Confused

Reloading a .308Win with 150g Hornady Interlock ST and Hodgdon Varget.
The hornady manual states 35.9g to 44.9g of varget powder.
The Hodgdon datasheet for a 150g BT bullet 44.0g to 47g.
while the Interlock bullet is not a BT I am surprised at the weight of powder difference. This is not the first time I have found discrepancies between the powder manufacturers datasheet and the bullet manufacturers.
Which is correct? Can anyone shed some light on this?
Thanks
 

Muir

Well-Known Member
There is always a discrepancy. Powder manufacturer first. Hornady's loads are becoming more generic. If you notice, for 150 grain 308 loads they list 10 bullets comprising two weights (150 and 155). It simplifies their work but leaves a lot to be desired in the performance arena.~Muir
 

Rider

Well-Known Member
I also use Varget a lot in the .308 with varying bullet weights and designs. 35.9 grs is nowhere near a sensible starting load. Go with the Hodgdon recommendation.
 

Sako308

Well-Known Member
I had recently discussed this on here with RL15 powder and .308 150gr bullets. Lots of variation between min and max loads in various different manuals. Max loads varying between 44.8gr (Sierra), 46.0gr (Nosler) to 49.0gr (Alliant). The advice was to use these figures as a guide, start low, work up carefully, keep checking for pressure signs. This should enable you to safely tailor a load for the components you have used and your particular rifle.
 
Thank you all for taking the time to reply. I will stick to the powder manufacturers recommendation. Muir, I did notice the number of heads and weights Hornady list for one load which I did wonder why. Sako the advice on starting low is very good, thanks.
 

straightpull6547

Well-Known Member
I’d just load 46gn and get shooting, that has worked in every .308 i’ve loaded for. Work up if you wish but 46 will work and its a lot less than the proof load. Tweak length to tighten groups..
 

Rider

Well-Known Member
I’d just load 46gn and get shooting, that has worked in every .308 i’ve loaded for. Work up if you wish but 46 will work and its a lot less than the proof load. Tweak length to tighten groups..
Never follow such advice without working up a load!!!

I just started on a new batch of Varget and had to reduce a previous load of 47 grs. by 1 gr. (just an example of one specific load).
 

srvet

Well-Known Member
why? Has 46gn of varget ever been unsafe in any .308 with a 150gn bullet???

nope..its a safe starting load.
It may be safe in your rifle but not in someone else’s. These cases were loaded to the exact specification of a factory round including bullet, case, powder, primer and bullet seating depth. Each charge was weighed exactly but the pressure in my rifle was clearly excessive as the primers dropped out! I will never again just follow a recipe!!

71BD763B-3CB2-42EF-A65B-3637DB7F36C6.jpeg
 

Milligan

Well-Known Member
why? Has 46gn of varget ever been unsafe in any .308 with a 150gn bullet???

nope..its a safe starting load.
what's your sample size and insurance cover?
Not as big as the powder company I wager.
small differences in chamber, barrel, OAL and capacity can make the difference between safe and lethal.
 

kenbro

Well-Known Member
It may be safe in your rifle but not in someone else’s. These cases were loaded to the exact specification of a factory round including bullet, case, powder, primer and bullet seating depth. Each charge was weighed exactly but the pressure in my rifle was clearly excessive as the primers dropped out! I will never again just follow a recipe!!

View attachment 93773
Hi, just curious to know how you can load to exact factory specs?
No way of telling which powder is in factory ammo, and very doubtful you could buy any.
Regrads,Ken.
 

dodgyknees

Well-Known Member
I sometimes wonder how many young fellas read this stuff, inexperienced, a bit impatient, impetuous, working with old range brass and no reloading manual. There's that many YouTube reloading disasters out there showing over pressures, squib loads, exploding actions, bolts blown back into faces and eyes, fingers shredded.

Gives me the creeps to think that people think its ok to promote a "safe starting load" that's close to the top of the powder manufacturer's published range. Internet forum "advice" like this sucks. Its just deliberately provocative and needs to be stamped on.
 

srvet

Well-Known Member
I was given the spec in writing from the manufacturer and it was a commercially available powder
 

Laurie

Well-Known Member
The other factor nobody has mentioned is case make and capacity. There is a fair variation in case capacities and that in turn affects pressures. In 308 for instance, there is a grain weight difference between a safe H. VarGet maximum charge in Lapua and Winchester brass give or take a smidgen.

Throw in a noticeable pressure difference between the very 'hot' Rem 9 1/2 standard primer and a mild example such as the S&B or Russian PMC/Murom and you've now potentially got a 1.2-1.5 difference in maximum loads from these two factors combined.

And ..... 150gn bullets are not necessarily the same across all makes. Jacket hardness and thickness, variations in lead core alloys can change the amount of resistance or inertia two identical weight and dimension bullets produce on being forced into the rifling. More inertia means slower 'engraving' and also potentially greater resistance once in the lands/grooves. Time in this context = pressure. Once it starts to burn, the charge produces gas in accelerating quantities multiplied by elapsed time from ignition, and the only thing that stops the resulting chamber pressure going past the red line is forward bullet movement into and down the barrel which increases the volume of the combustion chamber.

Also, gas production v time is not linear - ie we don't see X cc gas produced by Y gn of powder Z per millisecond, as powder combustion 'feeds on itself'. If something slows the bullet movement / combustion chamber volume increase thereby producing higher pressures early in the burn, the rate of burning of the powder charge and hence gas production also increases as a result of the higher pressure environment. This creates yet more gas, yet higher pressure, and a yet higher combustion rate creating a potentially dangerous positive loop.

And that's before we take into account bearing surface length.

Taking a selection of 150/155gn bullets they range over:

155gn Sierra MatchKing (#2156) ........0.254"
150gn Sierra GameKing ................... 0.255"

155gn Sierra TMK ........................... 0.260"

150gn Lapua FMJBT ........................ 0.270"
150gn Sierra MatchKing ................... 0.271"
155gn Sierra MatchKing (#2155) ...... 0.273"
150gn Hornady SST Savage ............. 0.279"

155gn Hornady HPBT Match ............. 0.289"

155gn Nosler Custom Competition ... 0.290"
155.5gn Berger BT Fullbore ............. 0.293"

155gn Berger Classic Hunter ........... 0.326"

155gn Berger Hunting VLD .............. 0.337"

150gn Hornady BTSP ...................... 0.351"
150gn Hornady FMJBT ..................... 0.355"
155gn Hornady ELD-M .................... 0.357"
155gn Berger Target VLD ................ 0.359"

155gn Hornady AMax ...................... 0.376"

150gn Hornady SST BT ................... 0.382"

150gn Nosler Ball Tip ..................... 0.391"

155gn Hornady TAP ....................... 0.403"
150 Berger Target Flat Base ........... 0.408"

That's a 60% variation between the shortest and longest bearing surface lengths which will change the amount of bullet to barrel friction and hence pressure build-up markedly. FWIW, Hornady bullets tend to be at the longer end of the list and when I've used the old 155gn AMax in load development testing, I'd always found it would produce pressure signs earlier than equivalent Bergers or Sierras, so much so that I'd use a full grain less powder as my initial top charge.


AND !!!! ............... all this is before we get into individual rifles' freebores as they leave the factory, some makes (in particular Remington 308 Win 700s) now notorious for huge jumps into the rifling. At least that should be a constant in the powder and bullet companies' ballistics lab testing as they will use SAAMI standard dimension barrels - but that doesn't stop it being a major issue as between two individual rifles from different makes or between factory and custom.
 

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