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Thread: Attention Myth Busters!

  1. #31
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    Excellent info

    That was a very indepth study of both options. Well done.

    Now let me throw in a few wrenches to muddy things up again.

    1) 80gr MK is the lowest BC bullet in this class. The 80gr Amax is .45 to .49 (depends alot on the pipe). The 80gr Berger is listed at .47ish.

    These two bullets put the BC of the smaller cal right in there with the 180/190gr match bullets.

    2) you have chosen a 223 velocity that is SAAMI speced. However, the 308 velocity is HOT. SAAMI puts the 308/155 combo in the 2800/2900fps range. Let's say 2850fps.

    For the 308/190, SAAMI/load manuals peg this at 2400/2500fps. Say 2450fps

    Don't get me wrong, I know all about what the 308 can do (been there and got the loose primer pockets to show too) but that argument can be applied to the 223 as well ie 80gr at 3000/3100fps.

    Redo the numbers using a 80gr Amax or Berger at 2900fps (readily achieved in a 26" barrel), the 308/155 at 2850fps and 190 at 2450fps.

    How about 90gr Berger (.517) at 2900fps, 155gr at 3000fps, 190gr at 2650fps?

    AHHHHH, things aren't so clear cut anymore are they?

    And that's my whole point. It is not an absolute that the 308 IS better. So much matters on the bullet, load, and accurate velocity. Some barrels are fast, others slow.

    What will the velocity be when the rifle is shooting its best?

    What will happen to the 308 barrel as it heats up much more over a 22rds relay? Will it walk all over the target?

    How well will the shooter fair 45 rds later?

    As said before, a fast 223 will trump a slow 308.

    The only definites are the 308 makes a bigger hole, heats up barrels, and recoils more....

    F(F) or F(TR) is one of the most interesting precision shooting comps because you have two very different cartridges that are so equally matched. Fine tuning and oddities can push one infront of the other then back again.

    Unfortunately, where I compete, all F class shooters are lumped together so I shoot F(O). Like to see what the scores are like when there are good numbers of each cartridge competing on the same weekend.

    Jerry
    Last edited by mysticplayer; 01-11-2008 at 09:34 PM.

  2. #32
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    Wrenches...

    I hate wrenches!!!

    1) 80gr MK is the lowest BC bullet in this class. The 80gr Amax is .45 to .49 (depends alot on the pipe). The 80gr Berger is listed at .47ish.

    These two bullets put the BC of the smaller cal right in there with the 180/190gr match bullets.
    C'mon Jerry, you know what I'm going to say to this...
    Of course if you compare .223 VLD's to .308 non-VLD's, the .223 looks good. If you compare apples-to-apples (VLD's to VLD's), the 190 grain .30 caliber bullets still has a higher BC than the .224 (.574 for the 190 VLD compared to .47'ish for the 80 grain VLD)

    2) you have chosen a 223 velocity that is SAAMI speced. However, the 308 velocity is HOT.
    Granted. I don't have any experience loading the .223, so I didn't know where 2900 fps is in the spectrum of realistic pressures, it just sounds hot to me. In fact, my Sierra reloading manual gives a max velocity of 2600 fps for the 80 gr SMK. Granted, the test bble was a 20" Colt. The Nosler manual doesn't list an 80 grain bullet, heaviest is 68 grains, max velocity 3030 fps from a 24" test bbl. Assuming equal pressure and KE at muzzle, this corresponds to just under 2800 fps for an 80 grain bullet. All this leads me to believe that 2900 fps is quite hot for the little .223, but I've never done it.

    The .308 velocity is on the warm side, but you know it's not too hot. Lots of guys get more than 2450 with the 190's too.

    And that's my whole point. It is not an absolute that the 308 IS better. So much matters on the bullet, load, and accurate velocity. Some barrels are fast, others slow.

    What will the velocity be when the rifle is shooting its best?
    I see what you're getting at here. It's possible that a .308 shooter has the misfortune of getting a bbl that likes slow loads. It's also possible that a .223 shooter will luck out and find a bbl that hums at max pressure. So it is possible for the .223 to beat the .308 in the wind, on an odd occasion. However, the odds are in favor of the .308. Both my Palma rifles and most others that I've known have liked 2950 to 3000 fps just fine with the 155's. I don't have much experience with the heavier bullets. The limited experience I do have indicates that 168's and 175 Bergers did best at high pressure.

    What I'm saying is that if it were very common for .308's to be more accurate at lower velocities, then your point would be stronger. Like I said, I don't have any experience with the .223, so I don't know what pressures they like. If you compare max charges for both, or the same % of max charge for both, and the same class of bullet (SMK, VLD, etc) I think the .308 will always have less wind deflection to some degree.

    What will happen to the 308 barrel as it heats up much more over a 22rds relay? Will it walk all over the target?
    This is a good point I didn't think about. The pace of shooting can be quite a bit faster in F-class than slow fire prone. I can see barrel heating playing a role more for the larger bore.

    How well will the shooter fair 45 rds later?
    Important consideration, it depends on the shooter. I know (few) guys who shoot 220 and 240 grain bullets out of big magnums all day long and turn in tremendous scores. I also know some who have tried and couldn't handle it.

    As said before, a fast 223 will trump a slow 308.
    I agree this is possible. But can you be sure your .223 will be 'fast'? More importantly, do you want to gamble on everyone else's .308 being slow?

    F(F) or F(TR) is one of the most interesting precision shooting comps because you have two very different cartridges that are so equally matched. Fine tuning and oddities can push one infront of the other then back again.
    Again, I agree. There are many things in favor of the .223 and a lot of shooters would do better with it.

    However, I maintain that in the long run... on average... the .308 is better in the wind... even if that's the only advantage of the larger round.

    Unfortunately, where I compete, all F class shooters are lumped together so I shoot F(O). Like to see what the scores are like when there are good numbers of each cartridge competing on the same weekend.
    That's too bad. I'm sure those who shoot .223's and .308's know who each other are, and compare notes afterwards, even if it's not an official class.

    Thanks for adding your thoughts Jerry. I know you are a very good shooter, and you know what you're talking about. In the hands of a really good wind reader like yourself, I wouldn't bet against the .223! I just wish I knew more about the pressures and velocities that the .223 is realistically capable of so I could better understand the comparison.

    -Bryan

  3. #33
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    Brian,

    One thing to consider - 155gr is the limit for F/TR north of the border. As I understand it, 175s or 190s would put one in the Open class. Same for bullet weights above 81gr in .224 cal.

    I think this might be getting into the area of calculated vs. empirical data. As an example: you can calculate how the .223 *should* be better til the cows come home. A fair number of people (NRA High Power) seem to have tried that route already, and opted for something else . A few people maintain that they shoot better/ use less wind/ have better looking kids using the .223... but the majority seem to have moved back to .308. Similarly, I've spoken with some prominent Palma shooters who provided anecdotal tales of shooting 155gr loads on the line side by side with shooters using 190gr loads. They came off the line with less than a 1/2 minute difference in windage, but a steady diet of 190s proved harder on the barrel over time. Such tales from shooters of that level of experience are hard for me to completely discount.

    There had been some smack-talking going on before SOA/FCNC in '07, the usual tripe from the heavy bullet crowd about the whoopin' they were going to lay down on 155 shooters There was discussion about getting some people from each camp together during the squadded practice day before SOA and after getting both shooters centered up for teh conditions, have them hold center and fire on command from a coach. Subsequent plotting of the shots fired at the same time under the same condition would hopefully provide some 'hard' data vs. calculated or anecdotal. Sadly, no heavy bullet shooters showed that day, and the test never happened. FWIW... there was *one* .223 Rem @ FCNC, and suffice it to say that while Lapua 77s did indeed raise some eyebrows @ 600, 1000yds was a whole 'nother story. I do wonder how he would have done w/ a more suitable bullet.

    It would be an interesting (and hopefully educational) project for someone to put together locally... even if just at 600yds. Chronograph the loads before hand to get an average MV, have shooters firing known good loads from known good rifles, and line up a .223 Rem shooter firing 80s, and a couple .308 shooters firing 155s vs. 190s or 210s. I'd be willing to try it but I can only fire one gun at a time

    In the end... I think it comes back to what F/TR is all about (to me)... you can worry about theoretical 'advantages', or you can hold harder and read the wind better, and still end up coming out smellin' purty good


    Monte
    Last edited by milanuk; 01-11-2008 at 10:49 PM.

  4. #34
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    milanuk, that is such a simple solution to a very complex problem. The key is to ensure that all test rifles can shoot similar accuracy levels, say 1/2 min so you don't get huge distortions due to mechanical accuracy problems.

    zero all the rifles for elevation at distance but retain a zero windage setting. Line them up, call and fire. See where the bullets land. Repeat 10 times on maybe two targets so you can get some idea of how things fared. Note wind conditions for each shot to help diagnose relative wind drift.

    I'll see if I can get some 308 shooters to help with a test in the spring.

    Bryan, thanks for your vote of confidence on my wind reading skills. You give me more credit then I deserve. It is surprising how well you can do when you just close your eyes and pull the trigger.

    As for not knowing what type of 223 I would have, the answer is preparation and is no different then any shooter on the line.

    If I were to campaign a 223, I would have the best damn 223 I could make on the line. I would know that I had a rig that was competitive or else why even bother shooting it?

    Up here, we are limited to 80gr 22cals and 155gr 308's for F(F). That narrows down things alot. Now you just have to optimise your poison and learn how to drive it.

    As for 308's performing better then SAAMI speeds, yep, that's a no brainer. However, I have been blessed with a few slow pipes so dud barrels are certainly out there.

    Recoil and barrel heat are going to be the limiting factors in the super heavies in a 308. The case capacity is simply too small to get these bullets moving fast WITHOUT excessive pressure.

    No matter how fast you go, if that barrel starts warping after 12rds on a hot summers day, you are pooched. The 223 has a huge advantage here.

    What I think SHOULD happen is that both the 223 and 308 be regulated for muzzle velocity to keep all shooters safe.

    Yes, we can run up the velocities with 100% function but how much pressures do these loads actually have?

    I know that proof loads will extract easily from a commercial action let alone a BR quality action. No primer pocket leaks. No real obvious pressure signs.

    A 155gr at 3000fps or faster in some rifles might just be proof load type pressures. There is simply no way to know by guessing.

    I have heard of some shooters saying their 208gr loads at 2700fps were without pressures signs. I don't care if you use a 32" barrel, that is in 300WM territory.

    Here is something that should be of interest to those looking for 'screamer' performance.

    The 223 with its smaller case head and small primer actually can withstand MORE pressure. The brass around the case head is proportionately stronger. The bolt thrust is less and the camming force of the bolt higher on the case head.

    Get creative with throating lengths and you can squeeze another grain or two into that case. In such a small case, that is ALOT of juice.

    Why some are pushing 80gr bullets to 3000/3100 fps.

    SAAMI, nope. Safe, debateable.

    I am sure someone will come up with an over the top receipe that might even shoot accurately.

    That person may even win a few matches and then...

    We have PPC type time bombs in F class rifles.

    I am going to do some testing this summer with my 223 and see how it does.

    No matter which way you go, 223/308, neither is a wind bucker and you got to drive well to score.

    My 6.5 and 7 Mystic shoot with 1/2 the windage of my 223 and 308. That makes life a whole bunch easier and so much nicer to drive.

    Jerry
    http://www.6mmbr.com/223Rem.html

    Lots of 223 info here.

  5. #35
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    Very interesting thread this has turned out to be

    Guys, I shoot both guns and actually prefer the 308 as I have a lot more experience with it. This journey started when I bought my wife a Savage Model 12 LRPV in 223 with a 1:7 twist barrel (she did not like the recoil of the 308) and immediately the fellow shooters started telling me how it would not work at 1000 yards due to wind drift even though the QL and QuickTarget tables indicated it would be on par with my 308 and 155 gr. SMK's at 2950.

    The point of my original question was to get information as to why the ballistic tables and reported range results varied so much. The discourse in the thread and the one over on Long Range Shooting has been very informative and I really look forward to seeing the range results mysticplayer will report on.

    Thanks for all the discussion. I am learning a lot!

    George

  6. #36
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    Gentlemen, the 155gr Lapua has a BC of .508 and shoots great at 2950+, lots of DCRA guys here do just that easily.

    I'm fairly certain one can get 2900 out of a 223 with heavies, kind of ties it up doesn't it.

    Its all good,
    Cheers,
    Rob

  7. #37
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    Travelor, since you have both cals, why not do the test next time you are at the range. Add in a few more shooters to increase the tests results. Even with the same bullet and similar velocities, I bet you find that the drift values vary between rifles.

    Chronie a few shells from each shooter at the time of the test using the same chronie.

    All go with zero windage adjustment on a windy day. Aim dead center, shoot at the same time and have the shot scored. In 10rds, it will be clear which is drifting less. Change shooters on each rifle and repeat so there is no bias on the equipment.

    That would be alot faster then waiting for me as I would have to get together in the spring and I would be limited to just two rifles.

    Ballistics programs are notoriously simplified. ALOT of variables get avoided or else we would need super computers to crunch. I have used most ballistics program and they all produce similar results. In many cases, that print out has little to do with real world shooting. I adjust my drop tables for my particular set up.

    We know that the value of ballistic coeffecient is 'dimensionless' so bullet mass should not matter. Only the planform and its relative drag determines how it flies through the air. I am sure any rocket scientist will tell you that is overly simplified. The G functions we use are also simplified/inappropriate and may not account for new bullet shapes - big reason ballistics programs are not exact in the real world.

    With the 223 and 308, both are ballistically very very close - at least on paper. However, I am unaware of anyone taking the time and doing a proper test to compare relative wind drifts. We do this everytime we shoot and compare notes but the amount of error is enormous.

    So the easiest solution is to test side by side under the very simple process described above. Holes in paper are going to resolve alot of math.

    Jerry
    Last edited by mysticplayer; 01-12-2008 at 03:05 PM.

  8. #38
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    Wind Drift Test

    Jerry,
    “Holes in paper are going to resolve alot of math.”

    Holes in paper can tell the tale, but it may just be fiction if the test is not done correctly. I feel it is not enough to rely on a shooters zero to help determine wind drift. To get an accurate idea of the wind drift of the two calibers would require chronographing the rifles the morning of the test to confirm the speeds are really where you want them. Then zero the rifles (preferably in a no wind condition) at say 300 yards and synchronize them by volley firing; then moving back to 1,000. Re-volley fire (if possible in no wind) to check no wind zeros (they can change between ranges) and then volley fire a good number of shots to complete the test.

    A group of friends and I did this a little over a year ago to test 6.5, 7mm and 30 cal drift. It was written up in PS magazine. Quite an interesting day! I must say the weather worked out perfectly for us going from zero all morning and part of the afternoon and then abruptly to 4 moa and then up to 10 moa. I don’t ever expect to have that happen again.

    It would be interesting to see the results of a .223 vs. .308 test done accurately.

    Larry Bartholome

  9. #39
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    Any chance of posting some of your results. NO PS mag around here.
    Thanks,

    Jerry

  10. #40
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    Ballistics

    Monte,
    First of all, thanks for informing me about the 155 and 80 grain limits you have in Canada. I wasn't aware of this restriction, and it's important to the potential comparison of the .308 and .223.

    Jerry and others,
    Your lack of confidence in ballistics programs is understandable. Many people use these tools, but there are a lot of pitfalls that keep the average guy from realizing the full potential. Here are a few examples of common errors:
    1. Atmosphere. The atmosphere will default to standard sea level conditions unless you input something else. The standard atmosphere at sea level is far denser than what we usually shoot in (hot summer air, possibly humid, and some amount above sea level). If you don't input the correct atmospheric conditions, the results of the ballistics program will not be accurate.

    2. Muzzle velocity. To avoid a long discourse on chronograph accuracy, I'll simply say that it's possible to have significant error in velocity measurements. Even if the chronograph is accurate, how many shooters take the time to account for the velocity lost between the muzzle and the chrono? This is roughly about 10 fps over 5 yards. Obviously, you can't expect the program to be accurate if the MV input is incorrect.

    3. Zero range. How carefully do we insure that the value input for zero range is accurate?

    4. Scope tracking. Adjusting 30+ MOA from a 100 yard zero to 1000 yards is asking a lot of a scope. The higher end scopes can be expected to be better at this than less expensive ones, but who takes the time to confirm the scopes MOA adjustments over the ENTIRE range of travel? This becomes an issue when you compare MOA 'come-up' on the scope to drop predicted by a ballistics program. The only way to eliminate the scope adjustment variable is to zero a known distance high at close range to impact at range, or zero at close range and hold over at a known distance at range. This removes the scope adjustments from the problem.

    5. Winds. For now I just mean vertical winds that could deflect the bullet up or down, effecting the drop and causing it not to match the ballistics program predictions.

    6. BC. There are several problems here. The most common 'violation' is using inaccurate BC. It's not the users fault, we're at the mercy of the manufacturers who are obviously compelled to advertise high. Another problem is that G1 BC varies greatly with velocity. Sierra addresses this problem by quoting different BC's for different speed ranges. Many shooters don't understand how to use this information, and just use the high velocity BC for all calculations. The proper way to do it is to either enter the multiple BC's, or average the BC's over the expected velocity range. A common example of this is using .450 for the BC of the 155 SMK. .450 is only the BC at high speed. Over 1000 yards, the average BC is more like .437. That error (.450 vs .437) is not the ballistic program's fault, it's erroneous input.

    7. BC. Another problem with BC is that we're using the wrong standard (G1) for long range bullets. The G1 standard is for short nosed, flat based bullets and very poorly fits the drag model of our long range bullets. This poor fit is the reason why BC has to be defined in terms of velocity. If we were to use a more fitting standard like the G7, the programs become much more accurate. It's too bad the industry is so stuck on G1. Here the shooter has no option to improve the accuracy of the program. Most programs can use BC's referenced to the G7 standard, but how do you know what the G7 BC is? Not easy.

    8. Rifle support. I've never done this test, but I think if you zero a rifle at 100 yards from a benchrest, then lay down in the prone position with a sling/coat, etc and shoot at the same 100 yard point of aim, the rounds will not impact the same point as those fired from the bench. This is also not the fault of the ballistics program.

    So there are many reasons for the print out of the ballistics program not to match real world observations. That doesn't necessarily mean the ballistics program is lacking. It's just like any other tool: you have to use it properly to get the desired results.

    So we turn to the 'real world'. There's a lot of talk about shooting things side by side, etc. I agree with Larry (great article by the way) that it's a very involved process to do this test properly and effectively. There are many steps required to 'calibrate' the rifles and zero's, etc before the test. I agree that GOOD empirical data is the best kind, but it's not easy to get. Just like with computer programs, there are a lot of 'gottchas' that can make the test invalid without you even knowing it. Many people who are thirsting for the empirical data will take the results as gospel without questioning the credibility of the test.

    In order to determine the wind drift of one bullet over another, here's what I WOULD DO...
    MEASURE the G7 BC of the bullets to be compared. This is a more practical test than testing for wind drift. Less spread in the data, shorter ranges required, etc. Once the BC's (referenced to the proper standard) are known, then use a ballistics program with accurate inputs to calculate the wind drift of the two rounds. Many people refuse to believe it, but the often misunderstood BC is a very important piece of information.

    For example, BC is not unit-less. It has units of mass / area. It does include a dimensionless 'form factor'. This form factor is what relates the drag of the bullet to the 'standard' (G1, G7, etc). The form factor is constant if the bullet is similar to the standard. If the bullet is different from the standard (as in the case of long range bullets and G1) the form factor varies, and this is what causes BC to vary.

    There's really far less mystery involved in ballistics programs than most people think. All a ballistics program needs to know in order to calculate: downrange trajectory, velocity, time of flight, and flight path angle is: BC (which includes information about the caliber, mass, and aerodynamic drag of the bullet), atmospheric properties required to calculate air density, muzzle velocity, and a description of the geometry (sight height, max range, zero range, etc). With those input parameters, the equations of motion can be solved in any number of ways (closed form, numerical integration, etc) for the outputs of interest. Bullet mass/inertia IS accounted for in the BC. There are no physical mechanisms that 'fall thru the cracks' of modern ballistics programs.

    Having said all that, the wind still gives us problems due to it's fluid nature. What I mean is, when you describe wind to a ballistics program, you give it a speed and direction, and the program applies the same values for the entire trajectory. We all know this is a poor model of reality. Also, vertical winds are present in the real world, and are not addressed with typical ballistics programs. IF there were a situation where wind was steady in speed and direction, and consistent with height above ground, the ballistic program would give accurate answers for wind deflection.

    I've sent a series of 3 articles into PS magazine that describe my BC test results for 3 Palma bullets: Berger, Sierra and Lapua 155's. My testing methods are very precise (I can repeat BC measurements within 1%) using a system of acoustic time of flight sensors spaced in 200 yard increments from muzzle to 600/1000 yards. These articles should be appearing in PS within the next few months. Measured G7 BC's and average G1 BC's are provided along with effects of meplat trimming and pointing on BC. Wind drift and drop comparisons are made. Also, comparisons are made between trajectories calculated by G1 and G7 BC's. The articles are very relevant to this discussion.

    Take care,
    -Bryan

  11. #41
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    Range test

    Jerry and others, I will test at the range.

    Our range is currently 300 yards and is in the process of being increased to 600 yards. Construction is well underway and should be done in 2 months or so depending on weather and contractors. By then my 223 will be back from Larry Racine and I will test my 308 and 223 in a heads up test at 600 yards as soon as possible and report.

    We have access to a 1000 yard range, but it is a National Guard range and we can't get on it except for Matches so it will not be possible to do this test before our next Match their in March and at that time there are no benches to shoot from (I know, some would rather shoot prone).

    I like the idea of getting now wind zero's and then shooting in wind side by side with no wind correction in the rifles - this should tell the tale at least in my guns.

    This thread is getting better each day!

    George

  12. #42
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    .223 Rem load

    This load might give the .308 a little competition;

    http://gunloads.com/modules.php?name...nloads&did=415

  13. #43
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    Quote Originally Posted by manitou210 View Post
    This load might give the .308 a little competition;

    http://gunloads.com/modules.php?name...nloads&did=415
    AR2208 is identical with Varget, so that load is slightly above the Hodgdon recommended max charge of 25.0gn for 80gn SMK. I think any comparison would need to use this as limiting factor?

    Alan

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