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What ammo to use?

PostPosted: Sat, 31 Aug 2013 21:03:43
by kelu
So, I have a new Remington 700 SPS, .308 Win, stainless steel barrel, 24", 1/10 twist.
I am trying to find out what she likes.
Today I was at the range, and I tried 3 different kind of ammo, 100 yards. That's a quarter coin.
Left is Core Lokt 150gr, Right is Federal Gold Medal 168 gr.
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IMAG0310 (2).jpg (43.66 KiB) Viewed 2969 times

Below is PMC Bronze 147 gr.
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The test is not very careful made, I was tired, but I think it shows something.

To me seems Gold Medal is what she likes most of what I have tested so far.
I just picked this evening a box of Hornady superperformance 150gr, maybe I will be able to test them next week.
I remember couple discussions (and even mentions about some magic formula) here about the right ammo weight for a caliber and twist, what do you recommend for given rifle?
And what is interesting (new to me) is that aiming each time in center, point of impact is quite different. That is up or down, I can grasp, but why left and right?

Re: What ammo to use?

PostPosted: Sat, 31 Aug 2013 21:26:27
by GeneFrenkle
Will this help?

http://www.bergerbullets.com/litz/TwistRuleAlt.php

And

http://kwk.us/twist.html

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Re: What ammo to use?

PostPosted: Sat, 31 Aug 2013 21:59:09
by Palladin
The different weights and speeds mean the bullets leave the muzzle at different points of the harmonic whip of the barrel. That's what I would suspect is moving your groups around. Pick the size group and load that you are comfortable with, and adjust your sights for that.



http://www.shootingsoftware.com/barrel.htm

Re: What ammo to use?

PostPosted: Sat, 31 Aug 2013 22:18:03
by NovaHunter
I've got a Remington 700 PSS, which was old version of the 700P. 1 in 10 twist barrel. I've shot hundreds rounds of the FGMM and it shoots around .6 in groups at 100 yards out of my rifle. IMO, It's some of the better factory ammo you can buy that is widely available. Black Hills is also very good as well.

From the groupings you showed, looks like your gun liked the FGMM the best of those 3. Keep shooting and trying a few different types to see if you get any difference in performance. If you can find some 175 gr SMK loads, (FGMM, Fiocchi, Black Hills are all good) try that weight bullet too.

The stock SPS is a pretty decent barreled action, but the accuracy potential is really held back by the flimsy Hogue stock. One the of easiest upgrades you can do is a new stock like the from Bell & Carlson:
http://www.midwayusa.com/product/486263 ... etic-black

The Bedding block securely holds the action, free floats the barrel, and the fore end is stiff and will not bend and make contact with the barrel when shooting off a rest as the Hogue does. Having the fore end of the stock contact the barrel at anytime when shooting will mess with the consistency of the harmonics and hurt accuracy.

Keep shooting and experimenting the loads you use. If the gun is brand new, then you are still breaking in the barrel, so make sure you cleaning the bore often and you might find that group sizes start to settle down after 20 to 60 shots. Alot of guys take the base SPS and make minor upgrades such as the stock and trigger and get very good shooting rifles for pretty good prices all things considered.

Re: What ammo to use?

PostPosted: Sun, 01 Sep 2013 08:16:57
by gunderwood
Palladin wrote:The different weights and speeds mean the bullets leave the muzzle at different points of the harmonic whip of the barrel. That's what I would suspect is moving your groups around.

+1

Groups moving with different ammo is not a problem as long as it's consistent. It's expected as Palladin explained.

Corelokt and FGMM/SMK have two very different purposes. Corelokt is a hunting bullet, while FGMM is loaded with Sierra Match Kings which are intended for target shooting. What are you trying to find a load for?


Matching the barrel length and twist to bullets isn't very hard. Here's a calc if you want it: http://www.jbmballistics.com/cgi-bin/jbmstab-5.1.cgi
However, a 1:10" twist and a 24" barrel is going to be fine for bullets up to about 190gr; pretty much anything you're going to want to shoot out of a .308Win. 1:10" is a bit high for the 150gr Corelokt and the 168gr FGMM, but they will shoot fine too. As long as the bullet is stable, you're ok. Such a long barrel and high twist rate in a .308Win is intended to push heavy hunting bullets or heavy target bullets. All of this is really academic for a basic hunting rifle. If you want to build towards a high end target/tactical rifle, that's another story.

For now, if the bullet weight is less than about 190gr, don't worry about it. You're gun should shoot it just fine. I'd recommend staying around 175gr as that will be the sweet spot.


What you really noticed was that not all ammo is created equal. Corelokt is a lower quality hunting cartridge. It works, it's cheap, but it's not intended to give the best groups. FGMM on the other hand is high quality match grade ammo that is well known to work in many firearms. It's use in hunting is highly debatable and generally discouraged except in very specific, long range circumstances. This brings me back the original question, what do you want this ammo to do?

Re: What ammo to use?

PostPosted: Sun, 01 Sep 2013 09:57:59
by kelu
Thanks all, these are very informative comments so please go on. I learn from this.
I forgot to mention, this will be a hunting rifle. It is lighter than other rifles I have looked at the gun show, which probably is good for carrying in the woods, but not so great for stability and accuracy.
I don't really expect a good target rifle for under $1000. This was $650, with the x-mark pro trigger. This rifle probably is already better than me, and I don't have a lot of time to spend on the range to train.
However, I want to see what ammo is best to use. I haven't found anything on stores above 168 grains, to test. I have also tested PPU 147 grains, with not good results, so looks like I have to go to the heavier bullets.
Why FGMM is not good for hunting? Does not expand well?

Re: What ammo to use?

PostPosted: Sun, 01 Sep 2013 11:22:16
by NovaHunter
Kelu, the SMK that FGMM is loaded with was specifically designed to be a target bullet. It is a hollow point bullet not designed to penetrate tough targets so you risk the bullet essentially blowing up if you hit the shoulder blade of a deer and wounding the animal instead of killing it.

For hunting, see if you can find a box Trophy Bonded Bear Claw Tipped (TBT)165gr. This round is a great hunting round, and in my rifle the impact and groups for TBT are nearly identical to FGMM 168gr at 100 yards. I practice with the FGMM, and hunt with the more expensive TBT. You may or may not get the same results so do shoot some groups to test.

Sent from my Verizon Droid.

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Re: What ammo to use?

PostPosted: Sun, 01 Sep 2013 17:26:16
by gunderwood
kelu wrote:Thanks all, these are very informative comments so please go on. I learn from this.
I forgot to mention, this will be a hunting rifle. It is lighter than other rifles I have looked at the gun show, which probably is good for carrying in the woods, but not so great for stability and accuracy.

Lighter hunting rifles are generally a good thing as long as you can handle the recoil. For a .308Win, you should have no problems. A light 375H&H is another story. I hunt with a light .45-70Govt with no problems.

Bullet stability has nothing to do with how heavy or light the rifle is. To a point, thicker barrels tend to be more accurate because they are stiffer (same reason shorter barrels, within reason, are typically more accurate too). However, they tend to be heavy.

IMHO, a light weight .308Win is a good hunting rifle choice.


kelu wrote:I don't really expect a good target rifle for under $1000. This was $650, with the x-mark pro trigger. This rifle probably is already better than me, and I don't have a lot of time to spend on the range to train.
However, I want to see what ammo is best to use. I haven't found anything on stores above 168 grains, to test. I have also tested PPU 147 grains, with not good results, so looks like I have to go to the heavier bullets.
Why FGMM is not good for hunting? Does not expand well?

PPU is also lower quality ammo. Bullets are moving and spinning very fast, any slight difference from bullet to bullet will cause accuracy issues. Same goes for the rest of the cartridge. PPU 147gr sounds like they are loading "NATO like 7.62" bullets which are not the highest quality. Without going to a lot of trouble to find what target loads work best, anything with an SMK will likely work very well. FGMM is one such choice. 168gr or 175gr are your best bet.

As for hunting you typically want to focus on terminal performance. Some of the best out there are Nolser Ballistic Tips or Accubonds. That would be my first choice, although Barnes (e.g. Corbon loads), Hornady, Winchester, Federal, etc. all make very good loads too.

Nosler Ammo: http://www.nosler.com/trophy-grade/
I'd shoot the 165gr BT or AB. E-Tip if you want lead free, but I prefer Barnes for lead free.

Barnes Ammo: http://www.corbon.com/corboncart/dpx308168-20

For deer you don't have to be very picky, but we all still have our favorites.


FGMM is loaded with the Sierra Match King bullet. It's a target bullet that never was designed for terminal performance. It is purely focused on building very consistent bullets for accuracy. The "hollow point" in them is not for expansion, it's just a side affect of the manufacturing process (they shove the lead from the top vice the base of the bullet and then crimp it). Not that they can't and don't kill, but it's simply that there are much better bullets on the market if you want terminal performance. Punching paper and SMKs are some of the best around.

Just like a good SD bullet, you need expansion/fragmentation, but without sacrificing too much penetration. HPBT match bullets like the SMKs in FGMM is basically a FMJ bullet (just one with a good long range boat tail and a HP from manufacturing). It's only because they have very thin jackets that they sometimes have ok terminal performance.

Re: What ammo to use?

PostPosted: Sun, 01 Sep 2013 20:03:18
by jdonovan
kelu wrote:To me seems Gold Medal is what she likes most of what I have tested so far.


For factory ammo, its VERY hard to get better than Federal 168 match in a 308. It really is the standard by which others are measured.

For a hunting rifle 2" groups at 100 yds is more than enough accuracy. The average hunter shooting from a standing unsupported position will probably be shooting 5" 50 yd groups. ... which as bad as it sounds will still be inside the 10" 'kill zone" of your average virginia whitetail at 100 yds.

I'd say focus on finding some expanding projectile hunting ammo, that you can get reasonable (< 3") groups from and use it for this season. You can spend the off season looking for a better grouping load, or perhaps some upgrades (like the stock) as another poster suggested.

Another thing to check, is what did the trigger pull come set from the factory at? If its a 'lawyer' trigger and set to something unreasonable like 8-10lbs, that won't help anything. I've got a trigger pull scale and we can check that out and make sure the trigger is set to something reasonable for a hunting rifle.