OzFclass

my 284 reamer was set up for 180 gn berger vld, which also allows 180 hybrid. 0.2"freebore.
with the shortage of bergers, and the price, i am looking at alternatives.
would anyone havebearing lengths for the following bullets.
hornady 180 eld
hornady 162 eld
sierra 180 matchking
sierra 183 matchking
nosler 185 rdf
kens 180s
any comments on freebore requirements for above would be appreciated.
also i have an 8.5"twist so comments here would also be appreciated.
how bad is it really to seat bullets below the neck/shoulder junction?
maybe i will need to get a throating reamer
if i do i am really tempted to try a 0degree 30 minute angle, after seeing how this reduced pressure in another calibre.
bruce.

From the projectiles I have I can tell you the following from measuring with a hornady comparator vase to ogive:

Hornady ELDM 180gr 0.813”
Sierra 183gr Matchking 0.830”
Berger 184gr Hybrid. 0.820”

My current batches of 180 hybrids are .784” and .791” measured at the same time if that helps.

I also found some old RDF 185gr which were the longest of the lot at .849” BTO

bruce moulds wrote:...would anyone havebearing lengths for the following bullets...

How do you measure a bearing length? Comparators just measure to an arbitrary point on the ogive (or boat-tail) and can't give an exact bearing surface measurement.

You need two comparators, one to pick up at the start of the ogive and one to pick up at the start of the boat tail.
Simple actually.
Bearing lengths vary considerably from batch to batch, be they Berger, Sierra or anything else, and this variation does affect exit speeds, AND available case capacities, AND seating depth.
Important measurement in my opinion.

alan,
you are right.
however using 2 comparitors as barry describes must give relative lengths.
say one bullet measures 0.045 longer than another, the actual length difference would probably be similar.
in my case with short freebore it might help make choices.
i might have to look at the hornady 162 eld for its balance of b.c and bearing length for example.
bruce.

Barry Davies wrote:You need two comparators, one to pick up at the start of the ogive and one to pick up at the start of the boat tail.
Simple actually.
...

Agreed that is the simplest way - I have a Davidson checker and it would cost about $50 to get another one, so there is a cheaper method using one comparator and some addition and subtraction . Measure base to ogive and tip to boat-tail junction with the comparator, then do a direct measurement of base to tip. Add the first 2 measurements and subtract the third.

May I suggest a simple way to measure bearing surface. Perhaps not quite as precise as possible but probably good enough.

Get an old barrel. Or maybe the small piece that your gunsmith may have cut off the muzzle when he fitted a new barrel. Some barrels makers such as Bartlein assume that you will discard about 1 - 2 inches from the muzzle. Some others don't so research this and insist that you get it when a barrel is fitted.

Face off very carefully from the cut end of the barrel stub and remove any burr. Perhaps pass a bronze brush back and forth in it a few times. BTW, some barrels are lapped to a measurable taper which will change bearing length in different parts of a barrel.

Take a pristine projectile and lightly place in bore and twist it slightly. You will have a very distinct ring on the projectile. Felt pen blue may help. Repeat this with the bullet reversed.

Now, with a decent magnifier, adjust the jaws of calipers to correspond with the marks from one to the other.

You should be able to read to 5 thou without any trouble - without having spent a cent on special tooling.
OK - there are other methods but this may be all you want.

My thoughts on Bruce's question of having the bullet seat back below the neck are that - it is important to avoid any donuts so I would be careful here. Unfortunately, a projectile seated out long, needs to move forward as the throat wears so a compromise is needed. A collet die tends to avoid donuts more than any other type of sizing die.

Peter Smith.

Just get a throating reamer Bruce. If I'm not mistaken the bearing surface length does not relate directly to the required throat length because of the different bullet nose profiles and throat angles that exist. And I would buy bullets in yellow boxes for competition waaaay before getting them in red boxes. Btw over here we get absolutely shafted for yellow box boolits. Just look online. Your Berger prices over there are great by comparison.

well we have hornady bullets reputed to blow up, noslers that give fliers,sierras hard to get, and bergers impossible.
might have to ring ken.
then his bullets would turn out to be excellent and a drunk druggy driver could take him out.
bruce.

bruce moulds wrote:...and bergers impossible...

What's impossible about Bergers??

alan,
they are not always available, and sometimes when they are they are not easy.
also cheaper options attract attention should they do the job.
bruce.

180 VLD Match are on special $79 at the VRA. Most 7mm Berger varieties are available at BRT. You need to stock up when they're available - cheaper and makes sense in terms of getting uniform lot numbers over a long period. Not sure how Ken's 7mm projects are going - he's had a lot of trouble getting jackets and then forming dies out of the US.

the other thing about berger is that they are financing the u.s. team to the tune of $1.00 per box.
if they did this for the oz team as well i would like it better.
bruce.

Bruce,
Sent you a PM (need your postal address) to send a couple of my 7mm 180 grain VLD Copperhead Bullets to see if it meets your FB/throat length.
Ken @Copperhead Bullets
Just ask Michael Diffird how well they shoot