rough test

[dg]

while fireforming some blue box 6mm BR brass this morning at 1000yds.

the following results were obtained

temp 14 degrees C

conditions overcast, down range very slight breezes 0-5 knots

105 grain berger hybrids (coated and straight out of the box)

velocity range - 2848 - 2861 fps

103 grain copperheads (coated and straight out of the box)

velocity range - 2839 - 2856 fps

using the same point of aim and scope settings, at 1000yds both groups shot to the same point of impact.

on the target, both groups had less than 6 inches vertical dispersion on top of each other.

make of these very basic and limited findings what you like, but in my opinion when projectiles travelling at near identical velocities shoot to the same POI at 1000yds, i reckon their BC's must also be near identical.

cheers
dave g

[justjeff]

Hi Dave,

You could argue that since the copperheads had a slightly lower MV, they maus have a slightly higher BC to compensate. Interesting test result, as I was looking at the copperhead for the LG, which will still be first choice.

Jeff

[dg]

jeff

i marked the first group location on the target (the hybrids) and then shot the 2nd group (the copperheads).

for both groups i don't know the order in which they landed, but i am just going on the overall location for each group which for the rough centre of each, were very very similar in vertical location.

the motivation for this test was because in my 6x47lapua and stuart's 6mmBR, the copperheads seemd to be shooting flatter than i expected.

yeah mate, i am sticking with the copperheads as well.

i don't bother with any checking, just coat em' and load em'.

they just re-affirm that i am the problem.

cheers
dave

[Camel]

jeff



they just re-affirm that i am the problem.

cheers
dave

Don't you just hate it when you get proven wrong by some totally inert metal bits.

[Tony Z]

Gooday Dave. Cheers for the recent message.

This is a no brainer Dave. For the Inbreds you'll need a Jeunke. For the Copperheads you won't.

[aaronraad]

while fireforming some blue box 6mm BR brass this morning at 1000yds.

the following results were obtained

temp 14 degrees C

conditions overcast, down range very slight breezes 0-5 knots

105 grain berger hybrids (coated and straight out of the box)

velocity range - 2848 - 2861 fps

103 grain copperheads (coated and straight out of the box)

velocity range - 2839 - 2856 fps

using the same point of aim and scope settings, at 1000yds both groups shot to the same point of impact.

on the target, both groups had less than 6 inches vertical dispersion on top of each other.

make of these very basic and limited findings what you like, but in my opinion when projectiles travelling at near identical velocities shoot to the same POI at 1000yds, i reckon their BC's must also be near identical.

cheers
dave g

Good stuff Dave!

I've had a bit of feedback on long range performance, but it's not often you read where someone has the time and resources to record muzzle velocity and atmospheric conditions to give a more complete picture.

Did you notice any significant difference in the windage adjustment required for the groups? I would think not, but stranger things have happened.

Aaron

[dg]

Aaron

This test and results were basically a combination of luck and circumstances.

In my experiences, usually regardless of the calibre, it is rare if projectiles of differing weights happen to provide the required accuracy standards at similar velocities.

As an example, for the 6x47 the accurate loads for 105 and 103 projectiles are around 80-100 fps apart.

The variation between 108 and 103's is around 150fps.

Whilst it is possible to load projectiles of differing weights to similar velocities, unless the required accuracy is attained, in my opinion, the results obtained are meaningless.

I also accept that other 6mmBR's (for all the many differing variables involved) may or may not give similar results.

I was surprised when this 6mmBR gave the results obtained.

On Monday i went to the range with some less than precise fire forming loads, just to blow out the cases and to make some sighting corrections at 1000yds.

When these loads also seemed to shoot very close together, i decided to fine tune the remaining cases for the test yesterday and see if the same results were obtained.

In regard to the wind effects, by chance yesterday was a very good condition day at N-D and whilst shooting, most of the time (by my rough estimation) there was less than 1 or 2 knots maximum sideways drift at times.

I therefore did not worry about trying any sideways hold off and held dead on for all shots.

The targets reflected this with expected width dispersion being around the same for both groups.

Each to their own, but when testing at N-D 1000yds, my aim is to minimise vertical dispersion.

i know and accept that the width is me!!!!!

cheers
dave