Optimal gun weight distribution between the front/rear rests

[Bginvestor]

Hi Folks,

For light/heavy bench rest guns, I'm looking for any guidelines on optimal gun weight distribution between the front/rear rests. I'm expecting there's a good compromise between splitting the center of mass of the gun to the front/rest rests for maximum accuracy.

Any suggestions/guidelines? I'm going to range soon to test out.. Thanks!

 

[Bginvestor]

Ha ha! With over 30 views, I guess I stumped accurateshooter!

That's ok, I'm going to the range and going to carefully test this out. I believe this is a big deal to get right.

 

[Pawnee Bill]

Not a benchrest shooter, but I really don't see what the Center of Gravity of a rifle has to do with accuracy. Please enlighten me.

 

[Bginvestor]

Ok, my heavy gun is about 40 lbs. the front and rear rest has to react this total load. Depending on the front / rear position to gun’s mass CG location, the front rest will react load magnitude different with different rest positions. I believe there’s an optimal ratio of reaction load distribution that produces best tracking and gun accuracy ( vertical dispersion). One of the less talked about topics but all things need to be considered for 1000 benchrest.

 

[rayporter]

balance matters and it matters a lot.

once when shooting at a day before a match a fellow [new shooter] was having considerable trouble shooting a group at 100y. read half in groups. 4 or 5 guys milled around him and i was 10 benches away so did not say anything. after a an hour or two. they all wandered down to my bench and asked me to help.

i had a half dozen shells loaded and just set the guy down at my rifle and had him shoot. he shot fair. ok - shooter eliminated

next had him bring his rifle and some ammo down and shoot on my rest. after i tweaked his load a little he shot decent.

so shooter and rest and ammo now eliminated. what's left? we go down to his bench.

this was a LV gun and he had the rest set so it was way far back. way heavy in the front and light in the rear. custom made for vertical.


i was going to have him shoot off of it for me but before i did, i adjusted the rest so it was near the front of the forend and i taped a bullet box up so he could only push the rifle ahead to the box which kept the weight between the rest and the rear bag,

instant success. instead of half inch groups he shot less than a quarter and near .2.

it pays to find where your rifle likes its balance and where it does not like it.

 

[gunsandgunsmithing]

I agree that good balance/tracking/handling are critical to a good build. You'll get lots of answers as to the ideal balance point. I think most will tell you that the cg needs to be at the receiver face to about an inch forward of it.
I think the reason you'll hear different answers is that there are lots of factors at play, like overall weight, recoil, rest and shooting styles. I use a different balance point for a 13.5lb 30 cal as opposed to a 10.5lb ppc, for example. But when in doubt, I'd rather deal with a butt heavy gun than a nose heavy one.

 

[newbieshooter]

Ha ha! With over 30 views, I guess I stumped accurateshooter!

That's ok, I'm going to the range and going to carefully test this out. I believe this is a big deal to get right.

Experiment with Fore and Aft Rifle Position on Rest and Bag « Daily Bulletin

To get the best accuracy out of any benchrest rifle, you need to find the optimal position of front rest and rear bag. The important point to remember is that each rig is different.

bulletin.accurateshooter.com

 

[Bginvestor]

I agree that good balance/tracking/handling are critical to a good build. You'll get lots of answers as to the ideal balance point. I think most will tell you that the cg needs to be at the receiver face to about an inch forward of it.
I think the reason you'll hear different answers is that there are lots of factors at play, like overall weight, recoil, rest and shooting styles. I use a different balance point for a 13.5lb 30 cal as opposed to a 10.5lb ppc, for example. But when in doubt, I'd rather deal with a butt heavy gun than a nose heavy one.

your opening up another can of worms which is the gun's mass CG location.. I was just talking about front/rear rest position relative to a gun. lol

 

[gunsandgunsmithing]

your opening up another can of worms which is the gun's mass CG location.. I was just talking about front/rear rest position relative to a gun. lol

I'm very sorry. I didn't mean to open up a can of worms but I think the two are related. Play with where the stop and rear bags are a bit and I think you'll find what you and the gun like best. It can make a big difference in how the gun works in the bags. Good luck and Merry Christmas!

 

[Bginvestor]

I'm very sorry. I didn't mean to open up a can of worms but I think the two are related. Play with where the stop and rear bags are a bit and I think you'll find what you and the gun like best. It can make a big difference in how the gun works in the bags. Good luck and Merry Christmas!

Thank u sir!

 

[mdbruce]

50-50. Put scales under your rests and look like a stud.

 

[Bginvestor]

50-50. Put scales under your rests and look like a stud.

did u pick a number out of ur head, or is this based on testing?

 

[Terry]

I have shot nose heavy rifles and balanced rifles. I shoot balanced rifles better. I strive for 50/50. I have weighed my rifles end for end to check this. If I must shoot a nose heavy rifle I look for a longer stock to compensate. Most of my rifles balance at the front of the action.

 

[357Mag]

Hi Folks,

For light/heavy bench rest guns, I'm looking for any guidelines on optimal gun weight distribution between the front/rear rests. I'm expecting there's a good compromise between splitting the center of mass of the gun to the front/rest rests for maximum accuracy.

Any suggestions/guidelines? I'm going to range soon to test out.. Thanks!

Bg -

Howdy !

If your rifle is configured w/ a " barrel block ", ITS location on the barrel....its contribution to " balance " of the barreled action ...and its contribution to dissipating unwanted "vertical" are perhaps the larger questions ?


With regards,
357Mag

 

[Bginvestor]

Yup , its nose heavy! The mass CG is 5.5" in front of the action w/ the heavy barrel block.

I'm an engineer, and I did the static calcs. No way I can get 50/50 or ratio of 1. More like ratio of 1.8 (front):1 at best , at least with my arrangement.

This gun was a boomer with the Obermeyer barrel, but we recently brought it out of retirement, and the old rest setup was sold off. I developed a new rest system that is being tested now.

this is getting interesting..

 

[357Mag]

Yup , its nose heavy! The mass CG is 5.5" in front of the action w/ the heavy barrel block.

I'm an engineer, and I did the static calcs. No way I can get 50/50 or ratio of 1. More like ratio of 1.8 (front):1 at best , at least with my arrangement.

This gun was a boomer with the Obermeyer barrel, but we recently brought it out of retirement, and the old rest setup was sold off. I developed a new rest system that is being tested now.

this is getting interesting..

Bg -

Howdy !


Thanx for the prompt response.

Please let us know how this progresses for you.


With regards,
357Mag

 

[rayporter]

another
at a big shoot that had over 50 benches i was talking to a hall of famer with a LOT of HOF points as he walked down the firing line. it was a LV class and he was observing rifles. on occasion he would lift the butt of a rifle testing its wt on the rear bag. it was something he considered important.

 

[Bginvestor]

I did some testing yesterday, I was able to make some observations.

I shot some 3 shot groups at several front rest positions at 100 yards. I found that if I push the front rest way forward, it shot worse. My hypothesis is that the flexibility of the stock is causing more vertical dispersion.

Anyway, I have a barrel block, so I don't think this will be useful for a lot of folks, but posting if interested.. Hopefully you guys can follow my spreadsheet. The Reactions loads are calculated using hand calcs, not a weight scale. The reaction ratio is simply the front reaction divided by rear reaction. no way I can get to ratio of 1 , which is 50/50.

Maybe folks will find it a little interesting.. any thoughts, appreciated.

 

[Alex Wheeler]

I would not conclude it was stock flex because things did not progressively get worse. In a light gun 60/40 works well, its very hard to get 50/50. In a 36lb gun I do not think it will matter much. The problem is with lighter rifles the butt can bounce off the bag, in a heavy rifle thats far less of an issue.

 

[SHall]

I would not conclude it was stock flex because things did not progressively get worse. In a light gun 60/40 works well, its very hard to get 50/50. In a 36lb gun I do not think it will matter much. The problem is with lighter rifles the butt can bounce off the bag, in a heavy rifle thats far less of an issue.

Alex is on par here of course. Another great gunsmith, Clay Spencer was big on balancing a BR rifle. Most BR gunsmiths these days do the same. Like Alex said, Clay use to say the same, if I remember corectly, about 60% front, and 40% rear. And Clay wanted the weight between the bags. He did not like to add anymore weight in the rear of the butt than necessary. He would rather have more weight in the action itself than put lead in the butt in other words. On a long range BR rig, Bill Shehan told me to balance about 1 inch in front of the action is about right.
From my experience over the years, there is no perfect formula, we may think there is, but there is not. I just try to get close to the 60/40 ratio anymore. Like Alex said, you mainly dont want the rifle nose heavy and butt so light it will bounce in the rear bag. A great barrel tuned to great bullets is where the utmost accuracy lies. Not a perfectly balanced rifle. I would rather go to the line with what I call a great barrel or “hummer” mounted on a tobacco stick wrapped in baling twine, than shoot a new barrel I had not found the best load for and mounted on the best stock available and balanced out to be theoretically perfect. Those great barrels seem to shoot no matter what they are mounted on. Samuel Hall