168 vs 169 no load data

S

Shadow9mm

New member
So I just ordered some of the new .308 169g SMKs to play around with in my 30-06. However I can't find data for 169g bullets after looking several places. I even got the digital version of Sierra's manual and it only has data for 168g bullets.

Is it ok to use 168g data for 169s and just work it up like normal looking for pressure signs? It seems less than ideal.
 
Load data from Hornady and Nosler combine data for bullets of similar weight. Even if the bullet construction is different, for example Hornady combines 120 and 123 gr. 6.5 bullets for the widely loved 6.5 Creedmoor :D. Those weights include solid copper, A-max and SST bullets.
 
Colorado Redneck said:
Load data from Hornady and Nosler combine data for bullets of similar weight. Even if the bullet construction is different, for example Hornady combines 120 and 123 gr. 6.5 bullets for the widely loved 6.5 Creedmoor :D. Those weights include solid copper, A-max and SST bullets.
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Unfortunately hornady weight are 165-168, then 178-180. Nothing in the middle
 
if you really think 1 grain of difference will make a darn, send them to me. I will pay for the shipping. I like to live dangerous

seriously go look at Nosler and Hornady load data
 
1 grain difference in weight will make no difference because of the weight.

A difference in bearing surface area and jacket hardness MIGHT make a difference.

Contact the bullet maker.
 
Just looked at my manuals

Nosler load data for .308 Win - 165 gn to 168 gn, 7 bullets all the same powder data

Sierra load data 175 - 180 gn 5 bullets same powder data

Berger 168 gn 4 different bullets same powder data

Hornady 8 different bullets 165 - 168 gns, same powder data table

all manufacturers list several different bullets with drastically different bearing surfaces and some with up to 5 gns gns of weight difference with the same powder data table. I seriously doubt 1 gn of difference between two SMKs will make a rats patoot in pressure difference. Use the 168 starting load data like you should on any load development

Or just call Sierra Monday

Or as I said , send em to me I will gladly load and shoot
 
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It isn’t like the every single bullet weighs exactly 168.00000 gr or 169.0000 gr. The variance in bullet weights may be as much as the 1 gr difference in bullet design.

Assuming you begin with the 5%-10% reduction in max powder charge and work up, that powder difference is much greater than the difference in bullet weights. 1 gr is 0.6% of 168.

According to Sierra the 169 gr is a redesign of the 168 gr including a longer boat tail. So the heavier bullet may have LESS bearing surface and infinitesimally smaller friction and pressure fir the same powder charge.

Even in a 68 vs 69 .224” bullet I would consider the effect of 1 gr on resulting pressure to be negligible.
 
NWPilgrim said:
It isn’t like the every single bullet weighs exactly 168.00000 gr or 169.0000 gr. The variance in bullet weights may be as much as the 1 gr difference in bullet design.

Assuming you begin with the 5%-10% reduction in max powder charge and work up, that powder difference is much greater than the difference in bullet weights. 1 gr is 0.6% of 168.

According to Sierra the 169 gr is a redesign of the 168 gr including a longer boat tail. So the heavier bullet may have LESS bearing surface and infinitesimally smaller friction and pressure fir the same powder charge.

Even in a 68 vs 69 .224” bullet I would consider the effect of 1 gr on resulting pressure to be negligible.
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Inherited some stuff from Dad. One box had bullets from military pulled down ammo segregated by weight at the grain (no fraction/decimal ) level that showed a 4 grain spread from ammo in the same lot for nominal 165 grain bullets, 164 to 168 grains.
 
How long is the new 169gr SMK -- compared to the classic Sierra 168 SMK ?
That will tell us the shank seating depth, and the relative pressure difference
for the same powder loads.

~~~~~~~~~~~~~~~
OK -- Midway Q&A says Samples range from 1.3025 to 1.3040" for the 169 SMK
JBM says 1.222" for the 168gr

Since the increased length is apparently in a longer boattail vice bearing surface
-- and were "I" loading it for a 6.7% difference in length of 80-thou --
I'd call it a wash for the same OAL.





Interesting that it's not on Sierra's main website
https://www.sierrabullets.com/product-tag/matchking/?filter_diameter=0-308&query_type_diameter=or
 
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That will tell us the shank seating depth, and the relative pressure difference
for the same powder loads.
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don't forget the ogive shape. However it's probably not nearly as much as going from a 180 SMK to a 180gn RN yet Sierra uses the same powder weight table on both in their manual. Other manufactures do the same thing. Spitzers and Custom competitions on the same page, ELDX's and VMaxes, VLD's and hunting bullets.

I would bet the manufacturers lawyers make sure that they have a serious safety margin built into all data. People load for everything from a 16 inch barrel to a 30 inch barrel off the same tables.

Of course I like to live dangerously, I don't even take a calculator to the toilet to calculate the angle of the dangle when taking a whiz like my wife insists I should
 
mehavey said:
How long is the new 169gr SMK -- compared to the classic Sierra 168 SMK ?
That will tell us the shank seating depth, and the relative pressure difference
for the same powder loads.

~~~~~~~~~~~~~~~
OK -- Midway Q&A says Samples range from 1.3025 to 1.3040" for the 169 SMK
JBM says 1.222" for the 168gr

Since the increased length is apparently in a longer boattail vice bearing surface
-- and were "I" loading it for a 6.7% difference in length of 80-thou --
I'd call it a wash for the same OAL.





Interesting that it's not on Sierra's main website
https://www.sierrabullets.com/product-tag/matchking/?filter_diameter=0-308&query_type_diameter=or
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Would agree that the apparently reduced bearing surface in the 169 may offset the slight intrusion to powder space, if loaded to same COL. Chronographs can be useful items in load development.

One of the advantages of the 168 in the 308's currently loading for is the ability to getting the full dia closer to the rifling in rifles limited to max COL for magazine fit or cycling in a specific design. While the newer/longer designs may certainly have better ballistic coefficients, they may give up other values. Depending on what you want, or value more.

At least in 308, the new 169 gives up less powder space than the 168 TMK, when loaded to same max COL.
 
zeke said:
Would agree that the apparently reduced bearing surface in the 169 may offset the slight intrusion to powder space, if loaded to same COL. Chronographs can be useful items in load development.
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Always chrono during workup

One of the advantages of the 168 in the 308's currently loading for is the ability to getting the full dia closer to the rifling in rifles limited to max COL for magazine fit or cycling in a specific design. While the newer/longer designs may certainly have better ballistic coefficients, they may give up other values. Depending on what you want, or value more.
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COL will be determined by the distance off the lands. magazine length it not an issue, the TC compass magazine has TONS of room. Only limiting factor is the short throat in the rifle

At least in 308, the new 169 gives up less powder space than the 168 TMK, when loaded to same max COL.
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Never was a fan of the tipped bullets. I know in certain applications they can be beneficial, however, not particularly for my uses.
 
Good, let us know how they work out? Am using the 168 TMK's in a rifle that allows them to be loaded out past max. Noticeable difference in how they carry compared to 168 HPBT at 600 yds.
 
zeke said:
Good, let us know how they work out? Am using the 168 TMK's in a rifle that allows them to be loaded out past max. Noticeable difference in how they carry compared to 168 HPBT at 600 yds.
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Will do. Only have out to 500 here to play with, and that is a 2hr drive. Hoping to get out to my buddies in OK this year to shoot out to 1000.

Based on what was stated for these bullets they just looked really good for my needs.
 
I ordered 500 of these to play with, too. We'll see what we get. In 30-06, the difference in powder space intrusion by the longer, lower angle boattail as a percentage of the total case volume should be small enough to ignore, especially if you can't seat out far enough to meet the chamber's throat. In a compressed load in the .308 in a short neck and freebore tight match chamber, as the Palma Match reamers make, I would look a little more carefully.

These bullets are most likely intended to address the dynamic instability in the original 168-grain design that tends to cause it to tumble out beyond 700 yards when fired from a 10" twist, especially in windy conditions. The 169's 9° boattail versus the 168's 13° boattail should fix that. The closed point should improve ballistic coefficient consistency a tiny bit and eliminate the need for meplat trimming and pointing dies. The ogive is tangent rather than secant like the TMK, so it should be more forgiving of concentricity errors. Overall, an interesting looking design I am looking forward to experimenting with.
 
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