Balancing your Rifle? Theories?

[KhaymKhaym]

Hey guys,

I have an MDT setup and an MPA setup, I'll put my build lists below but I am trying to balance both rifles to take as much wobble out as possible and am having some issues. My MPA chassis is balanced about 1-1 and half inches in front of the magwell and it has resulted in pretty amazing stability yet most folks seem to recommend 3-4 inches Infront of the mag well, this is also where my MDT is balanced at.

The MDT though is no where near as stable as the MPA, even though it should be more, in theory. The MDT weighs 26lbs vs 22.5 on the MPA. The MDT has a 4 inch contact area on the bag vs 3 inches on the MPA.

Why is this happening?

MPA Matrix Build
Valdada IOR Recon 4-28x50
ARC 40mm Rings
MPA Internal Weights
MPA Butt stock weight
MPA Competition Side Rails
Bartlein 6BRA Barrel
Hellfire Brake
Defiance Ruckus (Branded Alpha Omega Volition)
Atlas V8 Bipod, sometimes MDT Cykepod


MDT ACC Build
Leupold Mark5 7-35x56
Leupold Rings
Impact 737R
Bartlein 6XC By A-Team Precision
APA Lil Bastard Brake
SendIt Level
MDT Cykepod
MDT Interior Weights
MDT Steel Bag Rider
MDT Butt Stock Weight
MDT Baker Wings
SP Dual Exterior Weights

 

[CoryT]

Physics is your friend. Think about what you are doing when you create the position for the rifle. If you draw a force diagram, what do you see? Many positions can be considered a tripod, where you have three points of contact. Bipod prone has the two bipod feet and your body as contact points. A tripod is most stable when the center of gravity is centered between the points of contact. If for example, we move the bipod back to the balance point on the rifle, you can see how it would be far less stable than if we move the bipod out as far as possible.

General principles, separate the contact points as much as possible and center the weight of the system between those points.

Build a position. Drop a plumb line from your center of balance on the rifle and see where it falls. A balance point that is more centered on the rifle makes it easier to build a position where that weight is centered between supports, if the rear support is always at the butt of the rifle. As the rear support moves forward, the balance point should move forward. Put a bag under the pistol grip and the bipod all the way forward and now the 4" forward point is more centered between supports, and therefore more stable that the magwell centered system.

So, what balance point you choose is (or should be) dictated by the most common positions used and how those positions are built and used. Stability is a trade off for maneuverability. Got targets with wide swings? Center the balance point on a support point and move easily, but be less stable when you finally get there. Center between supports and be solid on target, but more work and time to goto to another target.

 

[b6graham]

remove some front weights to make the balance point identical to the MPA. don't conform to where everyone else says balance should be

might also just be how you interface with the grip/front support hand position of each chassis as well

fwiw i feel more stable behind a matrix versus an ACC also and if i didn't shoot an HRP it would be a matrix

 

[CK1.0]

Sounds like some of that 26lbs on your MDT is in the wrong place..?

The proverbial “3-4” in front of the magwell” seems to mean different things to different people: make sure it settles into a bag there (so you can walk away and leave it there), not just teter-tottering on your palm or something, like when you hold it up.

You might not need all that weight out at the front of the chassis.

FWIW, I use a Lapua blue box to find where I like my balance:

 

[KhaymKhaym]

Sounds like some of that 26lbs on your MDT is in the wrong place..?

The proverbial “3-4” in front of the magwell” seems to mean different things to different people: make sure it settles into a bag there (so you can walk away and leave it there), not just teter-tottering on your palm or something, like when you hold it up.

You might not need all that weight out at the front of the chassis.

FWIW, I use a Lapua blue box to find where I like my balance:

View attachment 7929273

Appreciate the response, and other responses above as well. Let me preface a little bit. The rifle will balance like how you pictured. The MDT honestly balances about where yours does. Yet I have a good bit more wobble with it than I do the MPA. Like B6Graham said though, it could be how I'm interfacing with the rifle myself. Have thought of that just haven't really thought of a way to quantify that and test the theory. I just love my ACC chassis and would really like to make it as stable as my Matrix. If it's just simply not possible then maybe the ACC Elite will be a better fit or one of the new J Allen's when they drop.

 

[b6graham]

the rifle on the Lapua blue box would be WAY too front heavy for me so if that's where your ACC is that may be why it feels off, compared to the MPA which probably balances up against the magwell

 

[BuLLet]

Is that some sort of cat torture device connected to the window?

Is it sleep related?

Sounds like some of that 26lbs on your MDT is in the wrong place..?

The proverbial “3-4” in front of the magwell” seems to mean different things to different people: make sure it settles into a bag there (so you can walk away and leave it there), not just teter-tottering on your palm or something, like when you hold it up.

You might not need all that weight out at the front of the chassis.

FWIW, I use a Lapua blue box to find where I like my balance:

View attachment 7929273

 

[CK1.0]

Is that some sort of cat torture device connected to the window?

Is it sleep related?

Lol, yep, it’s just a bed for cats.

 

[Hoyt7mm]

Balance is very personal preference. Most prefer to setup the rifle so that it will sit on a bag/barricade and not move (IE fall forward to backwards if you come off the rifle). I generally try to setup my rifle so that it balances over the center of a narrow prop (think cattle gate or 2x4 on edge) when I put a bag on it and run my magwell into the bag without a bipod. But again, personal preference.

Couple of things to look into:
1. Strip down your ACC and refit it to you. MPA and MDT are both great chassis, but if you try to set one up to mimic the other, you'll probably be disappointed. Go from the ground up and work on what fits.
2. Get rid of the steel bag rider and rear weight. This will help you pull some weight out of the front and make everything feel more maneuverable.
3. Play with adjusting the ACC grip to get the best interface and 90 degree trigger finger you can (this is my favorite part of the ACC and makes a big difference).
4. Not sure if you have or not, but I'd try raising your ACC butt plate and see if that improves stability.

 

[CK1.0]

the rifle on the Lapua blue box would be WAY too front heavy for me so if that's where your ACC is that may be why it feels off, compared to the MPA which probably balances up against the magwell

Yeah, I’ve just recently gone to a more forward bias (so far I’m digging it), the pic looks deceiving though, in that that’s as far out as it’ll go, most of the mass is still closer to the magwell. IIRC I actually ended up putting 1 of the weights back into the rail near the magwell after taking that pic.

I agree though that the bias is probably what’s messing with the OP: the forward-bias is great for barricade/bag type stuff, but since taking a little more than a full pound off the ass end, it’s not nearly as easy to shoot groups with off a bench or whatever.

 

[Commander184]

Balance is very personal preference. Most prefer to setup the rifle so that it will sit on a bag/barricade and not move (IE fall forward to backwards if you come off the rifle). I generally try to setup my rifle so that it balances over the center of a narrow prop (think cattle gate or 2x4 on edge) when I put a bag on it and run my magwell into the bag without a bipod. But again, personal preference.

Couple of things to look into:
1. Strip down your ACC and refit it to you. MPA and MDT are both great chassis, but if you try to set one up to mimic the other, you'll probably be disappointed. Go from the ground up and work on what fits.
2. Get rid of the steel bag rider and rear weight. This will help you pull some weight out of the front and make everything feel more maneuverable.
3. Play with adjusting the ACC grip to get the best interface and 90 degree trigger finger you can (this is my favorite part of the ACC and makes a big difference).
4. Not sure if you have or not, but I'd try raising your ACC butt plate and see if that improves stability

Like he said in point #2 Get that rear weight outa there!

 

[KhaymKhaym]

Yeah, I’ve just recently gone to a more forward bias (so far I’m digging it), the pic looks deceiving though, in that that’s as far out as it’ll go, most of the mass is still closer to the magwell. IIRC I actually ended up putting 1 of the weights back into the rail near the magwell after taking that pic.

I agree though that the bias is probably what’s messing with the OP: the forward-bias is great for barricade/bag type stuff, but since taking a little more than a full pound off the ass end, it’s not nearly as easy to shoot groups with off a bench or whatever.

I'm shooting off barricades with it, the group aspect I'm not as worried about. I want the rifle to be heavier though than the MPA cause.im shooting 6XC 115 DTACs on the MDT, 6BRA 108 BTTs on the MPA. I'm gonna play with the front weights tonight and see if I can get it to steady up any. I do run the butt pad a tad higher than where it is now also, just lowered it to flush for pics.

 

[kthomas]

Sounds like the MPA just fits you better.

Everyone is different, and everyone interacts with stocks and chassis' in a different way.

Maybe it's a simple setup issue that can be rectified relatively easily. Maybe the MDT is not for you. I love JAE chassis's (my personal favorite), but try to do the simple fix before spending a bunch of money.

 

[b6graham]

^^^ not every chassis fits everyone (ask me how i know X-Ray, MPA BA COMP, JAE, Manners PRS1, ACC, Matrix, XLR Envy Pro, McMillan Z1/Z10; before finally settling on a Henderson HRP (still undecided on my HNT26 versus getting a McMillan Game Warden 2.0)

not sure on your reach, but maybe move the furthest external pair behind the Baker Wings if simply moving both pair backwards as far as possible doesnt move the balance point back a few inches

but i wouldnt be too worried about needing 3.5 more pounds on a 6XC versus a 6BRA. removing a set to make it balance to match the matrix would be worth it to me

i think having two different chassis would be way more annoying

i wouldn't be fighting to make the ACC work if the matrix gives you want you want. probably isn't too hard to add a few pounds to a matrix to get it to 26 pounds for your 6XC

 

[KhaymKhaym]

So last night I was playing with both rifles trying to figure this out and if it was just balance or not. I realized the MPA was certainly rear heavy rather than front. So I took 4lb off the front of my MDT and it balanced an inch further back and it got way more stable. So I tapped a 1lb weight to the rear of the rifle and then it got stupid stable. It seems I stabilize with rear heavy rifles and most folks seem to hate rear heavy rifles.

 

[MDT_Josh]

So last night I was playing with both rifles trying to figure this out and if it was just balance or not. I realized the MPA was certainly rear heavy rather than front. So I took 4lb off the front of my MDT and it balanced an inch further back and it got way more stable. So I tapped a 1lb weight to the rear of the rifle and then it got stupid stable. It seems I stabilize with rear heavy rifles and most folks seem to hate rear heavy rifles.

It's all personal preference and just one thing I'd like to note (take this for what you will): Pay attention the shape of your wobble and what your Natural point of Aim (NPA) looks like.

Typically, if you're fighting and improperly (for you) weighted rifle, your wobble zone is going to be more vertical (as you teeter-totter the balance), whereas as an improperly FITTED stock will provide you with a larger, circular NPA wobble. If you can get behind both guns and observe the reticle movement on target in an unstable position, this should quite quickly tell you which issue you're actually fighting.

An improperly fitted rifle can be adjusted by: LOP adjustment, cheek riser adjustment, buttpad height and angle, grip position and even forend accessory (like the Baker Wings) placement! Keep in mind that in every position, you want your head, shoulder and hips (knees and toes optional) square to the target as best you can for the optimal recoil control!

YMMV.
- Josh

 

[KhaymKhaym]

It's all personal preference and just one thing I'd like to note (take this for what you will): Pay attention the shape of your wobble and what your Natural point of Aim (NPA) looks like.

Typically, if you're fighting and improperly (for you) weighted rifle, your wobble zone is going to be more vertical (as you teeter-totter the balance), whereas as an improperly FITTED stock will provide you with a larger, circular NPA wobble. If you can get behind both guns and observe the reticle movement on target in an unstable position, this should quite quickly tell you which issue you're actually fighting.

An improperly fitted rifle can be adjusted by: LOP adjustment, cheek riser adjustment, buttpad height and angle, grip position and even forend accessory (like the Baker Wings) placement! Keep in mind that in every position, you want your head, shoulder and hips (knees and toes optional) square to the target as best you can for the optimal recoil control!

YMMV.
- Josh

Preciate the response. It was a bit of both. I actually increased my LOP substantially and raised my butt pad up and man, I'm falling in love with the rifle all over again. Going to the range tomorrow to test my work on steel.

 

[KhaymKhaym]

I make all my balance points just in front of the barricade ramp or stop/ magwell on chassis. It provides an index point on a bag that can be intuitively found. When you're shooting a stage and you drop your gun on a barricade or bag, do you want to be trying to focus on the gun being on it's balance point? If it's a vague distance (3.78") forward of the magwell, how do you know you're actually on it when you set the gun in? Are you assuming and then finding yourself with a ton of wobble zone? If it's right in front of the magwell, you just drop the gun in and slide it forward until it stops.

The other thing potentially going on here has nothing to do with the balance point of the gun and is just your position building. In most shooting sports prior to PRS the shooter provided most of not all support to the gun's natural point of aim. By building a gun that balances on a bag/ prop or prop on it's own we're separating the guns mechanical "natural point of aim" from the shooters positional "natural point of aim". With today's 20+lb PRS guns you can bag a gun in on a prop so that it is aimed at a target perfectly. At that point all you have to do press the trigger. And a 14oz trigger press won't disturb a 23lb gun sitting on a bag in it's mechanical point of aim. So you mounting the gun is imparting all the wobble zone in the equation. You could not mount the gun and free recoil the gun but then you would little to no recoil management. Until you add more weight to the gun. And go down in caliber. So you want to mount the gun, execute some amount of recoil management, and watch trace or impact. If your gun balances on it's own, and you can repeatedly find that balance point in the conduct of a stage, then all you have to do is mount the gun without imparting body-wobble into the system. This is where I see the majority of shooters struggling.

Perfect example is shooting from the low-wall position on the PRS barricade. I watch guys single-knee kneel and try to use a pump pillow between their knee and elbow. You are a lot less stable in a single knee kneeling position than a double knee, squared up, isosceles position. You will impart much less body-wobble into a bagged gun that on it's own wants to just sit still with the reticle perfectly centered on the target. Remember, you just have to mount the gun enough to manage a little recoil. And with a 26lb 6BR that ain't a lot. Make your body position solid and ease up on how much you are gripping, grabbing, and pushing on the gun. Like it or not, this is what PRS is. It's a heavy gun, barricade, precision rifle, action shooting sport.

PS, this is not the way I would suggest shooting any other gun in any other sport. It is what it is.

Preciat the response man. Yeah positional stability and position building are absolutely huge and could certainly use more work. However the way I'm testing is using a solid barricade at home that I also use to dry fire off of with a DFAT to practice nightly. Goal is to dial everything in and start going for W's next year. Never the less, right now I just want to make sure all the mechanical setup is where it needs to be to allow me to do my part as easily as possible. Seems like I have got it figured out. I'll be at the range in 2 hours to confirm.