.308 168 gr. TMK's Problem

[Sargesniper]

Having a problem with these bullets. Loaded the same loads as I normally do with the SMK's. I get a sticky bolt lift and opening the bolt. Could someone with a manual showing these bullets give me the Sierra OAL? Wondering if they are as sensitive as the Bergers are. My Sierra Manual is the 5th. Edition (pre TMK's ) These may not even be listed yet so I may have to Call Sierra after the Thanksgiving Holiday. Thanks

 

[Sargesniper]

Having a problem with these bullets. Loaded the same loads as I normally do with the SMK's. I get a sticky bolt lift and opening the bolt. Could someone with a manual showing these bullets give me the Sierra OAL? Wondering if they are as sensitive as the Bergers are. My Sierra Manual is the 5th. Edition (pre TMK's ) These may not even be listed yet so I may have to Call Sierra after the Thanksgiving Holiday. Thanks

Guess I'll have to make a phone call.

 

[Darkker]

Why don't you just make a dummy cartridge and measure the jam length yourself???

 

[Sargesniper]

Why don't you just make a dummy cartridge and measure the jam length yourself???

I want the Sierra recommended length. This is why I asked in the first place or did you not read my post?

 

[Darkker]

I did. It struck me as though you were looking for "the" answer of how to load them accurately in your rifle. Thus my question to you about it.

 

[venatic]

I have two .308's that shoot the 175gr tipped with a .050 jump very well. So my experience is they are not too sensitive to seating depth.
I shot both seated to lands but due to mag restrictions on one rifle I tried both seated shorter and they shot just as well if not better.

 

[cwall64]

So I emailed Sierra on the .224 SMK vs TMK as the were not in the latest manual and I got a response, but not before I found the Sierra blog - https://sierrabullets.wordpress.com/2015/06/22/do-you-have-load-data-for/.

Here is email response:

Hi Chris,
Yes, both styles of 77s use the same powder charges. You may need to adjust your COAL to accommodate the longer #7177 which could necessitate a slight reduction in powder of a 1/2 grain or so.
Otherwise the SMK and TMK use the same data. - Rich Rich Machholz
Ballistic Technician NRA Endowment Member
1400 W. Henry St. Sedalia, MO 65301
Questions? Call us toll free 800-223-8799

Check out my latest blog post at sierrabullets.wordpress.com.

 

[Sargesniper]

I have two .308's that shoot the 175gr tipped with a .050 jump very well. So my experience is they are not too sensitive to seating depth.
I shot both seated to lands but due to mag restrictions on one rifle I tried both seated shorter and they shot just as well if not better.

Are you using all the same components and weight and just changing the bullet? I changed only the bullet and had a problem. That is why I asked about the Sierra manual.

 

[venatic]

I used same load as before with standard MK..... Just changed OAL

 

[Michael Eichele]

Did you change anything else at all?

New lot of powder, new lot of or different primers, new lot of or different cases, etc.

Are the necks trimmed properly?

TMKs have a shorter bearing surface than their SMK counterparts and should offer less pressure with everything else being equal.

I have found that the 155s and the 175s are not sensitive to jump or jam and that they are extremely easy to tune.

Charge weights for the 175 SMK seem to work with the 175 TMK. At least in my rifle.

The typical SAMMI spec COAL for the 168 in 308 is 2.800". I'm sure that's what any loading manual in the future will read.

If the SMK and TMK are loaded to the exact same COAL, the TMK will have more jump to the lands. The SMK will have less jump.

 

[Sargesniper]

Did you change anything else at all?

New lot of powder, new lot of or different primers, new lot of or different cases, etc.

Are the necks trimmed properly?

TMKs have a shorter bearing surface than their SMK counterparts and should offer less pressure with everything else being equal.

I have found that the 155s and the 175s are not sensitive to jump or jam and that they are extremely easy to tune.

Charge weights for the 175 SMK seem to work with the 175 TMK. At least in my rifle.

The typical SAMMI spec COAL for the 168 in 308 is 2.800". I'm sure that's what any loading manual in the future will read.

If the SMK and TMK are loaded to the exact same COAL, the TMK will have more jump to the lands. The SMK will have less jump.

Everything was same except for the bullet. I should not have the problem. Just trying to figure it out. Here is what was loaded; 168 gr TMK--- 41.5 gr. IMR-8208xbr--- Russian Primer --- IMI Match Case --- CBTO ---2.323. This load shoots with no problems using the SMK. I broke down the remaining 3 to check all weights on bullets and powder. No mistake was made in their measurements. Cases will be full length sized and trimmed before I reload this combo again to see if this will settle the issue. This one has me scratching my head. No reason for it to do what it did.

I have a large number of the 168 and 175's to use so I will have to figure it out.

 

[DMP25-06]

To Sargesniper ,
I was shooting the 175 gr SMK bullets in my rifle when the new Tipped Match King bullets came out last year . Of course I wanted them as they listed a higher BC than the previous SMK , so I ordered 500 from O.K.Weber .
Before loading them , I first contacted Sierra Bullets customer service , and asked if these new TMK bullets would be a direct substitution for reloading in place of the SMK . The gentleman at Sierra said that the new TMK bullets had more of a secant ogive profile than the SMK bullets , were slightly longer overall , and therefore , if using the same seating die , the overall cartridge length would be slightly longer than that of a cartridge loaded with the SMK bullet , and that in their testing the TMK would shoot nearly the same as the SMK bullet had before .
He said that if I were to seat the TMK deeper , to make the overall length the same as the cartridge loaded with the SMK , then it would increase the pressure , due to reduced case volume .
I loaded mine to the longer length , used them single-shot in an F-TR match , and they shot just as accurately , with less elevation adjustment than the SMK , and no discernible difference in pressure , at the same velocity .
Just my personal experience .
DMP25-06

 

[Sargesniper]

To Sargesniper ,
I was shooting the 175 gr SMK bullets in my rifle when the new Tipped Match King bullets came out last year . Of course I wanted them as they listed a higher BC than the previous SMK , so I ordered 500 from O.K.Weber .
Before loading them , I first contacted Sierra Bullets customer service , and asked if these new TMK bullets would be a direct substitution for reloading in place of the SMK . The gentleman at Sierra said that the new TMK bullets had more of a secant ogive profile than the SMK bullets , were slightly longer overall , and therefore , if using the same seating die , the overall cartridge length would be slightly longer than that of a cartridge loaded with the SMK bullet , and that in their testing the TMK would shoot nearly the same as the SMK bullet had before .
He said that if I were to seat the TMK deeper , to make the overall length the same as the cartridge loaded with the SMK , then it would increase the pressure , due to reduced case volume .
I loaded mine to the longer length , used them single-shot in an F-TR match , and they shot just as accurately , with less elevation adjustment than the SMK , and no discernible difference in pressure , at the same velocity .
Just my personal experience .
DMP25-06

I don't see how loading further away from the lands is going to increase pressure as you will have more jump to the lands but I will not argue what an expert in ballistics says. My load was not max. to start with. I shoot the SMK's with this load regular and no issues at all. If anything I would say they may be too close to the lands. I am going to load this same load again with the bullet seated deeper in the case. May be something to do with it, I don't know at this point. Only way to tell is try.

 

[venatic]

5 Shots at 100