.260 Remington: Need Some Advice on an Starting Point for Load Development

[jab00]

Can you guys give me some advice if my starting point below seems okay to do an initial pressure test for my 24" Accuracy International factory .260 barrel? I've read a bunch of posts and think that I have a good starting range figured out but I'd appreciate some feedback before I get started with the loading . I'm going to magazine feed the rounds, so I'm confined to the max length of the AI magazine.

Components:

• 136 Lapua Scenar-L projectiles
• Lapua .260 cases (virgin brass)
• Federal 210 primers
• H4350 powder

Powder Charges to Test: 41.4, 41.6, 41,8, 42.0, 42.2, 42.4, 42.6, 42.8 (stopped there as II tried to aim for the middle ground of what I've seen other guys list as their "node" with a "moderate" muzzle velocity)

 

[Eric32]

I am at
42.5 of H4350
2.805 oal
140rdfs

In my AI, i am getting 2930 ish fps

I would say your at a pretty good start. The lapua are pretty forgiving on searing depth.

Where are you at now OAL wise now?

 

[lash]

Perfect pressure test set to use! I’ve been shooting the 136g Lapua Scenar-Ls for many years now. I personally choose a mid range velocity/pressure load as it makes my barrels and brass last a long long time. 41.8g H4350 nets me 2750-2800 in 26” barrels, which is not fast. But then I get 3500-4000+ good accurate rounds using this load. Plus it is a great node that just keeps shooting without adjustment.

In my opinion, there’s something to be said for consistency over sheer speed, but different strokes for different folks.

 

[jab00]

I am at
42.5 of H4350
2.805 oal
140rdfs

In my AI, i am getting 2930 ish fps

I would say your at a pretty good start. The lapua are pretty forgiving on searing depth.

Where are you at now OAL wise now?

I haven’t loaded anything yet, but was planning on starting at 2.800” OAL and see what happens there before doing a seating depth test after I figure out what my pressure test shows

 

[jab00]

Perfect pressure test set to use! I’ve been shooting the 136g Lapua Scenar-Ls for many years now. I personally choose a mid range velocity/pressure load as it makes my barrels and brass last a long long time. 41.8g H4350 nets me 2750-2800 in 26” barrels, which is not fast. But then I get 3500-4000+ good accurate rounds using this load. Plus it is a great node that just keeps shooting without adjustment.

In my opinion, there’s something to be said for consistency over sheer speed, but different strokes for different folks.

I was thinking the same thing in terms of consistency vs. speed. My range maxes out at 330 at the berm, so I’m definitely looking for consistency over speed for my use, not to mention that I don’t want to beat up my brass or barrel chasing speed

 

[ACard]

Perfect pressure test set to use! I’ve been shooting the 136g Lapua Scenar-Ls for many years now. I personally choose a mid range velocity/pressure load as it makes my barrels and brass last a long long time. 41.8g H4350 nets me 2750-2800 in 26” barrels, which is not fast. But then I get 3500-4000+ good accurate rounds using this load. Plus it is a great node that just keeps shooting without adjustment.

In my opinion, there’s something to be said for consistency over sheer speed, but different strokes for different folks.

I am also right here at 41.7 H4350 grains and shoot bugholes. Nice midrange pressure load and I have been very pleased out to 1500

 

[Defender3]

Here's my ladder test with my AI, but it has a 24" Proof CF. I could have gone higher and found another node, but I was comfortable with that 2850fps node.

 

[jab00]

Thanks for all of the comments. I’ll hopefully get my test rounds loaded and fired this week. I’ll post my graph when I’m done

 

[FALex]

42.5 is the perfect starting place, IMHO. Some may say 42, but I've noticed that a significant number of 6.5's thrive in the 42+ grain area. I run 41.7 in my .260, but it's a gasser. Anything bolt looks to 42+.

 

[TxWelder35]

42.5 h4350 with the 136 scenar in my gun. Peterson SRP brass. 2830fps 8fps SD

 

[Matt_3479]

Not specifically the scenar’s but I’m at 42.2gr for the 140’s at 2850fps, Lapua brass, fed 210m, and h-4350.
Was able to get 2975 FPS but was at some pressure and had a great node between 41.9-42.4. Got damn lucky and while fire forming brass to chamber I loaded up 42gr’s and was initially running closer to 2820fps and fired a 3 round group at 640 that printed .908”

 

[gonzaga]

42.6 of H4350 and 139gr Scenar bullets. Lapua brass, CCI Large Rifle primers.

 

[jab00]

So, I landed at 42.5 grains of H4350 with the 136 Scenar as my “winner”, but now I’ve got a problem as I only have about 1/2 pound of that powder left so that’s not going to last much longer until I can find more of it.

I do have a 5 lbs jug of RL17, so I’m thinking about starting the testing again at 39.2 up to 42.3 grains (in Lapua brass) and seeing how that goes. Does this seem like a reasonable load range for the 136-L?

ETA: I’d also like to figure out a starting place for 123 Scenars and RL17 (using Lapua brass)

 

[ScottDWallace]

43.0 of H4350
Lapua 136L's
2914fps