Improving accuracy through harmonics

[falldowngoboom]

This may be a pointless question, but I've taken my rifle as far as it will go through handloading. It shoots about 1 MOA. It's a Marlin XL7 in 30-06.

I've read about people simply slipping cards between the stock and barrel to put slight upward pressure on the barrel to increase accuracy. I plan on trying this, but is there anything else that is REVERSIBLE and can improve accuracy? If a card under the barrel does improve accuracy, how would you make that permanent?

I've also considered sanding down the small support knobs at the end of the stock which holds up the barrel (essentially the opposite) and free floating the barrel. Does anyone have an opinion on if this is a good or bad idea? If it worsens/doesn't improve accuracy, could I just put some epoxy or something to build the knobs back up?

Sorry for all the questions, but I'm a bit stymied as to whether or not I should just leave well enough alone with this rifle.

 

[Afy]

You might want to read up on Optimal Barrel Time, it is something that seems to work. I use it to figure out a starting point for my loads, and then work up from there.

 

[JimmAr]

Free floating the barrel is a popular choice for XL7 owners in terms of increasing accuracy.. sanding the points would be the general idea.. and then bedding it.

I use JB weld for my bedding jobs cheap(3 dollars) and it works.

This should increase the rifles accuracy considerably.

 

[falldowngoboom]

What about just sanding the points? How would bedding the action after doing that help?

 

[JimmAr]

Recoil lugs often have some free space to move around in..factory stocks arent always perfect despite pillar bedding. Down range.. that "little space" can have a big effect on accuracy shot after shot.. now if you bed that the action and recoil lug's free space to almost nothing.. your consistency increases which makes your 3-5 shot groups improve.

After this is done.. some clear nail polish can seal your action screws better once you torque down on them stopping them from loosening up while the gun is fired which is what normally happens w/o a use of sealer.. in my experience at least.

 

[browningguy]

First I would bed the action. I usually try free floating first, and most of the time that works well combined with bedding the action. The few times that doesn't work (my .300 Winnie for example) I usually fully bed the barrel and action. There are better options now, I've seen one system on-line that adds a tunable pressure screw in the foreend. I have not tried one yet but it has possibilities.

 

[Vern Humphrey]

I plan on trying this, but is there anything else that is REVERSIBLE and can improve accuracy? If a card under the barrel does improve accuracy, how would you make that permanent?

By epoxying the card in place with AccraGlas or a similar bedding compound.

I've also considered sanding down the small support knobs at the end of the stock which holds up the barrel (essentially the opposite) and free floating the barrel. Does anyone have an opinion on if this is a good or bad idea? If it worsens/doesn't improve accuracy, could I just put some epoxy or something to build the knobs back up?

Yes. You could use epoxy to build the V-block arrangement back up. One way of doing this is to completely free-float the barrel -- opening up the channel a bit farther than usual, then wrapping the barrel with a couple or three layers of masking tape. Cut holes in the masking tape to corespond with the knobs you want. Coat with release compound and bed the whole barrel. When you remove the barreled action and stripp off the masking tape, you will have a free-floated barrel with two "knobs."

But shoot the gun after free-floating and before replacing the "knobs" to see if all this is necessary.

Bedding the action, as other posters have said, ensures a perfect fit between action and stock at critical points -- such as the tang and recoil lug.

 

[jester_s1]

Isn't the XL7 stock hollow plastic? It's going to be tough to get consistent pressure on the barrel with that material. A bed and freefloat job usually does improve a rifle, but that gun isn't likely to do better that 1 MOA without a barrel and stock replacement.

 

[falldowngoboom]

Thanks all for your responses. They have been very helpful. I will try the card trick and read up more on the process of bedding the action.

Isn't the XL7 stock hollow plastic? It's going to be tough to get consistent pressure on the barrel with that material. A bed and freefloat job usually does improve a rifle, but that gun isn't likely to do better that 1 MOA without a barrel and stock replacement.

Yes, the stock is synthetic, much of it hollow. Why does getting a new stock matter if it's gonna be filled with bedding material anyway?

I was concerned about my gun being capable of sub MOA, but I have shot a few five shot loads during load testing that could have been 1/2" groups if it wasn't for a single flyer. This makes me suspect it's something to do with the configuration of the gun rather than the barrel itself. I could be wrong, so that's why I'd like to try a few tweaks that aren't too difficult to reverse.

 

[hardluk1]

Two things that gave the same results. Simms has made bow vibration eguipment for years and now have a ring for rifle barrels and it does works on 22's. Have seen them on centerfire rifles too. Can get this at midway usa. The cheaper version- A small handfull of large heavy rubber bands all wrapped up just ahead of the stock. If it works buy the simms product.

 

[GodGuns&Guitars]

Limbsaver makes a thing that slips over the barrel that's suppose to cut down on vibration. Have no idea what it's called, but you might check into that.

 

[falldowngoboom]

I think you guys might be talking about the same thing. Boy is that thing is ugly! I'm sure it works and seems like a good idea, but something about putting that thing on the barrel doesn't sit well with me. Also, since this is a hunting rifle, I'd rather not add anything that might slip or move and affect POI.

Update: I slid some super light fishing line between the barrel and stock and ran it up and down. I found a couple places where it was tight, and the stock was either touching the barrel or really close to it. It seemed like a stock imperfection, so I dremeled down the areas so the fishing line could slip through with no resistance. I'm thinking this might make a big difference since the gun barrel was designed to not touch any part of the stock except at the pillar bedding and the support knobs at the end of the stock. Or at least I'm hoping it will...

 

[jester_s1]

About the hollow stock: bedding material won't give you the same rigidity as a quality composite stock. You are talking about adding a pressure point to the barrel, which is commonly done, but if the stock isn't stiff and consistent then your shots will move around vertically.

About the flyers: Typically, a gun problem manifests itself consistently, such as vertical or horzontal stringing or big group size. Flyers are usually caused by inconsistent ammo or poor shooting technique. Small changes like how you sit on the bench, pressure on your shoulder, grip pressure, trigger finger placement, bag placement, and anything else that could influence tension or movement in recoil will throw off your shots.

 

[Bart B.]

Anytime one puts something between the barrel and the stock's forend, they've set up something to move (bend!) the barrel when any pressure's put on the fore end. Rifle weight, sling tension, pressing on the cheekpiece with the fore end resting on something....these all transfer pressure to the barrel through whatever's wedged between the fore end and the barrel. And it ain't gonna be exactly the same for each shot.

Free float the barrel; it better not touch anything except the receiver. Have at least 1/16th inch clearance around it; more's fine. The flimsier the fore end, the wider the gap's gotta be.

If one doesn't want the rifle to be too accurate, then put that stuff back in between the barrel and the fore end.

 

[Vern Humphrey]

You are talking about adding a pressure point to the barrel, which is commonly done, but if the stock isn't stiff and consistent then your shots will move around vertically.

In a hollow, flimsy stock, a pressure point will normally make things worse.

 

[pbrktrt]

I think 1 moa in a hunting rifle especially at that price is amazing. I would leave it alone and go hunting.

 

[USSR]

I think 1 moa in a hunting rifle especially at that price is amazing. I would leave it alone and go hunting.

+1. Quit trying to make a silk purse out of a sow's ear.

Don

 

[jester_s1]

I gotta agree. You're getting alot for your money already. To improve it from this point is going to make very minor changes, unless you put some money into it. You could switch out the stock for an HS Precision or McMillan, but that's a pretty big investment. Work on your shooting technique and handloading technique and those flyers will become less common.

 

[falldowngoboom]

I appreciate the opinions to leave the gun alone. I'm definitely not trying to screw it up, and I'm not trying to make a range rifle out of a hunting one.

That said, if a small (reversible!) tweak can make a difference, I definitely want to make sure that gets done. The slight dremeling I did to the stock was because it was clearly a manufacturing imperfection. Except for the two knobs at the forend, most of the stock wasn't touching the barrel except in two asymmetrical places, so it obviously wasn't meant to be that way. Now that that's gone, maybe that's all I'll need to do. I know... big maybe

As for my shooting technique. It can definitely improve, but my testing is done from a vise with the clamp always pretty loose.

 

[Romey]

Trigger and scope improvement can and often make quite a difference on a rifles groups..

 

[rangerruck]

First things first; improve the trigger. make it lighter, smoother, and with less creep. This ALLWAYS HELPS!!!! No matter even if you are allready a world class shooter(like me!)
Then do 2 things, that are not permanent, won't hurt or sand or damage anything, but will tell you alot.
put a door cabinet close rubber thingy, under the front of the bbl, between the stock, right at the tip of the stock. shoot 2 or 3 groups. then move it rearward in the stock, about 1/4 inch, and repeat, do this 4 times. see which placing gave best accuracy. Get these at home despot. since they are hard rubber, they will not change much, from differing weather, and rain won't effect them at all.
Then for bedding; again Home Despot. get you some aluminum tape.
cut into strips the size of finger bandaids. stack 2 or three on top of each other, like stacking bacon.
take these stacks, and put them inside the bottom of the action inside the stock; on the bottom, sides, front and back, of where the action ' sits down'
inside the stock, this will make it nice and super snug.
then repeat the above shooting steps.
After this, if still not accurate enough for you, it would be time to sand down
the stock channel, which is not reversable. Once you do this though, you will need to repeat the above 2 steps, after trying it in it's natural form first, just now with a freefloated bbl.
this is what the pad thingy's look like;

they have a peel off , sticky backing, so they won't move around, plus since the tops of them are rounded, if you want, get an exacto knife, and cut the tops nice and straight and flat. This will also make the bump lower, and you won't have to correct with your scope so much...

 

[falldowngoboom]

Great tip, rangerruck. I will definitely give that a go. I've already adjusted the trigger down pretty far. It's somewhere between 2.5 and 3 pounds. I'm not sure it goes much lower and am kinda leery about cranking it down much lower anyway.

How much of a gap do I need between the stock and the barrel for it to be truly free floating? 1/16" was mentioned, but is it not enough that I can slip light test fishing line through it without resistance? I'm not too keen on dremeling down the entire barrel channel of the stock to create that much space.

 

[Uncle Mike]

Except for the two knobs at the forend, most of the stock wasn't touching the barrel except in two asymmetrical places, so it obviously wasn't meant to be that way.

Ever wonder why those two knobs are at the end of the barrel channel? People act as though the manufacturer put those pressure points there to intentionally degrade your rifles accuracy...not!

I'm definitely not trying to screw it up,

it can happen when you start making mods to a rifle that is all it can be to start with.

I was concerned about my gun being capable of sub MOA, but I have shot a few five shot loads during load testing that could have been 1/2" groups if it wasn't for a single flyer.

Your serious...! your getting 1/2" groups, except for a flier every now and again and your hot to rip into your rifle?
You have a Marlin XL7..... do you really think it's going to do much better?
Most guys would be happier than a pig rollin; in poopie to get 1/2" groups...!

You can grind all day long, wedge all the junk between the stock and barrel that you can find but I bet a 1/2" is all the better she'll do.. try different ammo first... nothing like cutting your head off to comb your hair, huh. lol hehehe

That stock wiggles around so much that your going to have to have a pretty wide barrel channel, otherwise just the weight of the rifle is going to cause contact... and why grind out the pressure points and THEN put them back with rubber baby buggy bumpers?

If your shooting MOA, or better, 1/2" groups, I'd leave well enough alone before you end up throwing cash on a new stock...leave it alone, save your money, buy better scope, or new stock, or better ammo.

Good luck with it!

 

[falldowngoboom]

Well like I said, I don't want to do anything irreversible to the gun or the stock. I think I made that pretty clear. I figure I can epoxy back the knobs on the forend IF I went as far as to shave it off. And I never for once thought that they were placed there as some way to lessen accuracy. If I did, they'd be off already. Also, I don't plan on shaving down the channel in the stock if that's what I must do to free float it.

I did trim small areas of the stock because it was touching the barrel UNEVENLY. That is definitely not by design.

Also, I can't consistently shoot 1/2" groups. I can't even consistently shoot 1" groups--not all the time. I mentioned that I've gotten groups that would be 1/2" if it wasn't for a flyer. But I always seem to have a flyer if I shoot 4 or 5 shot groups. This is why I suspect it's something to do with inconsistent pressure on the barrel since I test loads from a vise.

I'd love for the gun to shoot MOA or better ALL of the time as opposed to most of the time. And please understand that I'm not complaining about the gun or expecting more out of it. But if I can get more out of it by a couple minor tweaks, why not?

 

[Uncle Mike]

I hear ya... I do think it's doing fine, unless you swap stocks, I don't see any improvement in shimming, but who knows.

As for the fliers...that's pretty much normal with most all sporter, run of the mill hunting guns..shucks, I have some $$$ rifles that consistently fling one south!

Sounds like it's shooting good!