Conflicting information Sierra Tables vs. Hodgdon

[Jim Buck]

I was working on some .308 loads and noticed the information varied between the Sierra and Hogdon tables.

Example: Bullet is Sierra #2120 .308 125gr spitzer / powder IMR 4895

The Hodgon table is 24" barrel, Sierra 26" barrel. I am shooting a 20".

Sierra says the low is 42.5 and 46.2 max. grains.
Hogdon says the low is 48.0 and 51.8 max. grains.

Gentlemen it's been a long time since I reloaded, please help.

 

[ollie]

I would tell you to stay with the sierra manuel. 50+ grains in a 308 is a lot i dont even think that much would fit in the case.

 

[Jim Buck]

Thats how I figured it out, I was loading different powders and weights and tried 50 grains. Not much room left, so I started comparing tables and found the conflict.

 

[wooger]

FWIW I use Hodgdons data all the time and regularly load up to their maximums. I have often found Sierra's data to be conservative. Do what you feel is safe for your application.

 

[fdshuster]

I've seen a lot of conflicting information from different sources. Powder burn rate charts are another example. Even information from the same source: the older Lyman reloading manuals compared to the newer Lyman manuals. Velocity results taken with different chronographs, identical loads, yet another example. I have to write it off as different testing equipment, conditions, components (different lots of powder ), etc. Loads that were considered "safe" 20 years ago, may be borderline today. I always go conservative and start with the lower numbers, until I can prove otherwise. No doubt, some of the lower pressure loads are also related to the liability issue, and are lawyer mandated. Just the litigation world we live in now.

 

[plinker625]

Pretty simple you are comparing apples to oranges.

Sierra data used Federal Brass and Hodgdon data used WW brass. That is big difference!

 

[HillbillySniper]

I would tell you to stay with the sierra manuel. 50+ grains in a 308 is a lot i dont even think that much would fit in the case.

I shot 47 grains in my 308 with the 155gr Amax and even with it just off the lands it was crunching a lot. Id stay with the sierra manual as well.


Hillbilly

 

[kdvarmint]

I'm not the expert. But in my opinion, in these Lawyered up days were living in, I tend to believe manufacturers take liability in great consideration before they print charts. I don't go over the highest load printed. False sense of security? That my friends is why I start LOW and work up. Hard to have a problem you don't cause yourself that way.

 

[bheadboy]

a number of correct answeres above,,

my 2 cents worth as i have been in the Sierra crono lab a number of times
-different lots of bullets
-different chambers
-different bbl dia and throats
-different bbl lengths
-different primers, lots of powder, cases
-powder of same source 1-2 years ago will likely be different from today particulay those now made out of country vs earlier production
-look at Hod CUP on different powders same bullet etc. they vary from 46m to 50m, tell me why they dont all show 50m max?
-Sierra uses Sierra bullets Hodgded does not, different bearing surface/dia

check the threads on this sight re the differance between IMR Canada/and now.

Bob

 

[CanusLatransSnpr]

I remember one time I was loading for my .243. I looked in my Hodgdon book for the max load and then looked in my Lyman book for the max load. The Lyman book listed their max load for that particular powder and bullet weight about 3 gr. higher than Hodgdon's. I went with the Hodgdon load!

Mike

 

[watercam]

I couldn't agree more with the 'start low' group. You will be using components of your choice, not necessarily those in the manual. If you have access to a chronometer it is a good indicator of pressure. When the velocity is getting towards a manuals max. speed and you have no other pressure signs, stop or proceed carefully (.5 gr. at a time). For your 20" bbl, subtract 25 fps/inch from manuals velocities for equivalent speeds.

 

[RJinTexas]

Jim, This info taken from Quick Load ballistic program. Keep in mind that I put in the OAL @ 2.600 which is deep but will give you 0.304 bullet shank seating depth. I doubt if you'll seat you bullet this deep, just remember that a seating depth of less decreases chamber pressure where seating deeper increases it. Here's the data.

SAAMI set P-MAX (MAP) @ 60191 PSI for the .308 Win.
Sierra 125gr #2120 with OAL @ 2.600 from a 20" barrel
42.5gr IMR 4895 = 35031 PSI @ 2589 FPS (Very low pressure)
50.0gr IMR 4895 = 58801 PSI @ 3078 FPS (This is what I'd work up to as MAX LOAD if you can get it all in the case.)
51.8gr IMR 4895 = 66752 PSI @ 3197 FPS ** DANGEROUS WAY OVER PRESSURE DO NOT USE **

Note: Data corrected to show your barrel length.

RJ

 

[wapiti25]

start low and work up. Your gun will tell you when it's had enough. As stated by others, so many variables. Lot's and mfg. dates change the powders. Not to mention what country it's made in. I had a Chemist friend that told me just because you have the formula it does not mean that the result will be the same. He works in rocket propellant's.

 

[bugsplat]

start low and work up. Your gun will tell you when it's had enough. As stated by others, so many variables. Lot's and mfg. dates change the powders. Not to mention what country it's made in. I had a Chemist friend that told me just because you have the formula it does not mean that the result will be the same. He works in rocket propellant's.

+1million!

Max loads don't mean anything. Start at the lowest and work your way up watching for over pressure signs after every round. When you start getting flattened primers and sticky bolts you have reached your max load. Different brass means different volumes, means different pressure. Any time you change component you need to start over with your load tests. I have loads that are 2-3gr higher than what my manuals say. Pressure is still very low and I'm getting the FPS I want.

 

[KevinThomas]

Jim,

Both manuals are correct. Problem is, they're correct for the components being used, right down to and including the lot of powder, of bullets, cases (which as has been pointed out, are different makes) and primers. The Hodgdon data was perfectly safe in their gun, and was in fact pressure tested. So that's empirical data, not a computer projection, and it was fine. That's not to say, however, that you'll be able to reach the top load listed in anyone's given manual. You may, and you may not. All depends.

I've always said that handloaders would be better off if they'd learn to read reloading manuals as a report that essentially says, "we tried this combination, and these are the results we observed. Your milage WILL vary." You've also highlighted why I think all reloader should have a number of current reloading manuals available on their bookshelves. Perusing a number of these allows you to see the sorts of differences that can, and do, appear in the reloading process. Like the man said, start low, work up judiciously, and follow what your pressure signs are telling you. Do that, and you'll do just fine.

 

[Jim Buck]

Kevin,

This may be a dumb question. I use a variety of different powders and bullets working on the correct/accurate load.

Let's say I don't see a particular load in a sierra or hogdon manual. Lyman whoever, but I do see the same weight and powder type for another bullet weight. is it safe to use the minimum load weight to test the bullet with the powder?

 

[necchi]

That's a Million Dollar question Jim, and because of saftey concerns I don't think there is a consentious loader out there that can or will answer you with a Yes (an please don't take that as a Yes).

It's something that each loader has to learn with experiance.
Naturaly no loading manual can nor does test every powder for every bullet in every caliber, but you can see that some powders work well in a given cartridge family and in a range of bullet size.

Research beyond just the manuals at the Powder makers web sites, some places have lists of proven loads, but again, all caution to start low and work up.

I've used H4895 instead of IMR4895 one is listed a little hotter than the other, but I found a good load. I've used RL15 instead of Varget, 4064 is another very close to those 2. But each time I start low for my gun and bring it up slow. (aka: Experiance, I've put the time in to learn my gun)

Dare I say I've learned with some of my guns when using some powders starting at a listed minimum is a waste of time an powder? Simply because I know I'll never be happy with the starting load velocity BUT, I've already been there with a very close similar powder, AND I don't just jump to loading a tight spread in the middle of the pack either.

I've only been loading for a few years, and experimenting with different powder/bullet combos is still fun. But of all the stuff I've loaded,(so far) I've only found 1 that grouped well at the listed max and 1 other that groups well at 1 grain over max with no pressure signs.

Can I live with a primer that looks a little flat? Well ya, if all other issues are working well, but I know I'm beating up my brass at the same time.

 

[pgg]

Just be careful and make me some ammo... ;D