Larger than MOA groups. What would you check first?

[Lefty2506]

Then the whole rifle, then finally a few pages later, the whole rifle fell off the bench and landed on the turret. I think you knew the answer to the question the whole time. Maybe hoping for a miracle that it was load.

Not to be critical of anyone, and to be fair, if I had dropped my rifle off a bench and onto the the scope turret, I'd be on here asking for suggestions to see if there could be another possible problem, not just because something else could be wrong, but because I wouldn't want to admit to myself that I'd dropped my rifle 3 ft onto the turret. On the up side, Vortex has a great warrantee

 

[Gun Man Dan]

117 replies. Did everyone forget he said the rifle dropped 3 feet to the floor and it landed on the scope turret with the weight of the rifle on it.

I’m just the new popular kid in town. Haha

 

[RegionRat]

117 replies. Did everyone forget he said the rifle dropped 3 feet to the floor and it landed on the scope turret with the weight of the rifle on it.

You quoted my post, why?

 

[dellet]

Not to be critical of anyone, and to be fair, if I had dropped my rifle off a bench and onto the the scope turret, I'd be on here asking for suggestions to see if there could be another possible problem, not just because something else could be wrong, but because I wouldn't want to admit to myself that I'd dropped my rifle 3 ft onto the turret. On the up side, Vortex has a great warrantee

It’s funny how certain details are sometimes glossed over. That certainly wasn’t meant as a jab, other than the whole story is important.

Years ago trying to help someone shooting 240 Matchkings in a 300 Blackout, the guy had the exact opposite attitude and he was bound and determined to get a sub MOA subsonic group. Actually kind of tough to do past 100 yards. At some point in the multi page thread he mentioned that he thought that the problem was a stupid chamber design where it was impossible to load to the lands with the cartridge. I thought me meant at magazine length, and told him at magazine length he should have a .010” jump, if he wanted a jam, single feed it.

He was adamant that a 240 SMK would fall out of the case before it hit the lands and the discussion got a bit lively. The chamber was designed for that bullet ti jam at 2.270”, he was loading to 2.400” +.

A quick search of previous posts and the reason I remembered his name was clear. Not long before he had been advocating his cleaning methods and had been pounced on by a number of people. Seems his preferred method of cleaning carbon out of the chamber involved a stainless brush and a Makita.
That explained the long jump.

 

[Gun Man Dan]

It’s funny how certain details are sometimes glossed over. That certainly wasn’t meant as a jab, other than the whole story is important.

Years ago trying to help someone shooting 240 Matchkings in a 300 Blackout, the guy had the exact opposite attitude and he was bound and determined to get a sub MOA subsonic group. Actually kind of tough to do past 100 yards. At some point in the multi page thread he mentioned that he thought that the problem was a stupid chamber design where it was impossible to load to the lands with the cartridge. I thought me meant at magazine length, and told him at magazine length he should have a .010” jump, if he wanted a jam, single feed it.

He was adamant that a 240 SMK would fall out of the case before it hit the lands and the discussion got a bit lively. The chamber was designed for that bullet ti jam at 2.270”, he was loading to 2.400” +.

A quick search of previous posts and the reason I remembered his name was clear. Not long before he had been advocating his cleaning methods and had been pounced on by a number of people. Seems his preferred method of cleaning carbon out of the chamber involved a stainless brush and a Makita.
That explained the long jump.

I try to be open minded. Text mood isn’t dictated by the writer so much as is dictated by the reader’s mood.

 

[RegionRat]

I try to be open minded. Text mood isn’t dictated by the writer so much as is dictated by the reader’s mood.

Just trying to help and not trying to be condescending, but when you were asked for the background back at post #17, you didn't reply.

That would have closed much sooner on two salient points. 1) you dropped the gun on the scope. 2) you just changed to a different barrel and were not happy.

The rest of the confusion becomes inevitable due to your experience level and is to be expected, but leaving out the very critical parts of the background story was not helping you.

It makes this troubleshooting process take much longer than is necessary if you hold back critical points when asked background questions.

I will still stand by my follow up advice... Go to a club and get a mentor, learn to keep notes.

You show that you live in Canton Ohio, so you have clubs and mentors within range that would help you get up the steep parts of the learning curve.

They would have swapped the scope and discussed the details in closed loop on everything else, and probably shot the tests for you to eliminate the driver, and possibly your ammo too.

Learning this as an adult and in a vacuum isn't easy, and the internet is full of noise. Go take a look at the local clubs and see if anyone there is teaching reloading and mentoring. Good Luck and in for the range reports.

 

[Coyotefurharvester]

Reloading requires attention to detail. Precision/accurate shooting requires attention to details. So a question which is accompanied with a lot of information, is in the wheelhouse of this crowd(Accurate Shooters forum members). Besides being informative, for myself reading/participating on this site is entertaining and enjoyable. Yes, I do take my tools to sight in days at the range. RegionRat I was typing and just read your remarks, still posting my thoughts, hope they aren't to redundant.

 

[Gun Man Dan]

Sorry I missed some of your questions. I appreciate your help.

 

[Jeff Porter]

Dan - while I believe you will find your problem lies in the scope, let me share some recent result with an old ‘98 Mauser action with a .308 barrel on it. TLDR - Skip down to the pictures if you do not want to here the whole story about the rifle.


This rifle was sporterized decades ago into a pencil barreled .243 win by a gunsmith in Ossian Indiana. Came into my possession about 30 years ago and I schwacked a ton of coyotes with that rifle. About 10-12 years ago it quit shooting the tight knots with the 58 Vmax so I decided I would try my hand at rebarreling and chambering a new barrel. I got a fluted Green Mountain barrel and rented the reamers and borrowed an action wrench and barrel vice and the experience and garage of Bruce Drake and had myself my first .308. I took the gun out of the Ramline plastic stock and put it in a Magpul pillared stock. The gun shot about 1 moa with the 3-9 scope and weaver rings I had on the .243 version with standard 168 match loads. I wanted to mount a better scope but I discovered that the receiver had been driller for the Weaver mounts quite a bit out of line. When I put a one piece mount on it. I ran out of windage before it was zeroed. I had a “gunsmith” drill a MGW rail for me but he did not understand the problem and basically drilled the holes in line with each other but not the bore. The gun sat in the safe I fired for a long time. Years. A couple of years ago I got some 30mm Burris rings and used the 20 moa inserts to get the scope aligned with the bore. Scope on the rifle is a 4-16 Millet Long Range. Not a high dollar scope but better than what I had on it. I shot some factory ammo again about 1.5” groups, not happy. then got some very accurate bolt rifles and the rifle went back in the safe while I played with the tack drivers.

Recently I got the idea I needed to pick a sub moa load for that rifle and load up a stash of ammo for it as a back up hunting rifle / SHTF gun. I have been to the range playing with 168 Nosler Sierra SMK and TMK and 175 SMK and Nosler too. But … all with Varget powder. Keeping the load at magazine length ( even though the Mauser is a long action and can take up to 30-06 3.3” rounds ) I tried a charge ladder from 42-45 gr and never had a 5 shot group better than 1.2”. So today for a change of pace I pulled a box of 175 SMK loaded with 42.5 gr RE-15 at mag length(2.800”) first shot was just off of the next 4. 5 shot group 0.65 moa group. I re set the scope knobs to “0” and shot three more shots into another 1/2” nest. On top of each other.

Moral of the story - it may be the scope, it may be the shooter But it could be your new barrel doesn’t like one of your components for whatever reason. Keep your barrel happy.

TLDR folks
.308 Mauser long action, GreenMountain fluted barrel, Millet 4-16 Long Range Mildot scope on MGW rail mount.
Using LC-11 2x fired brass, WLR primers 168 SMK,TMK and Nosler 168. Nosler and SMK 175’s. Varget powder. Mag length ammo. No groups under 1.2” most closer to 1.5-2” range. Typical test target shown

Switched to RE-15 powder at 42.5 gr. All other components the same.


Now to see if it repeats the results in larger samples.

 

[Gun Man Dan]

Here’s a question for the group. Scope mount lapping. Do or don’t? Now that I have my scope off I noticed what looked like areas where the scope came into contact with the rings and areas that might not be. I’m considering lapping the rings, but wanted to seek some guidance first or maybe someone else’s experience.

 

[RegionRat]

How about this time you describe the mounting hardware and post photos up front.
There may be something in the way you are assembling hardware, or it may just be low quality stuff that needs work, but we can skip a whole lot of posts if you add the details up front.

ETA: sometimes a drop and some bad luck, and the hardware is trashed to where you are better off in the long run to pull it all off and re-torque everything with new fasteners and Loctite and and a critical eye. We don't want to put a good scope on broken mounts....

 

[Gun Man Dan]

Vortex 34mm rings. There are faded areas and shiny areas on the insides of the scope rings mounted to a 20 MOA base.

Tada! I followed instructions.

 

[RegionRat]

After what that hardware went though, I would take it all off and clean everything up, then re-Loctite the base to the receiver and then retorque the rings.
They shouldn't need to be lapped, but if they are bent they may need it.
You will want to ink up and use a lap bar to see if they are straight or if they even need lapping.

Don't throw any babies out with the wash water, in other words... look for loose fasteners while you work backwards.

Have you ever used layout ink to test area contact?

ETA: is that a cleaning rod through the action... no bore guide?

 

[Gun Man Dan]

After what that hardware went though, I would take it all off and clean everything up, then re-Loctite the base to the receiver and then retorque the rings.
They shouldn't need to be lapped, but if they are bent they may need it.
You will want to ink up and use a lap bar to see if they are straight or if they even need lapping.

Don't throw any babies out with the wash water, in other words... look for loose fasteners while you work backwards.

Have you ever used layout ink to test area contact?

I have never used layout ink. I’ll take everything off tomorrow. I need a new bottle of lock tight. Good idea.

 

[Coyotefurharvester]

And a torque wench(inch pounds) for assembly.

 

[RegionRat]

The concept is simple.

You lay a tool called a lapping rod in the bottom rings and very gently apply light pressure and see how the ink pattern is affected after you slightly spin that tool back and forth a little. It should show area contact. In a bad example, it would be all edge contact that would require lapping (or part swapping) to correct.

There is a chance the drop could have caused damage, but this is why we double check everything as we troubleshoot in your situation. Check the top straps for damage too.

In fact, while you wait for the scope to return, now is the time to scrub the whole rig. Pull the action from the stock and make sure you don't have damage. Watch for loose fasteners as you go. Put everything back to spec torque as you go.

I would even double check the barrel is still at headspace and make sure the barrel nut hasn't moved. Scrub the barrel and make sure the crown isn't damaged.

Go through the whole bolt and trigger assembly while you are at it.

This kind of rifle should be what I call a Fat Minute Gun, meaning it shoots inside a minute for 5 shots, and holds roughly a Fat Minute for 20 or 30.

Every now and then, one of these runs better, but not always. You have replaced the barrel, and the odds are in your favor that it should shoot.

 

[Benchrest Braxton]

lapua brass doesn't fix 1 moa groups

 

[misser]

I’m having issues with my groups being pretty big. I have a 24” shilen SS barrel in 6.5 creedmoor with a 1:8 twist. I shoot out to 100 yards 95% of the time. I do not have a chronograph, but I trust my reloading processs with 140gr Hornady ELD match and 39.5 gr of H4350 powder with CCI primers. Hornady brass that’s been fired 3 times now. I’m getting runout pretty consistent if 4 or 5 thousandths.

I’m at a loss. Where would you look first to make a difference?

for runout ? get a device to straighten them. my self i dont used hornady brass ,found it to be a bit off ,1-2 thousands when spun in the checker . really nothing to be worried about

 

[Gun Man Dan]

The concept is simple.

You lay a tool called a lapping rod in the bottom rings and very gently apply light pressure and see how the ink pattern is affected after you slightly spin that tool back and forth a little. It should show area contact. In a bad example, it would be all edge contact that would require lapping (or part swapping) to correct.

There is a chance the drop could have caused damage, but this is why we double check everything as we troubleshoot in your situation. Check the top straps for damage too.

In fact, while you wait for the scope to return, now is the time to scrub the whole rig. Pull the action from the stock and make sure you don't have damage. Watch for loose fasteners as you go. Put everything back to spec torque as you go.

I would even double check the barrel is still at headspace and make sure the barrel nut hasn't moved. Scrub the barrel and make sure the crown isn't damaged.

Go through the whole bolt and trigger assembly while you are at it.

This kind of rifle should be what I call a Fat Minute Gun, meaning it shoots inside a minute for 5 shots, and holds roughly a Fat Minute for 20 or 30.

Every now and then, one of these runs better, but not always. You have replaced the barrel, and the odds are in your favor that it should shoot.

Thank you. I’ll give that a go. I’ve been doing a lot of reading and am currently struggling with a carbon ring. There have been several situations where the bolt was tough to open. I didn’t know that was linked to high pressures. The carbon ring is an absolute pain to remove. I’ve been working at it for hours already.

 

[Gun Man Dan]

lapua brass doesn't fix 1 moa groups

No, but it will take out any inconsistencies in the brass I am using. It’s not going to be an overnight fix. One thing at a time. I think it’s a worthy investment. Next is a chronograph when I get my bonus at work.