Sporter weight and Balance

B

Bob Kingsbury

New member
At one time, I recall seeing someting about two scales being used
to determine how much weight on front bag and rear for sporters
and LV. May have been something from speedy. Was this study ever
completed.
 
I'm beginning to think the "tune" is the sum of many factors. We use to think of changing the tune by powder charge only, then "tuners" were added as a variable. I've also long believed that changing bullet jam is essentially the equivalent of a couple tenths of powder, And I wouldn't be surprised if neck tension changes couldn't be mirrored by power changes too.

That said, if you look at Varmint Al's modeling, where the front rest is placed also seems to affect tune. I had a 1995 Kelbly-built rifle with their weight system. The common opinion was that if you put in the rear weight --about 2 pounds -- all you got was a butt-heavy rifle. Yes. Well, if you then moved the front rest back, less of the weight was on the rear bag, and it shot lights-out. In fact, it shot better as a HV (rest moved back) than as a LV. Of course, all the other variables (powder, jam, neck tension, etc.) were the same.

So, I don't think there is any theoretical *ideal* balance. Obviously, you don't want the rifle too light on either of the bags. But I believe weight distribution (i.e., bag loading) is just one of the tune factors.

FWIW, & that's probably not much. (FWIWBTPNM, but not NSOLWFMO)
 
For new shooters. How a gun groups has a great deal with how the "bag balance" is. Especially if you are shooting free recoil, the gun must be balanced so it recoils smoothly and exactly the same each time.

Balance in the bags can be fine tuned for smooth recoil by where the front bag sits in relation to the forearm and where the rear bag sits in relation to where the butt plate is. For example, if the rear bag is in a position where the bag ears are contacting the butt plate or if the butt plate is sitting on the part of the rear bag where it can hang or rapidly drop down and cause the gun to suddenly tip up in recoil.

Set the gun in the bags. Pick the gun up at where it sits in the front rest and guess at the weight at that point versus what the whole gun weighs. Pick up the gun at the butt stock where it sits on the back bag and feels how it weighs. Generally, for me, I like about 60% of the gun weight is on the front and 40% is on the rear.

And, as Don Geraci told me one time, put the gun in the bags and back off, then look at how it sits and how it looks. You can tell a lot by just looking at the setup.

Within all the above, the further the two rest points are apart the more stable the setup will be.

Always, always, press down on the gun hard while sliding it back and forth before firing the first sighter shots.

(FWIMBW, CE)
 
Lets suppose that you had a good sporter. Apparently balanced well,
because it was a good shooter. Then You changed the Barrel and
added a Maximum HV barrel. Nothing added to rear and bag placement
same as sporter set up. All this in a McMillan stock with rounded
bottom at rear bag contact. This gun is not balanced on the front
rest, but very very light in back. Now, with out thumb pressure or any
thing similiar--What can be expected ---any real experience here
 
One very good (HOF) shooter that I know, shoulders, cheeks, and makes trigger hand contact with his rifle. From that we know that your hypothetical can be made to shoot (all other things being equal), but, in my opinion, you would be giving up the free recoil option (assuming you will be staying under 10.5#), one that I value, especially when done heads up, in switchy conditions.

Some time ago Dick Wright was asking for questions to ask Tony Boyer for a second (or third) interview for PS. My question, which he used, was whether Tony would sacrifice barrel weight for rifle balance. The answer was yes.

Since barrel weight as it related to accuracy is an interest of mine, I have asked several top shooters whether the barrels commonly used on sporters need to be as heavy as they usually are (for peak accuracy). Invariably, the answer was no.
 
More Barrel = Nothing

I have proven to myself, (for my own satisfaction), that you do not need a gosh awful heavy barrel for great agging capability.
Several years ago, I added tuners that add about 6 ounces of weight to my Rifles. I had to get rid of some weight to make 10.5 pounds.
I started cutting my barrels to where there was only about 1 inch of "straight" left on a standard 1.200 LV-Sporter barrel profile. This yeilded a barrel that weighs only 76 onces at 21 1/4 inches.
This is what I use on my favorite Sporter. That Rifle has did pretty well for me over the past 4 years.
When I went to the lighter BRX Stock two years ago, (lost four ounces), I added a brass butt plate in the rear rather than adding barrel weight to get it back to 10.5 pounds. If anything, performance is better.
I really do not know at what point the light weight of a barrel will affect it's agging capability, but it sure isn't at 76 ounces.
Bt the way, I am no big fan of weight systems and the such to convert a LV-Sporter to HV. If you are going to shoot a HV, put the weight in things that (might) count, like added material in the stock, barrel, etc........jackie
 
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