260 Rem Load development advice please

[Trigger puller UK]

Today Ive Been testing a new bullet, The bullet is a solid CNC machined bronze\brass material. The weight of this bullet is 118gns. Ive been told that I should be able to push this bullet at 3100 fps, that is yet to be seen as I haven't chronographed it yet. Below is a pic of the 118gn bullet standing next to the Amax 140gn bullet.

The Rifle I'm using is a Accuracy International AX260

The Load
Lapua 260 rem brass 3rd firing, annealed after the 2nd
CCIBR2 primer
H4350 powder
118gn bullet (unknown BC)
OAL 2.800 measured from tip to base = 0.42" jump

Below is a pic of my OCW test results

What advice would you give me of what to do next, repeat the test or just retest only some of these charge weight?

Thanks for reading Ady

 

[RyeDaddy]

Re: 260 Rem Load development advice please

I'm lazy, so if it were me I wouldn't redo the whole test. I'd certainly try the 43.5 grain load again, maybe load .1 grain on either side of it and try them out. If it shoots like that again I might leave it alone or I might play with the seating depth just to see. My current rifles are restricted in mag length so I don't have to worry about that personally. Run it over a chrono to see what the numbers say afterward.

If the 43.5 didn't shoot the same the second time I'd redo the test with charge weights slightly different than this run, say .1 grain off from current values.

Certainly looks good. I'd be very interested to know the velocity.

Edit: the load my 260 shoots best with is almost exactly the same, but a very different rifle.
Lapua 260 brass
CCI BR-2
43.5 grain H4350
130 VLD loaded at 2.805" OAL (.090" jump)
My velocity from a 22" 1 in 9 twist barrel is 2810 FPS

 

[Mendocino]

Re: 260 Rem Load development advice please

I'd redo the test with the 43.5g with a set at 43.3, 43.4, 43.5, 43.6 and 43.7. I'd use a known good chronograph and shoot five round groups, not three. With the top three performing loads from that group (accuracy, speed, SD and ES) I would do the test with ten of each, shoot 5 round groups and go with the best accuracy and chrono results (lowest SD and ES).

 

[jrob300]

Re: 260 Rem Load development advice please

If you are very confident in your shooting, 43.2 looks like a scatter node... accuracy somewhere between 43.5+ to 44+. I'd feel better if these were 5 round groups accompanied by some velocities with ES and SD. I'm not usually worried by horizontal because it's normally me.

If you are not super confident in your shooting, you need to go to larger groups to get a better idea of POI.

FWIW, I'm running 43.7 gr H4350 under 139 Scenars. Unless the material makes a huge difference, I would think you could go a bit higher. Do you have a chrono?

Signs of pressure?

John

 

[Trigger puller UK]

Re: 260 Rem Load development advice please

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: jrob300</div><div class="ubbcode-body">If you are very confident in your shooting, 43.2 looks like a scatter node... accuracy somewhere between 43.5+ to 44+. I'd feel better if these were 5 round groups accompanied by some velocities with ES and SD. I'm not usually worried by horizontal because it's normally me.

If you are not super confident in your shooting, you need to go to larger groups to get a better idea of POI.

FWIW, I'm running 43.7 gr H4350 under 139 Scenars. Unless the material makes a huge difference, I would think you could go a bit higher. Do you have a chrono?

Signs of pressure?

John </div></div>

I dont have a chrono but a good friend of mine who I shoot with has a very good one. Ok this is what Ive decided to do, Ive loaded up 4x of the following charge weights 43.3 43.4 43.5 43.6 34.7 43.8 I'm only doing 4 round groups because I only have 24 cases left to fire that has been pre preeped. This time I will get data from the chrono. I will post a pic of the results in the next couple of days.

Ady

 

[jrob300]

Re: 260 Rem Load development advice please

If that was *my* target, I would load up (since you have 24 pieces of brass) 6 at 43.5, 43.8, 44.1 and 44.4 and see how they shoot and look for pressure. If you STILL see no pressure, you can keep pushing up as long as is shoots. it will probably stop shooting soon after 44 gr and the next node may not be feasible without excessive pressure.

43.8 looks to be the middle of a nice shooting node. It could be higher but we have no data. You can tweak .1 gr at a time once you get an idea where the sweet spot really is. 6 rds. will give you a clearer idea of grouping also and be more statistically relevant with your chrono numbers. I would pick the load in that range that gives you the best ES. When is the last time you annealed your brass? Neck tension variability can have a large impact on ES and SD.