OzFclass

When measuring bullets, ogive to base what is the exceptable maximum variation of the projectile. I use 2 thou, is that excessive or should one give more 3 or 4 thou in variation.

I can’t give any proof that it makes any difference to groups, but I sort by BTO into groups that are within 0.003”
Of the last batch of 800 Berger 215hybrids I sorted, 600 fell into one group, about 150 into batches immediately either side the rest relegated to velocity testing/fouling and run in duties.

In other batches of Berger’s I have found the occasional wild outlier or a bullet with damaged jacket etc. I’ve heard of people finding a VLD amongst a batch of hybrids so it’s worth doing.

Are you actually sorting from ogive to base? or ogive to another comparator on the boat tail, so bearing surface? I haven’t done it yet and wondering which way to go?

depends on what you are wanting to achieve if these are boat tail bullets.
2 Thou is fine for a general measurement - on boat tails it won't tell you where the variation is but it will catch outliers.

Another measurement to watch is base to position seating stem sits on projectile. I have found up to .008 difference. As this position is what controls seating depth, I figure it is important. Especially those who load close to lands. I do not think it is as important if loading with reasonable jumps in the vacinity .025-.050 or beyond. cheers,
Trevor.

For me 1 thou . For what that’s worth . Regards Graham.

What does "ogive to base " prove after all?
It does not necessarily consistently fix seating depth of a loaded round. That depends upon the diameter at which the seating cone picks up the projectile.
I have seen projectiles from different batches with the same " base to ogive " but with up to .010" difference in seating depth. Why? Because the ogive is a different shape. --Different shape--different BC--different strike point on the target.
If the projectile diameter varies at this point then the seating depth ( case base to ogive) will probably vary also.
Case base to ogive is important for consistent seating, be it jump or jam.
More important ( in my opinion ) is bearing surface length, which means two comparators, keeping in mind that the assembled round then needs gauging for seating depth.

I think base to ogive measurement is only relevant to flat base projectiles, as measuring from the base of BT projectiles has 2 factors of variability.
Two comparators seems to be a lot of mucking about.
Pete

I have no information on tolerances and whether it is worth going to the extra trouble and measuring bearing surface.

Could be - maybe ?

Most comparators measuring base-ogive use a dial gauge directly on the base. If a small 'tube' was made to fit on the dial gauge stem or thread into the dial gauge stem, it would then measure from Ogive to start of Boat-tail - ie. bearing length.

Thus one could do a more comprehensive sort by

1/ Sorting on Base-Ogive first.
2/ Resort these measuring the bearing length using the above system.

Of course, it would not measure the detailed shape of the Ogive (or for that matter the shape of the Boat-tail). This is a very complex thing to measure.

Whether this is worthwhile - who knows ??

Ultimately, we have to depend on the integrity of the bullet-smith for consistency - even jacket thickness and balance - so to me reputation and past performance is always very important. Maybe more important ?

Peter Smith.

pjifl wrote:I have no information on tolerances and whether it is worth going to the extra trouble and measuring bearing surface.

Could be - maybe ?

Most comparators measuring base-ogive use a dial gauge directly on the base. If a small 'tube' was made to fit on the dial gauge stem or thread into the dial gauge stem, it would then measure from Ogive to start of Boat-tail - ie. bearing length.

Thus one could do a more comprehensive sort by

1/ Sorting on Base-Ogive first.
2/ Resort these measuring the bearing length using the above system.

Of course, it would not measure the detailed shape of the Ogive (or for that matter the shape of the Boat-tail). This is a very complex thing to measure.

Whether this is worthwhile - who knows ??

Ultimately, we have to depend on the integrity of the bullet-smith for consistency - even jacket thickness and balance - so to me reputation and past performance is always very important. Maybe more important ?

Peter Smith.

I have the very same thoughts as you Peter. For me any measurements that can be carried out will not be accurate enough to make any worthwhile difference and are a waste of time. I have tried most of these bullet sorting methods, developed headaches and eyestrain only to win shoots with the rejected bullets!! So I use good bullets and prove each batch in club shoots and save myself much frustration!!
Keith H.

Base to ogive can be very useful when comparing lots. Some lots are significantly longer .2-.3 and thats enough to require a new work up as it would indicate significant dimensional differences that could alter pressure significantly
Base to ogive has no relationship to seating depth - in fact IME there are other factors that affect the end seated depth more than bullet dimensions..

could base to ogive affect case capacity in a meaningful way?
bruce.

bruce moulds wrote:could base to ogive affect case capacity in a meaningful way?
bruce.

I've read that on smaller cases it can.