260AI roll call

[46and2]

I think if we definitely should mention freebore in relation to posted load data.

I

I just loaded some 140 Matchburners with n160. 44.5gr was about 95% capacity with my long throated chamber.
Will update.
45gr of H4350 shot very very well, hopefully n160 can best it.

45.5gr of n160 only got me to 2750fps in lapua brass and Ginex LR primers. I need to find pressure, accuracy was only in the .4s at 200 yards with 20 mph winds today. I just loaded up to 46.8gr ( still only 98% capacity) to see where I need to be. 45.5 gr of H4350 was 2955fps on my 26" barrel.

Will update.

 

[Fast14riot]

I would expect N160 to be closer to H4831 needing around 47gr or so with a 140. But thats not based on any calculations, just what I would punch into GRT to start with.

 

[46and2]

I would expect N160 to be closer to H4831 needing around 47gr or so with a 140. But thats not based on any calculations, just what I would punch into GRT to start with.

Yes it seems my lot of n160 will probably replicate h4831 with less bulk.


I entered my H4350 load and only got 2875fps at 68k psi, which I do not agree with. I dont have GRT or quickload.

 

[Ron Gorski]

I've been shooting the 260AI in F/Open for the last 5-6 years and have some good loads, but between social media and at the range I keep seeing it pop up as a new chambering for shooters.

So, let's post up our known good loads. Fire forming and formed. Target pics are always a plus.

My data Fireforming:
44gr H4831 under any 130-145gr bullet and a soft primer like WSR.

View attachment 1479788

Formed with 140 class bullets:
47.3-48gr H4831 in lapua or Peterson brass.

View attachment 1479789

Formed with 150+gr bullets:
45.3gr RL23

View attachment 1479790

I've been shooting F Class with the 260AI. I have my own reamer with a tight neck and .210 free bore. I use a Whidden hydro form die instead of fire forming. Right now I use Hornady 153 Atip over 43.5 gr of reloder 16 at 2870. Could go faster but this load is very accurate.
Ron

 

[Fast14riot]

View attachment 1550942

Yes it seems my lot of n160 will probably replicate h4831 with less bulk.


I entered my H4350 load and only got 2875fps at 68k psi, which I do not agree with. I dont have GRT or quickload.

I do have GRT and can run some numbers for you tonight after work if you want to see what the OBT node might be. I would need your case volume (gr/h2o) COAL, bullet and exact measured velocity for a given charge of N160 to calibrate for your lot. Lmk.

 

[46and2]

I do have GRT and can run some numbers for you tonight after work if you want to see what the OBT node might be. I would need your case volume (gr/h2o) COAL, bullet and exact measured velocity for a given charge of N160 to calibrate for your lot. Lmk.

Thank you very much.

55.78gr h2o,
2.963" coal,
Barnes 140gr Matchburner, 1.345" length,
44.5gr n160 2755fps, 14 ES, 6 SD (Labradar).
I HBN my bullets, not sure how much HBN affects pressure compared to naked bullets.

 

[Fast14riot]

Cool, got dessert cooking up right now for the family, I'll get some numbers crunched for you shortly!

 

[Fast14riot]

@46and2

Here is the entered specs:

Bullet resistance is set to negative to tune your measured velocity to match your powder charge, which makes sense with HBN coated bullets.




Here is calculated output matching your velocity:



This is calculated OBT showing adjusted charge and node #5:



This is the next half-node up #4-1/2 (more powder) and adjusted charge and calculated velocity:

 

[Fast14riot]

Took the N555 load to a 1000y match today. I also switched primers. I noticed a few hang fires with the Ginex srp last time, click-boom type of situation. The 7-1/2 didn't have any problems today for sure. Still shot very well. I dropped my charge down to 45.0 to see how it does, and pulled off a 2nd place with 436-13. 1st shot a 437-12 (with a 284, too). High x count was 17 today, and that was a Palma shooter on a big target. Lots of 9s posted across the field.

Also got velocity data for my last 18 rounds of the match. Avg 2810, SD 5.5

 

[swd]

Took the N555 load to a 1000y match today. I also switched primers. I noticed a few hang fires with the Ginex srp last time, click-boom type of situation. The 7-1/2 didn't have any problems today for sure. Still shot very well. I dropped my charge down to 45.0 to see how it does, and pulled off a 2nd place with 436-13. 1st shot a 437-12 (with a 284, too). High x count was 17 today, and that was a Palma shooter on a big target. Lots of 9s posted across the field.

Also got velocity data for my last 18 rounds of the match. Avg 2810, SD 5.5

View attachment 1554334View attachment 1554335View attachment 1554336View attachment 1554337

But don’t forget the 444 HOA was a Dasher, lol

 

[Fast14riot]

But don’t forget the 444 HOA was a Dasher, lol

And a former national champion, lol!

 

[46and2]

@46and2

Here is the entered specs:

Bullet resistance is set to negative to tune your measured velocity to match your powder charge, which makes sense with HBN coated bullets.

View attachment 1551291


Here is calculated output matching your velocity:
View attachment 1551288


This is calculated OBT showing adjusted charge and node #5:
View attachment 1551289


This is the next half-node up #4-1/2 (more powder) and adjusted charge and calculated velocity:
View attachment 1551290

I'm on vacation in TN so I didn't bring my labradar. No pressure on my Lapua brass. May go to 47.8gr of n160.

 

[Fast14riot]

View attachment 1554396
I'm on vacation in TN so I didn't bring my labradar. No pressure on my Lapua brass. May go to 47.8gr of n160. View attachment 1554402

GRT Did show the next OBT node for your load as 46.95gr. If you're still good on pressure, I'd sneak up to 47gr and see what it looks like.

 

[swd]

And a former national champion, lol!

True, LOL

 

[Fast14riot]

Forgot to post my final load for the new powder

260AI
Peterson SRP
Berger 153.5
Rem 7-1/2
Vhutavouri N555 45.0gr
2.433" CBTO (3.110" COAL)
2810 fps avg
5.5 SD

 

[46and2]

GRT Did show the next OBT node for your load as 46.95gr. If you're still good on pressure, I'd sneak up to 47gr and see what it looks like.

200 yards, the orange dots are 3/4". Still on vacation so no chrono.
#5 on 47.2 was me...I choked!

46.9 and 47.2 has the same POI. Its probably a stable load. No pressure, no extraction issues at 47.2, its right at 100% case fill. Just loaded several at 47.1gr to verify.

 

[Fast14riot]

View attachment 1555225
200 yards, the orange dots are 3/4". Still on vacation so no chrono.
#5 on 47.2 was me...I choked!

46.9 and 47.2 has the same POI. Its probably a stable load. No pressure, no extraction issues at 47.2, its right at 100% case fill. Just loaded several at 47.1gr to verify.

Predicted velocity was 2913fps. I'd be curious to see what it is when you finally get to chrono it. Cool to see nice groups matching up with the predictions!

 

[Bill Norris]

View attachment 1555225
200 yards, the orange dots are 3/4". Still on vacation so no chrono.
#5 on 47.2 was me...I choked!

46.9 and 47.2 has the same POI. Its probably a stable load. No pressure, no extraction issues at 47.2, its right at 100% case fill. Just loaded several at 47.1gr to verify.

Looks like you have it dialed in really well.

 

[46and2]

Looks like you have it dialed in really well.

Thanks. It's a slow process for me with a non published AI cartridge with HBN and a long freebore. That's why I only went .3gr increments.
I wouldn't have guessed it but n160 is behaving as slow as I imagined H4831.

 

[Bill Norris]

Oh yea, I load for a 260AI with HBN coated as well. I have wanted to try N-160 for awhile but just never got around to it. Been using H-4350 and H-4831 but I think I will be moving away from Hodgdon with it real soon. Hard to leave something that is working well though. Was shooting 47.5 gr. of H-4831 on Monday with Sierra 142 M Ks for my last 10 shots @ 700 yds. and cleaned a 600 yd. target with 5 Xs. Really hoping to get the VV powders to shoot.

PETERSON SRP BRASS
142 GR. SIERRA HPBT MK 2.205 O M 2.871 COL T/L B S .511 B C .626
POWDER 47.5 GR. H-4831 PRIMER CCI 450M
SEATED @ 2.199 O M 2.865 COL .006 OTL
LAST TIME I CHRONOED THIS LOAD IT WAS @ 2948 FPS