bullet for .308

In both instances where I saw it tumble (748 yard popper in a Gunsite class where everyone in the class was using PMC match ammo loaded with the Sierra 168 and nobody hit the popper but me, and that was a happy accident, IMHO) and in a long range firing school at Camp Perry where the first firing done was on 800 yard targets and nobody on the line shooting 168's could stay on paper and the pits reported back keyholes from the rounds that did happen to hit paper.

That year Kevin Thomas, who was still working for Sierra as a ballistic tech at the time, was also attending the school. After all the moaning and groaning on the line (most people shooting 30 call had brought ammo with 168's), we asked him about it when the class broke for lunch. He explained the 168 was developed as a 300 meter International Rifle match bullet. That it also proved to shoot well at 600 yards had proven to be a big bonus for Sierra. But he said going beyond that was nothing it was made to do. He recommended the 175 grain SMK for that. It was developed in conjunction with the military for sniper ammunition after the Adjutant General's opinion (1984?) that non-expanding hollow points were OK for combat was published and that bullet sails right through the transonic range, unperturbed.

Incidentally, the whole transonic range bothers the 168. That's usually taken as about Mach 0.8 or 0.85 to Mach 1.2 or 1.25. All the tumbling I saw began when velocity dropped to about 1400 fps, which is Mach 1.25 in standard ICAO conditions.
 
So I picked up some factory federal match ammo with both 168 grain and 175 grain SMK's. I will see how each one shoots and then decide which one to make my match loads out of.

Here is a question though, do yall think this is a viable way to evaluate bullet performance? I mean given that when I load it I will trim it, probably use a different case, and maybe a different powder? I think the simple answer is yes, but usually when I select a bullet I literally buy some different bullets and test them over a specific powder.
 
Here is a question though, do yall think this is a viable way to evaluate bullet performance?
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At longer distances it will likely give you an idea as to how each bullet performs but it will be over their Federal powder loads and not what you can work up using different powders with each bullet. I likely would have bought 100 of each bullet, got some uniform brass and tried a few powders with each bullet. Typically loading ten rounds per sample. However, using the Federal loaded match ammunition is also a good way to go I guess.

Ron

Ron
 
Ron:
That is typically what I do, but this time I wanted to try a shortcut...we will see if it works.

As an aside, if the factory load works really well..I could just use the same cases, powder, and primers and mimic the factory load. Im sure I will need to do some minor tweaking but I can make federal match ammo for about $0.50/round in .308 rather than pay $1.50/round if it works really well.
 
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Mississippi, absolutely nothing to lose. Once you have some data please do post how this goes as I am curious. The Federal Match stuff shoots real well in all my 308 guns, bolt and gas.

Ron
 
Id say no the Fed gmm will not tell you which will do better for you . Ok maybe if you shoot both past 700yards . You would then know if the 168s will work because you already know the 175's will work . The thing about factory ammo is it uses virgin brass . It often seems to be an important factor . There has been guys that broke done Fed gold medal match ammo . They then used the very same components they pulled to reload to the same specs . Nobody that i know of has been able to reproduce it's accuracy from the factory .

Anyways what you're doing will help but not sure how much detailed or reproducable info you'll get from the test .
 
metalgod: Anyways what you're doing will help but not sure how much detailed or reproducable info you'll get from the test .
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What I am doing is seeing if the SMK's shoot well in my gun, and what the factory velocity is. I have had bullets that were supposed to be accurate shoot like crap in my gun...i.e the Berger vld in my .338 LM.

I realize the smk is the gold standard in match bullets, but I'm a bit gun-shy after a recent supposedly hyper accurate bullet didn't perform in my testing. Sure there is the chance that I could have tried some other powder, jump etc but I don't like finicky bullets.


The other valuable test is : can I do as good or better than match grade factory ammo?

And, if I am able to replicate the velocity/ results, it is totally worth it.

Finally, I don't think virgin brass helps. Consistent neck tension, consistent volume and general uniformity is what matters. I would rather have thrice fired, annealed, rolled, and trimmed lapua brass than virgin federal brass any day.
 
I understand your point about the brass . How ever my point was not "Federal" virgin brass was the factor but that the ammo was loaded with Virgin brass . Many guys have shot some of there smallest groups using Fed gmm that never can reproduce that accuracy even when literly using the same components .

Again I understand your points . I'm just trying to help you understand there is "something" about gmm that is very hard to reproduce . So even if it shoots spectacularly for you . It does not mean you'll be able to reproduce the results or vice versa for that matter .

I'm in no way challenging you . This is just one guy that has shot a lot of Fed gmm in 308 sharing his experience .
 
Fair enough Metal God.

I do not have any reason to dispute your claim. And with your experience I'm sure you are right. Maybe I cannot duplicate Federal's results with their components. But maybe once I get a baseline for their accuracy/velocity, I can duplicate their results with different components besides the bullet.

I may try BR-2 primers which I have never used before, and since it is an AR 10 I do want a firm cup (don't we all)
 
The Federal loads are a good idea for the unusual reason that we know the powder they prefer is IMR 4064 (or was). I pulled 20 of their 168 grain loads down long ago and found 43.5 grains ±0.2 grains of 4064. I know this because there is nothing else in the appropriate burn rate range with that same grain size, and also because, when I put that load into QuickLOAD it came within 2 fps of their advertised muzzle velocity.

Subsequently, published descriptions of the Mk 316 mod. 0 military sniper round that Federal developed for the M24 system included and Federal match primers (210M) and Federal match brass rather than military brass, and that it uses modified IMR4064 (flash suppressant added; I don't know if there are any other modifications). At one point, and you may find some older Federal GMM (not as old as the lot I pulled down) with Reloader 15 inside. ATK had caused Federal to move over to Alliant Reloader 15 at some point, presumably because they owned Alliant, too. But the military reported problems with high pressure in desert heat, so IMR4064 was brought back. 41.7 grains is the nominal load used.

IMR4064 is really quite good about temperature, as powders in general go. This is why it has been a popular match powder for a long time. I don't know if the switch to Reloader 15 has remained in the Gold Medial Match ammo or not. You could pull a sample and tell by the grain size which one it is. But even if the test ammo you get isn't IMR4064, you now know you can get the desired result with it.

ALSO: Be aware that those loads were for nominal lots of IMR4064. If you get some to try to copy the load with, be cautioned that this is not your lot of powder. You still want to back down at least 5% and work back up watching for pressure signs, and that is if you are using the Sierra bullet at the same COL, Federal brass, and Federal 210M primer. If you change anything other than just the powder lot, caution dictates that you back down 10% and work up, watching for pressure signs.
 
I pulled a couple 168gr GMM in 2014 and they did not have the short cut powder like you see with RL-15 .

Here is a pic of the pulled powder on left and IMR 4064 on right . Very close looking but the IMR powder does look to be a darker black . I also got 43.3 to 43.5gr from the pulled 168gr GMM
9BkbIZ.jpg
 
Hmmm,

It seems from what y'all say I may not be able to precisely replicate fed Gmm using the exact same components.
Mainly because I cannot acquire the exact same components. But I may be able to replicate the results using different components. If I can get the same velocity and accuracy safely, would that not be worth knowing?

I will begin working on this immediately and report back my results!
 
Mississippi:
Hmmm,

It seems from what y'all say I may not be able to precisely replicate fed Gmm using the exact same components.
Mainly because I cannot acquire the exact same components. But I may be able to replicate the results using different components. If I can get the same velocity and accuracy safely, would that not be worth knowing?

I will begin working on this immediately and report back my results!
Click to expand...

Don'y let things dissuade you. No, you can't duplicate the powder used but you can load 168 grain or other Sierra match bullets. Yes, there is a little more to it than duplicating the same velocity because you can't see the actual pressure curve that generated that velocity.

On average, shooting some Federal Gold Medal Match 168 grain HPBT from my 26" barrel bolt gun I get right around 2700 FPS. That does not mean that if I shoot a similar load and get that same 2700 FPS my groups will be the same. However, I have nothing to lose by trying different loads. So if I were you I would pursue things and see what you get.

Ron
 
. Don'y let things dissuade you. No, you can't duplicate the powder used but you can load 168 grain or other Sierra match bullets. Yes, there is a little more to it than duplicating the same velocity because you can't see the actual pressure curve that generated that velocity.
Click to expand...


Ron, don't let the fact that I acknowledge the point these guys are making allow you to believe I'm dissuaded from trying. I will still try to make this round as best I can using the same components. It may work for me, it may not
...but if I get close, I let you in on my findings ron
 
Older thread but useful info for me.

Just signed up. First post. doing a lot of reading. My favorite rifle is a .308 and I intend on reloading so I am "borrowing" some of your info. I live 6 miles from a 1500 yd range so have an amazing resource for tests. They do long distance competitions there and I fully intend to spectate with a note pad. People come here from all over North America and it's in my backyard so to speak so I hope to have some useful tips someday. But until then, I'm here to learn. Lodi, WI.
 
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So I tested some federal gold medal match in my AR10. 40 rounds of 168 gr and 40 rounds of 175 gr smk's.

200 yards
16.25" barrel chrome lined, hammer forged 1:10 twist
Swarovski 4x12x44 scope
61 degrees
Wind 1-4 mph from 7 o'clock to 1 o'clock
4 shot groups were alternated i.e. shooting 4x168 grain then 4x175 allowing barrel to cool in between groups

168 gr (rounded up to nearest quarter inch center to center) 4 shot groups
Best Group .75"
Worst Group 2.25"
Avg group 1.75"

175 gr (also rounded up) 4 shot groups
Best group .5" (x3)
Worst group 1.75"
Average group. 1"

So it seems the 175 gr is the ticket in this gun, both bullets average sub moa, but the 175's had not only the tightest groups, but the most consistent. now I need to select a powder. For primers I will use BR-2

I didn't check velocity because my 9v battery was dead :mad:... but I will buy another box of 175's and test velocity to see how close I can get my load to mimic Federal GMM
 
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