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Advanced Marksmanship 175 Gr. Federal Gold Medal Match @ 750 yds

S

ShawnAcker

Private
Full Member
Minuteman
Feb 6, 2013
17
0
49
Tomball, Texas
#1
Ok will try to explain the best I can, Hoping to get some input.
I am shooting a Remington model 700 sps with a 20" barrel 1 and 12 twist. Sunday went out in my back pasture to shoot. Here is how it went.
100 yard zero 3 shots same hole.
500 yards 5" plate put a minimum of 20 shots on target. no issues at all shooting 1 moa.
600 yards 8" plate put a minimum of 20 shots on target. no issues at all shooting probably 1 moa I didn't go measure.
750 yards cant hit shit. I am a decent shot but this is my first time with 175 Gr. Federal Gold Medal Match. "GM762M2"
any thoughts would be greatly appreciated. by the way had a full wind value of 5-10. yes I adjusted for it.
shot 45 rounds at it and hit it maybe 5 times.
shot at a thousand 5 shots have no idea where I impacted but it was not on my 36" x 36" plate.
 
#2
First you need to know where you are hitting. With the info you provided you most likely were affected by the wind more then you thought. And at that distance the wind could have been all over the place. Place a large backdrop if you don't gave a spotter or set a video camera and shoot a few and check the feed
 
#3
Did you have someone spotting for you? That can make all the difference. Helps you figure out what you are doing wrong and what the wind is doing to your bullets.

Also: Looks like you put maybe 100 rounds down range. That would be a lot of rounds to put down range, for me anyway, in one precision shooting session. I stop at 20, because I just can't maintain mental and visual (old eyes syndrome) focus past that.

Lastly, could the condition of your bore be a factor? Do you know how your rifle groups after 50 rounds? After 100?
 
#5
What is your muzzle velocity?
What is the projected velocity at 750 per your ballistic calculator?
Do you have previous positive experience with similar ammo at this distance?
Pehaps you are transonic or sub-sonic? A 20" barrel will give up a lot velocity and you need every bit of it with the 308 at longer distance.
 
#6
I'm driving down the road so bare with me I'm going to try and respond to all these questions I think I know most answers. I did not have a spotter. Looks like I need a4 by 8 sheet of plywood so I can see where I'm heading it hasn't rained in awhile but I still could not see dust due to the hay field. I have not chrono these bullets boxes 2600 feet per second ballistics calculator says its 700 it all to be 1199 feet per second I did she exactly 100 bullets my gun normally after 50 shots will make one moa at 100 yards first shots sub MOA my rifle tends to shoot better fouled then clean

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#9
Chrono that lot as the other poster said with a 20" shooting 175's out of a 1:12 you might start to lose stability at lower velocity. If you are shooting one hole at 100 and 1moa at 500 then there is something physical going on downrange. I shot the same ammo to 850 without issue, however that was with a 22" 1:10 twist. What is your elevation, if you are near sea level you could be losing enough oomph to keep rounds accurate at that range. You may just have a 700 yard gun in its' current configuration.
I know people will flame me and say they have seen 18" 308's shoot to 1k yards. I'm not doubting this, but with this ammo we haven't confirmed the velocity with a chrono and some barrels are faster than others. Also the shorter the barrel the faster twist it takes to stabilize. I'm saying that if the ammo isn't truly 2600 fps out of his barrel then 1:12 might only get him to 700 yards or so accurately. You might be able to wring a little more distance if you start handloading for the rifle-With 155 scenars you could make up the difference in both velocity and RPM's without giving up and significant BC... Good luck and happy shooting.
 
#10
ahhshoot said:
I know people will flame me and say they have seen 18" 308's shoot to 1k yards. I'm not doubting this, but with this ammo we haven't confirmed the velocity with a chrono and some barrels are faster than others.
Click to expand...

That's what I am thinking - and yes I have seen a guy make good hits at 1k with a 20" barreled 308, but he was using a tight bore barrel, custom twist and some hot loads - very specialized set up.

Factory 175's and this 20" inch rifle may equal 600 yard set up.
 
#11
Great information guys thank you very much. I will start with the chronograph before I do any more shooting at distance. What I didn't put in here that I might mention I do and lube for this rifle hundred eighty Green Hornet the inner Ponce they will shoot my 36 inch plate at 1000 yards all day long but I cannot find enough bullets to reload for a class I'm going to take my need a minimum of 300 rounds therefore I bought the Federals

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#13
I do currently hand load for this rifle.. But due to a class I bought federal ammunition. I could not find enough bullets to handload 300 rounds. Normally I shoot 180grain Hornady interbonds

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#14
ShawnAcker said:
I do currently hand load for this rifle.. But due to a class I bought federal ammunition. I could not find enough bullets to handload 300 rounds. Normally I shoot 180grain Hornady interbonds

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Click to expand...

Hey the FGMM is great stuff. It's probably the best factory ammo you can buy imo. But that won't change the laws of physics. When you get done with the class I bet you would have much better luck with those 155 Scenars. Personally I've never tried them, but for your equipment they might be the ticket. The BC is nearly equal to the 175's and you will get much greater velocity, and you won't lose stability as soon because the combination of different bullet style as well as increased velocity will both help in stabilizing at longer range. Good luck man
 
#15
GM762M2 is good to go. Here is a picture of a group at 1000 yards last October with my LaRue OBR, 18" barrel, temperature about 55 degrees, DA around 1000. Every gun likes different ammo, and yours does fine with the FGMM at the other ranges, so I would guess that windage was the issue.

obr1000.png
 
#16
Very nice. Got the chronograph out tonight I'm going to run some bullets through tomorrow I think this will give me a lot more insight to what's going on and I believe you're right on the wind I don't think I was reading it correctly I don't have a Castro just looking

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#17
If I may,
I have an old FN SPR with a 1 in 12 twist and I shot the 175 gr FGMM and had results very similar to yours. I could not hit a 3' x 4' target at 1000 to save my life. I had chrono'd the load and was using two ballistic calculators plus the FDAC. Data was spot on to 600 yds and groups were consistently under 1.5 moa. I should have had a 20" group at worst but could not hit at all. I think the 1 in 12 is just not enough twist.

JoeZ

I don't mean to disparage the FGMM at all!! This ammo is very accurate in anything I use it in. It's just at this range with too little twist I think things fall apart.
 
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#18
The 175 GMM is all about getting rounds to 1000 with an M14 in most conditions. Not reading a 5 MPH wind at 1000 will produce about 50 inches of error, while the same wind at 600 would only produce about 18 inches of error. Without pit service and a Data Book a shooter is not going to learn much of anything important to LR since to learn anything requires plotting calls and shots, shot to shot. That may be the best reason if you need one to participate in NRA LR competition, where someone in the pit will spot your hits.
 
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#20
I truly appreciate all the wisdom. I'm going to a class in June just to help me with long range shooting so maybe that will help in my endeavors. I'll never shoot anything hunting past four hundred yards. this is strictly a hobby

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#24
ShawnAcker said:
What do you all suggest for a good barrel to a thousand. Length and twist.

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Click to expand...

Having read some of the other comments there may be more to the wind than I initially led on to. I forgot the 308 has so much wind drift at that range. I have been shooting 338 Lapua and 6.5 Creedmoor too long.

If you do rebarrel you might want to look into the Creedmoor or a 260. You get better terminal ballistics beyond 500 yards, less wind drift, less drop and less recoil. Also some more accuracy. I will take this as an opportunity to brag a bit. Target attached is 10 rounds rapid fired from my buddy's 6.5 Creed. I spent some years with a .308 and I do love that caliber, but the creed is admittedly more accurate in general. Not to sidetrack but you mentioned re-barreling, if you did rebarrel to 6.5 creed I'd go with a 1:8 twist and Bartlein makes some great barrels and they are really good guys to work with. The 6.5 and 260 will both get you well beyond 1k with accuracy we regularly shoot 1,200 yards with 140amax and have great results on an IPSC size target, for length you typically wouldn't want to go below 24" for the 6.5 and with both calibers the longer the barrel the more horsepower you will have downrange, of course since the 6.5 has smaller bore diameter you will see more benefit to longer barrel with that caliber with diminishing returns around 28"-30" for both calibers. You would get beyond 1200 without issue with a 24" 6.5 Creedmoor if you rebarreled. 308 you might want to think about 24" as well, yes it can be done shorter but if you want to stretch it out the extra horsepower is nice.

65Creedmoor_zpsa344f876.jpg
 
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#26
It doesn't matter what size your barrel is, 175s are stable past the barrier. I'm not saying you will get .5moa groups, but it shouldn't be a problem doing 1moa.

Anyways, I think you main issue is that your not spotting your misses. Without good feedback on where your missing, you might as well be dry firing. Estimated velocity is not good enough to get an accurate dope, and even with the correct velocity and bc, that usually doesn't produce exact dope either.

You might have been way off on the wind calls and you were all over the place, like other guys are saying. Or you might have had a 5 inch group but just inches to one side or the other side of the Plate... You wouldn't know without seeing your misses.
 
#27
With that barrel and bullet you are getting in the 2500 range of vel. which also means you are going subsonic around 800 or less. At 1k target your come ups from 100 yd. zero is in the 40moa and higher. since you didn't mention what your come ups were it could be you aren't getting to the target beyond 750. 400 inches is way up in the air where the wind is more of a factor than close to the ground and at subsonic vel. the bullet moves around much more by the wind.
 
#29
I'm in agreement with all the comments about wind being a huge factor. Although it is possible that your bullets are going transonic at 750 yards, it isn't nearly as likely as wind being the problem. Having wind that changes speeds (gusting), or changing directions over the course of the bullet's flight can make big changes in where your bullet impacts.

Although you didn't mention anything about barrel heat, depending on your rifle's setup, barrel heat may be a factor. When I was shooting a 300 Win Mag at 600 yards, barrel heating would require that I dial down .5 moa after about 12 rounds. What was happening was that the stock's proximity to the bottom side of the barrel caused the bottom of the barrel to not dissipate heat as quickly as the upper (unprotected) portion. Just like the bimetal strips used in thermostats, my barrel expanded more on the hotter bottom portion than on the top. So, the heating caused my bullets to go a little higher as the barrel heated up.
 
#33
This past Sunday I did a little shooting with .308 175FGMM over a chrongraph, 85F, humid, near sea level with three different rifles.

R700, 25.5" 1:12 Schneider- 2640fps av.

R700 5R 24"- 2550fps av.

AR-10T 16"- 2430fps av.

As usual, YMMV.

Keith
 
#34
Well I haven't had a chance to respond. Sorry about that. Went out and shot on tuesday . Went in the shop made sure everything looked good. Found front scope ring loose. Got loktite tightened it all down. Got everything sighted back in and went over to a thousand shot 12 inch plate 8 out of 12 shots at a thousand.

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#36
I didn't see any comments about the scope you are using. What are you using and are you dialing up with power for your longer shots ? I was shooting with friend last year that taught me a lot. I shot on paper at 100-300-500 yds keeping my NF F1 on 10x. I didn't dial up on power until 800yds. Later that day I ended up banging steel at 1235yds. My FN-A5 is by far the best 308 I've owned yet.
 
#37
Ok... And correct me if I'm wrong ... You , shot 88 rounds that were ON TARGET. How many weren't on target?? I'm going to presume you shot over 100 rounds. Now, take the wind into effect, 3x3' plate should be easy to hit at 750 with a 175. A tip: back your scopes magnification down and watch for splashes. You've got to have a good follow through to do it but I do it all the time if I'm missing. The key is not too high but not to low on your magnification. If you see it splash low left hold high right. And if your bbl is too hot , your screwed before you pull the trigger in terms of grouping good at distance.
 
#38
My 18" 1/12 Rem barrel with 175SMK from Black Hills (which is traditionally a bit slower than FGMM) averages 2450fps, and I have been able to hit steel out to 1200yds. Yes I'm subsonic at that distance but the bullet seems to tolerate the transition fairly well. When I missed they were close enough to easily see splash.

One thing I haven't seen mentioned is that you're shooting the "7.62" version instead of the ".308" version of the FGMM. The differences are subtle, but my understanding was that the 7.62 version was "optimized" for gas guns or something along those lines. It's been a while since I researched it but there was supposed to be difference between the two.
 
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