Testing the Apex-Outdoors 135gr Afterburner

[Petey308]

I’ve shared this in a few other places, so it might be a repeat for some (my apologies), but for those that it’s not, I thought it would be good to post this up here as well. Most of this first part will read a bit funny, since this was written in sections as I started the testing and moved to present day. Here goes:

As soon as they were released, I placed my order for some of the new Apex-Outdoors 135gr .308" Afterburners, as I’m excited to test them out for myself. Follow along in this thread, as I’ll update it as the testing goes.




I'll be starting the testing in a 24" 1:10 twist 308win and the intent is to test them close range first on whitetail this month.

First thing was first, I wanted to see how consistent these bullets are out of the box. So I weighed all 50 on my AnD FX120i and then measured all 50 with my Sorteez digital indicator. The results are pictured below, in the notebook.





The extreme spread for weight was .9gr with the average coming in at 134.85gr. The extreme spread for base to ogive was .0065" but the majority were within .0025"

I did some initial comparing in QuickLoad to determine which powder combo would likely be best. My go-to powders in 308 (albeit with heavier/longer bullets), being Varget and RL-15.5 look to be too slow burning, and thus fill the case up way too fast. Both are showing compressed already at starting loads, and way compressed at max loads. Not a big surprise, but nice to know ahead of time.

IMR 8208 XBR looked the the most promising temp stable option, with a potential node possibly being around 2922fps. This of course will change once I start testing it, but it gives me an idea of what to maybe expect. I'm still hopeful I can get 3000fps.

I decided to use small rifle primer Peterson brass, as I really like the consistency I get from them, as well as I have more SRPs on hand lol.

COAL looks to be around 2.810" based on that’s as far as I can seat them out without the bore rider and crimp groove negatively interfering and potentially producing issues with runout. I don’t plan on crimping these, for what that’s worth.

The next step is to load up a few rounds each at 3 different charge weights so I can go shoot them and record velocities. I'll then use that to calibrate QuickLoad to my actual results. That'll allow me to get much more accurate node estimates from it. Then I'll be able to load up some more to confirm where the node actually is. If that goes well, I may or may not need to do a seating depth node test, then I should be set for deer season with bullets to spare.
The ballistic chart below shows the potential at my altitude for this bullet with a MV of 2922fps. For this initial test, it’s unlikely I’ll take a shot further than 300 yards.



So to be more transparent, I did look at several other powder options too, and I just didn't find anything that I thought looked like it would ultimately be worth dealing with groups opening a bit with temp swings, such as using ball powders or non temp treated extruded powders.

I looked at CFE 223 first, since it's well known to produce top speeds with a lower rate of pressure, and it's 8.4% compressed at max load, at 51.5gr (wow) and at 3030fps. I know it's very dense stuff so that's why it's over 51gr and only 8.4% compressed. It would be a better option than RL-15.5 as far as top speed potential vs compression, but not for true temp stability.

Also, FWIW, I know compressed loads don't translate or mean anything in regards to pressure. It's not like compressing a gas or liquid. It just makes seating the bullet to a consistent depth (COAL), difficult and very frustrating lol.


Fast forward a bit:



Got the initial rounds shot today. The following is the data gathered from those rounds:

42.0gr

1- 2953
2- 2953
3- 2962
A- 2956
SD- 5
ES- 9

42.5gr

1- 3004
2- 3011
3- 2993
A- 3002
SD-9
ES- 18

43.0gr

1- 3003
2- 2996
3- 3017
A- 3005
SD- 10
ES- 21

So that’s exciting and means it is faster, like anticipated, and as discussed with the owner of Apex-Outdoors. It’s definitely capable of the 3000fps mark. So with all that data plugged into QuickLoad and with it now calibrated, the estimated OBT node is 42.8gr with an estimated MV of 2991fps.

So next, I will load up some more rounds below, at, and above that estimated charge weight and then go shoot those and confirm where the actual node is.

Here’s the best group of those shot:

 

[Petey308]

New, and most recent, update:

Finally took a day off work just so I could get to the range and hopefully finish my load development before deer season got here first. This will be a bit of a lengthy post, but since there’s a lot of things tied to how I’m also using QuickLoad and Optimal Barrel Time in this test so far, I want to include how that all affected things and turned out. So here goes.

So after my first shots with this bullet to get actual muzzle velocities with three different charge weights, I took that data and changed the Ba in QuickLoad to make it match my actual MV. Since this bullet is a lot quicker than most, I had to change the Ba quite a bit and it made the pressures show really high, which did not reflect at all on the fired brass or with the rifle while shooting them. At the time, I decided to just ignore the pressure it was showing, and trust the velocities and thus where the estimated charge weight was for the OBT node. I loaded up 15 rounds based on that, that I would shoot next to look at where the most consistent load was (the actual node).

Well, a couple weeks passed because I wasn’t able to get out to the range when I thought I was, and during that time I had plenty of time for it to eat at me that those pressures weren’t right lol. So, I went back and redid my initial QL work up because I was thinking about it more and more, and I just thought I must have done something wrong before. The pressures in QL were showing like well above 64,000-66,000psi, even though I know it couldn't have actually been that high based on all the other evidence and signs.

So I took my range data from last time again and played with the Ba (powder burn rate) in QL some more, along with the weighting factor, and actually got velocities and pressures looking WAY better and matching up well with what I got. That in turn changed the predicted charge weight for the OBT node though.

The MV data during my initial range trip showed single digit SD/ES at 42.0gr and now my new predictions showed 42.05gr was bang-on right at a good OBT node. So that made me feel pretty confident in that being accurate now too since the previous data reflected that as a real possibility. My previous QL predictions said 42.8gr as the estimated node and that's what I had loaded up already to shoot a couple weeks ago, when I didn't end up getting to go. In hindsight, it’s good that trip didn't work out lol.

I ended up pulling all 15 of those loads and charges I had made already, and redid them. I was confident enough in what I had now too, that I only loaded 12 rounds total, instead of the 15 I had before. I did three at 41.8gr, three at 42.0gr, three at 42.2gr and then I decided if it was where I was thinking, I kinda wanted to look at 42.1gr too, so I loaded three of those as well lol.

I was kind of dumb though, by not bringing anything to warm up the barrel and get the cold bore out of the way like I would normally do, so the first batch at 41.8gr I think appeared worse than it likely really is/was. Also, all of them were shooting faster today than last time (compared to the initial velocities I got at similar or the same charge weight), and thus also faster than QL estimated. That didn't seem to affect the node though. Here are the results:

2nd round Afterburner test

41.8gr

1- 2923
2- 2985
3- 2992
Avg- 2966
SD- 37
ES- 69
QL Estimated- 2944fps

42.0gr

1- 2988
2- 3003
3- 2984
Avg- 2991
SD- 10
ES- 19
QL Estimated- 2957fps

42.2gr

1- 3007
2- 3016
3- 3006
Avg- 3009
SD- 5
ES- 10
QL Estimated- 2969fps

**Extra:

42.1gr

1- 2996
2- 2995
3- 2993
Avg- 2994
SD- 1
ES- 3
QL Estimated- 2963fps

So after all that, I decided 42.1gr was the clear winner. I had two touching on the 100 yard group, and one that I pulled . I was shooting terribly that day, but luckily velocities were what I was after, and not so much groups (although I wanted both lol).
Also, I think the second shot at 42.0gr was just a weird one, regarding the velocity. Something might have been different with the brass on that one, or who knows, but I think it was more of a fluke being that high on MV. That's one of the things that sucks about doing only 3 shots per charge, but I'm trying to preserve components lol. I'd much rather do 5-10 shots per charge weight, but that eats up components really quick. I feel confident in my methods and my loading skills though to be able to work with just three, but unfortunately you sometimes still get those anomalies.

I also brought everything with me to the range that I needed in order to load up more rounds so I could either check a different charge weight if needed, or to load more of whichever one won so that I could zero my scope to it. Since I was confident 42.1gr was it, I loaded up 3 more and with those three I got my scope zeroed spot on at 100 yards, and that was it- done at the range and in less 2 hours total, including target setup and setting up the mobile reloading bench lol.

I ended up with a fully developed load, and zeroed, in just 25 shots total. Not too bad. Thank you QuickLoad and the Long Family lol. So you can see how useful this system is.

I'll call this load 3000fps since it only averaged 6fps under lol. I'm happy with that lol. Oh, and again, these are loaded with small rifle primer Peterson brass, for whatever that's worth.

So now I'll load up at least 10 rounds before the season opens next weekend. That ought to be more than enough lol.

Hopefully the next update is actually terminal performance!

 

[Petey308]

For what it’s worth, my current bullet preference is heavy for caliber soft/frangible lead core bullets, such as Bergers, Sierra TMKs, Hornady ELDMs, etc. That said, I keep an open mind and like to continue to test new bullets and innovative designs. This design has caught my interest, so I wanted to do my own testing with it.

I’ve also already done a dissection of this particular bullet, and have several thoughts on the design. I think I’ll wait to post that data later though.

 

[str8shooter]

Is this with 8208 xbr?

 

[Petey308]

Is this with 8208 xbr?

Yes