Ftr loads 155 hybred v 185 hybred

[plumbs7]

Hi just on the ballistics computer and running the numbers . Ok in my rifle I'm getting 3030 Fps 28" barrel 155 hybreds, which at 1000yds and 5 mph full wind I'm get 1.11 miliradian drift ( times 3.86 for minutes I thinks).
I've got no real data for speed on this next load but an educated guess. 185 hybred at about 2720 Fps gives 1.07 miliradians 5mph full wind at 1000 yds. Drift difference of .04 of a miliradian or .04 of 91.4mm or 36.56 mm difference .

Question ? If I'm correct ( most doubtful!) is it worth running more recoil and 2 loads for marginal gain?

Next question what are people using for loads and does the above figures ring true for you?
Regards G S

[plumbs7]

Just did it for 168 hybreds at 2900 Fps ( should be achievable ) . There was only 9mm difference worse against 185's at 1000 yds and 5 mph wind.

[mike H]

Start looking towards 2800 FPS for the 185 grain projectile.Recoil with a 8.25 kg rifle is a non event.

[plumbs7]

Just ran the numbers and at 2800 Fps for 185 hybreds v 155 hybreds it 90 mm more drift for the 155's that's considerable ! That's .5 of a minute one would have to get better wind calls if shooting 155 's against another person shooting 185's .

What load are people running and barrel length to achieve that 2800 Fps ? If they would be kind to share? Regards G.

[mike H]

Just ran the numbers and at 2800 Fps for 185 hybreds v 155 hybreds it 90 mm more drift for the 155's that's considerable ! That's .5 of a minute one would have to get better wind calls if shooting 155 's against another person shooting 185's .

What load are people running and barrel length to achieve that 2800 Fps ? If they would be kind to share? Regards G.

Apart from 30 to 32" barrels,I am saying nothing other than a long throated chamber,I moly coat,others don't.Work up gradually as always.

[ShaneG]

Graham
I would say most are using minimum 30" and I personally have used 32" barrels for several years now.
With the reamer throat I use the 185 gr Juggernauts run 2840fps with 2208 in Palma cases.
The Palma cases use more powder to achieve the same velocity / pressure.
Most likely due to softer ignition of the small rifle primers?
However the Palma cases seem to cope with high pressure loads very well possibly due to all the extra brass at the head?
I could not achieve the same accuracy with the Hybrids as I do with the Juggernauts in several of my barrels?

A longer throat would give a higher velocity but then I would no longer be able to run the 155 Hybrids.
A fast 155 Hybrid load is much more enjoyable to shoot for me personally.
The 155 Hybrid was the pill I used for all ranges at the Nationals in Brisbane last year.
As Mike said start low and go up with 2208 watching pressure and velocity.
Different chamber reamers; barrel diameter; twist etc all produce varying pressures so I would not quote my loads for others to use.
BTW 1/11 probably best compromise twist for both these pills although 1/10 will work also.
Cheers
Shane

[plumbs7]

Hi Shane , I enjoyed watching u shoot the last detail at the Nats . Also thanks for the wind reding advice.

Also thanks for the avice above . I'm just thinking of where to go next with my F class . Eg Ftr or open .
Kind regards Graham.
Ps thanks also Mike as well!

[williada]

Graham, I look at your solution from a different perspective. May I say, that marginal differences in drift advantage are not worth considering but significant ones are. As F class establishes itself the gear will standardize itself. I’m sure shooters will volunteer loads they use. Note we are seeing the trend to 7mm and its not just a fashion. So what will separate the shooters in the future in F class is: (a) wind reading ability and (b) grouping ability.

While the key to wind reading is estimating the strength and direction of weather, it is the ability to calculate using nice rounded numbers in your head as estimates when you learn the basics that will generate high scores because the targets are so tight. It will not be hoping your gear can absorb the wind change. While considering your different projectiles, look at the drift numbers where one is more easily used than the other for mental arithmetic. Now if you apply that to Peter Smith’s software simulation on wind reading you will know what I mean. You can use the 10mph left wind to establish your basic drift at each range. Then stick with the fishtail sync. wind pattern as basic practice. The advanced use of the software is a discussion in itself.

With regard to grouping ability, I give a tighter tune greater preference than drift performance within reason in the same caliber. Its no good if your groups are opening up when you think you are getting less drift. Proper load development is essential.

A simple chronograph test is a way of determining whether your rifle is more tunable with a certain projectile. You don’t need a target to shoot at. After firing 3-4 warm up shots, for this test, load EACH round in a .2 increment, say 12 rounds, going down from a safe max load. Record each shot with a chronograph. Now graph the load against speed, manually or with a spreadsheet. If the graph has no flat spots, it is generally indicative the component combination (powder/projectile) are not optimal. Of course a pitted barrel or one that fouls has to be taken out of the equation. That stuffs any testing.

If the graph has two or more relative flat spots, you have a barrel that is easier to tune. One bullet may have more flat spots than the other. If they have the same number of flat spots, then choose the one that has more sections that are less steep than the other.

Do further testing about these flat spots (where varying loads hit in a similar spot) on a target at short range. You may choose to use .1 grain increments in round robin testing with 5 shots for each load increment to refine your tune on paper with loads about these flat spots using methods I have previously described.

Choose the projectile that groups the tightest over the one that uses less drift in the same calibre. You may get a combination that uses less drift, groups tightest and has easy figures to work with for windage calculation. There is more than one way to skin a cat. David.

[williada]

I just had an email from H. McRorie where he said I had to look at this link right to the end. Subtle message for all testing.
http://www.liveleak.com/ll_embed?f=24113d89dfd8

[plumbs7]

Hi David , we got ten mm of rain yeh!

Quote Choose the projectile that groups the tightest over the one that uses less drift in the same calibre. You may get a combination that uses less drift, groups tightest and has easy figures to work with for windage calculation. There is more than one way to skin a cat. David.

I think this is what I was thinking with the 155's. I have a lot of experiance in wind calls with that projectile.
But thought it would be good to open up for debate on the subject on fast pills versus slow n heavy and slippery .

Also thanks , Graham .

[RDavies]

Something I have often wondered about the slow/heavy vs fast/light argument is, if the wind drifts on paper are even, will the heavier pills be less affected than the light pills by range verticals at ranges which have big mounds and gullies. Engineers would argue that, if wind drifts were even, then effects of range vertical would be the same, but have F/TR shooters found that heavy bullets show less effect from wind over gullies and mounds than 155s????

[Tim L]

Something I have often wondered about the slow/heavy vs fast/light argument is, if the wind drifts on paper are even, will the heavier pills be less affected than the light pills by range verticals at ranges which have big mounds and gullies. Engineers would argue that, if wind drifts were even, then effects of range vertical would be the same, but have F/TR shooters found that heavy bullets show less effect from wind over gullies and mounds than 155s????

I wouldn't argue that. Wind drift isn't linier, it is compounded because the projectile accelerates laterally due to the force being applied over a period of time. Mounds and gullies apply the effect intermittently so fail to maintain the acceleration. Each time the force dies it gives a benefit to the heavier projectile because it will take longer to initiate the deviation when it starts again. Net effect is less deviation for the heavier projectile.

[williada]

Really good question Rod in terms of using the same calibre. I look forward to hearing others experiences here too, especially the Match Rifle guys. A greater mass is less affected by wind shears but there are other factors.

Certainly the Magnus force requires consideration when relating to projectile diameter and effects when hitting wind shears. The 7mm seems to be pretty optimal in other aerodynamic drag terms in trying to get the best out of all the drag factors and measure up in bag handling terms. Everything is a trade off. Its hard to get the perfect all rounder for all ranges and conditions. How many ranges have those gullies and high mounds and how often does that rear or frontal condition occur on those ranges when these shears pose a problem and at what wind speed? Some argue that the mass factor can be overcome by velocity. For instance, a 6mm/284 Shehane (if barrels were not a problem and good bag handling was more desirable) could reduce the need for greater mass but it probably would not be efficient as a 7mm in terms of the diameter working on bucking Magnus force effects on vertical.

[RDavies]

Really good question Rod in terms of using the same calibre. I look forward to hearing others experiences here too, especially the Match Rifle guys. A greater mass is less affected by wind shears but there are other factors.

Certainly the Magnus force requires consideration when relating to projectile diameter and effects when hitting wind shears. The 7mm seems to be pretty optimal in other aerodynamic drag terms in trying to get the best out of all the drag factors and measure up in bag handling terms. Everything is a trade off. Its hard to get the perfect all rounder for all ranges and conditions. How many ranges have those gullies and high mounds and how often does that rear or frontal condition occur on those ranges when these shears pose a problem and at what wind speed? Some argue that the mass factor can be overcome by velocity. For instance, a 6mm/284 Shehane (if barrels were not a problem and good bag handling was more desirable) could reduce the need for greater mass but it probably would not be efficient as a 7mm in terms of the diameter working on bucking Magnus force effects on vertical.

So back to 155s or 185s. The 155s have less recoil, less barrel time, making handling slightly more forgiving. 185s buck the wind slightly better and maybe have slightly less range affected vertical. Have F/TR shooters found any noticeable difference in range vertical between 155s and 185s at ranges such as Belmont with its big, high 1000, 900, 800 and NOW 700 mounds.

[GrahamW]

I just had an email from H. McRorie where he said I had to look at this link right to the end. Subtle message for all testing.
http://www.liveleak.com/ll_embed?f=24113d89dfd8

Yep, I think I got the message...... "don't shoot at champagne bottles!"

8-)