Getting back into reloading (thank God), starting with .308 out of a PA-10.
First loads are ladder testing Hornady 168gr BTHP with Varget.
According to Hornady the max charge is 44.0gr.
According to Hodgdon max is 46.0gr.
Erring on the side of safety I stayed at 44.0 max and found a good flat spot at 42.8-43.2gr giving around 2460 from a 16” barrel, all well within an inch of each other. Zero pressure signs.
I’ll definitely pursue this node but I have to wonder if I’m shorting myself another 2 grains of testing.
Comparing to other manufacturers in the same 168gr class with Varget:
More testing never hurts. I have 2 different rifles that have given me 2 nodes per test series. Barrel harmonics are always interesting
Edited to add:
Finding large discrepancies between manuals is normal. I loosely base my load development on the manuals and find what the rifle truly likes with chronograph data and precision on paper. Reading pressure signs from fired brass can be deceptive. However, chronograph numbers never lie. Velocity is a function of pressure.
Hornady and Hodgdon developed their data using different brass and lots of powder, which vary by like 5-10%. To be clear, you’re looking at Hornady’s bullet in Hodgdon’s data, correct? Same weight and design bullets of different manufacturers will usually be close, but the even the same book can differ sometimes. Are the COL’s the same? Primers same? Hornady’s books also commonly use real rifles; Hodgdon might be using a SAAMI minimum (worst case for pressure) barrel and chamber on a universal receiver. All of that will be listed in the preface to the data.
That’s not that big a discrepancy. This is why I always recommend people start with at least two books, one from a bullet manufacturer, and one from a powder manufacturer. Cross-reference, and start with the lowest.
Hornady and Hodgdon are my two most recommended guides to start with because of the data they present, the way they present it, and all the other info in there.
For comparison, my M21 does best with 168 gr bullet at 2550 fps. This number is no accident. It was derived from years of testing by military armorers for Camp Perry competitions. My shooting partner shoots the same bullet with his bolt action in the 2650 and higher range. Just like Bimmer noted, gas guns and bolt guns need different pressure ammo.
First, tried loading the 168’s at and around the 43gr mark where I had a flat spot. No dice. Best I got was a 1.25” group (100 yards), 2463fps and SD 18.2…yuck.
Loaded up another ladder test, 44.0-46.0gr Varget 168 Hornady BTHP match, Starline SRP match 308 brass. All seated to 2.800 +/- .002. Charges dispensed on my tuned chargemaster and verified on a jewelers scale, and both checked prior to loading with some calibrated weights. All same as last tests.
Only difference is that it’s 70 degrees today vs 55-60 prior…but it’s Varget so not a big deal.
44.0 gr -2583fps, pierced primer
44.2 - 2616, looked ok but primer was cratered
44.6 - 2590, pierced primer and blew the bottom out of the mag.
Nope.gif, done for the day.
Even my wife, who is actually a steadier shot than I am, saw that and went “wtf I’ve never seen that happen in all the time you’ve been reloading!”
Hodgdon only lists LR for .308, I think. I don’t have a Hornady book with me to compare. What’s the anticipated impact on pressure, of changing primer types? Hodgdon is using “match” primers vs your 41s.
Hodgdon also doesn’t list that bullet with Varget on their website for me to look a little closer.
I’ve heard of people having problems with firing pins not matching FP holes in bolts with .308 ARs. That doesn’t sound like the problem you’re having, since you’re only getting it while approaching the limits, but it has me curious.
I wouldn’t think the 41 vs a LR primer wouldnt make that much of a difference but, it has to be something.
I have been reading, from starline themselves no less, that their brass is thicker and thus requires slightly lower charges. I’m going to call them about it tomorrow. That would explain getting higher than expected velocities. I was surprised getting 2460 with less +/- 43gr. Hornady data has that bullet doing 2600fps at 44gr from a 22” barrel.
I was getting that at 44gr with a 16” barrel…
I will check out the firing pin thing, thanks for the heads up
Just spoke with Starline tech.
He suggested Remington 7 1/2, but that their brass capacity is less than Winchester, to the tune of a +/-2gr reduction in loads.
You will find that some bullet manufacturers have softer loads due to bullet design. Sure you can push them out faster but some may have a thinner jacket that can not withstand the centrifugal forces of the extra spin with the extra speed and will either fly apart or destabilize from not staying uniform.
So powder manufacturers are looking for safe pressures and bullet manufacturers are looking for safe speeds/rpms.
OK, so a 1-1/4" group isn’t great, but what’s wrong with an SD <20?
Good thinking… It could be that your rifle just doesn’t like that bullet.
Why are you loading at SAAMI spec?!
Why not load at mag-length, or ≈0.015" off the rifling?
That would explain the overpressure problems.
Also, I would guess/assume that a lot of the guys running hotter max of max loads are loading a bit longer, and therefore effectively have more case volume.
Example, I’m loading at ≈2.865" (vs. CBTO of ≈2.882"), and I don’t know how much more case volume that means, but just looking at them vs. factory ammo at ≈2.800, it looks like it’s significant.
I have been under the impression that single digit SDs were what to shoot for, just how I ‘came up’ in reloading. Might be unrealistic
My comparitor tool to check depth to lands is in the mailbox with my SMKs, but most of my reloading experience is with 5.56 in ARs so chasing lands just isn’t something I’m accustomed to. Nothing against it, just haven’t before.
Makes sense. I see a lot of guys loading out but I always assumed bolt gun loads.
