Bullet Ogive vs Weight (tolerances)

[Miyka-el]

I know this has been done to death but I need help on this one (there seem to be many million opinions, so time to sort through more

I'm in the learning process of handloading and finally (2 yrs later) bought a Hornady OAL gauge & bullet comparator. I don't compete yet but I figure that the best knowledge on making consistent ammo will be found with the benchrest community Thank you to the Accurate Shooter website & community!!! ;D

My hunting (target 175 SMK) setup:
Rifle - Savage 10 Precision Carbine in .308
Lapua Brass
CCI Primers
Barnes LRX 175g Bullets
IMR XBR 8208 powder

So, I spent a while not only measuring weight but also bullet ogive (after checkin my rifle's chamber).

With my novice measuring results on the LRX bullets, I got this many at these Ogive measurements (the box had 51 bullets):

.806 - 3
.807 - 7
.808 - 8
.809 - 7
.810 - 14
.811 - 6
.812 - 3
.813 - 2
.815 - 1

What is acceptable tolerance for the BR community (not for hunting)? I've been gleaning from forums & articles that ogive is more important than the bullet weight? Would the .808-.811 range be OK, or would the .809-.811 be better? TIA.

 

[wapiti25]

I would do a shooting test at 300yds or more using some of each and see how they look on paper.

 

[necchi]

In My Humble Opinion,
You've got the right idea beginning to segregate bullets, but the select tolerance is always what each individual determines for himself and what his gun will tolerate.
Of course finely tuned custom guns will show a better group with all of the variables as close as possible,,
with the factory guns less capable of knowing the difference.

In this case the Barnes bullet while being a superbly accurate bullet, isn't a "target" grade bullet and is indeed a hunter, the full copper has it's own issues, (in my experience a long jump being one of them).

I'd use the .810 as the select for the actual hunt and all others used for load development. If I had already determined a preferred load and these where to be for stock I'd go with the .809-.811 spread.
(spendy bullet to practice with!)

 

[BoydAllen]

Given the application, I am not sure that you will see a difference, since these bullets will probably be jumped a good bit, but if you like, under the most perfect conditions that you can manage, using flags, and shooting over a chronograph, try a group with a mixture of the extremes, and one where they are all the same.

It may be that you can use them all, if you have a micrometer seater. Seat them all about .020 long, then measure each loaded round, using a checker that approximates your chambers throat, and adjust your seater for each group, for the final seating, so that they will all have the same measurement on the ogive. There will be some slight variance, but this way, you should be able to use all of your bullets and have the same jump for them all. Personally, given the usual field conditions, I think that all of this will be "lost in the noise".

 

[Tuckerp229]

This is exactly what has driven me nuts for the last several days.
I ran a search on this topic, missed this fresh one and posted my own similar question just a few new post topics after this one.

At least three places to vary:

1. The ogive diameter, shank/ bearing surface length
2. boatail section length
3. any tail end of a bullet that is not square and flat could yield a varying length depending on how one spins the bullet in the calipers.


When grouping the bullets themselves by their length as measured by ogive to tail, how does one know that the length variance is from?

 

[BoydAllen]

I believe that there are tools that use the same sort of barrel throat simulator to make contact on the ogive, near the shank, and near the front edge of the boat tail. This can be done with an adapter on both jaws of a caliper. or as a purpose built tool that uses a dial indicator and base. The measurement taken is generally referred to as bearing surface length. This sort of thing is generally used for long range benchrest.
Before adopting any method, I think that it is a good idea to do some testing to see if you can see the difference at the target. Quite often I see fellows that go farther than they need to in one area, and ignore something that would actually matter.

 

[necchi]

Quite often I see fellows that go farther than they need to in one area, and ignore something that would actually matter.

Well said.

 

[Miyka-el]

Thanks to all for your insight and answers, much appreciated. I respect the BR crowd and it usually the first place I check for advice on load development. Yes, maybe overkill for hunting bullets, but I like the challenge without going all out like BR (to the level of precision) and also keeps me furthering my learning as I might make it to "F-CLASS FACTORY SPORTER" (or Tactical, Service) one day. Might as well learn the ammo making skills and maintain it I finally got another missing piece that I needed, a shooting rest, which will bring more consistency than just off the bipod. Will be back, thanks again for all the informative answers and advice.

Even if I don't bag anything, I'll know that I have the best ammo possible for hunting

 

[timeout]

I've not used a Hornady bullet comparator, but I think they are used in conjunction with a dial or digital caliper. Just by the nature of the method, I believe it would be harder to achieve as accurate base to ogive measurements, than when using a Sinclair stand and indicator. I try to keep my bullets not more than .002" apart, or + - .001" from zero. Probably not necessary for hunting loads, but good learning experience and pratice for the future. I have found Berger VLDs of the same lot number to be very even base to ogive. When changing lots, I had a jump of .005", however they were all mostly dead on within the lot. Some others I have measured vary a bunch. I have not loaded for or shot a .308. There is a lot of info on them. I do know that superb accuracy can be achieved with Berger VLDs being "jumped" a good bit in my 6BR. I have gotten slightly better results jumping them in my 6BR, than when loaded into the lands. Only actual load testing in your rifle will determine what works. As you probably already know, loading your hunting rifle into the lands may result in the bullet being stuck to the rifleing and powder littering your action, should you unload a round without firing it. Keep striving to produce the best ammo you can. It is a worthwhile endeavor. I'm going to try some Barnes triple X's in my wife's .223. I was hoping to try Berger VLDs in it, but they only make the target VLDs in .22 cal. One needs deep pockets to experiment too much with the Barnes!