Hey guys,

I'm pretty new to reloading. I'm working on a long range 308 round. Just shot my first few today.

178gr Hornady ELD match bullets
Once fired lake city surplus brass
Magtech 9 1/2 primers
IMR 4064
start charge 35.8gr averaged 2080fps with -1" groups

Final charge 40.5gr averaged 2465fps with 2.5" groups

I had the best groups with the lightest charge and it seemed to get worse with faster charges. According to my Hornady manual I'm reaching the limit with the 4064 charge of 40.5.

What is gonna be my next step to improve velocity without sacrificing accuracy?

Shooting out of AR platform with 24", 1 in 10"barrel.

You could try using a case with a larger capacity.  You could try a different propellant.  You could try measuring your case volumes accurately and employing ballistic software like QuickLOAD to help you safely approach the max MV for your components / chamber... and it can also help with powder selection.

I am fond of temp stable powders.  My current favorite is Varget but H4895 & Reloder 15.5 are on my investigational list whenever I am able to get my hands on some...

Are you maxed out as far as charge weight or can you go up more? Any pressure signs?

Typically you'll see things open up and tighten in waves. There's nodes across charge weights usually spread out about 3%.

Recoil can definitely play a factor in shooting for groups, the higher the charge weight is, the more the recoil is felt. This could translate on paper.

If you've reached pressure on that last charge weight, you could mess with seating depth. Another variable to play with that can tighten things up.

With that 24 inch barrel, switch powder to varget. I used to use 4064 but the longer barrel is better with varget. 4064 works good in 16 to 20 inch barrels. You want the powder to finish burning as the bullet is leaving the barrel. Varget is the answer.

Like I said, I'm pretty new to reloading so bear with me.

I don't see any obvious signs of over pressure, but even with my lightest charge, the primers are flattened. My Hornady manual shows 41.3gr of 4064 as the max with a 178gr bullet at a speed of 2,400fps. I've already surpassed that speed with a lesser charge. I get a lot of conflicting info from the different manuals I have.

Should I increase?

My cases were all trimmed, I don't have my notes handy but I believe I trimmed to 2.005"per the Hornady manual. Sized with Hornady full length die.

I seated to 2.800", might increase a little if my mags will allow it. I did not crimp. I'm not sure how to check neck tension, but it felt good when I seated the bullets.

I'd love to get my hands on some other powders, but right now I don't have much.

Also, I used to shoot a lot with this rifle, but I recently put a new barrel on it. I'm pretty comfortable with this style rifle, but I only have maybe 100 rounds through the new barrel.

A quick way to check neck tension is to measure the outside diameter of the neck of a sized and prepped case, seat a bullet, and then measure the outside diameter again.  
The difference is an indication of neck tension.

I get firing pin cratering when loading Lake City 7.62x51mm brass using IMR-4064. 40.5 grains with 168's is what I use for maximum. 41.5 grains is considered a maximum pressure load in LC brass.

Consider:
VihtaVuori N150
VihtaVuori N140
Varget
RE-15
IMR-4895
H4895

40.0 grains of IMR-4895 has been very accurate and reliable in my AR-10's using Lake City with 168's. It's probably a maximum load if you substituted 178's.

<This. My goal is .003" of neck tension and I never crimp match bullets.

I appreciate all the info. As everybody knows, supplies are hard to come by so for now I'm limited on powder. I do have some 165gr Hornady SSTs, I think I'll load some of those and see what the neck tension is. Great info!

My main concern is obviously safety, how closely should I follow the max recommended loads? If the brass still looks good and I'm creeping up, should I keep going even if I'm past book loads?

No, never go above published data, especially when using military surplus brass.

The "Armory" section on this site has a M1/M1-A/M1 carbine page on that has pinned load data at the top of that  page. Maximum loads using Lake City brass for semi-auto rifles.

Oh wow, I loaded some 165 SSTs last night and hogdon says a max charge of 46.3gr while that table shows 41.5gr for a 168 SMK. The brass can really make a 5gr difference? I loaded 43gr to 45.5gr in half grain increments.

What I loaded last night had right around .003" of neck tension.

Winchester commercial .308 brass allows for the highest safe powder charges. Lake City needs the lowest.

It's not just the brass, primer selection can increase or reduce any charge by 6,000 psi. Winchester standard large rifle primers, federal 210M GMM and CCI-34 primers are hotter than Remington 9.5's, CCI-200's and CCI-250's by a wide margin.

This is why load data varies so much between sources. BTW - 46 grains of Varget or IMR-4064 would be a maximum load with 155 grain bullets fired from a dedicated Palma rifle for 1000 yard tournaments. IMO way too hot for a 165/168.

If you are using Lake City brass and IMR-4064 you should consider the 41.5 grain powder charge as a maximum with 165's.

I start to get primer cratering using 40.7 grains of IMR-4064 in Lake City brass when loading 168 grain SMK's. Approximately 2500 fps when fired from a Super Match M1-A. Winchester primers.

I greatly appreciate all the info.

I loaded up some 165s and shot them today. Had a couple sub moa groups. Gonna try measuring my chamber next, looks like I got about .050" more room in my magazines for C.O.A.L.

Thanks again!

Hey everyone,

I've still been trying to dial in the perfect load for my AR10, now that powder and primers are becoming more available, I've had a few good combos.

With smks and varget I'm shooting 1.5" moa, looking to improve on that, But my sd/es is 6.5/16. From what I can find this is quite good for .308 in a gasser. I'm loading at max length for my mags, (2.125" BTO) but my chamber measures 2.335", jumping .0210".

This is not the best grouping round I've built but has the best numbers. Since this is my first load I've ever worked up, I'm wondering what my next move should be.

Thanks in advance.

I would mess with load length. Do seating depth test by seating deeper.