Go Back  HuntingNet.com Forums > Firearms Forum > Reloading
Seacant  and Tangent ogive seating ? >

Seacant and Tangent ogive seating ?

Reloading Share techniques for reloading, where to get the hottest in reloading equipment and learn how to reload from fellow hunters.

Seacant and Tangent ogive seating ?

Old 12-28-2014, 08:01 AM
  #1  
Fork Horn
Thread Starter
 
Join Date: Oct 2014
Location: Mississippi
Posts: 115
Default Seacant and Tangent ogive seating ?

Does it matter with ogive shapes when adjusting for seating depths ?


Do reloading manuals cover this topic ?

When you buy new cases , do they have to be trimmed to length ?

I see that some casings are crimped to the bullets and some are not , why is this ?

Thank you !
White Oak 06 is offline  
Old 12-28-2014, 09:18 AM
  #2  
Typical Buck
 
buffybr's Avatar
 
Join Date: Feb 2007
Location: SW Montana
Posts: 550
Default

Originally Posted by White Oak 06
Does it matter with ogive shapes when adjusting for seating depths ?
For cartridges held in magazines, the COAL (Cartridge Over All Length) must be shorter than the inside if the magazine.
The accuracy of many bullets is affected by how far the bullet travels before engaging the rifling. This distance can change with different ogive shapes.

Do reloading manuals cover this topic ?
Some may, I have not seen it, but I haven't read all manuals.

When you buy new cases , do they have to be trimmed to length ?
Generally not, but it doesn't hurt to do it.

I see that some casings are crimped to the bullets and some are not , why is this ?
Cartridges for guns with tubular magazines should have their bullets crimped so that the cartridges in front don't push the bullets back into their cases, especially under recoil.
Cartridges with heavy bullets, and with heavy recoil should be crimped to prevent the recoil from pulling the other bullets in the magazine or cylinder.
With proper case sizing, the neck tension usually holds most bullets in place.

Thank you !
I usually crimp my handgun bullets (except 45 acp), bullets for my 94 Win, but not for my other rifles, including .300 Weatherby and .375 RUM.
buffybr is offline  
Old 12-28-2014, 07:24 PM
  #3  
Fork Horn
Thread Starter
 
Join Date: Oct 2014
Location: Mississippi
Posts: 115
Default

Thanks for the reply.

If I find a sweet spot in the jump to the lands , will that distance work for tangent and secant as far as accuracy ?
White Oak 06 is offline  
Old 12-29-2014, 01:34 AM
  #4  
Nontypical Buck
 
Join Date: Feb 2003
Location: Eastern wv
Posts: 3,619
Default

Originally Posted by White Oak 06
Thanks for the reply.

If I find a sweet spot in the jump to the lands , will that distance work for tangent and secant as far as accuracy ?
Maybe, that's the best answer I can give you, some rifles like jump with some bullets, but not others, its basically a see what works deal.
RR
Ridge Runner is offline  
Old 12-29-2014, 08:51 AM
  #5  
Nontypical Buck
 
Nomercy448's Avatar
 
Join Date: Oct 2009
Location: Kansas
Posts: 3,898
Default

Originally Posted by White Oak 06
Does it matter with ogive shapes when adjusting for seating depths ?
Ogive shapes do matter when setting seating depth. You cannot seat two different bullets to the same COAL and assume that it will produce the same bullet jump (chamber leade).

Here's an example of a long radius spire point, for example a 16 ogive secant bullet vs. a rounder point, for example a 7 ogive tangent bullet. Examples A and B are seated to the same COAL, which produces an unsafe condition in condition B (unless the load is significantly reduced to account for the rifling jam), whereas Examples A & C are seated to produce the same bullet jump (when I drew these examples, the spire point actually IS a secant ogive), and the round nose actually IS a tangent ogive):



Originally Posted by White Oak 06
Do reloading manuals cover this topic ?
Most reloading manuals don't go into as much detail to describe secant vs. tangent ogive implications. Most do, however, provide specific COAL's for specific bullets, which will vary based on their relative bearing surface shoulder positions.

Beyond that, many manuals do cover how to determine maximum seating depth (depth to lands) for YOUR RIFLE CHAMBER. Most of these processes involve seating a bullet into an empty case and using it to determine maximum seating depth. Whether you 'soot' the bullet with a match (or magic marker) and crimp it tightly to let the rifling cut witness marks for depth, or seat it loosely and let the rifling press it into the case, or rely upon a tool like the Hornady Bullet Comparator to determine maximum seating depth, there are several ways to skin that particular cat.

In general, most folks start with a 0.005 to 0.01" jump, and work in or out to determine proper jump for best accuracy, of course watching for pressure signs as they go.

Also in general, you want at least one bullet diameter's worth of bearing surface length in your case neck to sufficiently hold the bullet properly, which limits how long you are able to seat the bullet.

Seating deeper, of course, eats up case capacity, as in the case of trying to load 90grn bullets in an AR-15, where magazine length limits COAL.

Long radius secant ogive bullets generally have better aerodynamics, but often require a bit more twist to stabilize because they are longer. These are often used by long range hunters for their advantageous flatter trajectory. They're more sensitive to seating depth and concentricity because of the angular disjoint between the bearing surface and the ogive.

Match bullets traditionally are tangent ogive, simply because they are so forgiving of throat jump and the distances are fixed (i.e. drop is known/constant). These are less sensitive because they have a smooth transition from ogive to bearing surface, letting them somewhat "self align" into the rifling.

Hybrid bullets (VLD's) offer a blended ogive with secant type tips and tangent type surfaces to join the tip to the bearing surface.

Rules of thumb for this topic:
  • 1 dia of bearing surface in the neck for proper grip
  • 0.005-0.01" jump
  • Long ogive secant ogive bullets have longer COAL for the same bullet jump than tangent ogive bullets
  • Long ogive secant ogive bullets have shorter bearing surfaces (full diameter straight sidewalls) than tangent ogive bullets
  • Long ogive secant ogive bullets are more sensitive to seating depth/leade jump variation than tangent ogive bullets
  • So called "hybrid ogive" bullets offer more forgiveness than pure secant ogive bullets, but with better aerodynamics than pure tangent ogive bullets
  • Rules of thumb and theories are great, but they only take you so far - you have to experiment with YOUR RIFLE, YOUR BULLET, YOUR CASE, AND YOUR LOAD to find the proper combination

Originally Posted by White Oak 06
When you buy new cases , do they have to be trimmed to length ?
They should at least be verified. I always size and verify length on brass, even if it's new.

Originally Posted by White Oak 06
I see that some casings are crimped to the bullets and some are not , why is this ?
All cartridges are crimped to hold the bullets. A taper crimp might not look like it's crimped, but all cases have to be crimped to at least a minimum tension to hold the bullet in place. Degree of crimp tension and crimp TYPE depends on the application. Some factory rounds are "collet crimped," similar to what the Lee Factory Crimp Die produces. Revolver cartridges are inevitably roll crimped, pistol cartridges that headspace on the case mouth must only be taper crimped. A taper crimp with a light tension is generally all that is needed to hold match bullets for single shot bench rest rifles, but a heavy roll crimp might be required for a heavy recoiling revolver cartridge like 454Casull or a tube fed cartridge like 30-30win.
Nomercy448 is offline  
Old 12-29-2014, 04:58 PM
  #6  
Fork Horn
Thread Starter
 
Join Date: Oct 2014
Location: Mississippi
Posts: 115
Default

Thank you for taking the time to help me understand .
Are nosler ABs and ballistic tips secant or tangent ?
What about fed. power shok ?
Oh ! Who makes the bullet for the power shok for federal ?

Thank you !!!!
White Oak 06 is offline  
Old 12-29-2014, 10:51 PM
  #7  
Nontypical Buck
 
Nomercy448's Avatar
 
Join Date: Oct 2009
Location: Kansas
Posts: 3,898
Default

Originally Posted by White Oak 06
Thank you for taking the time to help me understand .
Are nosler ABs and ballistic tips secant or tangent ?
What about fed. power shok ?
Oh ! Who makes the bullet for the power shok for federal ?

Thank you !!!!
I'll ask the loaded question - has someone mislead you to believe that the difference between secant or tangent ogive is important?

Having a secant or a tangent ogive, or a hybrid ogive, doesn't necessarily dictate that one will be more aerodynamic or more accurate than the other, and ultimately, it all ties together comparatively at the ballistic coefficient which is a lot easier to compare.

Here's a reality check - the Federal Power-Shok's aren't even in the same ballistic class as the Nosler Accubond or Ballistic tip, nor the same construction class:

Ballistic Coefficients for 30cal bullet, 150grn:

Nosler Accubond & Ballistic tip = 0.435
Federal Power Shok = 0.313

TERRIBLE aerodynamics for the Power Shok. They tend to have big, flat, wide meplats, poorly fit/formed lead points, and they're a flat base instead of a boat tail - Simply put, the Power shok is a run of the mill hunters bullet, not a precision long range hunters bullet.

Comparatively, launched at 2950fps from a 30-06, the 150grn Power Shok would drop an extra TWELVE FEET at 1,000yrds compared to the 150grn Accubond. The PS will have an extra ~10" of drop more than the Accubond at 500yrds.

Then if you look at the 'expansion envelope' for these bullets, i.e. the range of velocities that they'll effectively expand, you'll find that the Accubond and ballistic tip - and other bullets like them - will have a much broader range with much more reliable expansion, which means better killing performance in the field.

If I were spending my time and money reloading, and worried about nitty gritty details like secant vs. tangent ogive profiles, then Federal Power Shoks wouldn't even be in my vocabulary - which in fact, I DO spend my time and money reloading, AND do spend time considering secant vs. tangent ogives, and Federal Power shoks aren't welcome in my rifles. There are a lot prettier girls at the dance, with better personalities, that know how to cook better too.

There's really no magic in any of it. Pick an application, that'll dictate what you need your bullet to be able to do, then find a bullet that can do it, and a cartridge that can deliver it. If you already own the rifle, then you have to start from there and look for bullets that can perform with what your cartridge can deliver.
Nomercy448 is offline  
Old 12-30-2014, 04:37 AM
  #8  
Fork Horn
Thread Starter
 
Join Date: Oct 2014
Location: Mississippi
Posts: 115
Default

No one has miss lead me about these bullets, I'm trying to put this all together.
The power shoks group well and rem. sicrroccos group well. ( sub moa )

Hornady interlock and fusion do not.

I have only tried 4 types so far , I have owned my new rifle only a year now.
Vanguard s2 3006.

I'm just trying to find the science of why this is and a good start in reloading.

Two types of factory ammo on opposite ends of the spectrum that performs !
(Shok and sicroccos)

I've seen how shoks work on deer and I like the performance of the sicrroccos better.
I think I want to start with nosler when it comes time to reload or if you a better opinion!

Thanks again for your time !
White Oak 06 is offline  
Old 12-30-2014, 09:29 AM
  #9  
Nontypical Buck
 
Nomercy448's Avatar
 
Join Date: Oct 2009
Location: Kansas
Posts: 3,898
Default

There are really only two factors that you get to control with factory loads, which is the bullet type & weight. Everything else is out of your hands. If a high BC bullet factory load doesn't shoot as well for you as another bullet, that doesn't mean that you won't be able to "fix" whatever is wrong with it in your reloads.

The Power Shok's are a fine bullet, and much like the Remington Core-Lokt, I'm sure they'll enjoy a stable future just as they have a enjoyed a storied past. It does exactly what it's supposed to do for the average hunter - kill deer at 200yrds or less. Is a Honda a great car? You betcha. Is it the best car out there? Is it the best car for someone that is highly demanding of performance? Eh, not really.

A lot of bullets can be very accurate, especially if you're only asking them to perform at a few hundred yards.

Worrying about specifically looking about secant, hybrid, or tangent ogive bullets will take you down a fruitless path, especially if you're shooting out of factory chambers (i.e. not from a tight throat, specified leade chamber), or from factory barrels. The problem you can get into is that a long ogive tangent bullet might have better ballistic coefficient than a short secant bullet with a wide meplat - as appears to be the case comparing the Power Shok with the Accubond.

Equally, if you have an improper charge weight that's outside of the 'accuracy window' for your load, or you have inconsistent seating depth or inconsistent throat tension or concentricity, OR imperfections in concentricity of your chamber/bore it won't matter if you have a very high BC long secant bullet, because your rounds are going to string all over the place. Or if you have a short bearing surface secant ogive bullet in a long leade chamber, yielding a rather long bullet jump, it's just not likely to be accurate for you (how many guys made that mistake by jumping on the Berger VLD bandwagon with their factory rifles!). In the same situation, a long tangent ogive bullet might be a better choice for you and give much better results, even though its aerodynamics might not be quite as good.

The $20,000 question is this, as it will frame out all of your decisions from the start:

Do you have a particular goal/task in mind?
Nomercy448 is offline  
Old 12-30-2014, 11:24 AM
  #10  
Fork Horn
Thread Starter
 
Join Date: Oct 2014
Location: Mississippi
Posts: 115
Default

I have seen discrepancy in factory ammo / defects !
Spinning of Barnes bullets.
Dented cases at shoulder and bullets to.
Different seating depths from the same lot.

I'm thinking about starting with the Lee classic loader and then I might work up to a single stage press .

One more question though , Remington and Winchester say their new brass has to be full length sized , if so that means I would have to get a press.
Nosler comes ready to go they say, but to reload them would I still have to F.L.size after I shoot them ?

Thanks again for your time and this will probably be the last post on the subject .
White Oak 06 is offline  

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service -

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.