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4" GROUP AT 100 YDS!!!! WHAT THE HECK? - SOLVED!!

M

mram10

Sergeant
Full Member
Minuteman
Feb 8, 2010
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Idaho
I reloaded for a Sako A7 300wsm with mixed win and fed brass. I wasn't sure how many times each had been shot. Here are the steps I took:
1. FL sized
2. cut brass to size
3. tumbled for about 30 min
4. put in primers
5. hand measured powder for each case
6. set bullets to within .005 of lands
Then we shot them and they sucked! Scope was tight. Action screw were tight.
Help!
 
Re: 4" GROUP AT 100 YDS!!!! WHAT THE HECK?

1. Sort your brass into lots, neck size if head space is fine and shoot groups w/in lots.

2. .005 to the lands? Try .03 to .04.

3. Work up a powder charge using a method. Then vary seating depth.

4. Try different bullets. Try different powders.

Good luck.
 
Re: 4" GROUP AT 100 YDS!!!! WHAT THE HECK?

Buy a lot of new brass! Prep, and load all the same. I bet you will get moa.

Terry
 
Re: 4" GROUP AT 100 YDS!!!! WHAT THE HECK?

Chamfered, deburred,debur flashole and recut primer pocket. complete brass prep a must.
 
Re: 4" GROUP AT 100 YDS!!!! WHAT THE HECK?

Once you have the brass squared away work up loads in about .3 gr increaments until you get to the velocity that your barrel likes. A chrono is a great tool for working up loads.

You have to match the velocity to the harmonics of your barrel to get the best accuracy. See here Barrel Harmonics.

The .3 gr increaments will get you close enough to then do another batch up and down by .1 gr to find the sweet spot. The chrono really makes this interesting because you can record the velocities for each target and then visually see the groups get tighter as you approach the sweet spot and then see them spread as go above the sweet spot.

I suggest 5 shot groups for work up loads.

Once you have found that then you can fine tune it even more with things like bullet seating, neck sizing, etc.
 
Re: 4" GROUP AT 100 YDS!!!! WHAT THE HECK?

mram10 have you shot factory ammo out of this thing before and if so what was that accuracy like?
 
Re: 4" GROUP AT 100 YDS!!!! WHAT THE HECK?

any gun designation with an "A" and a "7" involved in the name is going to be inaccurate. Hope this helps

]:)
 
Re: 4" GROUP AT 100 YDS!!!! WHAT THE HECK?

Which bullet?
What is the twist rate of the barrel?
What powder?
What charge weight?
Which primer? Magnum, large rifle, good condition?
How were you shooting them? Bench, prone?

Is this rifle typically more accurate?

We need more info.
 
Re: 4" GROUP AT 100 YDS!!!! WHAT THE HECK?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: suasponte</div><div class="ubbcode-body">Buy a lot of new brass! Prep, and load all the same. I bet you will get moa.

Terry</div></div>

+1, remember inconsistent neck tension means inconsistent velocity. Inconsistent velocity means not only an inconsistent trajectory but inconsistent recoil as well. Inconsistent recoil means angular error, and this is what you're experiencing.
 
Re: 4" GROUP AT 100 YDS!!!! WHAT THE HECK?

I have loaded for this gun before and it has shot sub moa with the exact same recipe! 168 TSX, 66.5 & 66.8 R17, Win LR, Win brass. I mixed new and old Win and Fed brass and I wonder if that is what did it. Some might have had the necks turned and the others didn't. We bought new brass last night and will try it again today. I will do the "lot" way you guys talk about. Thanks for the input guys.

Primer pockets:I clean them with a brush, but have read others on this website saying you don't need to uniform them. Shoiuld I get a uniforming tool?
 
Re: 4" GROUP AT 100 YDS!!!! WHAT THE HECK?

I've been experimenting with identical loads and brass prep but with different types of brass. Just yesterday I zeroed at 100y with Lapua brass, then tried two other varieties. Both shot similar sized groups, but one was 2" low and the other 1" left.

Note that the groups were on the order of 1/2", so the movements mentioned were readily apparent.
 
Re: 4" GROUP AT 100 YDS!!!! WHAT THE HECK?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: mram10</div><div class="ubbcode-body">I have loaded for this gun before and it has shot sub moa with the exact same recipe! 168 TSX, 66.5 & 66.8 R17, Win LR, Win brass. I mixed new and old Win and Fed brass and I wonder if that is what did it. Some might have had the necks turned and the others didn't. We bought new brass last night and will try it again today. I will do the "lot" way you guys talk about. Thanks for the input guys.

Primer pockets:I clean them with a brush, but have read others on this website saying you don't need to uniform them. Shoiuld I get a uniforming tool?</div></div>


Exact same recipe? By that do you mean "mixed brass"? Any mixed brass, from mixed brands, or even of the same brand but mixed lots, will yield inconsistent neck tension no matter how you massage it. Once again the problem is your mixed brass.
 
Re: 4" GROUP AT 100 YDS!!!! WHAT THE HECK?

I would get a primer pocket uniforming tool. They are not that expensive, easy to use and only takes a few seconds to use. It is a recommended procedure in Glen Zediker's books.
myerfire
 
Re: 4" GROUP AT 100 YDS!!!! WHAT THE HECK?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Sterling Shooter</div><div class="ubbcode-body">
Exact same recipe? By that do you mean "mixed brass"? Any mixed brass, from mixed brands, or even of the same brand but mixed lots, will yield inconsistent neck tension no matter how you massage it.</div></div>

Not to mention inconsistent case volume. Without a load worked up for the gun and with mixed brass, the results aren't surprising. All the other brass prep... trimming cases, deburring, chamfering, flash hole deburring, primer pocket uniforming... those will get modest improvements, but do not explain the 4 MOA!

Use a single lot of brass, work up the charge weight using the Audette's Ladder Test or OCW (pretty similar), then work up the seating depth, and you should be able to beat factory match ammo.

If you want, you can add the other brass prep steps: trimming (which is a must, but not for virgin brass), chamfering, flash hole deburring (not necessary with Lapua), primer pocket uniforming (again, not necessary with Lapua, but you will want a primer pocket uniformer just to clean out the primer pocket after each firing anyway), and, if you really want, neck turning and case head squaring.
 
Re: 4" GROUP AT 100 YDS!!!! WHAT THE HECK?

4 MOA is a tough feat to accomplish, even with poor reloading technique, which doesn't seem to be your problem. Go ahead, try some new brass and see what you get. But your results sound like a mounting issue. I know you said the screws are tight, but check the base and rings again. If that is all straight, and you are still getting poor accuracy, then you might have a problem with the barrel, the crown, or just a really bad load. You need to work the load up with varying powder drops.
 
Re: 4" GROUP AT 100 YDS!!!! WHAT THE HECK?

Nobody mentioned you need to Anneal the necks. Neck annealing is one of those things many people forget about, but is absolutely crucial to continued consistent neck tension. Most people who do neck anneal, do so at 3 to 5 firings. To be on the safe side, 3 is good.

Brass quickly Work Hardens as you reload it. This work hardening can quickly cause inconsistent neck tension, thereby causing your loads to become erratic..

Now as for weight sorting, yes that's a good idea as well. Another thing to possibly consider is using 91% rubbing alcohol to measure the internal case volume. Use the good alcohol, rather than water, as it will quickly Flash Dry. Water can easily cause problems unless you take extra steps to make sure it evaporates.

Good Shooting
Gary
 
Re: 4" GROUP AT 100 YDS!!!! WHAT THE HECK?

Shot again today and it is not doing very well. Only a few loads groups decently. I will check all the thing syou guys have told me and get back to you. I did get lazy and didn't do a ladder test for it. I did clean it really well today and removed a bunch of carbon and copper that was in the barrel. 3 days till hunting season and I gotta get this figured out for my friend. Thanks again guys, I will keep you posted.
 
Re: 4" GROUP AT 100 YDS!!!! WHAT THE HECK?

4 MOA at 100 yards????. I would check scope and action to make sure that they are appropriately torque. Make sure that your charges are correct, ie, your scale doesn't drift. Neck tension and primer hole debur, and case weight aren't going to correct 4 MOA groupings. Yes, they will influence your accuracy, but 4 MOA??
 
Re: 4" GROUP AT 100 YDS!!!! WHAT THE HECK?

OP,

You could indeed have a multitude of problems, but starting with the fact that the bullet will always go in the direction the barrel is pointed, two things are clear, your ammunition and/or your relationship with the gun and ground are not consistent. Think about it, that's to say, call your shots and analyze the call/strike corollary. And, yes, mixed brass could easily get you 4 MOA groups at 100 yards. Since some of the effect is about inconsistent recoil, the angular nature of the error will show increased displacement at distance.

One more thing, as important to good shooting as loading is, it's a complete waste if recognition for the need to get a perfect position is not known. Stockweld, and butt-to-shoulder inconsistency can negate all the work to produce perfect ammunition.
 
Re: 4" GROUP AT 100 YDS!!!! WHAT THE HECK?

Hard to tell without actually seeing you shoot. Sometimes it is technique.

I can get guys who ask me at the range to consistently hit bull after I see how they are shooting.

Can you describe how you are doing your shooting? Like shooting off bags? What kind of rests?
 
Re: 4" GROUP AT 100 YDS!!!! WHAT THE HECK?

"I have loaded for this gun before and it has shot sub moa with the exact same recipe!"

With that record it's unlikely the 4" groups are ammo related nor is your shooting skill poor.

Either the stock has warped or the scope has taken a dump.
 
Re: 4" GROUP AT 100 YDS!!!! WHAT THE HECK?

Definitely buy some Hornady factory match ammo for a comparison. If it is still shooting 4 MOA, it is not the handloads.
 
Re: 4" GROUP AT 100 YDS!!!! WHAT THE HECK?

"mixed brass types = bad results"

Yeah, a little. I've seen 1 moa groups grow to 1.5 due to mixed cases. Never seen groups quadruple due to mixed cases. Have seen it with scopes that went bad due to loose lenses tho, several times.
 
Re: 4" GROUP AT 100 YDS!!!! WHAT THE HECK?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Master_Blaster</div><div class="ubbcode-body">any gun designation with an "A" and a "7" involved in the name is going to be inaccurate. Hope this helps

]:) </div></div>

C'mon, James Bond shot down a helicopter with an AR-7.
 
Re: 4" GROUP AT 100 YDS!!!! WHAT THE HECK?

4" at a 100? That's what I get at 50 yards your doing great!!
 
Re: 4" GROUP AT 100 YDS!!!! WHAT THE HECK?

John Doe,
Actually, I was bragging about my skills
smile.gif
Sorry, bad joke.
To answer your questions, my shooting technique was off a 12-23 Harris bipod (high, but it is my friends gun). Bipod was resting on fairly loose desert dirt, not rock. Right hand was gently gripping the stock and trigger (light trigger). Off hand was under the butt of the stock using a fist to adjust hight. I tried to keep my cheek in the same spot each time by keeping both eyes open while shootin and cycling the bolt with cheek still against the stock. Sometimes I am lazy on my form, but I tried to get back to the basics after it shot so bad. We both shot and got the same horrible results. I am going to take the whole thing apart and check for problems. I will keep you posted.
Note: I do not like the recoil lug engineering on the Sakos at all. Too many loose and moving parts.
 
Re: 4" GROUP AT 100 YDS!!!! WHAT THE HECK?

Frick!!
I just took it apart to make sure it was all as advertised. He had the scope bases (cheap aluminum) installed at Cabelas so I didn't think twice at first. After removing the scope I found that 2 of the aluminum base screws were stripped and the other 2 were not even finger tight. We shot 120 rounds in the last week and I should have checked that for him!! Thanks again guys. Either way, I learned a bunch from you guys as usual.
 
Re: 4" GROUP AT 100 YDS!!!! WHAT THE HECK?

Told you it was a mounting problem. You're welcome.
 
Re: 4" GROUP AT 100 YDS!!!! WHAT THE HECK?

Palmik,
Thats why I ask you guys. You always know the answers to my questions. Again, thank you.
 
Re: 4" GROUP AT 100 YDS!!!! WHAT THE HECK?

No problem man, any time
 
Re: 4" GROUP AT 100 YDS!!!! WHAT THE HECK?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: mram10</div><div class="ubbcode-body">Frick!!
I just took it apart to make sure it was all as advertised. He had the scope bases (cheap aluminum) installed at Cabelas so I didn't think twice at first. After removing the scope I found that 2 of the aluminum base screws were stripped and the other 2 were not even finger tight. We shot 120 rounds in the last week and I should have checked that for him!! Thanks again guys. Either way, I learned a bunch from you guys as usual. </div></div>

LIke I said before, I use mixed brass sometimes too. I have never ever seen a 4 MOA at 100 yards. May 1, or 1.5 MOA at very most, if I am sloppy. Anyway, I am glad that you solved the mystery. Happy shooting.
 
Re: 4" GROUP AT 100 YDS!!!! WHAT THE HECK?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: mram10</div><div class="ubbcode-body">I reloaded for a Sako A7 300wsm with mixed win and fed brass. I wasn't sure how many times each had been shot. Here are the steps I took:
1. FL sized
2. cut brass to size
3. tumbled for about 30 min
4. put in primers
5. hand measured powder for each case
6. set bullets to within .005 of lands
Then we shot them and they sucked! Scope was tight. Action screw were tight.
Help!</div></div>

Interesting, in your first post [see quote] you said that you checked scope and it was was tight, now, you say it was not tight. Kind of hard to help someone on-line when the basis for shooter/target analysis changes.
 
Re: 4" GROUP AT 100 YDS!!!! WHAT THE HECK?

"..we shot them and they sucked! Scope was tight. Action screw were tight."

Glad it was so easily fixed. You faked us out when you said the scope was tight tho; sounded like you had checked all that.
 
Re: 4" GROUP AT 100 YDS!!!! WHAT THE HECK?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: mram10</div><div class="ubbcode-body">Frick!!
.. He had the scope bases (cheap aluminum) installed at Cabelas so I didn't think twice at first. After removing the scope I found that 2 of the aluminum base screws were stripped and the other 2 were not even finger tight. .. </div></div>

I take tools to the range and help other people.

Fully 50% of the time I am getting bad groups or someone else is getting bad groups, it is the mount to receiver screws.

A suspicious indicator for this is two holes touching on the target and then two holes touching way over there on the target.

I suspect that this happens so often because people do not want to take the scope with rings off to check, for fear of losing zero. The ring cap screws and ring to mount screw do not seem to have many problems, probably because it is easier to check.

For guns I want to depend on, I:
1) glass bed between mount(s) and receiver, while fixtured to align mounts with the bore
2) clean screws and screw holes with alcohol
3) dry the screws and holes
4) Put Loctite 242 on the screws
5) Tighten the screws.
 
Re: 4" GROUP AT 100 YDS!!!! WHAT THE HECK?

I used to buy all that cheap mount stuff, but I learned my lesson. Was always fighting a mount prob. Now I only use the good stuff and Wheeler pro scope mounting kit. Amazing how those probs disappeared.
 
Re: 4" GROUP AT 100 YDS!!!! WHAT THE HECK?

Sorry again with the "fake out". I assumed they did their job with the mounting. We all know what that leads to.
 
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