What is the difference?

[DannC]

When I purchased my Ruger PR .308 I tried a box each of four premium factory and three hunting and bulk cartridges. New to LR shooting and before I learned here on the Hide that the Federal Grand Medal Match 168 gr. SMK was "the" most accurate/consistant factory ammo it was the cartridge of choice from my testing. Found the FGMM 168 gr. on sale and bought 200 rds. [box with a picture of the case head]. Quickly shot over 160 rds zeroing new scope and got several five shot groups at about 1/2 moa with one flyer that were still 3/4 - one moa.
The same ammo went on sale again same vendor and stock photo of box and specs so I bought 400 more. Noticed the new packaging [box with image of a scoped precision rifle on a bipod]. Continued to shoot the original ammo with similar results.
On my last four range sessions I used the newer [different packaging] and am now getting five shot groups of one to two inches with the groups being dispersed at different POI. Total of 380 rds. fired and cleaned bore twice with Hoppes Ultimate. Cleaned chamber six times with CLP until dry patches were clean
Checked the specs on the back and they are Identical. The only exception is the original 200 rds [old packaging] has on one end flap "Gold Medal Match". This does not appear on the new packaging only Gold Medal SMK. I thought it was just new packaging but is there a difference in these cartridges? I actually paid $1.00 more p/box of this newer ammo. Have I been had?
Have not been to the range to test the remaining old ammo against the new.

 

[hlee]

Looking at federal’s website, the difference seems to be to distinguish between the Sierra and Berger bullet offerings. I would be highly surprised if federal messed with the SMK loading (what was originally offered as fgmm), given the popularity and success of the fgmm line of ammunition.

 

[spife7980]

Just a different lot.
My cousin zeroed his 308 with his last box of one 168 fgmm lot and it was great. 1/2 moa and 2550 fps, wanted to verify the chrono numbers for the next batch since that was the one we would actually be taking out to distance and it was 2585. Took the ms3 off and it had opened up to about 1 moa. So not as bad as yours but its still a difference and why stocking up on a good shooting lot is important.

I also told him it was exactly why handloading was so much better.

 

[Xander3Zero]

Seems hard to believe that a different lot of ammo could cause the groups to open up from 1/2-3/4" to 2". It does seem like Federal has changed the packaging with the 168 SMKs?

The 168 FGMM I used to buy always looked like this box: https://www.targetsportsusa.com/fed...ra-matchking-hollow-point-gm308m2-p-1744.aspx

But the new box looks like this? https://www.targetsportsusa.com/fed...rra-matchking-hollow-point-gm308m-p-1163.aspx

 

[Hos777]

Scope rings etc still torqued down properly?

 

[moosemeat]

I would actually check for hard carbon build up before i blamed fgmm. I've shot old box and new box in same rifle mid group and not seen any shift. 25fps is withing the es of what i got in 5 rounds on a Magneto speed after last match.

Eta- not saying it isn't or cant be ammo related. I just went through this with my rifle suddenly opening up with handloads. Checked the normal culprits and nothing loose or wonky. Was told about hard carbon and rans some Iosso through it and back to sub 1/2 moa groups. I also shoot a lot of fgmm and i have found it slightly dirty but ridiculously consistent. Ive shot it in F T/R matches and pay absolutely no attention to lots when using fgmm.

 

[DannC]

After the second range session with the new ammo I did check every bolt and screw. With a bore light where should I be looking for hard carbon buildup?
Is it time to bring out the Kroll's and Sweet's?
One thing I have not checked are the screws holding the picatiny rail [Gen2] but the scope is solid.

Thanks for the advice - DannC