I am a reloading novice. I am getting ready to load up some 178 Grain ELD-X bullets over IMR 4064. I am shooting these out of a 20" heavy barrel Howa 1500. I have shot several different factory loads through this rifle. It really likes Federal 175 SMK's, my best is .65 MOA 5 shot group at 100 yards. It also did fairly well with the Hornady precision Hunters, best 5 shot group was a cloverleaf and two flyers. The muzzle velocity for the Federals was 2550,2555,2556,2557 and 2565. the velocities for the Hornady was 2580,2585,2587,2594 and 2604. I can get a little anal into all of the specs on the different bullets, I have dimensions, (base to shoulder on the case, base to the bullet ogive etc. ) prior to firing the rounds and afterwards. Based on the performance of the Federals I have set the shoulder on my prepared brass to the same dimensiond of those cases. I ntend to set the base to ogive lengths the same as well. I have looked at a couple of loading manuals and figure I need to be in the neighborhood of 42.7 grains of the IMR to get close to the same velocity. My theory is if I can match the specs closely enough to the specs of the Federal ammo I will get similar results. I am going to load 5 rounds each at 42.7 grains, (approximately 2559 fps), 43.6g, (2614 fps), 44g, (2620 fps), 44.4g, (2650 fps), 44.8g ,(2670 fps), and 45.3g, (2700 fps) and see how I come out.
I have shot this rifle out to 900 yards with some factory Sig Sauer 168g OTM bullets at steel and had fair results. I think the bullets were starting to go transonic out at that range, muzzle velocity was in the 2600fps range. Based on the Hornady ballistics calculator i should be okay with the loads I am considering out to the 1000 yard mark. Am I going about this all wrong or is there a way I can simplify finding the best load? I look forward to any input you guys might offer!

Its actually a 24" barrel, I had a brain lapse!

Don't load to factory ammo specs...that's basically loading to a garbage standard :P

And I would suggest that if you are not a seasoned/experienced loader, you should always start your loading at the MINIMUM grains/load and work up. Even loaders that have been doing it 10-20 years generally start from the MIN. load and work up - it's just the safe way to do it. Not doing it that way would be pretty reckless. Maybe some of you guys that are way more experienced than me can chime in on this one - you guys might not share my opinion on the topic.

And while you certainly don't have to use the powders listed in the bullet manufacturer's reloading manual - you might want to think about doing so as those are powders that were tested with the specific bullet, not just general reloading information from the powder manufacturer. And IMR 4064 is not one of the powders listed for that specific bullet in the Hornady manual. Although, I do see that they state IMR 4064 and VARGET provided the best results for the bullets they loaded with it. But for whatever reason they didn't provide IMR 4064 load results for the 178 - 180 gr. bullets...it could be because it performed poorly for those bullets and they didn't think it was worth listing. Seasoned loaders are probably comfortable loading using any powders that are good in the firearm type generally, but I've personally only ever used powders listed for the a specific bullet by the bullet manufacturer - I don't think I have near enough experience to be comfortable doing otherwise. But, I may just be overly risk adverse - again some of these more experienced guys might chime in and say something different.

Also, when working from the MIN load up...I would load in .2 - .3 grain increments (I generally go in .3 increments)....that's how you find by the best node... the increments you suggest, you're skipping over nodes...you could easily skip right over the best shooting node.

Just some things to consider.

Varget is my go to powder for the .308 and IMR 4064 worked very well for me as well. Both powders are great.

So the question I hear is that if you can match the external ballistics, for simplicity's sake the same muzzle velocity with the same bullet once the bullet has left the barrel, then YES in a theoretical bubble it should behave the same. So if whatever you're loading produces the same muzzle velocity as the FGMM with the same 175gr bullet, then you should more or less match the flight path. But if you try to match the muzzle velocity of the 175smk FGMM to your hand loaded 178 eld-x, then it will NOT be the same flight path. It might be "similar enough" but that's not a useful statement. Similar enough to get on a giant piece of paper at 300 is not same as "similar enough" for a 10" at 1000 yards, I assume.

The other issue being pointed out is the internal ballistics, all the behaviors from firing pin strike to bullet leaving. Now this part where it can get complex, including reloading. If I'm reading correctly what OP is saying then you should using the FGMM 175gr SMK ammunition's muzzle velocity as a target velocity in which you'd like to achieve. Getting there through reloading should not involve the FGMM as a reference otherwise especially since you're not using the same bullet; dimensions or weights of any sort. Btw, published velocities are hard to trust, at least all the ones I've been able to compare vs what my magnetospeed tells.

Honestly, i think you might be over thinking this thing. I get paralysis by analysis all the time, especially during reloading. I still consider myself a newb. You're probably better off not targeting any specific velocity for mimicing factory ammo but just finding out what combination get the best groups. Then once you have a load you like, then you can simply get the actual muzzle velocity (looks like you have a chorongraph) and use a basic ballistics calculator. Theoretically there will be at least a couple different powder charge weioghts for a given bullet, powder, brass, primer combo that works well. And the reason the FGMM shoot better ain't velocity itself but because the consistency in the ammo/velocity form shot to shot. the FGMM has the largest difference between max to min, the extreme spread, of 15fps. the Hornady hunter is 24fps.

Btw, why the eld-x? is this specifically for a long distance hunting load?

I appreciate all of the input, I can definitely get bogged down in the particulars. Based on what you guys have offered here and a couple of other posts on this forum I read last night I am going to try my hand at a ladder test with both powders. I chose the ELD-X because it has good bc numbers and appears to be a good bullet. I can find them for less $ than the smk or tmk projectiles so I would use them for hunting and for ringing steel. I have been happy with the performance on game animals in the factory rounds.

Actually you've alluded to why I ask. I was just curious. The eld-m is about 2-3 cents cheaper than the eld-x. I got hooked hard core into reloading my 308, I have a heavy barreled a Savage with a 26" barrel not that it matters. I hope you enjoy the experience and researching the countless fact-based opinions people have.

I do enjoy the process. I have read enough to really get lost in the minutia!

So after looking through some additional posts here and others online I wanted to see if anyone has actually loaded the 4064 under the 178 ELD-x. I pulled my numbers for the loads I was going to use from the second edition reloading book.it doesn’t show powders for the ELD specifically, so I looked at the load info for a 180 grain jacketed bullet. This manual showed starting grains at 40.7 and the do not exceed as 45.2. All of the other info I have found on a couple of different forums where guys have loaded this combo, has loads at around 42. I intend on starting low and working up, just wondering if anyone knows why I might be concerned with this bullet/powder combo?

Federal used 4064 in their 308 GMM for many years with 168s, no reason it would not work with the 178s. Varget is unobtainium right now and you could certainly get by with 4064 for a while.

Nothing is the definitive be-all , end-all source of info for reloading but I do like Hodgdon, which is the powders I mostly use. The following is their quick little blurp on the 308. They list the 4064 as one their powders they recommend for heavy 308 and 178 is heavy for 308. I like their site and their data.

https://www.hodgdonreloading.com/reloading-education/reloading-beginners/reloading-308-winchester
https://www.hodgdonreloading.com/

So guessing at your concerns, it really comes down to two separate issues. One is safety, which almost every aspect affecting safety can be wrapped up in shooting low charges, working your way up and looking pressure signs until either reach it OR you end up shooting them all without any issues. Meaning any and all bullet/powder combos should have this concern. The second is accurcay/consistency. Apparently 4064 is a good t ogreat powder for 308 shooting 170gr or heavier bullets. Alot of 178gr sierra matchkings with 4064 online and youtube. So aside from safety, which is a protocol to be followed fro all bullet/powder combos, you won't know if the accuracy is what you want until you shoot it. The only concern here I see is wasting time and cost but I got so hooked it hardly felt like a waste to me.

I used to shoot a 168 amax over 4064 with a gmm large rifle primer that would bug hole so it’s very possible..
You can shoot any powder or any bullet so long as you tune it to your rifle.

I am going to try and get out this weekend and shoot a ladder. I am going to start with 41g and work my way up to 45.1g In .3g increments or until I see pressure signs. I will post my target and results and we will see what I come up with!

Did you ever get to shoot? I am curious about your results. I am going to attempt the IMR 4064 with the 178 gr ELD-X.