Max published load for H4350 in .260 Rem (139 Scenar)?

C

Coloradocop

Sergeant
Full Member
Minuteman
Oct 17, 2010
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Front Range of Colorado
#1
I'm wondering if my sources are either overly conservative, or simply out of date with regards to the load I mentioned in the title of this thread. I'm currently in the early stages of load development for my new AIAX 260, and I'm setting up right now with Lapua brass, 139 grain Scenar bullets, and H4350 powder. My load data shows an operational range for this powder between 39.0 grains and 42.0 grains.

I ran some test loads today within that range, and found some indications of an accuracy node between 41.1-41.4 grains of powder. That's all well and good, except for the fact that the velocity is between about 2680-2720fps in that powder range. I'd like to go faster if it is safe to do so, but that would involve looking for another node above 42.0 grains of powder. I constantly see people talking of getting 2,800-2,900+ fps out of this caliber, but that would obviously involve using a much hotter load. Similarly, I see people listing loads for this rifle/powder between 42.0-45.0+ grains of H4350. The "hottest" of my sources listed 42.0 grains as a max load, which I reached without any pressure signs today.

So, what's the real story?

Are my sources for load data just on the conservative side for the powder charge?

or

Are most people just hot-rodding this caliber beyond its theoretical design limits? (and, if so, with what kind of long term results?)
 
#2
I am in the same place. I am doing load test on my 260 in lapua brass with 140 amax's. I started my loads at 42. Found an accuracy node at 42.3 and then tried all the way thru 43.5. I am sure I can make it to another node which I am going to try doing some loads from 43.8 thru around 44.5 or until I get some pressure signs. I feel your pain as book max was in the 42 gr realm, but see a lot of people accuracy loads in the mid 44 gr area. Think the book listings are just being lawyer safe.
 
#3
If you want the MAX for your rifle, you'll have to load up and find it. It's going to depend on your chamber dimensions, throat length, and how much fairy dust the builder sprinkled on the reamer before they cut the chamber. I've seen some guys report pressure signs under 42gr and some push over 44gr without any issues.

That being said, if you're not seeing any pressure signs at 42gr then keep pushing. Load up 1 or 2 rounds each in .2gr increments up to 44.5gr and see where you hit the ceiling.
 
#5
I also run H4350 in the 260 at 43.5 grains behind the 139gr Scenar.

I often wonder and plan to try H1000 in the 260 behind the same bullet.

I believe Hodgdon shows max at 44.5grs of H4350 behind the 142 SIE HPBT on their website.
 
#8
I'm running the 139 @ 42.0grs of H4350 in Lapua Brass with Fed Match primers and it's the most accurate load for mine without pushing into high pressure areas in the next node. It's stable and pushing at about 2830 out of a 26" tube.

I've also got a hunting load with 140 Accubonds running 43.5 grs out of the same rifle and Nosler brass and it's on the higher side of pressure, but I don't worry about load cycles on that brass either.

There's entirely too many variables to answer OP's question directly as previously mentioned. I'd load up some test loads in increasing increments to find the max load for the specific rifle.
 
#9
I am getting signs of pressure with 42 gr h4350 and 139 gr scenars. I turned the necks on the brass. Gun is a surgeon scapel. Does this seem low?

Sent from my SM-T310 using Tapatalk
 
#10
I shoot the 142 SMK with 41 grains H4350 pushing it and I get 2,739 fps. That's my 1K load and it's on the light side. My max load for my rifle which happens to be in a node is at 43 grains of H4350. 43.5 just started to give me a hint of an ejector mark.

I turn my necks down to .013 thick too. I can shoot .015 thick neck brass but I see pressure at 42 grains.
 
#11
In the FWIW category, I settled on 42.0 grains of H4350, the 139-gr Lapua Scenar, and Federal 210 Match primers for my AR-10, .260 Rem, 24-inch Krieger barrel, TBAC 30P-1 suppressor. Average velocity was 2759 fps. The last 200-yard 5-shot group came in at .852 inches, or sub-1/2 MOA. I also tried 42.5 grains, but the group size opened up and also showed pressure signs, so I'm staying with the 42.0 grains.

Cheers,
Richard
 
#12
rg1911 said:
In the FWIW category, I settled on 42.0 grains of H4350, the 139-gr Lapua Scenar, and Federal 210 Match primers for my AR-10, .260 Rem, 24-inch Krieger barrel, TBAC 30P-1 suppressor. Average velocity was 2759 fps. The last 200-yard 5-shot group came in at .852 inches, or sub-1/2 MOA. I also tried 42.5 grains, but the group size opened up and also showed pressure signs, so I'm staying with the 42.0 grains.

Cheers,
Richard
Click to expand...

It's interesting you settled at 2759 fps, because that's spot on the node according to OBT theory & quickload predictions for a 24" barrel. The next OBT node is in the 2900's for a 24", which is nearly impossible to hit without pressure signs.
 
#13
lte82 said:
It's interesting you settled at 2759 fps, because that's spot on the node according to OBT theory & quickload predictions for a 24" barrel. The next OBT node is in the 2900's for a 24", which is nearly impossible to hit without pressure signs.
Click to expand...
I was unaware of OBT theory. Obviously, I need to correct that deficiency in my education. Thank you for pointing it out to me.

Richard
 
#14
Coloradocop said:
I'm wondering if my sources are either overly conservative, or simply out of date with regards to the load I mentioned in the title of this thread. I'm currently in the early stages of load development for my new AIAX 260, and I'm setting up right now with Lapua brass, 139 grain Scenar bullets, and H4350 powder. My load data shows an operational range for this powder between 39.0 grains and 42.0 grains.

I ran some test loads today within that range, and found some indications of an accuracy node between 41.1-41.4 grains of powder. That's all well and good, except for the fact that the velocity is between about 2680-2720fps in that powder range. I'd like to go faster if it is safe to do so, but that would involve looking for another node above 42.0 grains of powder. I constantly see people talking of getting 2,800-2,900+ fps out of this caliber, but that would obviously involve using a much hotter load. Similarly, I see people listing loads for this rifle/powder between 42.0-45.0+ grains of H4350. The "hottest" of my sources listed 42.0 grains as a max load, which I reached without any pressure signs today.

So, what's the real story?

Are my sources for load data just on the conservative side for the powder charge?

or

Are most people just hot-rodding this caliber beyond its theoretical design limits? (and, if so, with what kind of long term results?)
Click to expand...

You've got stones just for asking, because when I posted my 140gr/H4350 load here all I got was claims it was subsonic and that my chronograph must be broken. Apparently the real-world load for 260 Rem and 140gr bullets using H4350 is quite different from that of the outspoken Internet commando.

For what it's worth, here's my load data:
Savage 12 LRP (26" barrel, 1:8.0" twist) in 260 Remington
Remington brass (full length sized)
TULA large rifle primers
42.0 gr Hodgdon H4350
140 gr Hornady BTHP Match bullets (perform nearly identical to 140 gr Hornady A-MAX)
2677 FPS at 10' using ProChrono at 4770' elevation 60F

I've used this load for the past year, and it performs well in no wind/light wind environments. I do a lot of windy shooting and have a supply of 140 gr Hornady BTHP bullets, so I'll be spending the next few weeks developing a new load. I suspect it will plateau around 43.3 gr H4350.
 
#19
I am shooting a .260 AI with 140 amax and 45 grains H4350. No pressure signs and brass is holding primers after 4 firings. I ran my gun to 46.8 before it showed pressure then worked down. There is very little data on 6.5-08 AI so I had to figure it out. It takes me 11.25 minutes to get to 600 with a 100 yard zero
 
#22
nexusfire said:
What is a 260 TAC?

Sent from my XT1060 using Tapatalk
Click to expand...

260 tactical reamer was developed by dave kiff at pacific tool and gauge.. It is a 260 remington with a slightly longer freebore to allow for seating berger 140gr and sierra 142 gr bullets slightly longer. Thats the chamber I am running. because with a regular 260 rem and those bullets you have to seat the bullet so deep into the case to make them be able to fit. I have a seekins cut mag well on my action too so the mag well in a little longer to allow for a little bit longer round to chamber.
 
#25
If the bullet is on the lands or jammed in a tad that will give higher pressure... not saying it is nor not.. i havent shot 139 scensars... they are shaped different than a berger tho so i donno... in any case i would worry about accuracy over speed. If you have a node under 42 play with it...

clean the carbon build up out of your barrel too with a good cleaner. That can releive some pressure on a minute scale. Its hard to say one way or another not being able to look at things first hand... what pressure signs do you get at 42? Are you FL sizing only or neck bushing? Could a neck bushing be a tad tight?

Mine will shoot up to around 44.5 until i see pressure signs on primers. Every rifle is different. You may look into trying imr 4350 or h4831. The h4831 will have less pressure.
 
#29
nexusfire said:
Primer cratering, ejector marks and occasional blown primer

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Click to expand...

damn... thats weird for 42 gr.... bro id personally... imo... look at trying 4831 or a lower pressure powder... h4350 is one of the highest pressure powders listed for a 260 cal... your gun may just not like it...
 
#30
Put 40.0 grains of IMR4350 behind a 140 AMAX and never look back... Not a hot load though so I can't help ya there. This was my most accurate load of every powder I tried including H4350. Good brass/barrel life and one-hole accuracy. This has been the ticket load for the last 3 6.5 Creedmoor's I've loaded for.

EDIT; Sorry I'm a bit slow today. Just realized we were talking .260. The numbers looked so similar to what the CM takes I wandered off into creedmoor land for a while. Hey maybe this load will do well in the 260 also..
 
Last edited:
#31
Through what barrel?

Onewolf42 said:
My two best loads for my Savage LRP 260 was H4350, 43.0gr for A-Max 140, and 42.8gr for SMK 142. Both shot around 2800-2820 fps.
Click to expand...

Was your barrel stock or custom? Also, what COL do you use? I have a Savage LRP .260, but I lost primers at 43.0 of H4350. Some shooting buddies think I was seating too deep. I didn't write down the COL, but is was definitely below 2.800.
 
#34
43 gr of H4350, Lapua brass and 142 smks was a good load for both of my 26" Bartleins. The first one was about 2825 for velocity, not sure on the second yet. Seems that 2775-2820 is a good spot for the 260 when using 140 grain class bullets. Oal on both were 2.815 or so which was about .010 off. Started seeing pressure signs at 43.6-43.9
 
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