Originally Posted By wyv3rn: Originally Posted By DevL: Im not talking match vs milspec I am talking cut vs button rifled.  Example... Which deforms the bullet less, a single cut Krieger or a button rifled PacNor? Oops, sorry DevL.  I should've read closer.  Well you have me there, I don't know.  This is the first time I've ever heard that Krieger (or other cut-rifled) barrels in certain calibers are unsuitable for use with thin jacketed match bullets.  I'm not even close that echelon of shooters, nor am I willing to dedicate the time or $ to get there, so I stay in the mil-std kiddie pool for the most part.  I don't know all the benefits and draw backs to cut-5R-polygonal-superfreak rifling.

All these match barrels are lapped so I doubt there's any real difference.  And the comment about rifling affecting high velocity rounds, 2,700 fps isn't high velocity.

Originally Posted By jmart: Originally Posted By wyv3rn: Originally Posted By DevL: Im not talking match vs milspec I am talking cut vs button rifled.  Example... Which deforms the bullet less, a single cut Krieger or a button rifled PacNor? Oops, sorry DevL.  I should've read closer.  Well you have me there, I don't know.  This is the first time I've ever heard that Krieger (or other cut-rifled) barrels in certain calibers are unsuitable for use with thin jacketed match bullets.  I'm not even close that echelon of shooters, nor am I willing to dedicate the time or $ to get there, so I stay in the mil-std kiddie pool for the most part.  I don't know all the benefits and draw backs to cut-5R-polygonal-superfreak rifling. All these match barrels are lapped so I doubt there's any real difference.  And the comment about rifling affecting high velocity rounds, 2,700 fps isn't high velocity.

I never spoke of match barrel vs. match barrel, I spoke of match vs. standard mil grade.  I clearly said I don't know about comparisons between all the different match barrels.  It was DevL who was told by someone else what you are referring to.I'm not sure which comment you are referring to, or if it was me or someone else who said it, but regardless, "high velocity" is a relative term.  Yeah, 2,700fps is not 4,000fps or a rail gun, but it is 2.5 times the speed of sound and I consider that to be "high velocity" in relative terms when speaking casually.

Oh, I think you are referring to DevL's post, well he did say OTHER calibers, so who knows what velocity he could've been referring to.

ETA: Oops, reading it again I don't think any of your comments were directed toward me, but to the post above mine.  You quoted my post so I thought it was, sorry.

Yes.  Sorry for the confusion, I should have just posted DevL's earlier response..

Yes I was discussing HIGH velocity rounds not .223 and wondered about the applicability in the rifling being defored more and having an effect on BC.  Probably totally unimportant for what we are discussing. Just wondering out loud.

Here are a couple of close-ups of the T1 and T2 bullets as well as the extruded and ball powders used in these loads.  (The squares of the grid measure 1/10th of an inch.)





Extruded powder from the FPD load.



Ball powder from the 5.56 load.

Nice camera skills.  How come mine never come out like that?

Thank you for the tips. I'll have to experiment.  I don't want this thread to get OT though, I'll bet there's a million threads on taking good pictures if I get off my ass and search.

VERY NICE WORK THANKS

Check out Hornady SD   outstanding

Originally Posted By wyv3rn: Nice camera skills.  How come mine never come out like that?

Thanks. I'm no Stickman, but I'm working on it.

tag for great info

Originally Posted By FMJ: Check out Hornady SD   outstanding

The standard deviations obtained with these TAP rounds are truly amazing for factory ammunition.  When I am hand-loading match-grade ammunition I strive for a velocity coefficient of variation of 0.5%.  For comparison mil-spec M193 requires a coefficient of variation around 1.2%.  

(Coefficient of variation is the standard deviation divided by the mean (average) velocity and then multiplied by 100 and expressed as a percentage.  It allows for the comparison of the uniformity of velocity between loads in different velocity spectrums e.g. 77 grain loads running around 2,650 fps compared to 55 grain loads running around 3,050 fps.)  

The average coefficient of variation for the TAP FPD from all three barrels used in testing was 0.46%!   The average coefficient of variation for the 5.56 TAP from all three test barrels was 0.44%!!  Kudos to Hornady.

Results like that are why I said on the first page that Hornady is hands down the best .223/5.56mm factory ammunition I've ever used.  What will really amaze you is that even their lot-to-lot consistency is so incredibly excellent lately that if going only by chrono data it could all be mistaken as ammunition from the same lot.  Their lot-to-lot consistency is better than many manufacturers' is within a single lot.  I still like to buy any and all ammo in bulk of all one lot though, JIC.

Great thread!

On a lighter note, here are a few rough snap-shots from the chronographing session.

The bench.

On a lighter note, I hope you didn't have much to do with the way that bench framing is chewed up.

great job brother.

Originally Posted By AR-10: On a lighter note, I hope you didn't have much to do with the way that bench framing is chewed up.

Definitely not due to me.  If it was, my chronograph would be in pieces.

Originally Posted By BRONZ: great job brother.

Thanks!  If the weather holds I'll be posting the accuracy results this weekend.

Accuracy Results - part 1


Normally when attempting to determine the accuracy (technically the precision) of a particular load, I use one of my stainless steel Krieger barrels for testing.  However, since part of this test involves the 5.56 TAP round loaded to NATO pressures, I was just not willing to risk pressure issues from firing a NATO pressure load through one of my match chambered, tightly rifled Krieger barrels.

I could have used a Krieger barrel for the SAMMI pressure 75 TAP FPD load and a different barrel for the 5.56 TAP load, but I felt this would have given an unfair advantage to the TAP FPD.  Therefore I decided to test both loads from a NATO chambered barrel.  What I was most interested in gleaning from this test was the relative accuracy of the two loads compared to each other anyway.  It has been my experience that NATO pressure loads tend not to shoot as accurately as loads that are downloaded by 150 to 200 fps (depending on the bullet weight.)
 
I have a 20” Colt HBAR with a 1:7” twist that shoots relatively well for a factory barrel that is chrome lined and  NATO chambered.  The barrel is free floated and is capable of shooting 10-shot groups from 100 yards that hover right around one inch.




All shooting for this test was done at 100 yards from a benchrest with the rifle resting on front and rear bags.  (Remember, I’m trying to test the accuracy of the ammunition and not particularly my shooting skills.)  As a control for this test, before firing the TAP ammunition, I obtained three 10-shot groups using Sierra 77 grain MatchKings.  (In an effort to reduce the human error involved in this test, I actually fired four 10-shot groups of each load and used the best three for analysis.)

The three 10-shot groups using the Sierra 77 grain MatchKings measured:

1.05”
1.07”
1.10”.

Here is a snapshot of one of the 77 SMK groups.



Now here’s the good part.  I obtained three 10-shot groups of the Hornday 75 grain TAP FPD load and the three groups measured:

1.08”
1.15”
1.18”.

Here is a snapshot of one of the 75 TAP FPD loads.



Next I overlayed the three 10-shot groups from each load on each other using the RSI Shooting Lab software program and obtained 30-round composite targets for each load.  The mean radius of the 77 SMK control load measured 0.32” and the mean radius for the 75 TAP FPD load measured 0.37”!  I consider this to be excellent accuracy for a factory load, especially from a chrome lined, NATO chambered barrel.

(See this thread for an explanation of the “mean radius.”)

Here are the 30-round composite targets for comparison.


Tomorrow I will be testing the 5.56 TAP load and I’ll post the results as soon as I get a chance.

Excellent work!  Very scientific.. I don't think you can get a much better depiction of how accurate a load is through a standard chrome lined barrel than that.  That is way more sophisticated than anything I am setup to do (way out of my league), so let me ask this.  When you test the 5.56 75gr TAP do you plan to fire one of these loads along side it as a "control" again for that particular day?  It seems like you are setup to measure even the slightest variations so any day-to-day changes/variations would better noticed.  Or is firing one of these as a control unnecessary?

ETA:  Who's 77gr SMK load is that and which "model" (for those manufacturers that have more than one 77gr SMK load)?

Originally Posted By wyv3rn: Excellent work!  Very scientific.. I don't think you can get a much better depiction of how accurate a load is through a standard chrome lined barrel than that.  That is way more sophisticated than anything I am setup to do (way out of my league), so let me ask this.  When you test the 5.56 75gr TAP do you plan to fire one of these loads along side it as a "control" again for that particular day?  It seems like you are setup to measure even the slightest variations so any day-to-day changes/variations would better noticed.  Or is firing one of these as a control unnecessary? ETA:  Who's 77gr SMK load is that and which "model" (for those manufacturers that have more than one 77gr SMK load)?

The control load used in this test is one of my "standard" handloads using the Sierra 77 grain MatchKing.  By "standard" I mean this load was not “tuned” for any particular barrel.  It was developed to have a velocity of around 2650 fps from a 20" NATO chambered, chrome lined barrel and to have a velocity standard deviation of 12 fps or less.  The load tends to have a velocity coefficient of variation of 0.4% or less.  This load shoots well in just about all of my 1:7” twist barrels.

Typically I use new or once fired Lake City brass along with Federal Gold Medal primers and VihtaVuori powder for this load.  I seat the bullet to a nominal overall length of 2.250” for easy feeding from a magazine.  The seated bullet run-out of this load usually averages right around 0.001” as measured with a NECO concentricity guage.

I have just returned from the shooting range where I was testing the 5.56 TAP load and yes, I fired a control load today also.  I’ll be posting the results as soon as I have everything tabulated.

Cant wait.

Tag for great info, thanks for the work.

Accuracy Results – part 2

Proceeding in the same manner as described in part 1, I conducted an accuracy evaluation of the 5.56 TAP load. Remember, all groups fired consisted of 10 shots each and were fired from 100 yards from a bench rest.

For this portion of the test, I fired a 10-shot group using the control load with the Sierra 77 grain MatchKing that measured exactly 1.00”.  This is the smallest group obtained with the control load, with the largest being 1.10”.  This group along with the three groups fired in part 1 of this test gives us four 10-shot groups of the control load fired from 100 yards that have an extreme variance of only 1/10th of an inch!  (1.00”, 1.05”, 1.07”, 1.10”)  I think this gives a pretty good indication of the capabilities/limitations of the barrel being used for testing and did not think that any more control groups were necessary.

Here’s a snapshot of the control load.



Now for the really good part.  I obtained three 10-shot groups of the 5.56 TAP load that measured:

1.16”
1.38”
1.45”.

For comparison the three 10-shot groups of the TAP FPD load from part 1 of the test measured:

1.08”
1.15”
1.18”.

Here is a snapshot of the smallest 5.56 TAP group.


I compiled a 30-round composite target from the 5.56 TAP groups and measured the composite mean radius.  The mean radius for the 5.56 TAP load was 0.46" while the mean radius for the TAP FPD load was 0.37".  While the 5.56 TAP load is clearly not quite as accurate as the TAP FPD load (and we are only talking about a difference of 0.37” from the smallest FPD group to the largest 5.56 group at 100 yards in this test), I think the 5.56 load shows excellent accuracy for a NATO pressure load.  As I stated earlier, it has been my experience that NATO pressure loads do not shoot nearly as accurately as loads that run 150-200 fps slower.

Here are the 30-round composite targets for comparison.


For my next trip to the range I am thinking of conducting a "stability test" for the TAP loads.

Awesome work Molon, thank you for the data.  I will also say that although I normally wouldn't touch anyone elses reloads, based on the character of your posts and your obvious attention to detail in the things you do that I would feel perfectly safe and confident in using your reloads if they were ever to be offered to me on the range one day.  The are obviously high quality.

Do you have access to Mk262 blems?  Would be interesting to see a comparison of 5.56 TAP and MK262.

Originally Posted By wyv3rn: Awesome work Molon, thank you for the data.  I will also say that although I normally wouldn't touch anyone elses reloads, based on the character of your posts and your obvious attention to detail in the things you do that I would feel perfectly safe and confident in using your reloads if they were ever to be offered to me on the range one day.  The are obviously high quality.

I was thinking the same thing, Molon needs to go into the high volume ammunition manufacturing business.  

As always, great information presented most thoroughly.

Thank you,
Scott

Any chance this topic could get pinned?

Excellent work. Thanks for the info.

Any idea on a cheaper bullet that would have near the same trajectory. I know Hornady sells the 75gr FMJ rounds as practice rounds, but from what I have seen it matches the 75gr TAP FPD better than the 75gr 5.56 TAP.

Originally Posted By Scotter260: Originally Posted By wyv3rn: Awesome work Molon, thank you for the data.  I will also say that although I normally wouldn't touch anyone elses reloads, based on the character of your posts and your obvious attention to detail in the things you do that I would feel perfectly safe and confident in using your reloads if they were ever to be offered to me on the range one day.  The are obviously high quality. I was thinking the same thing, Molon needs to go into the high volume ammunition manufacturing business.   As always, great information presented most thoroughly. Thank you, Scott

Thanks for the compliments gents!

Originally Posted By DevL: Do you have access to Mk262 blems?  Would be interesting to see a comparison of 5.56 TAP and MK262.

Funny you should ask…I was thinking the exact same thing as I finished testing the 5.56 TAP rounds.  Unfortunately, I only had 10 rounds of Mk262 left in my range bag at the time.  So, I fired one 10-shot group of the Mk262 from 100 yards for an extreme spread of 1.49” and a mean radius of 0.50”.  

When I get some time I’ll have to fire three 10-shot groups of the Mk262 for comparison to the 5.56 TAP.

best info on a round I have read on here in awhile. very through and I like the compost post on pg 3.

Tag.

Hey Molon, is that a Caldwell shooting bag rest your using? Do you fill them with sand or is there something besides sand to use?

Great post.  Taggage.

Great work - thanks.

Originally Posted By IBTLplus1: Excellent work. Thanks for the info. Any idea on a cheaper bullet that would have near the same trajectory. I know Hornady sells the 75gr FMJ rounds as practice rounds, but from what I have seen it matches the 75gr TAP FPD better than the 75gr 5.56 TAP.

Actually, the Hornady 75 grain "practice" round uses an OTM bullet.  As far as I know Hornady does not offer the T2 bullet as a reloading component    and I am unaware of any inexspensive substitute for the bullet.

Originally Posted By bc5000: Hey Molon, is that a Caldwell shooting bag rest your using? Do you fill them with sand or is there something besides sand to use?

Affirmative on the Caldwell bag.  This particular bag was purchased prefilled, but when I fill them myself I like to use walnut tumbling media.

Originally Posted By Molon: Affirmative on the Caldwell bag.  This particular bag was purchased prefilled, but when I fill them myself I like to use walnut tumbling media.

Thanks Molon, Midway has the unfilled Caldwell Tackdriver on sale for $25. They also sell the walnut media, hopefully 5lbs will fill it.

An interesting point that I noticed about the groups from the accuracy tests is how well Hatcher’s one-third rule works with those results.  You may recall from my explanation of the mean radius that Hatcher states that the mean radius should measure about one-third of the extreme spread of a group  (or conversely, the extreme spread of the group should be about 3 times the mean radius).

The three 10-shot groups from the Hornady TAP FPD load have an average extreme spread of 1.14”.   The mean radius for that load is 0.37”.  

3 X 0.37” = 1.11”

The three 10-shot groups from the Hornady  5.56 TAP load have an average extreme spread of 1.33” and a mean radius of 0.46”.

3 X  0.46” = 1.38”

There you go gettin' all DaVinci Code-ish on us.

(Pretty cool though)

Scott

Stability Test – preliminary results

After seeing the fine accuracy that the 75 grain TAP rounds are capable of out of a 1:7” twist barrel I was curious to see if they would be stable out of a 1:9” twist barrel.  I decided to use one of my 16” Colt HBARs with a 1:9” twist for testing.  I chose this particular barrel for several reasons.  First and obviously because it has a 1:9” twist.  Secondly, it has a NATO chamber to accommodate the NATO pressure 5.56 TAP load.  Thirdly, it is the shortest 1:9” twist barrel I own and stability issues are more likely to show up in a shorter barrel due to decreased muzzle velocities.  Lastly, this barrel is reasonably accurate for a NATO chambered, chrome lined barrel that is not free-floated.

It is generally accepted that cooper-jacketed lead rifle bullets should have a Gyroscopic Stability Factor of at least 1.5 – 2.0.  The 52 grain Sierra MatchKing bullet that I used as a control load in this test has a GSF of 2.5 when fired from a 16” barrel with a 1:9” twist.  The Hornady 75 grain BTHP bullet has a GSF of about 1.7 when fired from a 16” barrel with a 1:7” twist.  When fired from a 16” barrel with a 1:9” twist it only has a GSF of 1.02.  The RSI Shooting Lab software program states “This bullet is probably unstable at all velocities” for a 1:9” twist.  Because of this I decided to do preliminary testing at 50 yards.  If the TAP loads showed signs of instability at 50 yards there was no point in testing at greater distances.

A 10-shot group of the control load fired from 50 yards had an extreme spread of 0.64”.  (The X-ring on the target measures 0.75".) The rate of fire during this testing was relatively quick compared to the amount of time I usually take for a shot when testing for accuracy.  Remember, this test isn’t for accuracy per se, it’s looking for signs of instability such as keyholing or oblong bullet holes on the target or gross inaccuracy compared to the control load.  

10 shots of the TAP FPD load formed a group with an extreme spread of 0.99”.  The 10-shot group from the 5.56 TAP load had an extreme spread of 1.01”.  (I even fired a 10-shot group of Mk262 for an extreme spread of 0.88”.)  





The TAP rounds showed no signs of keyholing whatsoever.  All shots from the TAP loads formed nice round bullet holes on the target.  Even though the TAP groups were larger than the control load there were no signs of gross inaccuracy. Because of these results I will continue the stability testing at a distance of 100 yards on my next trip to the range.

what altitude and ambient temperature were you doing the stability testing at?

Oddly enough, I have some RED BOX TAP .223. Wonder what load that is.....

Originally Posted By fossil_fuel: what altitude and ambient temperature were you doing the stability testing at?

635 feet above sea level

75 degrees F

Originally Posted By AZ-K9: Oddly enough, I have some RED BOX TAP .223. Wonder what load that is.....

You most likely have the stuff pictured on the left.  It's basicaly the same as the TAP FPD, it just doesn't have the black nickel coated cases or the black box.

Molon-I had zero stability problems with my 1/9 Rock River heavy barrelled upper. It is a 16" barrel with NATO chamber and it is not chrome lined. I fired MK262 and TAP FPD (75GR).  I alo started at 50 and then 100 yards. My 50 yd groups were very similiar to yours and my better 100 yd groups were probably just over one inch. Sorry that I don't have as  precise of measurements.

Keep up the great posts. I am learning so much!

Originally Posted By beerbarron: Molon-I had zero stability problems with my 1/9 Rock River heavy barrelled upper. It is a 16" barrel with NATO chamber and it is not chrome lined. I fired MK262 and TAP FPD (75GR).  I alo started at 50 and then 100 yards. My 50 yd groups were very similiar to yours and my better 100 yd groups were probably just over one inch.

That's good to hear.  I'm looking forward to doing the 100 yard testing, but I problably won't be able to get to it until next week sometime.

Molon

Excellent post!