Adding Weight

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Tony Q
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Joined: Mon Jun 20, 2005 8:04 pm
Location: Adelaide (MBRC)

Adding Weight

#1 Postby Tony Q » Thu Jul 14, 2005 3:46 pm

Adding weight to a rifle is something, as some tell me, that can improve how the rifle behaves under recoil with resulting ‘possible better accuracy’. Obviously a 20 kg rig is going to be steadier than a 10 kg rig but at what point does it become worthwhile if at all?

If your rifle is 8kg what true affect, bringing it up to say 9 kg, is the result?

Is the extra weight added to keep the original balance point of the rifle ( split between front and rear) or is it trial and error?

Is the extra weight placed in line with the receiver as low as you can to lower the center of gravity?

Any thoughts???
MBRC F-Class standard ... and proud of it!

RAVEN
Posts: 1978
Joined: Sun Jun 19, 2005 9:37 pm
Location: Adelaide South Australia (CTV)

#2 Postby RAVEN » Fri Jul 15, 2005 12:55 am


"RSI Shooting Lab" RECOIL ESTIMATOR

Recoil for a 17 lb. firearm
175 gr. bullet @ 2720 fps Muz. Vel.

impulse = 3.2 lb./sec.
free velocity = 6.1 fps
free energy = 9.9 ft. lbs.


Recoil for a 14 lb. firearm 175 gr. bullet @ 2720 fps Muz. Vel.:

impulse = 3.2 lb./sec.
free velocity = 7.4 fps
free energy = 12.1 ft. lbs.


Tony this is the difference between my old rem 700 sendaro HS stocked
and the re-barreled blue thiny
it doesnt boot any were as much and I can shoot it free recoil with out being hit
Its only 2lbs diff but makes a very dif when you are behind it!!
Cheers
RB :)

Guest

#3 Postby Guest » Fri Jul 15, 2005 7:40 am

I understand Richard, your 7mm kicks quite a bit so any reduction for you is a +++

But what about a mild kicker like the 308.

Is ther anything to be gained by adding weight to the rifle?

RAVEN
Posts: 1978
Joined: Sun Jun 19, 2005 9:37 pm
Location: Adelaide South Australia (CTV)

#4 Postby RAVEN » Fri Jul 15, 2005 9:44 am

Hey Tony give me the weight of your rifle and velocity of bullet and I can work it out

Tony Q
Posts: 1044
Joined: Mon Jun 20, 2005 8:04 pm
Location: Adelaide (MBRC)

#5 Postby Tony Q » Fri Jul 15, 2005 10:30 am

well my rifle weighs 5 kg so i can go another 1 kg.

I know the absence of recoil is one of many factors atributed to finer accuracy. But in regard to my original question .. where do you add the weight?

it makes sence to keep the outfit balanced but i read a post on another thread where he adds or removes lead shot from the butt untill the rifle behaves.

I guess one answer is to just try it with a bit of lead blank and see what happens :)
MBRC F-Class standard ... and proud of it!

RAVEN
Posts: 1978
Joined: Sun Jun 19, 2005 9:37 pm
Location: Adelaide South Australia (CTV)

#6 Postby RAVEN » Fri Jul 15, 2005 10:56 am

I don’t know much about reloading 308 cal and velocities they achieve but here is an example what recoil reduction you would gain with adding weight


Recoil for a 11 lb. (5Kg) firearm with 47 gr. smokeless powder firing a 155 gr. bullet at 2850 fps Muz. Vel.:

impulse = 2.8 lb./sec.
free velocity = 8.2 fps
free energy = 11.4 ft. lbs.

Recoil for a 13.22 lb. (6Kg) firearm with 47 gr. smokeless powder firing a 155 gr. bullet at 2850 fps Muz. Vel.:

impulse = 2.8 lb./sec.
free velocity = 6.8 fps
free energy = 9.5 ft. lbs.

Most weight is added to the butt Tony
There are also recoil reducing products that are inserted into the rifle butt
that can reduce felt recoil
Cheers
RB

Tony Q
Posts: 1044
Joined: Mon Jun 20, 2005 8:04 pm
Location: Adelaide (MBRC)

#7 Postby Tony Q » Fri Jul 15, 2005 11:02 am

Thanks Mate.


i might just try it and see if it has any improvement in overall accuracy. The rifle will print 1/2 min at 300 but additional weight may take care of some of those odd shots (if they are recoil related)
MBRC F-Class standard ... and proud of it!

Cochran
Posts: 26
Joined: Sat Jun 25, 2005 5:42 am
Location: Texas

#8 Postby Cochran » Fri Jul 15, 2005 12:39 pm

Hi Tony

In my case the 30" straight taper barrels I use are about 10 to 11 lbs. The complete rifle runs about 18 lbs. but tends to be nose heavy. The butt tends to ride up or jump out of the rear bag. I put about 2 lbs. of lead in the butt, held in with clay so it doesnt rattle around and have the pad held on with screws. I add or remove enough untill I like the way the rifle tracks. Then I mix the shot with glue and glue the butt pad on permenantly. I'm not trying to make max weight or reduce recoil. Just balancing the rifle. I think to much weight in the rear tends to make the front jump around on the front rest. I was scoring for a guy not long ago with a fairly light barrel. The left side of his forend would jump up off the front rest about 10-12mm when he fired.
I have a buddy who's rifle balanced well but wanted to reduce recoil. He had mercury recoil reducers installed in the butt and forend.

Jeff
Texas

Tony Q
Posts: 1044
Joined: Mon Jun 20, 2005 8:04 pm
Location: Adelaide (MBRC)

#9 Postby Tony Q » Fri Jul 15, 2005 3:42 pm

Hi Cochran


Thanks, my question was not in regard to reducing recoil but rather what affect would the extra weight have on overall accuracy potential.

Is it slim?

Is it non?

Is it trial and error?

Is your accuracy improved because of the reduced recoil?
MBRC F-Class standard ... and proud of it!

Cochran
Posts: 26
Joined: Sat Jun 25, 2005 5:42 am
Location: Texas

#10 Postby Cochran » Sat Jul 16, 2005 6:01 am

I dont think adding weight just to make the rifle heavier improves accuracy. In benchrest plenty of people use thier light guns in heavy gun class without any disadvantage.
I think adding weight to balance the rifle reduces fliers. As far as how much weight. Enough so the rifle is not decidedly nose heavy or tail heavy is all I'm looking for. For my rifle configuration its usually 1.5 to 2 lbs to put the balance point just in front of the reciever. Its problably alot more critical in a light weight gun.

Jeff


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