308 168 fgmm load change?

[iukamedic]

I have a Remington 1-10 twist 5r that I’ve been working on loads for. This thing shoots about everything I have put in it at 1moa and less at 100 yards (after I changed the trigger). This varies at farther ranges. I have shot it with a slick barrel, with a brake, and suppressed. It actually shoots the best with a suppressor over a quick attached break instead of direct thread. I have shot a few .3 but most seem to land around 3/4 moa 5 shot groups. I picked up a box of federal gold medal match 168. With the exception of a slightly higher cold bore the next 9 shots landed in a .85 group. I pulled one of the bullets and found 40.7 grains of extruded powder. The powder is about half the size of varget. I’ve read that the clone load includes 42.5 of imr 4064. So my question is has the load for fgmm changed? When I look at the data from Sierra looks like there are a few powders that might fall In small range.

 

[Straightshooter1]

I have a Remington 1-10 twist 5r that I’ve been working on loads for. This thing shoots about everything I have put in it at 1moa and less at 100 yards (after I changed the trigger). This varies at farther ranges. I have shot it with a slick barrel, with a brake, and suppressed. It actually shoots the best with a suppressor over a quick attached break instead of direct thread. I have shot a few .3 but most seem to land around 3/4 moa 5 shot groups. I picked up a box of federal gold medal match 168. With the exception of a slightly higher cold bore the next 9 shots landed in a .85 group. I pulled one of the bullets and found 40.7 grains of extruded powder. The powder is about half the size of varget. I’ve read that the clone load includes 42.5 of imr 4064. So my question is has the load for fgmm changed? When I look at the data from Sierra looks like there are a few powders that might fall In small range.

I had heard on more than one occasion that Federal was using AR-Comp (or if not, something very much like it). I've been using AR-Comp for a few years now and that 40.7 grains you found is right in line with what I use in AR-Comp for my 168 SMK's (like I typically load my 168's with 40.5 AR-Comp).

 

[iukamedic]

Straightshooter1 thanks for the reply. About everything that I thought was about that weight was bigger extruded except h4895 and it is a unicorn. I don’t know that I have ever looked at arcomp.

 

[Jeff Porter]

Jeff - I have seen what looked like Re-15 in GMM too. Is it gray black or gold tone in your example ?

 

[iukamedic]

Jeff it has a darker appearance than varget but is small kinda similar to br 8208. At the price of the gold medal match with the rebate it’s about as cheap to just by ammo. It shot really good in that particular rifle.

 

[Doom]

Prior to what seems to be the current loading for FGMM 168 the load was assessed to be IMR 4064 around 43 gr. Deconstructs showed from 42.8 to 43.2 as I recall. When the packaging change to the current the load dropped to just under 41 gr and the powder was suspected to be AR-Comp which was new at the time. It was not a ADI or IMR powder. It is also not RL15.

 

[iukamedic]

I have been told that most rounds produced commercially are a mixture of powders. That powder all looked the same when I poured it out. It sure shoots good in factory configuration. I’ll see if can find ar comp. Bad thing about new powders is that you can end up with more in a round than you could have bought them for. I don’t know if a new reloaded just starting can ever break even now. I was fortunate to start way before when primers were cheap and powder was 25 ish a pound. I think my Dillon press and all the goodies was less than 5. Anyway thank y’all for the answers.

 

[Jeff Porter]

8208 pull down is darker small kernels too.

 

[D-4297]

If my failing memory serves ; the "original" load for that round was 42.5gr of IMR 4064 , with their "gold" primer , that is not available to us civilians . Half grain less powder if using a Lapua case .

 

[Jager]

I'd be surprised if Federal was using a canister powder in their commercial factory ammunition.

 

[jk80]

Jager brings up a good point. It could be anything or a blend to obtain the pressure and velocity perimeters they're looking for.

 

[Doom]

Like a good whiskey most all powders are a blend of batches of a given formulation or a blend of different formulations to meet a specific requirement. Improvements in instrumentation and control systems over the last 40 years have vastly improved the consistency of batch processes such as powder manufacture. I don't have direct knowledge of powder manufacturer but the following description reflects what I have been able to put together from various sources. The concept of canister powder is different than bulk powders based on how it is used. Canister grade powder is an off the shelf item that will be used and will depend on a somewhat standard specification, in this case loading data, that will work for all lots. Bulk powder in large shipments that will be used in ammunition manufacturer will likely be tested before use to insure it will meet the ammunition specification (Velocity) and the SAAMI requirements. Canister graded powders such as the Valleyfield IMR powders are likely the same powder as general production powders but with a tighter specification. It is likely to be true with ADI/Hodgdon powders. In these extruded powders the size of the powder kernel is controlled in the manufacturing process. In Ball/spherical powders the sizing of the kernels is not directly controlled so that after manufacture the powder is screened to different sizes so each batch can yield different burn rate powders from the same formulation. Those can then be blended back to a specific burn rate or blended with other batches for the same purpose. It is common to see this in the spherical powders as the powder will show definite differences in kernel size.

Remember that burn rate is a function of grain size/surface area and surface deterrent coatings.