Surprised @ difference between Siera & Hodgdon loads for 168 SMK

[Steve Ladino]

Starting to load some 308 Win with 168 SMK's using H4895. COAL for both is 2.800. The difference is very high.

Sierra range is 38.2 to 41.3 (max)
Hodgdon range is 41.0 to 43.5 (max)

Almost No overlap at all. Can that be right?

This Sierra loading looks like charge weights for the M 1-A

 

[fatelvis]

So is the consensus that Sierra posts milder loads in general?

 

[SPQR70AD]

I see most new manuals come out the loads are getting lighter even with better powder that gets more velocity even with the new powders they barely match standard loads from 35 years ago. only when the launch a new round like the 6.5 Screech Moor do they juice up the load for it.

 

[dolek]

I see most new manuals come out the loads are getting lighter even with better powder that gets more velocity even with the new powders they barely match standard loads from 35 years ago. only when the launch a new round like the 6.5 Screech Moor do they juice up the load for it.

What load books from 35 years ago and what books of today are you referencing , and what calibers do you speak of. I am looking at books from the 60s and 70s today and do not see what you are claiming . My older books are Nosler,Lyman,Speer,Hornady, Sierra,etc . . Today i am mostly crossing loads for the 25-06 ,257 Roberts, and 257 AI .

 

[SPQR70AD]

I had a speer manual from the early 80's that I threw away cause the pages were falling out that had a 30-06 load 150 gr bullet at 3100 FPS I think with 4064 powder. I cant remember that many from there but that one stuck in my mind. I have a nosler manual from 2002 that has a 175 gr bullet from a 280 rem going 2819 FPS. a 220 grain bullet from a 30-06 at 2615 FPS 180 grain bullet for the 06 at 2880 FPS all with 24" barrels. it has a load for a 30-06 AI 180 grain bullet at 2985 FPS 24"barrel. those loads are not with super performance powder or any of the new powders

 

[Zero333]

Hodgdon's 308win data uses WINCHESTER brass.

Sierra's data uses FEDERAL brass.

I just spent a better part of 1 hour weight sorting and comparing H20 capacities between Federal and Winchester 308win brass I have that was shot in the same chamber.

Long story short... MY Winchester 308win brass has on Average 2.5 gr more H20 capacity than the Federal 308win brass.

Also very interesting how my Winchester 308win brass came from all over the place, and varied a HUGE amount in weight, and it's weight indeed correlated to it's H20 Capacity !!! On Average, the Heaviest brass (around 164.6 gr with primer) had less H20 Capacity than the Lightest (156.2 gr) by about 0.3 gr.

The Federal brass was all from the same lot of FGMM loaded ammo and varied less than 2.5 gr from lightest to heaviest.

That explains part of the reason why Hodgdon's MAX is 2.2 gr higher.

Remember these are Fire formed in the same chamber and have not been resized.


Winchester fireformed average was 57.8 gr.
Federal fireformed average was 55.3 gr.

 

[Brians356]

Notice Hodgdon posts data for two different 168-gr bullets, a Barnes TTSX and a Sierra HPBT (not the SMK.) The data are quite different between the two bullets, the TTSX being lower charge range 39.0 - 43.0. Sure, the solid bullet is quite different from the jacketed bullet, but still it illustrates how different bullets can be. Hodgdon does not publish for the 168 SMK so I would start with the Sierra data and work up.

If you think Hodgdon's data run hot today, dig out their older manuals; some loads run even hotter.
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[Linko]

I was loading F.C. brass. So my takeaway is the Hodgdon data would be too hot.

I loaded the 168 SMK HPBT starting at the Sierra low end of 37.9 in .2 increments, up thru the Hodgdon 43.3

The lower sierra loads has the best groups.

 

[Linko]

By the way how does the F.C brass volume compare to the Lapua or Starlight

 

[chapstix97]

FWIW This past September I loaded 175 smk with reloder 15 with FGMM and large primer Lapua brass. The fgmm brass took .5 grain less rl15 than the Lapua large primer brass to get same velocity. I didn’t load 175 smk with Small primer Lapua brass , but past experience it has more volume than the large primer Lapua brass

 

[oley55]

Hodgdon's 308win data uses WINCHESTER brass.

Sierra's data uses FEDERAL brass.

I just spent a better part of 1 hour weight sorting and comparing H20 capacities between Federal and Winchester 308win brass I have that was shot in the same chamber.

Long story short... MY Winchester 308win brass has on Average 2.5 gr more H20 capacity than the Federal 308win brass.

That explains part of the reason why Hodgdon's MAX is 2.2 gr higher.

I edited out some info in the quote above to zero in on my point. Hope that doesn't skew understanding.

Bold text versus red text, are we assuming powder by volume is roughly equal in weight to that of water by volume? I am not at all sure I am comfortable with that assumption. Or am I misunderstanding something?

 

[Laurie]

are we assuming powder by volume is roughly equal in weight to that of water by volume? I am not at all sure I am comfortable with that assumption. Or am I misunderstanding something?

The issue here is combustion chamber volume of the obturated case at approaching full pressures shortly after ignition. Heavier brass usually (not invariably) produces a lower internal capacity / combustion chamber which all other things being equal (bore size; bullet weight/model; primer model; COAL; powder grade and lot) will produce higher pressures for a given weight of powder.

Here are 308 Win QuickLOAD results based on an F/TR rifle I used to own between Lapua and Winchester brass. Winchester cases held 57.0gn water (unsized fireformed case from that rifle filled level with the mouth) and Lapua fired in the same chamber held 56.1gn. The old 1980s era thin-wall 160gn weight Norma brass held even more than Winchester at 57.4gn. (Note modern Norma is 20 odd grains heavier and holds less than I quote here.)

With Hodgdon's maximum of 43.5gn H4895 for Winchster brass, QL calculates (24-inch barrel for MV):

Old Norma (57.4 H2O) ........... 53,505 psi ............. 2,701 fps

Winchester (57.0 H2O) ........... 54,342 psi ............ 2,709 fps

Lapua (56.1 H2O) .................. 56,334 psi ............ 2,728 fps

IME, experience Federal 308 cases are at least as heavy as / have similar capacity to Lapua, usually slightly heavier / lower capacity.

These QuickLOAD calculations may or may not be accurate (although the Winchester brass model is within 6 fps of the Hodgdon result), the more important thing is the effect of changing brass between high and low capacity examples. There is more than enough change to see a combination that produces maximum pressure in one set be a few thousand psi over maximum in another, certainly enough to produce primer leaks, blown primers, hard extraction, instant case scrapping or worse.

This is yet another reason for load compilers / publishers to often reduce their safe tested maximum charge a bit. They know that no matter how often they put warning notices on the data stating clearly that maximum loads apply only to those listed components, they know full well that some fool will change case, bullet and primer makes and go straight into testing with the printed maximum, then try and sue if it all works out badly on the day they shoot the resulting cartridges.

 

[Uncle Ed]

If you look in your reloading manuals and a specific firearm is listed for testing then a strain gauge is glued to the barrel to measure chamber pressure. When a strain gauge is used a cartridge of a known chamber pressure is test fired to check the calibration.

In the Lyman reloading manual, you will see loads tested with a universal receiver and pressure test barrel that has a chamber and bore at minimum SAAMI dimensions. The pressure will be tested with a copper crusher or piezoelectric transducer and are direct pressure readings.

Then you add all the variations in reloading components, bullets, cases, primers etc. and you will see variations in the reloading data.

One of the first things you need to do using Quick Load is to get the case capacity of a case fired in your rifle. Then you use a chronograph and change the burn rate until the Quickload velocity matches the chronograph. After all this you have the "ball park" chamber pressure for your rifle.

My Savage .223 with a 1in9 twist has a longer throat than my AR15 rifles, and most load data you see is for short throated .223 rifles with a 1in12 or 1in14 twist. Meaning my Savage .223 can be loaded warmer than most manuals.

Below look at the variations in freebore length "N" and freebore diameter "G" and you will see why the reloading data can vary. And this is just chamber throat variations and we haven't included variations in reloading components, bullets, cases, primers etc.

Below is a custom hand lapped barrel and the bottom photo is a new button rifled Savage barrel. And I always wondered how much difference in chamber pressure would be between these two barrels.

 

[fatelvis]

If you look in your reloading manuals and a specific firearm is listed for testing then a strain gauge is glued to the barrel to measure chamber pressure. When a strain gauge is used a cartridge of a known chamber pressure is test fired to check the calibration.

In the Lyman reloading manual, you will see loads tested with a universal receiver and pressure test barrel that has a chamber and bore at minimum SAAMI dimensions. The pressure will be tested with a copper crusher or piezoelectric transducer and are direct pressure readings.

Then you add all the variations in reloading components, bullets, cases, primers etc. and you will see variations in the reloading data.

One of the first things you need to do using Quick Load is to get the case capacity of a case fired in your rifle. Then you use a chronograph and change the burn rate until the Quickload velocity matches the chronograph. After all this you have the "ball park" chamber pressure for your rifle.

My Savage .223 with a 1in9 twist has a longer throat than my AR15 rifles, and most load data you see is for short throated .223 rifles with a 1in12 or 1in14 twist. Meaning my Savage .223 can be loaded warmer than most manuals.

Below look at the variations in freebore length "N" and freebore diameter "G" and you will see why the reloading data can vary. And this is just chamber throat variations and we haven't included variations in reloading components, bullets, cases, primers etc.

Below is a custom hand lapped barrel and the bottom photo is a new button rifled Savage barrel. And I always wondered how much difference in chamber pressure would be between these two barrels.

Wow! What a difference!

 

[Linko]

Notice Hodgdon posts data for two different 168-gr bullets, a Barnes TTSX and a Sierra HPBT (not the SMK.) The data are quite different between the two bullets, the TTSX being lower charge range 39.0 - 43.0. Sure, the solid bullet is quite different from the jacketed bullet, but still it illustrates how different bullets can be. Hodgdon does not publish for the 168 SMK so I would start with the Sierra data and work up.

If you think Hodgdon's data run hot today, dig out their older manuals; some loads run even hotter.
-

Sierra doesn't list a 168 gr other than TMK & Matchking. At least that I can see/ I have #2200 which is labeled as HPBT Matchking

 

[Linko]

The issue here is combustion chamber volume of the obturated case at approaching full pressures shortly after ignition. Heavier brass usually (not invariably) produces a lower internal capacity / combustion chamber which all other things being equal (bore size; bullet weight/model; primer model; COAL; powder grade and lot) will produce higher pressures for a given weight of powder.

Here are 308 Win QuickLOAD results based on an F/TR rifle I used to own between Lapua and Winchester brass. Winchester cases held 57.0gn water (unsized fireformed case from that rifle filled level with the mouth) and Lapua fired in the same chamber held 56.1gn. The old 1980s era thin-wall 160gn weight Norma brass held even more than Winchester at 57.4gn. (Note modern Norma is 20 odd grains heavier and holds less than I quote here.)

With Hodgdon's maximum of 43.5gn H4895 for Winchster brass, QL calculates (24-inch barrel for MV):

Old Norma (57.4 H2O) ........... 53,505 psi ............. 2,701 fps

Winchester (57.0 H2O) ........... 54,342 psi ............ 2,709 fps

Lapua (56.1 H2O) .................. 56,334 psi ............ 2,728 fps

IME, experience Federal 308 cases are at least as heavy as / have similar capacity to Lapua, usually slightly heavier / lower capacity.

These QuickLOAD calculations may or may not be accurate (although the Winchester brass model is within 6 fps of the Hodgdon result), the more important thing is the effect of changing brass between high and low capacity examples. There is more than enough change to see a combination that produces maximum pressure in one set be a few thousand psi over maximum in another, certainly enough to produce primer leaks, blown primers, hard extraction, instant case scrapping or worse.

This is yet another reason for load compilers / publishers to often reduce their safe tested maximum charge a bit. They know that no matter how often they put warning notices on the data stating clearly that maximum loads apply only to those listed components, they know full well that some fool will change case, bullet and primer makes and go straight into testing with the printed maximum, then try and sue if it all works out badly on the day they shoot the resulting cartridges.

Thank you for this info.

Despite having an inexpensive Howa magazine fed barreled action (2.80 coal), attempting to use mixed range brass, appears to be a fools errand. Thought I would be cheap with this rifle. That looks to be a waste of time, and could be dangerous if loading close to max. I would be much better off with just one brand of brass.

Question. Short of $$$ Lapua is there a brand of brass less expensive that has proven to be a good choice?

 

[Rsadams]

Thank you for this info.

Despite having an inexpensive magazine fed barreled action, attempting to use mixed range brass, appears to be a fools errand. Thought I would be cheap with this rifle. That looks to be a waste of time. I would be much better off with just one brand of brass.

Question. Short of $$$ Lapua is there a brand of brass less expensive that has proven to be a good choice?

Since I am thinking this is not an all out benchrest gun , any brass as long as it's one head stamped will be fine.... Take a look at the Sig brass if available for your caliber.... If not just buy a box of your choice of flavor , shoot it and reload etc.... Remington or Federal wouldn't be bad really....

 

[Laurie]

I would be much better off with just one brand of brass.

Despite the cost, it's always best to start with new brass and once you have loads you're happy with stick to it. Most makes are good nowadays, but you may well get the extra outlay back and a bit more by buying Lapua (and maybe Peterson which looks to be as good) cases as you'll likely get more firings out of them.

Winchester was long reckoned to be good for the price bar a few damaged examples in most baggies. However, there is widespread dissatisfaction becoming evident these days from formerly happy purchasers thanks to the number of 'issues' with recent production lots, principally poorly punched flash-holes - not properly centred, variable and over-sizing, and often misshapen / not properly round.

If you buy a quality make use straight out of the box is nearly possible - just chamfer the mouth inside (and in the case of Lapua which frequently has very tight necks from the factory, run cases over an expander ball or mandrel before priming and charging. Many of the cheaper makes have flash-holes though that are roughly punched leaving metal spikes (is there a proper technical term for such?) on the outlet side of the holes inside cases. A noticeable improvement can often be seen through use of a simple flash-hole debur / uniform hand tool - once-only job. All tool suppliers offer them these days - I use an ancient wood handle Lyman tool I've had for maybe 25 years.

If you get into custom built rifles for bench or long-range precision shooting, you'll learn there is brass and brass and usually a single, sometimes couple, of must-choose makes and that can just be a starting point for further modification / preparation. As you're on the AS Forum with 650 posts in, I'm sure you've already noticed the near tribal loyalty often exhibited for one case make or another though amongst top precision shooters.

 

[Laurie]

Adding to my last post, here's a photo from 2012 of the chips I removed from the flash-holes in some early production Hornady 6.5mm Creedmoor cases with a debur tool. These cases gained a reputation back then in the cartridge's early days as having rather 'soft' case-heads and being of shall we say variable quality.

Note the two large spirals where much of the punched-out metal remained attached to the the flash-hole rim partially obstructing it. They would have had a major effect on cartridge performance consistency. These are the worst examples I've personally seen, but illustrate the concept rather neatly.

 

[Brians356]

Despite the cost, it's always best to start with new brass and once you have loads you're happy with stick to it. Most makes are good nowadays, but you may well get the extra outlay back and a bit more by buying Lapua (and maybe Peterson which looks to be as good) cases as you'll likely get more firings out of them.

Winchester was long reckoned to be good for the price bar a few damaged examples in most baggies. However, there is widespread dissatisfaction becoming evident these days from formerly happy purchasers thanks to the number of 'issues' with recent production lots, principally poorly punched flash-holes - not properly centred, variable and over-sizing, and often misshapen / not properly round.

If you buy a quality make use straight out of the box is nearly possible - just chamfer the mouth inside (and in the case of Lapua which frequently has very tight necks from the factory, run cases over an expander ball or mandrel before priming and charging. Many of the cheaper makes have flash-holes though that are roughly punched leaving metal spikes (is there a proper technical term for such?) on the outlet side of the holes inside cases. A noticeable improvement can often be seen through use of a simple flash-hole debur / uniform hand tool - once-only job. All tool suppliers offer them these days - I use an ancient wood handle Lyman tool I've had for maybe 25 years.

If you get into custom built rifles for bench or long-range precision shooting, you'll learn there is brass and brass and usually a single, sometimes couple, of must-choose makes and that can just be a starting point for further modification / preparation. As you're on the AS Forum with 650 posts in, I'm sure you've already noticed the near tribal loyalty often exhibited for one case make or another though amongst top precision shooters.

One advantage of having a Cabellas store nearby: I bought two bags of 50 Hornady 6mm Rem cases, opened them, and chose the 50 best cases out of the hundred. Some were grossly malformed, others only dented or had striated necks/shoulders. I took the 50 culls back to Cabellas in on opened bag and got a full no-questions-asked refund there and then - no shipping anything back to an online source. This is a viable approach to buying economy brass, not a substitute for premium stuff if you demand better consistency in case walls, flash holes, primer pockets, weight etc.
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