Working up some M118LR equivelent.... what I found

[fastex500]

I know this is a horse that has been beaten within an inch of it's life, but I wanted to pass along my findings and see if anyone out there can shed some light on my lack of velocity...

I have chrono'd factory M118LR out of my gun at 2620 avg, so I know the chrono is in the ballpark. Here are my test conditions and results:

Rifle: Savage 10FP, 24" factory heavy barrel, 1-10 twist, crowned muzzle.

Atmosphere: 686 ft asl, 54.5 F, 29.8 in hg, 66% humidity, chrono at 10ft

Loads in mil 308 brass (TOAA 08 - LC 08 equivelent)
Trimmed to 2.005" Lee trimmer, deburred, full length sizing die.

Bullet: Hornady 178gr A-Max

COAL: 2.830 in (best seating for rifle and accuracy)

Primer: Federal Match

Powder: RL-15

Load 1: 43.2gr
Spread: 2553 - 2574
Median: 2562

Load 2: 43.5gr
Spread: 2574 - 2596
Median: 2586

Load 3: 43.7gr
Spread: 2582 - 2620
Median: 2613

Load 4: 44.0gr
Spread: 2604 - 2622
Median: 2615

Load 5: 44.2gr
Spread: 2620 - 2642
Median: 2626

The pressure signs from previous loads of 43.2 (some primer flattening) seem to have disappeared with moving the COAL out from 2.80 to 2.83 on the same load and is keeping accuracy (.5/.75 MOA). I've seen suggested loads all the way up to 45.5 of RL-15 in LC brass, but don't think I would try that much, it's already filling the case up to the shoulder of the neck.

From seeing other numbers, It looks like my velocities are missing the corresponding load capacity by .8 gr. I'm seeing people with 43.3/43.5 matching the velocity of my 44.2

I am not crimping the bullet, it shoots fine, is accurate out to 850 yds.... but I'm just perplexed by needing so much powder to reach the low 2600 velocity range. My groups were 10 rounds each, and I do have some primer deformation (mild flattening), but no extractor marks or hard bolt lifts.... so am I just being picky, or am I missing something?

Quickload estimates the peak pressure at appx. 56000psi.. which is within limit, but at the high end for 308. Thanks guys!

-Disclamer... I am not a professional reloader, or manufacturer. My results are just that.. my results and not meant to be used as a guide. Your results may vary. Use published reloading manuals and work your loads UP FROM MINIMUM- DJ

 

[sinister]

Re: Working up some M118LR equivelent.... what I found

You're in the ball park given you're using different bullets, primer, powder, and cases than GI (plus you're not using bullet-neck waterproofing).

Military 175s have been loaded with WC 750, Reloader 15, and 4064. Lots of hand loaders use Varget, 4895, and other medium burn rate powders.

I'd recommend you shoot whichever is the most accurate vice faster.

 

[Scouter19D]

Re: Working up some M118LR equivelent.... what I found

Id say your numbers look pretty good. Tried to get a similar load established here. I wonder if the velocity would increase at all bumping back to published 2.8", but i can't imagine it changing much at all, and with the group sizes being what they currently are from a 30 year old battle rifle, I'm not touchin it. Got the dies LOCKED DOWN.

M1A 22" Med Weight Barrel

COL 2.810" (max for mag as far as I'm concerned)
178 gr AMAX
Fed Prem. Brass
43.0 gr RE 15
CCI BR2 Primer

Hi: 2539
Low: 2492
Avg: 2517
ES: 47
SD: 16

edit: I forgot conditions. It was roughly 32 deg up in northwest Illinois right after christmas. May have been a factor in lower velocities. Not sure just how temp sensitive RE 15 is. I put three more over the chrono back home in KY when it was 50, and it was roughly 20 fps faster on average. The above is 8 shots, not 10, I ran outta ammo.

I was a little put out by the numbers, really hoping for more speed, so I bumped up to 43.2, and 43.5 gr. Never even made it to the chrono, as the latter held an 8" group at 200 yards. Pitiful. The 43 gr, while on the slow side, will hold right below 2" at 200 yards. I have one 3 shot group sub-inch, but I stopped at 3 shots for that very reason : ) No need to ruin it... wanted something filed away for a rainy day when i CANT pull the trigger, cause lets face it, they happen more often than not.

 

[targaflorio]

Re: Working up some M118LR equivelent.... what I found

What is toaa 08? What makes you say it is lake city equivalent? Are the capacities the same? 2.83 is longish for a 308. If you seat the bullet out to the lands, which you might be doing, you will increase the pressure of the load. Have you measured your chamber to the rifling?
I get 2700 fps with Amax 178s out of a 22" barrel with 44.8 grs varget and win brass @ 2.823" oal. LC brass load is 41.8 - 42 of 4064. Never tried rl-15...
SD and ES will tell you about your loads as well.

 

[Pusher591]

Re: Working up some M118LR equivelent.... what I found

What's up David! Good to see you around here! Holler at me tomorrow if you want to get up and eat lunch.

 

[fastex500]

Re: Working up some M118LR equivelent.... what I found

Thanks for the info guys. Targa, I've got some LC on the way, but from info I've read the TOAA was produced for the USMil to use on belt fed guns and is a replication of the LC volume and design per mil requirements for the bid.

Pusher, yeh, I've been lurking for a bit, I'll start adding to the forum as I learn! I'll hit you up today.

On my OAL... I have not measured the chamber, I was going on info from other savage shooters and the rifle seems happy, but measurements are in the plans once the LC is here.