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FGMM powder charge consistency

M

m1ajunkie

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Feb 22, 2010
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#1
Has anyone measured the consistancy of the powder charges in FGMM 175gr .308?

I would take apart 10 or so myself, but I don't have any at the moment.

I am working up a load to come close to cloning fgmm 175's but I want to make sure my powder charge variance is within reason. I have my load targeted at 43gr, however I don't have a great scale and I am getting some variance. My charges look to range from 42.9-43.2gr. If it matters the furthest I shoot is 700yds at torso sized steel. I would like to get about 1moa and so far my groups seem to be hovering just a hair under but I always goof up and shoot two or so out of the main group.

I am loading:
43gr varget
175gr smk
2.802 avg oal
Win Wlr primer
wcc brass

My loads chrony 2570 fps with an avg es of 35-40. Out of the same rifle with the same chrony I get fgmm at 2573 with a es of 66. (One ten round string)
 
#2
Re: FGMM powder charge consistency

Try 44+ grains of varget under the 175. I use 44.2, which gives me roughly 2630 fps, and under 1/2 MOA consistently. My best ES with wolf primers was under 10. That load has gotten me out to 1050 yds on a 12" steel target. It really shines at 700-800 yds.
 
#3
Re: FGMM powder charge consistency

I never pulled any bullets on the factory FGMM, but I will tell you that the chrony read some very high ES with the 168 FGMM the last time I checked it; about 40 fps. Funny how the rounds shoot pretty well even with that spread.
 
#4
Re: FGMM powder charge consistency

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: palmik</div><div class="ubbcode-body">I never pulled any bullets on the factory FGMM, but I will tell you that the chrony read some very high ES with the 168 FGMM the last time I checked it; about 40 fps. Funny how the rounds shoot pretty well even with that spread. </div></div>

Thats what I was thinking. My handloads have a lower ES, but both the FGMM and my handloads shoot the same at 100yds.
 
#5
Re: FGMM powder charge consistency

I have READ .6 grains spread. I haven't personally pulled them and measured them though. It seems like a lot to me, for ammo that shoots so well...
 
#8
Re: FGMM powder charge consistency

I have pulled some of the factory ammo. I have seen up to a .6 grain spread (as high as .9 in some other expensive brand name ammo!) This is what equates to the high ES numbers of most factory ammo. The 308 match ammo is loaded on the lower velocity accuracy node with a forgiving powder where the powder charge does not have to be exact. This helps maintain decent accuracy even though the powder charge varies. The high ES will show itself at longer ranges vertically on the target. Most factory match powder is a ball/spherical type, which will vary the fps from hot and cold temps. The factory ammo is decent, but a fine tuned load made for the rifle using temp insensitive powder charged to .02 grain (or even .1 grain) accuracy will ALWAYS shoot better and be more consistant.
 
#9
Re: FGMM powder charge consistency

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ChadTRG42</div><div class="ubbcode-body">I have pulled some of the factory ammo. I have seen up to a .6 grain spread (as high as .9 in some other expensive brand name ammo!) This is what equates to the high ES numbers of most factory ammo. The 308 match ammo is loaded on the lower velocity accuracy node with a forgiving powder where the powder charge does not have to be exact. This helps maintain decent accuracy even though the powder charge varies. The high ES will show itself at longer ranges vertically on the target. Most factory match powder is a ball/spherical type, which will vary the fps from hot and cold temps. The factory ammo is decent, but a fine tuned load made for the rifle using temp insensitive powder charged to .02 grain (or even .1 grain) accuracy will ALWAYS shoot better and be more consistant. </div></div>

I find this very interesting.

Not that I have tried every single factory "match" 308 but FGMM in both 168 and 175 has shot remarkably well in every rifle and carbine in which I have tested it.

I have had a couple of guns that I couldnt even exceed the FGMM's consistency with my own handloads.

I would love to hear some more thoughts on the reasons why. I am anal about consistent charge weights, and am shocked to hear of this variance with the FGMM.
 
#10
Re: FGMM powder charge consistency

A couple of considerations for Fed Gold Match I can think of...

- Brand new brass
- Softer necks
- 168 and 175gr SMK's are forgiving with seating depth
- Reloader 15 powder is used in M118 Ball, LC Brass 175 SMK
- IMR 4895 or similar powder used Fed GM, Fed Brass 175 SMK

I would say a lot of research has been done to determine an optimal pressure load that gives consistency under a wide range of circumstances.
 
#11
Re: FGMM powder charge consistency

Call me dumb but I think the best way to pull bullets on FGMM is with the trigger on a good rifle.
That said, those numbers Chad put forth are pretty eye opening.
It always makes me happy to see my nice round groups out to 1000 yards using 44.7 Varget, 175 SMK and lapua brass.
 
#12
Re: FGMM powder charge consistency

Why would they not be using RL-15 for Fed GM as ATK is the parent of Federal and Alliant powders are a product of ATK.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: vman</div><div class="ubbcode-body">
- IMR 4895 or similar powder used Fed GM, Fed Brass 175 SMK
</div></div>
 
#14
Re: FGMM powder charge consistency

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: inode</div><div class="ubbcode-body">Why would they not be using RL-15 for Fed GM as ATK is the parent of Federal and Alliant powders are a product of ATK.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: vman</div><div class="ubbcode-body">
- IMR 4895 or similar powder used Fed GM, Fed Brass 175 SMK
</div></div> </div></div>

Not sure, you could but right but that is my understanding.

From what I have gathered in my travels, Rl15 is known to be used for mil applications but I have not seen factual evidence that says "x" powder is used in Fed GM. If someone would like to share this with me I would be delighted to know
smile.gif
 
#15
Re: FGMM powder charge consistency

Powders for manufactured ammo are usually not generally available to the average reloader. The formulations are normally quite different or at least that is what I have been told by several insiders at some very large ammo companies.
 
#16
Re: FGMM powder charge consistency

I've read in a couple of places that Federal uses 4064 in the Gold Medal loads. It's just what I've read.

To the OP, you're going about this the wrong way. The whole purpose of getting into reloading is to save money and find ammunition that shoots better than factory. If all you want to do is shoot factory, you need to scour the net for a good price on factory ammo.

Just trying to replicate a factory load isn't going to get you where you want to be; especially thinking in terms of how big of a margin of error you can operate in. Also keep in mind that arriving at a velocity identical to a factory load doesn't mean that you've duplicated the factory load. All it means is that you found a load with a like velocity.

If you want to work up an accurate load for a .308 and are looking to be pointed in the right direction, I'll offer this:

1. Start with either Varget or Reloader 15. These are two of the more popular powders for .308 and either will make good use of shorter barrels.

2. Try a few different projectiles. At least try the Sierra and Hornady equivalents of the 168gr and 175gr Match hollow points.

3. Get away from using Lake City brass. Winchester is cheap and works very well.

4. Use Federal GMM or CCI BR-2 primers.

Using these components you should be able to land on something that will allow the rifle to shoot to the best of its ability. If you can't with these components, you might just need more practice shooting or maybe your rifle needs some tweaking.

I'll also say this, always keep in mind that you can't just keep loading hotter and hotter trying to find the accuracy node. With a gas gun, you have to keep the firearm's health in mind. If you're getting a forward ejection pattern, it may be a sign that the load is too hot for the rifle.

After I got into shooting .308, a couple of the guys I know went the AR10 route. For them, the 168gr SMK and 42gr of Reloader 15 worked wonders. Also be sure that you work up.

I saw that a couple of guys were throwing out some loads that looked pretty hot to me with a 175gr bullet. It was either in this thread or your other one where someone mentioned a load of almost 45gr of Varget under a 175. That's a hot load. My rifle only needs 42.5gr of RL15 to give me better than 2600fps out of my 22" barrel.
 
#17
Re: FGMM powder charge consistency

TonyAngel,

Prior to this thread I was thinking that getting similar velocity = a close duplicate of a factory load.

I have worked my load up to 43gr of varget with a 175smk in wcc brass with wlr primers. I am experiencing some issues mentioned in the other thread that I now feel like could be shooter related, and something I am going to have to fix. i.e shooting off a bipod instead of sandbags.

When working up my load I shot five round groups selected the one with the least spread(43gr) and chose that to further expand on. I am thinking this is not the correct load for my rifle coupled with me as a shooter giving me groups I'm not happy with. I am thinking about going back and trying loads at 43-44gr varget and see what they look like. If I get good groups I will look more closely at one of those. I was asking the question about powder spread just out of curiosity about how much variation is seen in factory loads. I am seeing about a .3gr spread with my handloads and wanted to make sure factory loads were along the same line.
 
#18
Re: FGMM powder charge consistency

I recently had a customer that only fed his rifle BH ammo. It shot pretty good. He was able to get 1 group (just 1!!) at 300 yards into an inch. So, that was what I had to beat. After we had worked up a load with a 155 Scenar, we shot the 2 rounds side by side. My loads were right at 1.25" at 300 yards, and the best BH group was right at 3" (he and I shot a total of 3- 5 shot groups). The BH had a 48 fps ES on 5 rounds, and the 155 load had an 18 ES on 5 rounds, and was running 100+ fps faster. So, I didn't beat the factory 1" claim (that we couldn't duplicate), but it was close. Once you put the whole picture into focus on what handloaded ammo can do, you get it. You get tighter, more consistant groups, lower ES, faster speeds, and can use a non-temp sensistive powder. That's the full picture.
 
#19
Re: FGMM powder charge consistency

From what I've read, the GMM goes +/- .2 gr either way, so about a .4gr spread. When I load, I load to within .1gr on the powder.

If you are something akin to an expert shooter, shooting one groups of each load isn't going to tell you anything. The human factor can wreak havoc on test results. The best that I've ever been able to do is to shoot four five round groups with each load and see which one does the best on an over all.
 
#21
Re: FGMM powder charge consistency

I guess I should have qualified what I said above about one group not telling the OP anything.

An experienced shooter that has attained a level of consistency can, indeed, gather meaningful information about a load by simply shooting one group; however, the OP (based on this and other threads) appears to be somewhat of a beginner (or just hasn't attained a level of consistency). In the OP's case, I don't think that shooting one group of a load is going to tell him anything.
 
#22
Re: FGMM powder charge consistency

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ChadTRG42</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: TonyAngel</div><div class="ubbcode-body"> shooting one groups of each load isn't going to tell you anything. </div></div>
Please expand on this. </div></div>

There is going to be some natural variation in group size that is not based on differences in the load alone.

I could shoot a 5X5 of the same load and write charge weights next to each shot and it will look like some loads were great while my rifle didn't like some. It is very typical for my groups (of the same load) to vary from .2" to .6" at 100 yards. Is it because I am an inconsistent shooter? Maybe. But even with the shooter out of the equation, a load will not group exactly the same every single time. This is why there is a lot of friction here about accuracy guarantees.

Another way to say this is that the signal-to-noise ratio is low during load development. After you arrive at a load, I believe the best way to combat natural variation is to confirm it with a 5X5 or a couple of 10-shot groups... and I have had to go back to the drawing board before because a load that gave me a sub-1/4 inch group during development never produced sub-1/4 again. It was a lucky shot (or a lucky 5 shots, really).

Load development really is more of an art than a science. There are a lot of cool methods out there and they can all yield lemons from time to time.
 
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