loading 178gr a-max in 30 cal

[jwoolf]

What burnrate is best to get the best overall velocity out of this bullet?

We're going to try to squeeze the max range out of this bullet and need everything we can get. We may go to 190gr bullets but, we're limited to a magazine size so, we're kind of working with case capacity vs. bullet size vs. magazine length issues.

Ideas?

We can make the 1000yd line easily with the recipe we've been using but, my bud is using the same load I'm forced to shoot in my M1A and we'd like to work up something shooting slower powder than IMR 4895.

 

[bohem]

Re: loading 178gr a-max in 30 cal

Is he using a 308 as well or just the same bullet?

I'm hesitant to load something slower or higher energy than the usual suspects like Varget, 4895, etc in the M1A

For a bolt action load RL17 is showing promise with a lot of bullets in the 308 down to the 180 class.

 

[shoot4fun]

Re: loading 178gr a-max in 30 cal

Varget is IMHO the number one powder for the 308 with 175/178 grain bullets. If you want to "squeeze the max range" out of that bullet then put it in a 300 Win Mag.

 

[jwoolf]

Re: loading 178gr a-max in 30 cal

I'm shooting a supermatch with 308 and, I'm limited on burnrate based on the fact that I like my op rod in one piece but, he doesn't have the same issue. He's running an AR10 and wants to get the most velocity out of either a 178 a-max or 190gr smk. Sorry, I should have been more clear on the fact that this wasn't for the M1A. I've got a reasonable load worked up for that and, I'm not going to mess with it. It doesn't "ring" the op-rod and, it makes the 1000yd line. That's good enough for that rifle.

After looking a bit, maybe BL-C(2) or something in that range may be a place to start but, not sure yet.

FWIW, my long range gun is a 300wm and, I tend to launch the 208gr a-max out of it.

I do still have fun with the M1A, however.

Thanks for the RL17 suggestion. That may be the one we're looking for.

 

[bohem]

Re: loading 178gr a-max in 30 cal

BLC2 works pretty well in that regard, though the AR is a bit limited too depending upon how the gas system is setup. I've shot a lot of BLC2 under the 175-180 class bullets from a 308 and it does really well (though it is temp sensitive).

 

[jwoolf]

Re: loading 178gr a-max in 30 cal

thanks for the advice.

I'm not sure how my buddy's gas system is set up other than it's an AR10 with a 24" custom heavy bbl.... I don't have details and, he's a new reloader and, I'm helping out with that except, I haven't really done a lot of load research on 308 since I have my pet load that I shoot in the M1A.

His rifle shoots that load fine but, we're about to have some opportunities come up to shoot farther ranges and, he wants to work up the best load for his rifle possible for long range ( more than 1000yds ).

so, it seems that RL17 is much slower than BL-C(2) and, if it is what is working well, I'd like to try that except, we don't want to hurt his rifle.

So, since I don't own an AR10 and know very little about them, are the gas systems frajile in any way to slow powders?

 

[blklabs]

Re: loading 178gr a-max in 30 cal

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: jwoolf</div><div class="ubbcode-body">we're about to have some opportunities come up to shoot farther ranges and, he wants to work up the best load for his rifle possible for long range ( more than 1000yds ).</div></div>

I think you are going to be hard pressed to find a load that will make it much past 1000 yards in a 308 AR10. The 178 AMAX will make it to 1k, my bolt gun runs it at 2634 and its 11mils to 1k. I guess the question is how much past 1k do you want to go and what velocities are you getting now out of your load?

 

[bohem]

Re: loading 178gr a-max in 30 cal

I've shot the 178 Amax through the sound barrier at 28.0 inHg, 40F, 51% humidity via my 30-06. It transitions around 1500yd at that point, but it does transition fine.

If your buddy's rifle has the scope to get there, I've seen someone drive a 308 and 175 SMK's to a mile, I have little trouble believing that the 178 Amax would do the same now that I know it transitions well (under the conditions stated above).

The problem you're going to find on the AR gas system isn't an op-rod problem but will manifest itself from beating up on the BCG and especially the brass.

You can tune this behavior with an adjustable port gas block (such as the JP Enterprises one) or simply relegate yourself to shooting through the sound barrier.

I have an LR-260 with the 24" upper and have shot the 140 Amax through the sound barrier numerous times with it. It takes more time to get there and the wind makes you really work, but I don't push the cases any harder because I don't need my rifle to take undue abuse just for an extra 50yd of supersonic range.

Contrary to internet lore, the 308 bullet doesn't magically stop forward travel at 1100yd, it just becomes harder to drive, so the shooter needs to do a better job.

I would say overall, simply take that AR10 out and push the range on the existing load. With good spotters to help, it becomes a team sport for plinking at 1500yd with a 308, but there's nothing about it that is any "less fun" IMO.

As an example of pushing things... I had my 20" AR15 with 75 Amax's out at 1273 on the same day that the 178's were at the 1700yd line. They hit point on, made little splashes in the dirt, and ended up hitting the target just fine. Once I figured out WTF the wind was doing over the 2 valleys that the bullet flew over.

 

[jwoolf]

Re: loading 178gr a-max in 30 cal

this is all very helpful. thanks a lot guys!!!

the load he and I have been shooting is LC match brass with CCI primers, IMR4895 at 41.5gr under a 175gr SMK. It makes about 2600fps out of my M1A supermatch 22" bbl and, I'm usually up 36-39moa from a 100yd zero on most days at the 1000yd line with it.

 

[armymedic.2]

Re: loading 178gr a-max in 30 cal

im shooting that bullet over 41.5 gr imr 4064. just as an fyi, this goes subsonic and shits the bed around 875 yards. accurate as all get out at 850.

you can put more powder in and be below max, but my rifle didn't like it. the bullet did not transition well at all.

figured id help you rule one out.

 

[BCP]

Re: loading 178gr a-max in 30 cal

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: jwoolf</div><div class="ubbcode-body">
I'm not sure how my buddy's gas system is set up other than it's an AR10 with a 24" custom heavy bbl.... I don't have details and, he's a new reloader and, I'm helping out with that except, I haven't really done a lot of load research on 308 since I have my pet load that I shoot in the M1A.
</div></div>

He can get an adjustable gas block, carrier weight system, maybe a heavier buffer and spring. No reason to stop using 4895 although I like varget more. Beyond that not sure what to tell you other than 308=/=300 win mag.

edit: FWIW I use 42.5 varget in LC and 43.5 in win with the 178 amax at 2.78 COAL. I really like the 178 amax, just seems to shoot better than smk overall.

 

[Grump]

Re: loading 178gr a-max in 30 cal

The only AR system gas port specs I've ever seen were for the .223/5.56 system.

Never been able to find specs for the .308-size gas system, carrier and bolt system. If I had, I'd run some QuickLoad modeling for you.

Surprisingly, I found that loads with Varget were well within spec for the M14 gas system, 175-gr and 178-gr bullets, all the way up to somewhere beyond 2600 fps. Some published guy says Varget is too slow for the M14/M1A, but more than 2600 out of a 22-inch barrel is pretty good. I think it was predicting just over port pressure specs at about 2675, but don't hold me to that.

 

[Stallard]

Re: loading 178gr a-max in 30 cal

Savage 12FV 24x Sightron .308 Winchester
Lapua Brass NS & Body size (Redding)
178 Amax
42.5 Varget
CCI BR2
Seat to the lands

Makes a .485" 5 shots at 100yds

 

[jwoolf]

Re: loading 178gr a-max in 30 cal

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Grump</div><div class="ubbcode-body">The only AR system gas port specs I've ever seen were for the .223/5.56 system.

Never been able to find specs for the .308-size gas system, carrier and bolt system. If I had, I'd run some QuickLoad modeling for you.

Surprisingly, I found that loads with Varget were well within spec for the M14 gas system, 175-gr and 178-gr bullets, all the way up to somewhere beyond 2600 fps. Some published guy says Varget is too slow for the M14/M1A, but more than 2600 out of a 22-inch barrel is pretty good. I think it was predicting just over port pressure specs at about 2675, but don't hold me to that. </div></div>

Grump, that sounds about right to me. With 4895, I'm getting about 2600 flat out of my M1A and, it does make the 1000yd line. I may try varget now, however. It's a better and more current powder that will be better either hot or cold.

I know that guy you're talking about and, I've read those papers.... I think one was titled something like, "Loading for the Match M14" or something like that... It was good info but, if port pressure doesn't exceed the numbers then, I'll be willing to try it.

Hell, you can hear if you're hurting something. The op-rod will let you know.