bullet for .308 - Page 2

Metal god · November 22, 2016, 08:05 PM

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 .

Stats Shooter · November 22, 2016, 08:19 PM

Quote:

metalgod: Anyways what you're doing will help but not sure how much detailed or reproducable info you'll get from the test .

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.

Metal god · November 22, 2016, 08:39 PM

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 .

Stats Shooter · November 22, 2016, 08:47 PM

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)

**Unclenick** · November 23, 2016, 02:52 PM

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.

Metal god · November 23, 2016, 10:32 PM

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

Stats Shooter · November 23, 2016, 11:07 PM

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!

Reloadron · November 24, 2016, 08:57 AM

Mississippi:

Quote:

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!

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

Stats Shooter · November 24, 2016, 09:26 AM

Quote:

. 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.

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

jchaplin · November 29, 2016, 11:23 AM

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.

Stats Shooter · December 2, 2016, 08:42 PM

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

... 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

November 22, 2016, 08:05 PM	#26
Metal god Senior Member Join Date: April 10, 2012 Location: San Diego CA Posts: 6,875	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 . __________________ If Jesus had a gun , he'd probably still be alive ! I almost always write my posts regardless of content in a jovial manor and intent . If that's not how you took it , please try again .

November 22, 2016, 08:39 PM	#28
Metal god Senior Member Join Date: April 10, 2012 Location: San Diego CA Posts: 6,875	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 . __________________ If Jesus had a gun , he'd probably still be alive ! I almost always write my posts regardless of content in a jovial manor and intent . If that's not how you took it , please try again .

November 23, 2016, 02:52 PM	#30
Unclenick Staff Join Date: March 4, 2005 Location: Ohio Posts: 21,060	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. __________________ Gunsite Orange Hat Family Member CMP Certified GSM Master Instructor NRA Certified Rifle Instructor NRA Benefactor Member and Golden Eagle

November 23, 2016, 10:32 PM	#31
Metal god Senior Member Join Date: April 10, 2012 Location: San Diego CA Posts: 6,875	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 __________________ If Jesus had a gun , he'd probably still be alive ! I almost always write my posts regardless of content in a jovial manor and intent . If that's not how you took it , please try again .

November 29, 2016, 11:23 AM	#35
jchaplin Junior Member Join Date: November 29, 2016 Location: Lodi, WI Posts: 7	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. Last edited by jchaplin; November 29, 2016 at 03:06 PM.

November 22, 2016, 08:47 PM	#29
Stats Shooter Senior Member Join Date: August 26, 2016 Location: North Dakota Posts: 1,636	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)

November 23, 2016, 11:07 PM	#32
Stats Shooter Senior Member Join Date: August 26, 2016 Location: North Dakota Posts: 1,636	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!

December 2, 2016, 08:42 PM	#36
Stats Shooter Senior Member Join Date: August 26, 2016 Location: North Dakota Posts: 1,636	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 ... 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 Last edited by Stats Shooter; December 2, 2016 at 08:50 PM.