Tangent or Secant?

[Thor357]

I've gone to several forums including this one and Google to try and find the answer to my question and now I'm even more confused.
I just bought 1000 bullets of Sierra Matchking 77gr. HPBT .224 #9377's for my AR 5.56/.223
Are these secant or tangent ogive?
Is there a way to visually distinguish either?

 

[Dave M.]

I've gone to several forums including this one and Google to try and find the answer to my question and now I'm even more confused.
I just bought 1000 bullets of Sierra Matchking 77gr. HPBT .224 #9377's for my AR 5.56/.223
Are these secant or tangent ogive?
Is there a way to visually distinguish either?

It is a tangent ogive bullet, which Sierra uses for all of their bullets except where absolutely necessary due to design constraints (from Sierra’s website, not my mouth). But more importantly, why does it matter to you? Let the target tell you whether or not it likes that bullet or not. Too many people get tied up in all the fancy ogive shapes and terms. Fact is, I have shot both tangent and secant ogive bullets and won with both. Both are more than capable of being incredibly accurate, and for that matter, the hybrid ogive (which is a mix of the two) may be the best of them all. Good luck and shoot straight.
Dave M

 

[piie]

Hybrid Science: How to Load Hybrid Bullets for Best Accuracy « Daily Bulletin

SHOT Show 2016 kicks off in two weeks in Las Vegas. While at SHOT Show next month, we plan to get the inside scoop on new bullet designs from Berger, Hornady, Lapua, Nosler and Sierra.

bulletin.accurateshooter.com

 

[Thor357]

It is a tangent ogive bullet, which Sierra uses for all of their bullets except where absolutely necessary due to design constraints (from Sierra’s website, not my mouth). But more importantly, why does it matter to you? Let the target tell you whether or not it likes that bullet or not. Too many people get tied up in all the fancy ogive shapes and terms. Fact is, I have shot both tangent and secant ogive bullets and won with both. Both are more than capable of being incredibly accurate, and for that matter, the hybrid ogive (which is a mix of the two) may be the best of them all. Good luck and shoot straight.
Dave M

From what I understand one type of ogive prefers a particular seating depth vs the other prefers a jump.
I'd rather not send a bunch of bullets to figure out if my rifle likes tangent over secant or vice versa.
Where on Sierra's website did you find the info? I was just there.

 

[Twdmar]

77 sierras are meant to fired out of an AR15 magazine. They tolerate a lot of jump but will work .020" off the lands too. Don't get too wrapped around the axle. Use a standard load and you'll be fine.

 

[Thor357]

77 sierras are meant to fired out of an AR15 magazine. They tolerate a lot of jump but will work .020" off the lands too. Don't get too wrapped around the axle. Use a standard load and you'll be fine.

I understand that these bullets are meant for AR's. That's why I bought them!
I have some set to magazine length and I have some set beyond. I'm looking for accuracy out to 100 yards (MOA or better) and beyond. My intent is to find what my rifle likes the best to achieve my goal(s).
The type of bullet plays a significant role in that. Secant bullets like one thing and tangents like something else. That's why I asked the question.
Knowing now that 77gr. SMKs are tangent ogive gives me a direction to go with versus a secant ogive.

 

[Thor357]

Hybrid Science: How to Load Hybrid Bullets for Best Accuracy « Daily Bulletin

SHOT Show 2016 kicks off in two weeks in Las Vegas. While at SHOT Show next month, we plan to get the inside scoop on new bullet designs from Berger, Hornady, Lapua, Nosler and Sierra.

bulletin.accurateshooter.com

I didn't buy any hybrid bullets. I bought 77gr. SMK's

 

[piie]

I didn't buy any hybrid bullets. I bought 77gr. SMK's

You asked what the difference is between the different types- article even has pictures…

 

[Dave M.]

From what I understand one type of ogive prefers a particular seating depth vs the other prefers a jump.
I'd rather not send a bunch of bullets to figure out if my rifle likes tangent over secant or vice versa.
Where on Sierra's website did you find the info? I was just there.

It’s buried deep in their ballistics section.
https://sierrabullets.wordpress.com/tag/matchking/
Dave

 

[Kurz]

The basic answers you're looking for are in this illustration. Read each description so you understand which is which.

The problems you will be confronted with are that these simple descriptive answers will not solve the problem of which bullet, which barrel, which powder or which primer will perform the best. They are generalizations at best. You still need to load and shoot to attain the data on which bullet performs the best even given the seating parameters.

Enjoy the process!

 

[Dave M.]

I understand that these bullets are meant for AR's. That's why I bought them!
I have some set to magazine length and I have some set beyond. I'm looking for accuracy out to 100 yards (MOA or better) and beyond. My intent is to find what my rifle likes the best to achieve my goal(s).
The type of bullet plays a significant role in that. Secant bullets like one thing and tangents like something else. That's why I asked the question.
Knowing now that 77gr. SMKs are tangent ogive gives me a direction to go with versus a secant ogive.

Trust me when I say that there is very little chance that you will be able to load any bullet long enough in a commercially made AR to touch the lands and still feed through a magazine. You are going to be jumping bullets regardless of how far out you seat the bullets.
dave

 

[mikecr]

The whole thing about what ogive types 'like' is one of the biggest falsehoods ever endorsed in our community. Don't worry about this. Test seating from mag length & go with best from there.

 

[tomswede]

What works in AR’s is well known from high power shooters. The Sierra 77’s will shoot ( given sufficient twist) well out of almost all rifles, if it doesn’t it’s rarely a bullet issue. Load them to mag length with R15 or Varget and that should be it.
If you seat longer than mag length there is no reason to use this bullet.

 

[GLShooter]

I agree Tom. I like to mess things up though so I run ASC mags that let me run at 2.316 nominal. The horizon opens up a bit with those plus I shoot a ton of 6.5 and 6.8 wildcats and the extra room helps a lot. Worst case scenario just windowing the mag in from gives me 2.40. O have a custom lower that gets me to almost 2.5.

Greg

 

[Thor357]

Trust me when I say that there is very little chance that you will be able to load any bullet long enough in a commercially made AR to touch the lands and still feed through a magazine. You are going to be jumping bullets regardless of how far out you seat the bullets.
dave

One of the batches I made is not intended to be inserted in the magazine.
I'm aware that the use of a magazine, particularly in an AR, limits how long a bullet can be seated.
My intent is to find where the best seating depth is and work my way from there.

 

[Thor357]

View attachment 1302783

The basic answers you're looking for are in this illustration. Read each description so you understand which is which.

The problems you will be confronted with are that these simple descriptive answers will not solve the problem of which bullet, which barrel, which powder or which primer will perform the best. They are generalizations at best. You still need to load and shoot to attain the data on which bullet performs the best even given the seating parameters.

Enjoy the process!

I'm aware of this illustration. I'm aware that it is a general description of bullet types.
My OP asked what type were SMK's 77gr HPBT's.
Knowing a bullet's type helps in the decision making process of reloading it with what and where.

 

[tomswede]

One of the batches I made is not intended to be inserted in the magazine.
I'm aware that the use of a magazine, particularly in an AR, limits how long a bullet can be seated.
My intent is to find where the best seating depth is and work my way from there.

My comment was if you are not intending to seat these at mag length why use a bullet specifically designed for that purpose? There are many better choices if single loading.
If you got a quality AR it should be pretty easy to get under one MOA

 

[Jeff Porter]

77 SMK with their Tangent ogive do not gain any precision ( reduction in group size on target at distance) by seating them closer to the lands. In a quality AR build with at least an 8 twist barrel I would try a short jump test from maglength back to 2.230” OAL in 0.005” increments. Some match bullets I have used ( Nosler and Hornady) actually shot smaller rounder groups ( smaller mean radius) when pushed in a bit to 2.235-2.240”

SMK and Lapua 77’s shot well anywhere I seated them so I kept them near Mag length to allow maximum case capacity.

 

[Thor357]

Good to know.
I'm just conducting an experiment.
My barrel is a 1:7 twist.
I've got a batch made to fit the magazine. I have another batch that will need to be fired one at a time.
Just dinkin' around with loads and seating depth is all.

 

[Ned Ludd]

It is possible to carry out a seating depth test with rounds that will be fed from a magazine in an AR-type rifle, regardless of whether they are tangent or secant ogive bullets. First, determine the maximum cartridge overall length (COAL) that will reliably feed from the magazine. Set up the seating depth test with that COAL as the longest, and seat bullets incrementally farther into the case. As they only become shorter from the maximum COAL that will reliably feed from the magazine, all the loaded rounds should feed reliably.

FWIW - anecdotal information has been spread for years, if not decades, that secant bullets strongly prefer to be seated into the lands, a situation that may not always work well due to COAL and magazine length restrictions. This can be very misleading. I load several heavy .224" bullets for F-TR bolt rifles that have secant ogives. They are all jumped and shoot ridiculously well. Some AR reloaders prefer to use a set amount of jump (i.e. a predetermined COAL), often derived from common loads used with success among a wide range of shooters using loads restricted by mag length. This approach often works very well, and may be a part of the reason it is less common to see those reloading for ARs within the confines of mag length carry out seating depth tests as I described above. Nonetheless, seating depth testing moving the bullet unidirectionally into the case from the longest COAL that feeds reliably can be done if an individual wants or needs to do so and is willing to carry out the testing procedure.