Confusing .308 reload results...solved!

[SDeadeye]

I just got back from the range and I'm not really sure what to think of the results. Maybe someone here has an idea for me.

I'm shooting a Rem 700 SPS Tactical .308...1/12, 20" barrel. It's got an EGW 20 MOA base, Burris XTR 30mm rings, and a 6.5-20x44 Vortex Viper scope. I bought it a week ago, this was my second range trip. I am shooting prone off of a bipod with a rear bag.

I've got 2 different loads that I worked up using the OCW method on my first range trip.

168 grain Hornady HPBT Match
Win Brass (1x Fired in my rifle)
45.6 gr. RL-15
2.810" OAL
CCI 200's

175 gr. SMK
New Win Brass
44.7 gr. RL-15
2.810" OAL
CCI 200's

When I shot my OCW loads the first time out, these two shot under an inch at 100 yards, along with the loads above and below them in charge weight. I adjusted my scope between range trips, so I shot again at 100 yards today just to get it back on target. The 168's I put into a .5" 5 shot group and the 175's were just under an inch for 5 shots.

Then I moved the target out to 250 yards. I shot 2 groups of 5 shots each, one with the 168's and one with 175's.

I didn't change my scope from my 100 yard zero, and at 250 yd both loads hit about 8" below my point of aim, in about 1.5" goups. That was the first puzzling part.

I went down and checked the targets, taking my time so the barrel could cool off. It wasn't hot, but warm to the touch. About 15 minutes later I shot another set of both loads, and not one of them hit the paper. From the marks in the dirt it looked like i was shooting high, so I adjusted the scope a little. I shot about 5 more rounds and they were all over the paper. By that time, I was getting annoyed and the sun was going behind the trees, so I brought the target back to 100 yards to make sure my scope hadn't moved or something. I dialed back to my zero marks, and put 8 shots in about an inch, shooting pretty quick.

So long story short, I have no idea why it would go from .75 MOA groups at 250 yards and 20 minutes later not be able to hit the target. I loaded the ammo last night, and trickled every charge in to within 1/10 grain and probably closer to 1/20th.

Any ideas?

 

[jakermeister]

Re: Confusing .308 reload results

did you check your scale every 10 or so loads? Were the rounds going from good to bad? If so, it may have been your scale.

 

[SDeadeye]

Re: Confusing .308 reload results

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: jakermeister</div><div class="ubbcode-body">did you check your scale every 10 or so loads? Were the rounds going from good to bad? If so, it may have been your scale. </div></div>

I zeroed my scale at the beginning, and loaded about 20 rounds and took a break, then re zeroed before I started loading again. I purposely loaded rounds 1% above and 1% below my target charge weight, and marked those. At 100 yards those hit right with my optimum load, just like the OCW instructions say they should. So I would have to be over 1+ grains off for it to show up, and probably more to have that drastic of an effect.

It didn't really go from good to bad. The first set I shot at 250 were good groups, but 8" low. The second set didn't hit the paper. Like flipping a switch.

 

[tullius]

Re: Confusing .308 reload results

First groups ok. Second groups ok: 8" low @ 250 is fine if round is moving slow. 3rd & 4th groups are shooter error, probably in manipulation of optics.

First, rerun your ladder test twice as described by TresMon at 250 yds. Once @ 100 yds. is not enough.

Then run the same exact routine again, paying attention to things & use larger paper. Bet 3rd & 4th groups won't replicate.

 

[Niles Coyote]

Re: Confusing .308 reload results

Are you running the rifle with the factory hogue stock or something else?

 

[SDeadeye]

Re: Confusing .308 reload results

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Niles Coyote</div><div class="ubbcode-body">Are you running the rifle with the factory hogue stock or something else? </div></div>

Factory, shitty, hogue stock. I'm stuck with it until I can recover from buying the rifle and get some bills paid off. During the winter when it's too cold to shoot I'll work on upgrading the stock.

 

[tullius]

Re: Confusing .308 reload results

Not the stock.

 

[Niles Coyote]

Re: Confusing .308 reload results

When you say “all over the place” was a lot of it vertical stringing, like a string/oval or more of a large round circle?

On the next trip out pay very close attention to how much pressure you are loading into the bipod. If you have a partner with you have him check the barrel clearance with a dollar bill and see if it is touching while you are in your shooting position.

That stock is weak and will flex and touch the barrel with a bipod. It is very likely a contributing factor at the longer distance.

 

[Niles Coyote]

Re: Confusing .308 reload results

When I first got my 223 tactical, 3 years ago, I ran into a problem at 300y. The rifle was a solid ½ MOA at 100y, same load at 300y was large string pattern. After switching from the bipod to a sand bag under the action (not the forearm) the problem went away and I had my nice round group back with a little wind error in the mix.

 

[SSC]

Re: Confusing .308 reload results

What about scope and base mount? Do you have another scope you could try on it?

 

[gcoulsey]

Re: Confusing .308 reload results

+1 on bipod loading..
If I'm having a bad day laying prone, I get inconsistent point of impacts too, and it's always my error by loading the bipod more or less between shot strings as the feet dig into the dirt.
I can see how the more flexible factory stock could exagurate the problem for you.
I usually quit early, then next time at the range it's all magically better again.

 

[Kells81]

Re: Confusing .308 reload results

Get a new stock and repeat the test. As mentioned above bi pod loading is more than likely what is killing you.

 

[esromvre]

Re: Confusing .308 reload results

ok what were the enviormentals that day? You were shooting 1 moa @100 and .75 moa @250 not overly odd to me. what did the groops look like. elevation or was it wind?

bullet speed the bipod how clean the barrel is lots of differnt things can be part of this.

pm me if you want to get togather and shoot some time.

 

[Hummer]

Re: Confusing .308 reload results

You can also have a barrel that is not stress relieved properly and when it starts to heat up it bends.

The "dollar bill" method was the standard for a thousand years but with the plastic stocks being so flimsy and prone to shooter induced error from bipod torque, all bets are off. I like 1/8" clearance all the way around the barrel.
For instance I had a Savage 7/08 Scout rifle. The only way it would shoot was to have the rifle in a completely relaxed position with bipod out and butt on sand bag and reach up VERY GENTLY without disturbing natural point of aim, grip it and pull the trigger and it was on the money at 600 yards. ANY ROTATIONAL force applied I could then count on it to group in the back end of a bus at 600.

 

[SDeadeye]

Re: Confusing .308 reload results

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: esromvre</div><div class="ubbcode-body">ok what were the enviormentals that day? You were shooting 1 moa @100 and .75 moa @250 not overly odd to me. what did the groops look like. elevation or was it wind?

bullet speed the bipod how clean the barrel is lots of differnt things can be part of this.

pm me if you want to get togather and shoot some time. </div></div>

Weather was sunny, 75* F, off and on 5 mph breeze. I was shooting at Gov't field so elevation was probably 4200' ish.

I only shot .75 moa for the first 2 groups at 250, after that I was lucky to hit the 2'x3' target. When I did get holes in the target, it looked like someone had shot it with 00 Buck from 50 yards, just random holes.

I'm starting to think that as I got tired I started loading the bipod more than usual, which made the stock touch the barrel and throw my shots all over the place.

Since I'm stuck with the stock that I have for the time being, last night I bedded a piece of aluminum C channel into the fore end of the stock, and filled it with JB Weld. The stock is way more solid now, I can really lean into the bipod and the stock still has plenty of room before it touches the barrel.

Hopefully I can get out sometime this week between classes and work and see if that helped at all.

 

[ccoker]

Re: Confusing .308 reload results

interesting, let us know what happens

my dad did a similiar thing on a Sako 22-250 he built in 1966
cut a piece of aluminum tubing in half lengthwise, cut a channel in the forearm and glass bedded it

That gun still shots 1/2" 200 yard groups

 

[vman]

Re: Confusing .308 reload results


- Could be the stock piss-farting with barrel harmonics, as has been stated above.

Did you clean the rifle inbetween when it went from good to bad?

How is the crown?

How do you clean your brass cases? Are the cases wet after cleaning and if so how long do you dry your brass for? Could some of the reloads have been wet inside the cases?

 

[SDeadeye]

Re: Confusing .308 reload results

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: vman</div><div class="ubbcode-body">
- Could be the stock piss-farting with barrel harmonics, as has been stated above.

Did you clean the rifle inbetween when it went from good to bad?

How is the crown?

How do you clean your brass cases? Are the cases wet after cleaning and if so how long do you dry your brass for? Could some of the reloads have been wet inside the cases?

</div></div>

No cleaning in between, just went down and checked the target, came back and started shooting again.

Crown looks like new.

Brass is cleaned in a tumbler with corn cob media.

I'm leaning toward the stock idea myself.

 

[gcoulsey]

Re: Confusing .308 reload results

Aside from the stock flexing onto the barrel with bipod overload, it still makes a POI difference even with barrel clearance for me..

I certainly don't have clearance issues with the AICS, but bipod loading still affects recoil management, and alters my POI.
That's what I have to pay most attention too shooting prone on soil.

What I'm getting at is.. Even with your bedding fix, it will pay to keep consistent on loading the pod

Hope it all works out for you!!

 

[SDeadeye]

Re: Confusing .308 reload results

Well, I think I found the issue. After bedding the aluminum channel into the stock and giving the barrel a little more room the rifle is shooting much better. I shot the same loads at the same distance at the same location. The original loads shot into about 1.5 moa at 260 yards.

I tried out some loads that were seated .010" and .020" longer than the originals and accuracy got better as the bullet was seated farther out. The 168's ended up at about 1 moa and the 175's came out to just over .7 moa.

So, moral of the story, the stock flexing was causing the majority of my problems. Now that the problem is fixed, I can keep on with my load development.

So here is where I'm at with my loads so far.

168 gr. Hornady Match BTHP
Win. brass fireformed and neck sized
CCI 200 LR primers
45.6 gr. RL-15
2.830" COAL
Approx 2550 fps...seems a little slow to me

(Changed it until my drop matched the data from Shooter)

175 gr. SMK
Win. brass fireformed and neck sized
CCI 200 LR primers
44.7 gr. RL-15
2.830" COAL
Approx. 2700 fps

 

[Bloody_Tailgate]

Re: Confusing .308 reload results

If you have some laying around you should try some Win or Fed LR primers with your load. I have found that the RL powders don't agree with CCI primers.

 

[SDeadeye]

Re: Confusing .308 reload results

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Bloody_Tailgate</div><div class="ubbcode-body">If you have some laying around you should try some Win or Fed LR primers with your load. I have found that the RL powders don't agree with CCI primers. </div></div>

No Win or Fed, but I do have Wolf LR primers. Once I get these loads where I want them, I'll give the other primers a try and see if it helps any.