280 Ackley Ladder Test Results - 168g Berger

[kskevin]

Thought I'd post my ladder test results for others to reference.

Two powders:
H4831sc - tested @ 200yd (needed to move out to 300+ to see bigger differences in the drops)
IMR7828ssc - tested @ 320yd. Variable cross wind 3-12mph.
Bullet: Berger 168 VLD Hunting
Brass: Nosler
Primer: F210

Conditions:
Sunny
103F
1150' Alt
29.95" Hg

Couldn't get the velocity I was looking for with H4831sc. Max'd out at ~2800fps. No pressure signs all the way up to 59.5g max charge.

IMR7828ssc: This powder yielded better velocity. Max'd out at 2969fps with 61.5g. No pressure signs.

I'm going to now play with 60.0g IMR7828 and vary seating depths to see what kind of groups I can get. There may be another node between 61 - 61.5g but not sure the extra 100fps is worth the potential stress on the brass. Let me know if you see something I may be overlooking.

 

[steve123]

Re: 280 Ackley Ladder Test Results - 168g Berger

Just a few tips.

Doing a ladder test at 200Y with a accurate rifle is hard to do because most custom rifles are capable sub 1/2 moa.Even at 300Y it can be difficult sometimes.You have to be able to easily identify the vertical dispersion as the shots rise and stop.

Pick a calm day because when you hit a node often the shots will stop vertically and have small horizontal as well.Are you doing .3 grain increments ? Because .5 grain increments are too much.I do a double ladder test to lesson the chance of a error.

Did you let the barrel cool an equal amount of time between shots? I take a few other guns out and shoot them while the barrels cooling.

In the summer keep your ammo in the shade or covered so they aren't getting hot in the sun.

Make sure your not canting your rifle differently between shots and pay special attention to your shooting form.

Seems like their are always 2 nodes.A low and a high.Also seems like the high node has less SD.Probably has to do with load density and ignition uniformity.I recently tested the low node with a couple slower burning powders relative to the cartridge.The low node wouldn't work because the ES was poor.

 

[kskevin]

Re: 280 Ackley Ladder Test Results - 168g Berger

Thanks for the tips Steve. Never really thought about the wind and trying to assess horizontal grouping as I thought all I was really trying to do with the ladder test was find a tight vertical dispersion, pick a chg wt in the middle of this node range and then start working groups varying seating depths.

Agree on the 200yd test being insufficient range as it didn't show a whole lot as the drops just aren't big enough at that short of range. The 300yd test with the IMR7828 showed some very clear brackets of vertical groupings with 3 very distinct nodes. I'm going to do some additional work with the middle node. I chose the 0.5g increments given the fairly large powder charge (60g). I use 0.3g when I've worked up 223Rem loads.

Didn't check SD as I only did one shot per load. Now going to load 5 cartridges at each of the following ogive lengths: lands, -0.040", -0.080", -0.120" and see how each one groups (probably do this at 200yd).

 

[steve123]

Re: 280 Ackley Ladder Test Results - 168g Berger

Sorry,my computer didn't load the ladder test pic earlier when I replied to your post.So without looking at anything I was just giving tips.

It looks like you started with a mild charge and might not have hit max yet.I think that's why there appears to be 3 nodes in the top pic.I would repeat the higher charges and do .3 grain increments this time.

You probably know all this but I'll mention it anyway for others reading that don't know.You'll know when to stop with pressure because the primers will start to flow,the bolt will start to get sticky and on a calm day the shots will usually spread quite a bit like if there was wind.

Are you kissing the lands with the VLD's on your ladder test? I'd recommend doing so.That way you can go into the lands 10-20 thou or back about the same and the pressure won't be affected drastically.Do you need to do such a large jump to mag feed? Seating those bullets that deep(-0.040", -0.080", -0.120") is going to affect the pressures a lot.Might even be dangerous.It would also affect the results of the ladder you just did.

 

[kskevin]

Re: 280 Ackley Ladder Test Results - 168g Berger

The 3rd node is a real possibility but was getting a bit concerned with how heavy the powder charge was for this load even though I was just barely starting to see any pressure signs (primer just starting to crater little bit, no sticky bolt, no ejector marks).

I've had a hard time finding much load data for the 280AI in the 168g Bergers using the powders I have (H4831sc, IMR4831, IMR7828ssc). If anyone has quickload data on max load I would appreciate understanding what it is indicating as a max chg wt for the IMR7828ssc. Berger sent me data for 280 Rem and advised to start 2g below 280Rem max and work up from there.

All of these were loaded to the lands for this initial ladder test. No issue with mag length. The next step will be 5 shot group testing at 60.0g varying seating depth. Berger has published info indicating success with greater jump distances so I'm going to step the jump in 0.040" increments up to -0.120 off the lands and see if I find something this rifle likes. http://www.bergerbullets.com/Information/Lines%20and%20Designs.html

I like your suggestion of testing that 3rd node a bit more so I may have to test going up another step or two but I'm getting concerned with how heavy this load is as I was already getting ~2970fps with the heaviest chg of 61.5g. Just doesn't seem like I should be able to push a 168g much faster in this chambering without excessive pressure even though everything looked good thus far.

 

[saleen63]

Re: 280 Ackley Ladder Test Results - 168g Berger

KSkevin how has the load data for the 168berger been going?

 

[kskevin]

Re: 280 Ackley Ladder Test Results - 168g Berger

I never could get the IMR7828 to group well at all. Tried two different powder nodes and varied seating depths but the groups were terrible (1.5 - 2.5").

I ended up playing with the H4831sc and found a node and seating depth that worked very well in this rifle.
Berger 168g VLD, seated -0.070"
59.2g H4831sc
F210 primer
Nosler brass
Vel = 2810fps.
Groups of 0.5 - 0.7" at 100yds.
Shot some 3 shot groups at 500 (2.7").
6" at 775yds with essentially no vertical dispersion (all horizontal).

 

[jsthntn247]

Re: 280 Ackley Ladder Test Results - 168g Berger

I think your best grouping will be with H-4831 loaded between charges 8 and 9 (58.7 grains). This is going to give you about the same velocity as the 4891. It really looks like an big accuracy window and I love H-4831.

 

[ranger1183]

Re: 280 Ackley Ladder Test Results - 168g Berger

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: KSKevin</div><div class="ubbcode-body">I never could get the IMR7828 to group well at all. Tried two different powder nodes and varied seating depths but the groups were terrible (1.5 - 2.5").

I ended up playing with the H4895 and found a node and seating depth that worked very well in this rifle.
Berger 168g VLD, seated -0.070"
59.2g H4895
F210 primer
Nosler brass
Vel = 2810fps.
Groups of 0.5 - 0.7" at 100yds.
Shot some 3 shot groups at 500 (2.7").
6" at 775yds with essentially no vertical dispersion (all horizontal).</div></div>
KSKevin, I hope Quick Load is wrong because when I plugged in your recipe it came out with a chamber pressure exceeding 95K psi. At that pressure barrels, actions and bolts will come flying apart. I think you might want to check either the type of powder you are using (listed as H4895) or the powder charge (listed as 59.2 grains).

 

[ranger1183]

Re: 280 Ackley Ladder Test Results - 168g Berger

BTW,
your load looks great if you change "H4895" to either "H4831" or "H4831sc".

 

[kskevin]

Re: 280 Ackley Ladder Test Results - 168g Berger

ranger... thx. Typo on my part. H4831sc is what I'm using (been reloading some 223s last few days and H4895 was one of the powders being used causing the brain fart).

BTW, what pressure prediction did you get with H4831sc at 59.2g? Also curious what 61.5g of IMR7828 shows as I started to see some slight pressure signs at this charge with slight primer cratering and faint ejector marks but no sticky bolt lift.

 

[ranger1183]

Re: 280 Ackley Ladder Test Results - 168g Berger

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: KSKevin</div><div class="ubbcode-body">ranger... thx. Typo on my part. H4831sc is what I'm using (been reloading some 223s last few days and H4895 was one of the powders being used causing the brain fart).

BTW, what pressure prediction did you get with H4831sc at 59.2g? Also curious what 61.5g of IMR7828 shows as I started to see some slight pressure signs at this charge with slight primer cratering and faint ejector marks but no sticky bolt lift. </div></div>
You were maxed out at that pressure. Going higher is at your own risk and NOT recommended. As to other loads, I strongly suggest you purchase a copy of Quick Load yourself to find out. It's easy enough to use and by purchasing your own copy you can get all the info you want LEGALLY. Besides, everyone's got to make a living.

http://www.neconos.com/