed exactly that amount and came up with a water filled weight of 128.6 grains. So it looks like my water capacity in grains is 30.9. What pressure and velocity does Quickload give with that data?
 

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In loads with peak pressures roughly 30,000 psi and up, pressure expands the case to fit the chamber and stretches the head back before the peak is reached, so it doesn't make any difference whether it was sized more or less before hand. With those peaking below 30,000 psi, the sized case capacity does matter.

At 30.9 grains and 2.250" COL, QL gives 61,648 psi. Still above what the Hodgdon cup likely converts to, but under the CIP peak value for the cartridge. With the program's ideal 20" barrel and the default burning rate, this gives a predicted 2,895 fps. A pretty fair clip for that bullet weight. If Santa is nice, I'll be interested to hear what actual velocities you are getting so we can tweak the powder burn rate. Also, if you don't mind, get an actual average weight for the bullet.

Finally, go to the top of this handloading forum and take a look at the new sticky by Tang on Berger VLD loading. It may apply to the long A-max design as well?
 

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Discussion Starter · #8 ·
Yes, I just read that post about the Berger bullets. I found it quite interesting. I will go weigh 10 bullets and get you and average.
 

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Discussion Starter · #9 ·
Well, those little Hornady bullets are quite consistent in weight. I got an average of 75.03 grains. All of them fell between 74.9 and 75.1 except for one oddball that was 75.4 grains.
 

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OK. No adjustment for that. Now I need to hope Santa lets you get velocity numbers!
 

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Discussion Starter · #11 ·
If Santa don't bring me a chrony I will be ordering one just after the first of the year. Thanks for all the help Nick, I'll let you know how the Varget loads do.
 
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