2 inches high at 100 yards?!?!

greg11

greg11

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I'm shooting .308 175gr SMK's over 38grns H4895 at 100 yards.

I am having some big troubles shooting. Basically, I don't have a clue what I'm doing. Some of my shots hit my POA, but some hit 2 inches high. it's sort of 25% hit my POA, 75% are 1"-2" high. I'd adjust my optic, but then my next shot hits my POA and I get all confused and don't know whether I should turn the dial, or leave it where it is....

Just so I can eliminate one thing, can someone tell me how much difference in vertical POI 1 grain of powder would make at 100 yards? I imagine it wouldn't be significant at all at 100yds, only really showing at 200-300+ yards. I could be really wrong. In any case, my lee auto disk doesn't throw THAT terribly (not even close to 1 grain deviation, more like a spread of about 0.2 either way, MAX [0.4 total]). Just wondering for curiosity's sake, perhaps I can rule this out.

If that isn't it, then it must be my body positioning and how I absorb the recoil or something. But damn, 2"!?!? It doesn't FEEL like I'm being that inconsistent from shot to shot. Maybe I'm underestimating how inconsistent I actually am!

Clearly something is amiss, whether it's me or my load.

I know you'd have to see me shooting to really diagnose what's going on here... But I'm thinking maybe theres a total rookie mistake that "happens to everyone" or something. Just looking for some help before I blast another 40 rounds tomorrow trying to figure this out!!!

I'm shooting from a bench, BTW, which I suspect might have something to do with it (not as stable as prone). But I'm really trying to get behind the gun (body mass) on every shot.
 
If you are not focusing properly you can get odd elevation changes, as well as your shoulder placement and follow through.
Do you know what "automatic alignment " is?
if not PM me.

Cat
 
Check the focus on your glass and the parallax if its adjustable. Last but not least make sure you aren't canting the rifle

TDC

eta. Don't forget to check your mounts.
 
Jamie said:
get someone else to shoot a group
Click to expand...

This. Fasted way to eliminate a shooter as the problem.

Also, 1gr of powder can certainly make that kind of difference. Not just because of the velocity difference, but it will create different barrel harmonics that will change your point of impact. It can be in any direction from the previous load, it could be that in your case the change in POI is straight up.

One last suggestion: leave the scope adjustments alone until you are satisfied with your grouping.
 
Frm my experience working up loads for a 308 I dont think one grain of powder would raise your POI by 2" but I could be wrong.

The best thing for you to do is clean your barrel properly and run some copper solvent through it , then check to make sure everything is tight including your bolts that hold the action in the stock.

Next time you take it out to the range try and find a chrono to mesure your speed , I think your high shots are either faster or something is loose.
308's are easy to make shoot so ,by the sounds of it you are reloading for it so a scale would be better than throwing a charge.
 
oh going threw my reloading manual your load is under the starting point, I have starting 40grs and 42.7 max
 
-You might have a two inch ESA (Expected Scoring Area) at that range. If so, most any group you shoot consistently will be about two inches - minus 'called' flyers. By adjusting the scope, you are merely 'chasing errors'. Find a reasonable load, and fire several five shot groups. break your position after each group, then test and adjust your position and fire your next group. If the groups wander around the page, there is a lack of consistency on your part (probably). If the groups print on the same spot, adjust your scope so the groups print on the CZP (Correct Zeroing Position) which in this case, is your POA (Point of Aim) since you are zeroing AT 100 FOR 100.

Have someone else try the rifle as wisely suggested above. Don't worry if it prints in a different spot for him/her (it should, probably). Check out the group ES (Extreme Spread - 'size'). If the other firer can consistently group 1" and you group 2", it ain't the rifle/load/scope that needs practice.


Oh, remember to have FUN doing this.
 
I have a Sightron SIII 8-32x56mm. Shouldn't I be putting them all in one hole?

JOKE.

Just some more info base on your guys' inputs thus far...

I'm shooting a Savage PC .308 (figured you'd need to know my gun too...). Action screws are tight. I checked parallax while I was shooting, and it seemed to be right on. I have a Vortex bubble level on my optic, and was keeping the bubble in the same spot consistently from shot to shot.

I just checked my rings and it seems they were a little loose (backed off from where I had torqued them). I have Burris Sig Zee rings, and in the 30mm variety of these rings, there are four screws holding the top piece onto the bottom piece, I think I had them unevenly torqued, letting them back off through recoil...

I'll have to shoot again tomorrow and start from scratch.

Also, on my rings it seems that the top pieces are as tight to the bottom pieces as they can go. Shouldn't there be a bit of a gap there? I'm thinking the rings aren't biting onto the scope as tightly as they should be, and that instead the top ring-piece is bringing up against the bottom ring-piece (giving the illusion of "bite" when I am torquing my ring screws).

The scope seems quite solid, but maybe I should think about getting a 0.010" insert kit. As they would be fatter, maybe I'd be able to make the rings bite the scope body harder (instead of the top ring-piece butting up against the bottom ring-piece). Again, I don't even know if this is an issue. Perhaps there is actually enough bite. I'll have to wait and see tomorrow... The wait is killing me because I want to go shoot some groups NOW!

Tonight I made 20 180gr SMK's over 38.2 grains of H4895 and 40 168gr Hornady HPBT AMAX's over 40.2 grains of the same powder (I ran out of 175 grain SMK's, only have 200 180 SMK's left now ARGHHHHHHH!!!! Close enough to replicate today's conditions? Maybe).
TCBF said:
Oh, remember to have FUN doing this.
Click to expand...

I am!!!!!! :p

But I'm reloading for $0.70 a shot. I just hate "teaching myself" when I know 10 minutes with an experienced shooter could have me a lot of needless trigger yanking. But I suppose learning this way is the best way to learn, in some respects....
 
greg11 said:
I just hate "teaching myself" when I know 10 minutes with an experienced shooter could have me a lot of needless trigger yanking. But I suppose learning this way is the best way to learn, in some respects....
Click to expand...

Nope, learning from someone who knows what needs to be done and can coach effectively is the best place to start. By trial and error you are making mistakes, some of them will stick around for years.
 
No, I have not. I might be wrong, but I feel like at this point, withe the problems I'm having, I won't be able to tell for sure which loads are good, and which are poor. Until I can consistently shoot "groups" (that is, strings of shots which hover around my POA), I think I'd be guessing which of my hypothetical recipes is a good one. As of now, I'm all over the place, with no rhyme or reason, and 2MOA is quite a lot to be "off". I think at this stage, load development might not be the solution to my problem?

Again, that's just kinda what I'm thinking at this point. Perhaps I should work some loads up. Maybe that's all I need to do. So many variables it's enough to make one's head spin!!!
 
You need to work up a load if you want tight groups and you need a scale otherwise you are pissing away your amo imo.

You mentioned something about your scope rings ,it would be a good idea to lap your rings for optimum performance but the gun should still shoot reasonably well even if they are not lapped.

From what I have seen over the years working up loads for the 308 is that things start coming together when the pressure starts building up.

Look in your reloading manual and if it has a starting load of lets say 40gr load 5 and load 5 more 40.5 and work it up your groups will tighten up when you hit a certain node .

Then play with the bullet for lenth you should initialy load your bullet so it just touches the lands in the barrel it is a good starting point.
 
Gee, I'll take a shot at guessing.

No doubt about which is dominate eye?

Are the reloads partially filled or extremely full before bullet seating?

Are you leaving the gun alone and letting it recoil into your shoulder?

Are you positioning the forend on the rest the same each time?

Where is your off hand positioned every time you shoot? Are you holding the forend tightly?

Bullet weight, length velocity etc. compatible with barrel twist rate?

Usually when I get high POI it is my off hand support underneath.
 
skypilot said:
Gee, I'll take a shot at guessing.

No doubt about which is dominate eye?

Are the reloads partially filled or extremely full before bullet seating?

Are you leaving the gun alone and letting it recoil into your shoulder?

Are you positioning the forend on the rest the same each time?

Where is your off hand positioned every time you shoot? Are you holding the forend tightly?

Bullet weight, length velocity etc. compatible with barrel twist rate?

Usually when I get high POI it is my off hand support underneath.
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,

Thank you skypilot and dpopl8r, coyote and everyone else!! Lots for me to chew on!!!

I'm using a bipod...

I'm not leaving the gun alone, I'm kindof pulling it into me a little. My off hand is manipulating a sandbag I have under the butt of the riflestock (adjusting rifle's elevation). Maybe I should just leave the rifle alone. But then I get thinking about "loading" the bipod?

reloads are pretty full. Could probably squeeze a few more grains in there, but if you're wondering about an air pocket inside the cartridge, there probably is one in there, because I'm not "full" totally...

Rifle is 1:10 and I'm using 175-180SMK, which I think is appropriate for that twist.

I'm already thinking of some things to work on thanks to you guys...

Remember when Donald Rumsfield gave his "Unknown Unknowns" speech? That's how I feel. I feel like there are some things I know I don't know, but can read up on, discover, and master. But the on the other hand I feel like there are a ton of things that I don't even know I don't know. These unknown unknowns are what I need you guys to help me with. I very much appreciate all the comments here, and rest assured, I'm going to play around with the suggestions here.

I'll also begin working on some loads and playing with charges, safely of course. Thanks guys. Keep it coming! :p

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