6.5x55mm using Barnes ttsx 120gr - good development with Viht N540

[25 Sharps]

Some of the hunting I do with this rifle is in Africa. I have taken Waterbuck, Wildebeest, Impala and Red Hartebeest with it in South Africa and Namibia.

In some cases the first shot is over 200m. That requires maximum accuracy and good MV to deliver an ethical shot. Perfecting one round that can be used for both domestic and foreign use is part of the design brief.





I have neck damage and never shoot prone. I almost always use quad sticks. If I cannot, I am happy to let shot pass. In five years of using this rifle I have always managed to make that final check before pulling the trigger on live quarry. As an aid to doing that, I have also I have set the top-strap on my quad sticks such that the gape between forward and rear "Vs" are limited. Thus when I offer up the pistol grip to the rearward "V", the forward "V" is distal from the forend tip.

But I agree it is sub-optimum. I have been shopping for a later stock, but none have presented at the right price. One other option might be to increase the barrel-to-stock gap, or attempt to stiffen the stock with epoxy in its voids.

I would call under 300 metres a reasonable distance and an MOA group should do that on the quarry you list above. I shot a fox saturday(smaller than any of your quarry above) square on in the chest with a 75 gr v-max from my 25 - 45 at 248 yards with a 18 mph wind at 4-5 o'clock, adjusted aim for wind and drop from 100 yard zero. The 75s are not the best grouping in my rifle around 1" at 100 but they shoot well enough for what they need to do which is my point, as I say I think you are trying just a bit too hard for someone ho is not a target or serious long range varmint shooter.

I also think your stringing in your group is not down to the load it is down to either you or the rifle setup, likely a conbination of the 2.

I also think if an ethical shot is your ultimate concern you should at least try RS60 as it will give you more velocity and therefore be more ethical in terms of drop, wind drift and terminal energy.

I would also be changing the stock and if not the whole rifle, its an expensive set up to be finnicky about shooting position! 90% of my shooting is off of quads and even with a reputedly floppy hogue stock on the howa with a 26" heavy barrel accuracy is unaffected.

 

[25 Sharps]

49.6g and 2.940

3380fps with 100gn TTSX albeit through a 26” barrel.

assuming 57 gr h2o capacity you are 4000 PSI over pressure according to quickload

 

[zambezi]

No, if your head is aligning differently with the scope for the shots parallax will change the POI

Mmmm. I believe your statement only holds true if I did not make parallax correction at top of session. Which I did. Vortex explains thus:

 

[25 Sharps]

Mmmm. I believe your statement only holds true if I did not make parallax correction at top of session. Which I did. Vortex explains thus:

Your grouping says otherwise as does my own experience.

Are you setting parallax as the instructions in teh following link and getting zero movement?

http://www.reloadinginstructor.com/parallax---load-testing.html

 

[Ronin]

If you are lifting your head between shots or loading the forend differently either could explain the stringing

 

[zambezi]

Are you setting parallax as the instructions in teh following link and getting zero movement?

yes

 

[zambezi]

or loading the forend differently either could explain the stringing

more likely imo

 

[25 Sharps]

more likely imo

You need to change the stock then before you keep chasing tiny groups, or just shoot as you are as the groups are fine for what you're doing

 

[zambezi]

I also think if an ethical shot is your ultimate concern you should at least try RS60 as it will give you more velocity and therefore be more ethical in terms of drop, wind drift and terminal energy.

As you pointed out in an earlier post, the 2800fps N540 is delivering is close to the max MV listed on the Barnes website I do not need more MV than that.



And pretty much all loads that deliver higher MV are skirting SAAMI/CIP pressure maximums anyway.


In terms of ethical shot, 2800fps MV ensures the projectile will still be doing the 2000fps required by Barnes for full terminal performance beyond 380m. So speed is not the critical component in the ethical stakes here. Rather, it is about the groups: the closer I get to 0.5 moa the less likely I will make a poor shot at 250m.

 

[25 Sharps]

As you pointed out in an earlier post, the 2800fps N540 is delivering is close to the max MV listed on the Barnes website View attachment 173485 I do not need more MV than that.



And pretty much all loads that deliver higher MV are skirting SAAMI/CIP pressure maximums anyway.


In terms of ethical shot, 2800fps MV ensures the projectile will still be doing the 2000fps required by Barnes View attachment 173486 for full terminal performance beyond 380m. So speed is not the critical component in the ethical stakes here. Rather, it is about the groups: the closer I get to 0.5 moa the less likely I will make a poor shot at 250m.

Totally disagree unless you can deliver that .5 moa consistently off of sticks which most people can’t.

More muzzle velocity means less drop, less wind drift and more impact energy which buys you more margin for error. In my eyes that is more humane.

That fox I shot at 248 yards on Saturday didn’t know it had been hit by a 1 moa load!

QL shows RS60 buys you MV without going over pressure

 

[borbal]

40gr N540, MV = 2800fps as measured with Magnetospeed V3,

Really? If you look at the Vihtavuori reloading data for the 6.5 x 55 they quote 2684 for a 120 grain Sierra bullet using 41.5 gr of N540 - and that is out of a 670mm barrel....

 

[zambezi]

Totally disagree unless you can deliver that .5 moa consistently off of sticks which most people can’t.

That seems to miss the point altogether. It is this: if the round that has been developed introduces very little shot-to-shot POI variation, then there exists greater latitude for whatever other errors occur in a hunting scenario due to human skills or wind variation. A simple pair of sums probably explains it better:

bullets that deliver no better than moa accuracy + hunter error of 1 moa = 15cm error at 300m
bullets that deliver sub 0.5moa accuracy + hunter error of 1 moa = 11cm error at 300m

On larger bodied animals, perhaps not a big margin as you are probably still going to hit the vitals. What about the tiny 10? They are often shot at greater distances. For my money, eliminating possible error on the range developing consistent ammo is good hunting ethics. I do not claim the ability to shoot 0.5 moa off sticks consistently.

More muzzle velocity means less drop, less wind drift and more impact energy which buys you more margin for error. In my eyes that is more humane.

QL shows RS60 buys you MV without going over pressure

Good general statement, but Strelok suggests that tinkering with 2800fps by a few percent delivers no meaningful POI improvement in terms of drop or wind-cheating. Using a good bullet with a good bc is important, yes.

 

[JH83]

assuming 57 gr h2o capacity you are 4000 PSI over pressure according to quickload

No pressure signs whatsoever-no hard extraction, dented primers, soot etc, and in a sako 75 action.

 

[25 Sharps]

That seems to miss the point altogether. It is this: if the round that has been developed introduces very little shot-to-shot POI variation, then there exists greater latitude for whatever other errors occur in a hunting scenario due to human skills or wind variation. A simple pair of sums probably explains it better:

bullets that deliver no better than moa accuracy + hunter error of 1 moa = 15cm error at 300m
bullets that deliver sub 0.5moa accuracy + hunter error of 1 moa = 11cm error at 300m

On larger bodied animals, perhaps not a big margin as you are probably still going to hit the vitals. What about the tiny 10? They are often shot at greater distances. For my money, eliminating possible error on the range developing consistent ammo is good hunting ethics. I do not claim the ability to shoot 0.5 moa off sticks consistently.




Good general statement, but Strelok suggests that tinkering with 2800fps by a few percent delivers no meaningful POI improvement in terms of drop or wind-cheating. Using a good bullet with a good bc is important, yes.

10% could be achieved with RS60.

If you can’t shoot .5 moa off of sticks then the fact the load is capable of it off a bench is completely and wholeheartedly irrelevant as soon as it comes to shooting off of sticks.

Your sums are made up and a horrible mixture of moa and mil. If you can only shoot MOA off of sticks with the half moa load then sum 1 and sum 2 are one in the same.

let me put it another way, a bench rest shooter can shoot .25 moa consistently with his rifle. A new stalker has a go and can only manage 2 moa even off the bench, does the fact that the Benchrest shooter can shoot 1/4 moa groups with the rifle mean the stalker is likely to miss the POA?

 

[25 Sharps]

No pressure signs whatsoever-no hard extraction, dented primers, soot etc, and in a sako 75 action.

Doesn’t mean the pressure is not there, a lot of folk load to 60kpsi in modern actions but doesn’t change the fact they are 5k overpressure for the cartridge.

 

[75]

bullets that deliver no better than moa accuracy + hunter error of 1 moa = 15cm error at 300m
bullets that deliver sub 0.5moa accuracy + hunter error of 1 moa = 11cm error at 300m

1moa at 300m is about 8.7cm so not a million miles away.

2moa at 300m is 17.4cm
1.5moa is 13cm

 

[zambezi]

Really? If you look at the Vihtavuori reloading data for the 6.5 x 55 they quote 2684 for a 120 grain Sierra bullet using 41.5 gr of N540 - and that is out of a 670mm barrel....

Not sure what you are querying. I will address all possible questions I can think you have in order:



Do I trust the Magnetoscope V3 to give accurate readings? - Yes. I cannot find any negative press on any forum regarding this platform's measurement accuracy, bar one suggestion that a low battery scenario could give faux results [battery is new and voltage tested]. Also, I recently did a three-way comparison between a Chrony F1, a Labradar and this Magnetoscope tracking the same projectile and the differences in readings were negligible. The magnetoscope text readout is crystal clear . The Magnetoscope's assay of my .223, 30.06 and .375 cartridge MVs is also in line with expectations from factory and reload rounds.



Have you confused your tub of N540 with another powder? - Nope. Marked all powder tubs clearly on date of purchase. I only ever have one tub on the reloading desk at a time. I empty the powder thrower and powder trickle at the end of every reloading session.





Could you be dispensing the wrong amount of powder? - Nope. Beam scales zero'd before every loading session. Accuracy of the beam scales [and my operation thereof] is averified by using tare weights. E.g. bullets of known weight which are also weighed on digital scales.



Do online commentaries suggest that Viht tend to understate powder performance? - Yes.

 

[25 Sharps]

I have had an epiphany!
You need a 6.5 creedmoor

 

[borbal]

Do online commentaries suggest that Viht tend to understate powder performance? - Yes.

Ok, let us address the possible questions that arise from this:

Vihtavuori are honest people, but their chronograph is underestimating velocities...? Vihtavouri state on their website that, "...The data given here were obtained in laboratory conditions following strictly the CIP (Commission International Permanente) June 13, 1990 and November 9, 1993 rules."

Those rules state that, " Velocity V of the projectile is measured by the time taken by the projectile to pass two points in its trajectory. - the first point is situated at a distance of 0,50 m from the muzzle of barrel and the second at 1,50 m. - this time is measured by means of an electronic counter giving at least 10 µs".

So firstly, you can be sure they did not get their chronograph at the ACME Reloading Store. It will be nuts-on and carefully calibrated. Secondly, it is not ten metres down the range, so you could claim that the projectile has lost 100ft/sec. before it gets to the screens.

Upshot, I do not think this scenario is likely.

Vihtavuori are not honest people and they deliberately reduce the velocities they measure. Why would they do that...? They want to put the best light possible on their powders. They want people to think their powders give better performance than anybody else's powders. If they are going to be dishonest, they would put the listed velocities up, not down.

Upshot, I do not think this scenario is likely either.

So, what are we left with? Well, you listed the possible areas where problems might be. I respectfully suggest to you that one of them is not quite as you think.

 

[zambezi]

you listed the possible areas where problems might be. I respectfully suggest to you that one of them is not quite as you think.

First up: I did not in any way suggest dishonesty on the part of Vihtavouri. I believe they claim more conservatively than some of their competitors. I.e. their products perform better than claimed.

Until you have removed all the wrong answers, you cannot be 100% sure of the facts of the matter. On that we are agreed.

The absolute acid test is drop data at longer ranges. Remove the Magnetoscope from the equation altogether. In the near future I will test this load on targets out to 300m.

If the number of clicks on the Z6i elevation turret separating a 100m and 300m target correspond to the Strelok predictions for a 120gr bullet with a 0.420 bc leaving the muzzle at 2800fps, then the chrono data is validated.

If not, Strelok provides a handy means to calculate MV from drop data.