Is Hodgdon's 308 load data too hot?

[ColoradoShooter77]

Hodgdon list's 41 grains to 45.7 grains of IMR-4895 under a 168 grain HPBT.

I've been running 44 grains of 4895, seated at 2.830".

I had WEG run a quick-load for me, it showed a chamber pressure of 65,000 psi.

I've loaded and fired probably a thousand of these up to now, haven't had any pressure signs. What gives?

With my 20" barrel, I'm getting 2590 fps with this load on the chrono.

 

[jwrowland77]

Depends on a lot of things. Brass being used, primer being used, your particular rifle, etc

The thing about Quickload, you have to put in as many variables as possible. One of the big ones is case capacity. Seating depth, etc etc.

I had a buddy run his Quickload for some test loads I was doing for a .308 Win brass test I was doing with 9 different headstamps, and I wanted to use the same load. He was within 5fps of the averages I saw, but we put in as many variables as possible.

 

[KansasSasquatch]

Where are you getting that HODGDON data? Their website lists IMR-4895 41.0gr starting load to 45.4gr(Compressed) MAX with a 168gr Sierra HPBT. That's with a COL of 2.800", and max pressure of 58,000PSI, velocity of 2,758fps. That's from a 24" 1:12 twist barrel and a Federal 210M primer. Did you get your data from their paper manual? I don't have QuickLoad, but does it take into account things like the specific bullet being used or does it just have "generic" bullet styles. The amount of bearing surface and overall length of a specific bullet could play a role in the chamber pressure. And QuickLoad seems to be a good tool for getting a good estimate of a given load, but I highly doubt that it's 100% accurate even if you fill in all of the data.

 

[djmurf]

If you're using military brass (LC, WCC) that is a smoking hot round, and might explain what you're seeing!

 

[djmurf]

My bad.. Just realized you said that was from Quickload. I would be curious what he had the case capacity set to in his workup.

 

[ColoradoShooter77]

I had another typo, lol. I meant to type 45.4 grains, lol. My brain is getting ahead of my fingers.

I'm using Remington brass and Nosler 168 grain HPBT's. These are pretty similair to Sierra 168 HPBT's.

 

[gamestalker]

" Is Hodgdon's .308 data too hot? "​

I sure hope not, I just loaded a whole bunch using IMR-4895, not H4895 though. Also a bunch with 4064, 4320, and Varget with 165 gr. Speer SP. But my experience with Hodgdon data has been 100%, so I consider it a very reliable published source, therefore I trust it when doing developments based on their tables.

But if your asking if one can trust it enough to jump into a max charge without a proper development approach, I wouldn't do that with any published data. I'm comfortable starting at or slightly below mid tables, and then working it up from there in reasonable increments.

GS

 

[steve4102]

I had WEG run a quick-load for me, it showed a chamber pressure of 65,000 psi.

I've loaded and fired probably a thousand of these up to now, haven't had any pressure signs.

The pressure signs you seek will not rear their ugly head until the pressures are well above 65K.

The 300WSM and the 308 both use Large rifle primers. The WSM runs at 65K psi, the 308 runs at 62K psi. The large rifle primer is not smart enough to know that it is supposed to show pressures signs at or above 62K in the 308 yet remain unaffected in the WSM until pressures exceed 65K.

Shoot your loads and enjoy, QL is a great tool, but like our printed manuals, it is not exact.

 

[Sunray]

QuickLoad is a computer program, not a ballistics lab. Very few programmers go anywhere near a real firearm. And most have never seen one.
"...chamber pressure of 65,000 psi..." Not a chance. Hodgdon's MAX load of 45.4(C), runs 58,000 PSI.
2.830" is 30 thou too long too.

 

[ColoradoShooter77]

2.830" works good in my very long throated Remington 700 SPS Tactical. I'll keep loading at 44 grains IMR-4895, its producing very nice groups.

With a 9lb rifle, recoil is like shooting a 30-30, doesn't get any better than that.

 

[Bart B.]

Unless someone uses the same barrel, action, pressure measuring system, lots of components assembled and tested exactly as the data publisher lists their pressure at, they'll never equal it.

Lots of folks think they will equal what's published by assembling different lots of the components listed then assembling them differently, testing them in a different barrel fired in a different way of holding onto it. A 100 fps difference in average velocity and 5,000 psi or more difference in average peak pressure is normal.

Goodness, where has all the reasoning gone?

 

[Rule3]

Unless someone uses the same barrel, action, pressure measuring system, lots of components assembled and tested exactly as the data publisher lists their pressure at, they'll never equal it.

Lots of folks think they will equal what's published by assembling different lots of the components listed then assembling them differently, testing them in a different barrel fired in a different way of holding onto it. A 100 fps difference in average velocity and 5,000 psi or more difference in average peak pressure is normal.

Goodness, where has all the reasoning gone?

Well said!

Why people want to compare a computer algorithm program to actual test data is beyond me. It is a "guesstimate"

 

[ColoradoShooter77]

I think my velocities are right on the money, I'm getting 2590 fps from a 20" barrel, at 44 grains, that'd be about 2670 from a 24" barrel. The max charge of 45.4 grains, states 2750 from a 24" barrel, sounds about right.

 

[gamestalker]

If you feel pressures getting up there, as in stiff bolt lift, excessive primer flow with hard cup primers, CCI for instance, and chrony tells you that you are, in fact up there, then you might want to back off some. Other wise if all the usual signs aren't present, then your load is very likely within reasonable pressure limits.

I've had folks run some of my loads through QL and warn me that I'm running excessively high pressures, when in fact none of the usual signs were presenting, and never had over the course of years. QL is a program, not a rifle, it has it's purpose, but in the end, we should learn to read pressure signs.

GS

 

[Bart B.]

Caution; this post contains info on a load that may be unsafe in your rifle.

Other wise if all the usual signs aren't present, then your load is very likely within reasonable pressure limits.

I've had folks run some of my loads through QL and warn me that I'm running excessively high pressures, when in fact none of the usual signs were presenting, and never had over the course of years

You may well have been one of several people I handed several fired 7.62 NATO cases to so they could visually "read" them for peak pressure signs; some years ago. Half were normal service loads and half were proof loads; 50,000 cup vs. 67,500 cup. All fired in the same rifle. Same case, primer and powder/charge across all, just a 147-gr. bullet in the service load and a 172-gr. one in the proof load. Lake City Arsenals' data for both.

Everyone said they looked quite normal even if some had ever so slightly more primer flattening than the rest. Half of those that looked, to them, a bit high in pressure were the standard service loaded ones.

I wonder where the phrase "Don't judge a book by its cover." came from. . . . . . . ......

 

[steve4102]

QuickLoad is a computer program, not a ballistics lab. Very few programmers go anywhere near a real firearm. And most have never seen one.
"...chamber pressure of 65,000 psi..." Not a chance. Hodgdon's MAX load of 45.4(C), runs 58,000 PSI.
2.830" is 30 thou too long too.

Before you go on and make comments about the Author of Quickload, ya may want to do some research on him.

His name is Hartmut Broemel.

Broemel is not to be taken lightly. He trained in government labs (the predecessor code to QuickLOAD was based on 20 mm gun data), which typically have military test equipment budgets far in excess of commercial facilities. He writes software for the CIP, and is a respected ballistics authority on that side of the pond. Ken Oehler said, in an exchange at the 24 Hour Campfire, that Broemel had probably seen more real interior ballistics data than himself and others combined. This is partly due to the way Europe collected data historically through individual proofing of firearms and still collects through clubs that test handloads. Lots more data than we get here.

http://thefiringline.com/forums/showthread.php?t=527687&highlight=hartmut&page=2

 

[djmurf]

A buddy of mine has Quickload, and just ran this for me. This is the Nosler 168gr bthp, IMR 4895@44gr
Case volume was set to 56 grains of H2O. Basically shows about just what you're seeing at the range.

Pressure: 50880 psi
Velocity: 2575 fps

Have your buddy check the values he plugged in -- something wasn't right.

I have to agree with Steve4102 above -- I've seen some pretty impressive results come out of Quickload...



_______________________________________________________________________________

Cartridge................. = .308 Win. (SAAMI)
Projectile type........... = .308, 168, Nosler CC HPBT J4 53164 with boattail

Max.avg.pressure(Piezo SAA)= 62000 psi Shot start / init pressure = 3626 psi
Projectile weight (gr)= 168 Groove caliber (in)= 0.308
Length of cartridge (in)= 2.830 Length of case (in)= 2.014
Case capacity(Grains Water)= 56.00 Length of projectile (in)= 1.175
Length of barrel (in)= 20.000
**** Values calculated:
Seating depth (in)= 0.359 Volume displaced (gn H2O)= 6.13
Comb.chamber volume(gn H2O)= 49.87 Projectile travel (in)= 18.345
**** Input data:
Propellant type........... = IMR 4895
Charge weight..........(gr)= 44.0 Load density......(g/cu.cm)= 0.880
Heat of Explosion (cal/lb)= 442029 Ratio of spec. heats cp/cv = 1.234
Solid density (gr/cu.in)= 409.7 Weighting factor...........= 0.5
Burning rate factor Ba(1/s)= 0.52 Pro-/degressivity factor a = 1.586
Burning limit ......... z1 = 0.4 Combust.Chamber Vb(ft³)= 1.143399E-4
Factor.................. b = 1.670 X-S.Area of Bore A(ft²)= 5.114126E-4
Bulk density (gr/cu.in)= 232.7 Projectile mass mp (lb)= 2.399912E-2
Loading ratio (%)= 95.7 Projectile travel x(ft)= 1.528766E+0

**** Results calculated:
Maximum pressure ........ = 50880 psi Way of projectile at Pmax = 1.54 in
Muzzle velocity ......Ve = 2575 fps Muzzle pressure .......Pe = 9612 psi
Project. energy at muzzle = 2473 ft.lbs Fraction of powder burnt = 97.5 %
Projectile travel time from 10% Pmax to muzzle = 1.1 ms

 

[ColoradoShooter77]

djmurf, thanks a bunch. My load looks perfectly safe and its working good for me.

 

[W.E.G.]

 

[W.E.G.]

Notice the difference H2O capacity

 

[ColoradoShooter77]

I found some info on-line stating that the Remington 308 cases are 168 grains in weight. Would that make the 44 grain load too hot? I don't think it is, because I've already loaded hundreds at this charge weight, with no issues.

 

[djmurf]

52 grains of capacity is common to military brass, I load LC brass, and have to reduce my powder charge accordingly.

I haven't weighed Remington brass personally, but the Winchester I've weighed usually runs around 56 to 58 grains of capacity, and my understanding is the most civilian 308 brass falls into that weight category.

If you switch the brass in the Quickload calculation to 308 SAAMI spec, it defaults to 56 grains of capacity versus the 52 grains it's showing when using NATO 7.62

Is there a reason that you're estimating the load with military specs versus SAAMI specs? Does Remington brass generally have a lower capacity?

Dean

 

[djmurf]

BTW -- this is by no means authoritative, but this is the list I've collected of 308 case capacities over the years -- mostly from others measurements.

I would measure myself before I took it literally, but may help others as a guide...

Notice how LC brass is down in the 52 grain capacity -- this was a real eye opener for me when I started using LC brass. Following general load data for 308, you'll be way over pressure if you jump to the higher loads... There's a reason to start 10% lower & work up!

The screen shot of Quickload is a perfect example. Using civilian brass with 56 grains of capacity and that load is perfectly safe, however drop that same charge in some LC brass with a 52gr capacity, and now your about 10k over pressure.


Case Manufacturer Case Weight* H20 Capacity**
WCC 58 147.10 57.40
WCC 60 156.25 56.75
Remington BR 157.20 56.15
Winchester 157.40 55.80
Lapua 308 55.30
Hornady Match 308 55.20
Lapua Palma 173.00 54.90
Winchester Brass 159.60 54.4
Lake City LR 177.45 53.45
Lake City '66 53.00
Lapua Brass 177.50 52.90
Hornady Match Brass 172.50 52.80
LC LR 07 Brass 181.40 52.00
LC 09 Brass 178.50 52.00

 

[ColoradoShooter77]

Based on those case capacity figures, I'm good to go.

 

[gamestalker]

No, I don't think it was me Bart.

I never rely exclusively on primer flow, but rather I employ it in combination with data, chrony, bolt lift, and cylinder extraction if working with a wheel gun. But I can say this though, the data has almost always been closely in line with the signs.

Now back in the old CUP days, there were some minor issues with some data sources. But even then, as long as a guy was observant, and knew his powders, primers, brass, and firearms, the data would still be pretty consistent with the signs produced at various charges.

GS