My .260 is a very expensive piece of JUNK! [Lots of pics]

[Afy]

That is exactly what I want to do...

If my ammo is not good enough... bring some that is...
If the scope is bad...Well you're a leupold dealer so replace it...

The wind is too high at 300... let come down to 100...

Feel that the wind is still too high... hell lets come down to 50 meters and show me a 5 round group measuring 0.264 edge to edge.

 

[Doug b]

Afy I'm not at all familiar with vv powders so I went to Lapua to learn.N550's burn rate is the same as our IMR 4350 & RL 19, I'm thinkin this is a little on the slow side for this round.N530 is in the same burn range as IMR 4064 & RL 12.Might be worth a try.
Also Lapua load data says 38gr. N550 is max with a 139 gr. bullet.

 

[Afy]

Doug..

My once fired case has a capacity of approx 55 grains of H2O... plus my seating depth is way over the 2.80 OAL most manuals have.

I am not seeing any signs of pressure either...

Plus I do run QL for predictions.. the rifle is set up different to what the manuals say.

At 38 grains I would probaly see signs of low pressure including sooting et al.

Plus at this stage... if the manufacturer says x + y + z will give you a group under 1 inch @ 100 meters... that is what I want.

BTW QL Data:
Cartridge : .260 Rem
Bullet : .264, 123, Lapua Scenar GB489 6032
Useable Case Capaci: 49.303 grain H2O = 3.201 cm³
Cartridge O.A.L. L6: 2.839 inch = 72.11 mm
Barrel Length : 26.0 inch = 660.4 mm
Powder : Vihtavuori N550

Predicted data by increasing and decreasing the given charge,
incremented in steps of 2.0% of nominal charge.
CAUTION: Figures exceed maximum and minimum recommended loads !

Step Fill. Charge Vel. Energy Pmax Pmuz Prop.Burnt B_Time
% % Grains fps ft.lbs psi psi % ms

-20.0 73 33.70 2306 1453 25860 7053 91.0 1.721
-18.0 74 34.55 2361 1522 27496 7272 92.2 1.681
-16.0 76 35.39 2415 1593 29232 7485 93.2 1.642
-14.0 78 36.23 2470 1666 31059 7691 94.2 1.604
-12.0 80 37.07 2524 1740 32976 7890 95.2 1.567
-10.0 82 37.92 2579 1816 34993 8080 96.0 1.532
-08.0 83 38.76 2633 1893 37128 8262 96.8 1.496
-06.0 85 39.60 2686 1971 39390 8434 97.5 1.454
-04.0 87 40.45 2740 2050 41785 8595 98.1 1.415
-02.0 89 41.29 2793 2131 44322 8746 98.6 1.377
+00.0 91 42.13 2846 2212 47008 8885 99.0 1.341
+02.0 93 42.97 2899 2295 49855 9012 99.4 1.305
+04.0 94 43.82 2951 2379 52871 9127 99.7 1.271 ! Near Maximum !
+06.0 96 44.66 3003 2463 56070 9229 99.9 1.239 ! Near Maximum !
+08.0 98 45.50 3055 2548 59464 9318 100.0 1.207 ! Near Maximum !
+10.0 100 46.34 3106 2634 63065 9392 100.0 1.176 !DANGEROUS LOAD-DO NOT USE!

Results caused by ± 10% powder lot-to-lot burning rate variation using nominal charge
Data for burning rate increased by 10% relative to nominal value:
+Ba 91 42.13 2973 2413 56234 8631 100.0 1.242 ! Near Maximum !
Data for burning rate decreased by 10% relative to nominal value:
-Ba 91 42.13 2671 1949 38030 8689 93.8 1.469


Personally my thinking is that, given tis is the very first 1 in 8 for .260... he has messed up the barrel.

 

[alsaqr]

Cant be a staibility issue either... with a 1: 8 twist...

Are you absolutely sure the barrel is 1:8 twist? Sure looks like a case of a slow twist barrel.

 

[dalepres]

Considering the investment you have in the gun, Afy, it sounds like time for you and the maker to be at the range together... followed by one more attempt to fix it and one final test before the attorneys get involved.

 

[uncowboy]

I have the same problem

with a recently built 7mm08 for silohuette shooting. 100 Yd groops dimal :banghead:I was assured today that If I shot it at 300 Yds I would be happy. I talked to two shooters at the match That both said the 1 in 8 twist bbls at 100 yds are not stabalizing the bullets yet. I have to try 200 yds to make sure but I cant see 110 RDS of ammo shot at 100 yards all beeing bad . The guy I got the gun from shot a 1.5 " groop at 300 yards. I will have to get some VV powder and try his load but I am blaming the distance or the scope but not the rifle. I will shoot another 200rds through it and report back But I need a longer range! J.Michael

 

[cpttango30]

I don't think it is totally the rifle or the builder.

Some bullets and loads need time to settle in and shoot accurately. I have seen some rifles shoot 2" groups at 100 yards turn around and produce 1" at 300 yards.

I just have a hard time believing that the gunsmith did the same thing wrong both times.

It is either the ammo, rifle, SHOOTER or optics. Swap the scope for another one you have on hand. try different loads.

 

[dalepres]

I don't think it is totally the rifle or the builder.

If the rifle maker is saying they're testing with great results and even providing test targets but the customer can't reproduce the results, something is wrong. By now, the gun maker should have provided Afy with the ammo specs they used in testing. Also, the gun maker said they messed up the rifling but, if that were so, how did the gun get out of the shop the first time? For that kind of money, surely they should have test fired the weapon for accuracy.

I'm very amazed at Afy's patience through this whole thing. It's way past time for them to do a live demonstration of the accuracy of the gun to back up their promises.

 

[jlbraun]

Is the twist rate right for those bullets? 1:8 seems very fast. What about the diameter of the bullets?

 

[taliv]

guys, i'm not sure what you mean by "settle down" but i don't see how that can possibly account for those groups.

 

[jerkface11]

Did the guy actually rebarrel it? or did he just keep it for a while and send it back?

 

[jlbraun]

The "settling down" indicates that the tip precession of the bullet about its centr of gravity has stopped and the bullet is now flying straight and not on a spiral. A bullet actually doesn't follow a simple parabola to the target, it follows a helix a few inches in diameter if it's overstabilized.

 

[Tarvis]

If the builder screwed up the rifle, it wouldn't be the first time an amateur gunsmith sold a botched build as a custom gun. The only thing that sounds custom about it is how bad it shoots. $5000 had better live up to it's price tag. Take that SOB back.

 

[dalepres]

Yep. For $5000 I will build you a gun and guarantee that it will shoot .25 MOA... looking up how to build a rifle now. I should be an expert by the time your check clears.

 

[taliv]

jlbraun, you have any links or references for that?

 

[jlbraun]

Truly excellent resource:
How do bullets fly?
http://www.nennstiel-ruprecht.de/bullfly/

http://www.nennstiel-ruprecht.de/bullfly/fig21.htm
7.62x51


The numbers in the y axis correspond to bullet diameters - 8000 diameters is about 200 feet. This motion eventually settles out and the bullet flies straight. See how it's starting to settle towards the right?

However, if the bullet is over-stabilized, this precession/nutation never settles out and in some cases gets worse:


Something is borked with that gun.

Get your money back. For the same money you could have a nice AI in .260 that will shoot bug holes.

 

[Dr. Tad Hussein Winslow]

Man I hope you get that fixed. I think I'd be asking him to do it while you watch.

Something is borked with that gun.

Sorry, that made me snicker.

 

[taliv]

jlbraun, i'm having trouble reading the key on those pictures. are the lm and re axes supposed to be in bullet diameters as well? i.e. in the first case, is it moving roughly half an inch maximum distance from the center ?

 

[Howard Roark]

The lm and re are axis in degrees. The top graph is showing that the epicyclic swerve or "coning" is < 2deg. About 0.05". Less than one bullet caliber.

The bottom graph is actually a .38 wadcutter pistol bullet.

 

[jlbraun]

The lm and re are axis in degrees. The top graph is showing that the epicyclic swerve or "coning" is < 2deg. About 0.05". Less than one bullet caliber.

I don't think that their instrumentation measured displacement off flightpath. But deflecting the nose in a direction will cause the bullet to go that direction. In some long distance hunting videos you can even seen the helical path.

 

[Howard Roark]

Right, The graph is not showing trajectory. It's showing a bullets coning action in degrees.

The lm and re are most likely German abberviations for pitch and yaw. The funny lookind "S" is a function symbol (dirac I believe). The [o] is degrees. They are using this formula to calculate the coning action in degrees.

As far as pushing a bullet in a direction and it going in that direction, that is mostly correct. Precession comes into play. A rotating object when pushed in a direction will move 90 deg from the applied force in the direction of rotation. Like pushing on a spinning top.

The wake or "trace" of a bullet can indeed be seen in flight. The more humidity the better. This is how we see where the bullet is going to get on paper in long range competition. The History Channel was the first to capture this on film. They set up a camera over and behind a shooter while he shot. This was filmed at Ft. Benning. I think the show was History of the Magnum.

 

[Afy]

The recipe for most of the shots fired is the one on the Test Target.

2.73 grams of VVN550 with Lapua 139 scenars and CCI BR2 Primers.

Have also tried about 20 each of the following:

123 Scenar N160 CCI BR2
108 Scenar N150 CCI BR2
123 Scenar N150 CCI BR2
139 Scenar N150 CCI BR2
140 SMK N550 CCI BR2

Have had other people shoot the rifle as well.
Over the course of Saturday and Sunday have spent a total of 14 hours at the range.

The shop is closed today... first thing tomorrow it goes back.

 

[Afy]

Jerkface: Yes the barrel is new. I checked the twist rate using a rod and a pen to create witness marks... It is a 1 in 8 no question on that.


Dalepres: I am using the exact recipe as the gunsmith.

Uncowboy and cpttango30: I dont see how a 6 inch + group will magically shrink to 1 inch at 300 meters. I would probably believe it would open up to about 18+ inches... Nor can I see how you can over stabilize the .260 in any wieght with a 1:8.
A number of shooters including Zak Smith, Taliv and others are happily shooting bug holes at this distance with this caliber. THere are a number of shooters in France who are happily shooting bug holes.


I know it isnt optics.. have been tested on other rifles.
Ammo: See previous post.
Shooter: Entirely possible that I am goofing off. But would consider that unlikely. Plus others have shot the rifle and havent managed a result any different from mine.
Rifle: Is my current suspect.

I do want to see the results with any other shooter. Any ammo combo... only has to be powder/bullet/primer that is easily available in France.

I dont want some combo of a JLK + Reloader XYZ that someone brought over from the states in the hand luggage. These are not available in France.

So from what is available: Sierra, Lapua + VV or Tubal Powders + CCI Br2 primers. For brass the choices are: RP, Laupa .243 neck turned to .260, winchester .243 neck turned, Federal .260

This is an example of the groups I was seeing with the 1:9 barrel... which wasnt working:


Compared to what I am now seeing, it seems very accurate.


This group is about 4 inches across

 

[Boris Barowski]

where are you from, guessing from the powder choice available we could be living close

 

[35 Whelen]

Is that a rifle or a Bublaphonic Photon Beam Projector?

#1- For all anyone knows, the group fired by the gunsmith or who ever it was, was fired at 30 feet, not 300 meters.

#2- Forgive my ignorance, but is that some sort of collapsable stock? That thing looks as though it could easily wiggle, wobble or generally move which would easily ruin groups.

35W