Anybody know what powder Federal uses for GMM .308


PDA






hsiddall
January 6, 2008, 07:58 PM
Well ? of the day is what is the best way to copy Federal's GMM? I have 168 gr MKs just begging for a home and my 700p has shot 3/8" groups at 100yds with GMM and now I wnat to even improve that by handloading ( changing seat depth etc...). Please help...If you saw my earlier post regarding primers for the .308 well I got the right ones and im gonna try working up a few loads with the magnums also just to see.:D

If you enjoyed reading about "Anybody know what powder Federal uses for GMM .308" here in TheHighRoad.org archive, you'll LOVE our community. Come join TheHighRoad.org today for the full version!
kennedy
January 6, 2008, 08:36 PM
don`t know what federal uses, but i am using H4895 behind matchkings in my .308 rem 700, so far 10 rds in 1.25 in, still working on it.

USSR
January 6, 2008, 09:13 PM
hsiddall,

Federal uses a noncannister grade of RL15 in their .308 Gold Medal Match ammo.

Don

bearridge
January 6, 2008, 10:23 PM
Friend Don,

Do they use it in the 175 gr? Got a linky?

Thanks
bearridge

I love Mickey Mouse more than any woman I have ever known. Walt Disney

Bitswap
January 7, 2008, 09:26 AM
They're using 42 grains of 'something'.

If your trying to duplicate, try starting around 43.5 grains of Varget. I'm using Sierra 165 grain Gamekings, HPBT instead of the Matchkings. My pet load for this is 43.7 grains.

Even with the cheapist brass, will outshoot Federial Premium Match any day for about 50 cents a round... match prepped brass of course.

dmftoy1
January 7, 2008, 09:16 PM
Try some H335 too if you have it on hand . . . . I've had some really good luck with SMK's and 168 Hornady BTHP's over H335.

FWIW.

dwwhite
January 7, 2008, 10:15 PM
Ditto Bitswap's post, I've used an identical load to great effect,
This charge also seems to work very well with any premium bullet from 165 to 180 grns.

At one time, I was determined to exactly duplicate the Federal loads, but after seeing my results with these, I figured, What's the point?

Nom de Guerre
January 8, 2008, 12:32 AM
I took apart a FGMM 168 grain bullet today to measure the powder load. A friend told me he had done the same a while back, and it measured 42.7 grains. I found the same exact powder charge today in the bullet I disassembled: 42.7 grains.

Subjectively, the powder looks very similar to IMR 4895, which is what I am using to try to make a close match to FGMM. I don't think the powder Federal uses is exactly the same as IMR 4895, but it seems petty close. I'd love to look at some kernels under a microscope and check it against various brands of powder to really try to pin it down.

I went to the range and chronographed a series of 5 round test batches I made up last week. I used an Oehler 35P to chronograph the batches. The temperature was 47 degrees F, and it was partly sunny.

For components, I used 1X fired (in my 700 PSS) Federal .308 brass, Federal 210M primers, SMK 168 gr HPBT, and IMR 4895. I cleaned and prepped the brass including neck sizing with .336 bushing, uniformed the primer pockets, de-burred the flash hole, and chamfered the cases mouths inside and outside.

I made up batches of the following powder loads:

42.1 gr.
42.3 gr.
42.5 gr.
42.7 gr.
42.9 gr.
43.1 gr.

Incidentally, I weighed the powder by hand with an RCBS 10-10 sclae, and seated the bullets with a Redding competition micrometer seating die.
I shot a 5 shot control group batch of FGMM.

The FGMM measured:
Mean Velocity = 2679
SD = 4

The closest match I had velocity-wise was the last batch I made with the highest powder charge, 43.1 grains. It was not the tightest group I shot today, but more testing will have to be done as I hone in on the ideal load for my rifle. The wind started to pick up towards the end of my session, and my chronograph was blown over in the middle of measuring that string for the last batch.

Initially I was surprised that it took an additional .4 grains of powder to match the mean velocity of FGMM, but after thinking about it, I think I know why. I only neck sized the cases after they were fire formed in my rifle from their first firing. The body of these cases is clearly a larger volume than the never before fired FGMM cases, so it makes sense that a larger charge would be needed in my reloads (all other things being equal) to match the pressure and muzzle velocity of FGMM.

I'm tempted to try an experiment some time, and pull the bullets and powder from 5 rounds of FGMM, and then replace the factory powder with 42.7 grains of my powder (IMR 4895) and re-seat the bullet, and then chrono that against a batch of FGMM. I have a hunch they would produce pretty identical MV.

If I get around to trying that in the next week, I'll post the results.

MarshallDodge
January 8, 2008, 12:44 AM
I'm not sure on the powder either but I am experimenting with Varget and Benchmark.

Benchmark has shorter grains than Varget and definitely measures more consistent.

USSR
January 8, 2008, 07:23 AM
bearridge,

I would expect they use RL15 in both the 168gr and 175gr .308 FGMM loads, as it's the best suited ATK produced powder in both cases. No link to further info.

Don

30Cal
January 8, 2008, 11:57 AM
Initially I was surprised that it took an additional .4 grains of powder to match the mean velocity of FGMM, but after thinking about it, I think I know why.

The powder that goes into the cans you buy (cannister grade) and the powder that goes into loaded ammo (non-cannister grade) probably doesn't have the same burn rate.

USSR
January 8, 2008, 03:02 PM
Initially I was surprised that it took an additional .4 grains of powder to match the mean velocity of FGMM, but after thinking about it, I think I know why. I only neck sized the cases after they were fire formed in my rifle from their first firing. The body of these cases is clearly a larger volume than the never before fired FGMM cases, so it makes sense that a larger charge would be needed in my reloads (all other things being equal) to match the pressure and muzzle velocity of FGMM.

N de G,

With IMR4895, you are using a different powder than what is used in FGMM ammo. Federal uses a powder (Alliant) produced by their parent company (ATK), not a powder produced by their competitor (Hodgdon).

Don

Nom de Guerre
January 8, 2008, 03:15 PM
Well, t sure seems similar on a macro scale. I need to find a microscope!

A friend of mine who shoots a lot of precision long range competitions finds IMR 4895 to produce the exact same results in his "clone" version of FGMM. He finds 42.7 grains of IMR 4895 produces the same MV as FGMM for him. It seems like a big coincidence that the same charge weight to a 1/10th of a grain produces the same MV for him.

rcmodel
January 8, 2008, 03:38 PM
I need to find a microscope!There is no possible way to tell a powders burn rate by looking at it. Even with a microscope.

So many things are, or can be used during manufacture to change the burn rate that it boggles the mind.

Trying to look at it and I.D. it is just a good way to blow yourself up.

Anyway, the time spent trying to I.D. a non-canister powder lot would be better spent working up a better load then factory, in your rifle, with powder you can actually buy at the store.

http://i81.photobucket.com/albums/j219/rcmodel/KTOG/1224.gif
rcmodel

Nom de Guerre
January 8, 2008, 04:51 PM
Trying to look at it and I.D. it is just a good way to blow yourself up.


Now why would that ever happen? Looking at a kernel of powder under a microscope would hardly be risking "blowing myself up." My interest is not to try to ID a powder so that I can abandon all common sense and disregard recommended load minimums and maximums. If hat is the impression you got, what possibly gave you that? I never suggested anything like that.

Anyway, the time spent trying to I.D. a non-canister powder lot would be better spent working up a better load then factory, in your rifle, with powder you can actually buy at the store.


I am spending time developing loads for my rifle that better factory loads. It isn't an either/or issue. The search for more knowledge isn't a bad thing where I come from.

FGMM happens to shoot very well in my rifle. My 700 PSS was worked by a local smith to be optimized for that ammunition. I am trying to get as close to it as possible in reloads and then tweak it even better from there.

I am also using powder bought from the store. If that wasn't clear earlier, it's IMR 4895. It's available to the public.

I guess I don't understand your point, but it's clear that you sure don't seem to understand mine.

USSR
January 8, 2008, 07:20 PM
N de G,

Nothing wrong with your using IMR4895. Hell, I've got 50# of it and use it regularly for .308 loads. I'm simply saying that the reason for the .4gr difference in load weight is due to your using a different powder than what Federal uses.

Don

Nom de Guerre
January 8, 2008, 07:36 PM
Don, I hear what you're saying, and you might be right about the powder difference being part of the difference, but I do think the expanded size of my fire formed cases could be a contributing factor.

I'm still perplexed by how a friend of mine gets the exact same MV with the exact same powder charge weight. He only neck sizes as well. Maybe it's partly powder lot differences.

30Cal
January 9, 2008, 03:05 PM
A friend of mine who shoots a lot of precision long range competitions finds IMR 4895 to produce the exact same results in his "clone" version of FGMM. He finds 42.7 grains of IMR 4895 produces the same MV as FGMM for him. It seems like a big coincidence that the same charge weight to a 1/10th of a grain produces the same MV for him.

Which lot# of FGMM? As they move through different batches of non-cannister powder, they have to vary the powder charge to maintain a constant velocity from one to the next. If you pull bullets from different lots of the same commercial load, you will find that they don't necessarily have the same powder charge.

Additionally, 1/10 of a grain makes a very tiny difference in velocity.

USSR
January 9, 2008, 03:19 PM
Which lot# of FGMM? As they move through different batches of non-cannister powder, they have to vary the powder charge to maintain a constant velocity from one to the next.

Good point, 30Cal. I have 3 different lots of surplus IMR4895; medium-fast, medium, and medium-slow.

Don

hsiddall
January 26, 2008, 08:40 PM
I didnt use a chron as I dont own one, but I shot my copycat loads today and with 41.0 of rl15 under a seierra mk 168gr I shot two groups around .5 MOA. Best was .541" @ 100yds. Remy 700p with Millett TRS1...:DThis rifle will outshoot me for some time still. Im cecking with local smiths about blueprinting also...:D...

USSR
January 26, 2008, 09:49 PM
Im cecking with local smiths about blueprinting also...

hsiddall,

Save the blueprinting/trueing for when you're ready to put a nice custom barrel on it. Pretty much a waste of money to true your action and then put a $20 factory barrel back on it.

Don

If you enjoyed reading about "Anybody know what powder Federal uses for GMM .308" here in TheHighRoad.org archive, you'll LOVE our community. Come join TheHighRoad.org today for the full version!