Wow, that 153gr Apex Afterburner is an interesting possibility. I see the .264, .277, and .284 tentative options are very light. What was your impression of how they pressured up and the velocity potential compared to similar weight conventionals? Did they give you any idea when they plan to hit the market?
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Bullet testing, again....
- Thread starter yorke-1
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mcdil
Well-Known Member
Northkill,
We were really hoping to have all five initial bullets listed on the site ready for load work-up time prior to this hunting season, but that didn't pan out as we decided to iterate the design one last time prior to final release. We will start with the 30 cal 153 gr and hope to have those available by October. The others will follow shortly thereafter as well as other calibers and different twist rates within caliber.
The ones fired in the test above were the originals. The delineation between the proto above and the production bullets will be in the low velocity response and the petal reaction. All else will be the same. The proto above, has petals that predominantly travel along the same path as the shank after separation. The production versions will have petals that radiate away from centerline, something we feel is more desirable. Furthermore, the proto will open below 2000 fps, but we wanted ultimate performance at lower velocities as well, and the production version accomplishes that where the proto, in our opinion was lacking. If you happen to check out the FAQs section, you will see the result of the production version at 1644 fps. Full petal separation radiating away from center and straight penetration for the shank.
Thanks,
Mark
Thanks Mark for the response. Can you give me a rough idea of reasonable velocity potential on the .264's, .277's, and .284's out of 24" tubed 6.5 PRC, 270 WSM, and 7 Rem Mag respectively?
mcdil
Well-Known Member
Well, you've got three there that will all have extremely high muzzle velocities. I usually don't like to recommend velocities, because I don't want to give someone a false sense of "safe" should their particular combination be showing unfavorable signs, but I'll put some benchmarks out there that I believe, based off extrapolated data only, will yield velocities at or near 60 ksi internal pressures, which shakes out to roughly what many Federal factory rounds exhibit in those calibers specifically, with the 7mm maybe 3-4 ksi less in factory form. Please realize, it's only an estimation. No lab work or field testing backs up the below estimates with those specific cartridges. We will know more in time as our company matures.
As a side note, most that do the "work up until pressure signs exist, then back off a grain or two" are many times operating in the 70 ksi range in actuality. So please understand that going in to my recommendations, that I estimate the velocities below will match stout factory load pressures with an ideal powder. Always though, your own work on your equipment will be better than anyone's suggestion, including mine.
All with 24" barrels at an estimated 60 ksi max pressure
1. 6.5 PRC with 102 gr Afterburner ~ 3450 fps - This one's the hardest to extrapolate as most data starts at 120 grains, and loads listed for 100 gr bullets are lead core with compressed charge weights. MV could be higher, but I don't want to say that off the cuff. As a point of reference, I anticipate the MV of the Creed to be 3250 fps.
2. 270 WSM with 103 gr Afterburner ~ 3650 fps - If you're lucky enough to find RL17, it may be 3700 fps.
3. 7mm Rem Mag with 117 gr Afterburner ~ 3500 fps
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Thanks for that info. Gives us somewhat of a benchmark. Qualifications understood.
I should have asked about the 153 in the 308 Win as well. 
mcdil
Well-Known Member
I'll have to qualify the 308 Win in that it will need a 1:10" twist. Many newer factory rifles are coming in that way already. The majority are 1:12", however.Thanks for that info. Gives us somewhat of a benchmark. Qualifications understood.
If I can assume a 1:10" twist and a 22" barrel, the 308 Win should have no trouble crossing 2900 fps with the 153 gr. To guarantee perfect terminal performance, that allows a 1:10" twist 308 Win to be an 800 yard gun at sea level, and further at elevation.
We will address the 1:12" twist very soon, potentially the 6th bullet released. It will be an excellent option for the majority of 308s. It will shake out in the mid 130s to give you perspective.
I was pretty lazy with my load and didn't do any work up with the Afterburner. I took Mark's recommendation and started with load data for the 150gr TTSX, compared that to my experience with other copper bullets with minimal bearing surface (CE, Hammer, GS Custom), and took a chance on a load. I was able to match the listed velocities for the 150gr TTSX using the same powder, but going about 1.0gr over the max charge weight I found listed. That's not the best way to do it, but I've shot enough copper bullet to have a decent idea of what to expect. I'll say that case head expansion, primer appearance, case extraction/bolt lift on that load were all comparable to the Remington factory ammunition I was shooting on the same trip. I'm sure I could run the velocity up higher, but I'm not sure what I'd really gain. The ES/SD is great, the velocity is nothing sneeze at, and the groups look really good so far.
What's your experience with the GS Customs if I may ask?
I played around with some of their 338 and 375 bullets about 10 years ago. They shot well, I just moved on to other bullets for no good reason! LOL Now I feel like I need to get some to play around with again.
