6.5x55SE 140 gr Accubonds - H4831SC - Fed 210 - Lapua

A

azsixshooter

Beginner
Apr 30, 2023
31
69
I'm trying to work up a good load with the 140 gr NABs and H4831SC, my hoped-for goal was sub-MOA @ 2800 FPS or better with safe pressure in my rifle. The Nosler book stops at 47.0 gr but with some well-calibrated Quickload data (and max PSI set to 60K) and careful observation for overpressure signs I worked up to 48.8. I also use a .0001" micrometer to track casehead expansion - >.0005" being a hard stop - and watch speed on the chronograph every shot.

I wasn't seeing anything alarming and no casehead expansion up until 48.8. Velocities started ranging pretty wide (75+ fps) and bolt lift was beginning to show a little more resisitance than with typical factory loads, such as Hornady Superformance. I registered one shot at 500+ fps higher velocity than the rest so I stopped there and pulled the rest of my bullets (I had 10 more loaded for 49.0 gr; 5 at .010" off the lands, 5 at .005" off the lands). It may have been a sensor malfunction, my chronograph isn't a very expensive one and the bullet actually impacted lower than one that registered ~2800 fps. Plus, recoil felt normal, bolt lift wasn't extremely sticky and there were no signs of overpressure on the case. Still, with the other evidence and already being so far over the book max I decided to play it safe.

It doesn't look like I will be able to meet my goal in this CZ 550 American with this combination. During the previous round of testing I was seeing accuracy improve steadily from 47.4 --> 47.7 --> 48.0 with COAL of .020" off the lands. At 48.0 grains I tested .020", .015" and .010" off the lands with accuracy further improving steadily with the longer COAL. At 48.0 gr and .010" off the lands there were no pressure signs at all on my cases, normal bolt lift and an average velocity of 2740 FPS. If I can dial that in better I guess I can live with that speed, although I was hoping for 2800. I don't think the deer will notice ;-)

My next round of testing is going to be:
  • 47.8 gr @ 3.140" (.010" off lands)
  • 48.0 gr @ 3.145" (.005" off lands)
  • 48.0 gr @ 3.140" ← (already tested, baseline)
  • 48.2 gr @ 3.140"
  • 48.2 gr @ 3.145"
I had great luck in the past using the 130 gr Accubonds and 48.0 gr of N560 powder. I'm hoping I can tune this load and get some good sub-MOA performance. My best group so far has been the 48.0 gr @ 3.140", 5 shots in 1.218". At 2740 fps with this bullet I should be able to zero at 240 yards and have a MPBR on a 6" vital zone out to 283 yards. Out to 360 I can settle my horizontal crosshair on a deer's back and still be in the vitals with 1500+ ft/lbs and still have a good 2200+ FPS of speed for the AccuBond to do it's thing. If I get this load worked out this will be my go-to big game load for this rifle. The nicest thing is the recoil is so mild my 14 yr old daughter can enjoy shooting it too and I don't have to worry about her developing a flinch.

EDIT: I meant to mention that the 5 shot groups at 48.4 and 48.8 were not good, over 2 MOA. Based on the Quickload b_time predictions, I was hoping to hit an accuracy node at 49.0 and get the velocity I was looking for. I must have passed it around 48.0, hopefully I'll be able to find something promising next time out, maybe a little over 2750 if 48.2 comes in.
 
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2740fps isn't anything to lose sleep over. That is plenty of speed for what you're wanting to accomplish. I've poked a few deer with somewhat lower velocity and as you said the deer won't know the difference, the oil light will still come on. If you can get or have some, try Winchester Stabal6.5 as it gives good velocity and groups for me in my 6.5x55s. Couple of others are RL19 and 22 if you can find them. Glad you are using the Swede and keep after it. Hope your daughter enjoys hunting with it as well.
 
I was thinking about trying Stabal6.5. I was looking at Norma MRP too, but I don't know if that is commonly available anywhere. I would probably see if I could get ahold of some Viht N560 as well. Thanks for the good feedback about the Stabal6.5, I will be sure to add it to my list. It looks like 44.7 grains could get me around 2750 fps and is right on top of an accuracy node. I wish I could find RL 19 or 22, I gave up on that a long time ago after drooling over it in the data books. Looks like awesome stuff, but I've never seen it on a shelf.
 
In your CZ, you should be able to go to 64-65K for pressure...but if you are starting to get sticky bolt lift, you may not get there in your rifle.
AccuBonds also tend to like more jump to the lands than what you are trying. You might want to start at 0.050" and to see if they will perform better for you. (This has been a recommendation from other more experienced handloaders here over the years.)

Hunter and IMR4350 are other powders you can try.
I have had good luck with IMR 4350 in other rifles I have owned in the past with 140 gr bullets (Partitions and X Bullets), and will be trying this again in my two new 6.5 Swedes with AccuBonds. One a 24" barrelled Winchester Low Wall, and the other a 20" barreled Steyr. Although I may end up using a regular cup and core bullet in the Steyr due to less velocity potential with the shorter barrel (SGK pr Hot Cor).
(Luckily I have Re 26, 17 and 16 on hand to try as well.)
 
Blkram said:
In your CZ, you should be able to go to 64-65K for pressure...but if you are starting to get sticky bolt lift, you may not get there in your rifle.
AccuBonds also tend to like more jump to the lands than what you are trying. You might want to start at 0.050" and to see if they will perform better for you. (This has been a recommendation from other more experienced handloaders here over the years.)

Hunter and IMR4350 are other powders you can try.
I have had good luck with IMR 4350 in other rifles I have owned in the past with 140 gr bullets (Partitions and X Bullets), and will be trying this again in my two new 6.5 Swedes with AccuBonds. One a 24" barrelled Winchester Low Wall, and the other a 20" barreled Steyr. Although I may end up using a regular cup and core bullet in the Steyr due to less velocity potential with the shorter barrel (SGK pr Hot Cor).
(Luckily I have Re 26, 17 and 16 on hand to try as well.)
Click to expand...
I can second his recommendation on .050 off the lands. I was always shown to be close and that .030 was very max, until I came here. I shortened my CBTO and went with 50 off with great results. I am going to go back to some other rounds I have established and try this longer jump on them as well. It seems to be the ticket.
 
I don't know what my pressures were but at that 48.8 grain load the bolt lift was noticeably more resistance. In the past I have had loads that were way too hot and I had to strike the bolt handle with the palm of my hand to get it to open. This is nothing like that, but it was starting to get harder to open than normal. Combined with the erratic velocities (especially that one huge spike which may have just been a misread on my Pro Chronograph) I thought it would be prudent to not try and push any farther. Quickload was predicting these pressures to be around ~59-60K psi, but I don't want to ignore real-world signs.

The idea of seating out to .050" off the lands and closing in sounds like something worth trying. After my next round of testing I will give that a shot if I can't find anything sub-MOA .005 - .010" off the lands. I'm working on annealing and sizing brass today to prep for reloading for the next round of testing this week.

6.5x55SE in modern strong actions is really fun to load for. When I originally bought this rifle it was to be my Arizona antelope rifle. I was down to either the Swede or the 25-06. The Swede ballistics and the availability of cheap mil-surp ammo for plinking at the time made up my mind for me and I have no regrets. I do miss those cheap 200 rd battlepacks of milsurp though! That made for a fun day of bumming around the Sonoran desert with my rifle and Leica rangefinder!
 
FOTIS said:
This. I will be trying out RL 16 RL 17 when I get my 6.5 Swede.

Yes I bought brass ammo and dies for it. Now I have to find the gun. What a looney.
Click to expand...
I noticed that Scheels had RL 23 in Billings yesterday. I’d almost think RL 16 would be too fast, but I could be wrong. I have some but I didn’t think about trying it.
 
azsixshooter said:
I was thinking about trying Stabal6.5. I was looking at Norma MRP too, but I don't know if that is commonly available anywhere. I would probably see if I could get ahold of some Viht N560 as well. Thanks for the good feedback about the Stabal6.5, I will be sure to add it to my list. It looks like 44.7 grains could get me around 2750 fps and is right on top of an accuracy node. I wish I could find RL 19 or 22, I gave up on that a long time ago after drooling over it in the data books. Looks like awesome stuff, but I've never seen it on a shelf.
Click to expand...
Unfortunately I seriously doubt that anyone will ever see Norma Powders Stateside. Alliant has recently begun shipping Reloader powders, which was a long time coming. That said, even though they are considered the same, but slightly better QC product than what Alliant is selling, it’s not going to compete against its self. At least that’s what I was told from Western Powders back in 2021-‘22.
 
That's interesting, I guess if I can get RL19 or RL22 I'll be happy to try those out. When I took this rifle on an Arizona bull elk hunt in unit 4A in 2009 I wanted to try RL22 with some 160 grain Woodleigh's Weldcore .264" bullets I had got. I ended up using Viht N160 and I got good accuracy but never got the velocity I wanted. IIRC I was stuck around 2200 fps or so. I remember I thought the RL22 would get me closer to 2400 fps but I couldn't find it anywhere. These days I would just use these 140 grain Accubonds or maybe a 140 gr Partition or something similar and still limit my shots to close or medium range. Honestly though if I ever hunt elk again it will be a good excuse to buy a new rifle, like a Ruger M77 Hawkeye All-Weather in 7mm Rem Mag or another CZ 550 American if I could find one in 9.3x62.

I am changing my plan for the next round of testing to back the bullet out to .050" off the lands and see how it goes rather than trying different powder charge weights. The more I thought about it the more I started realizing that deeper seating will also raise pressures slightly and potentially give me better accuracy and higher velocity, more towards the 2800 FPS I was hoping for. I'll be happy with any sub-MOA load at 2700 fps or higher but you know how it goes, the endless pursuit of accuracy and performance! Here's my new plan and some sidenotes on potential accuracy nodes:

QuickLOAD prediction for 48.0 gr H4831SC with 140 gr AccuBond in fire‑formed
Lapua cases (57.6 gr H₂O) and 23″ barrel, varying COAL from 3.140″ down to 3.100″ in 0.005″ steps.
Barrel‑time values align with common accuracy nodes for a 23″ sporter barrel
(Node 3 ≈ 1.20–1.23 ms, Node 2 ≈ 1.18 ms).

COAL (″) Velocity (fps) Pressure (psi) B_Time (ms) Node Proximity
3.140 2740 55,078 1.216 Near Node 3 (1.205–1.225 ms)
3.120 2760 55,620 1.208 Near Node 3
3.115 2765 55,805 1.205 Center Node 3
3.110 2770 55,990 1.202 Near Node 3
3.105 2775 56,175 1.198 Transition to Node 2
3.100 2780 56,360 1.195 Approaching Node 2

Node 3 (~1.205 ms): Often yields a more forgiving, tight‑group sweet spot in many 23″ barrels. You’re dead‑center at 3.115″ COAL.

Node 2 (~1.18 ms): A second sweet spot for super‑flat trajectories; you’re transitioning toward it as seating moves from 3.105″ to 3.100″.

Pressure remains under ~56,400 psi through 3.100″, giving a safe margin below your 60 K psi ceiling.

Those estimates are calculations using a powder burn factor of .4331 for H4831SC based on my chronograph results from previous testing sessions. The COAL's align with the advice I'm getting here about the Accubonds liking the longer jump to the lands and the 48.0 grain load has been tested safe in my gun (and the most accurate load tested so far). Since the pressures will increase as I seat the bullet deeper I'll continue to work up in terms of increased pressure and watch carefully, although I'm not expecting to have any problems. The predicted accuracy nodes are encouraging, I'm hoping they hold up and maybe I'll get a good result at 3.100" right at .050" off the lands of my rifle and the real-world velocity gets me to 2800 or so. I might even do some further testing up to .060" or more off the lands if accuracy consistently trends towards tighter groups as the jump increases. At least until I hit a point of diminishing returns.

I have an 8lb pork butt marinating in the fridge, tomorrow my daughter will be home from a camping trip so I'm going to cook that thing all day on
the smoker. That should give me plenty of downtime to load some ammo!
 
My friend at church was just telling me how one year he traded a Glock and some levergun for a brand new Browning BAR MK II Safari in 30-06. He said he gave it to his wife for Sweetest Day lol! I guess she didn't like it so he sold it to a gun store. He said he already had one like it in 7mm Rem Mag.
 
I finally got another round of testing in today. I decided to take the best performing powder charge from last session - 48.0 gr H4831SC - and experiment with some longer jumps to the lands. Those of you who said Accubonds like a .050" jump were right on the money. I had 3 COAL's at this charge weight that gave sub-moa 3-shot groups at 100 yards today. Of those three the .050" jump (3.100" in my rifle) gave the best velocity. I'm going to call that my deer load for this season and go back to fire a few 5-shot strings to make sure it repeats. That will leave me enough ammo to get a good 280 yd MPBR zeroed in and to hunt with. When I raise enough money to get another pound of powder and more bullets I'll continue testing to see if I can tweak it in even better. My velocity is at an average of 2732 fps so I'm okay with that. I think closer to 2800 fps might be possible, but I'd rather not batter my rifle. I can live with 2732, but the bucks won't be able to!
 
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