rifle jump with benchrest set-up

[richard_123]

new to discipline of benchrest. what would cause rifle to jump (up) in front bag when fired? seems to slide well. Rifle balance? Hardness of front bag? Weight of rifle? Facts are: rifle is 14.5 pounds., 24 inch number 7 contour lilja barrel in 308, 3 inch front flat, edgewood front bag with 3" spread, Caldwell rock be front rest (don't like it--but what i have right now) , edgewood rear bag and donut. Does it regularly. need to solve before i start load testing

 

[Travelor]

I did not see what stock you are using.

My experience is that the "jumping" is probably caused by a combination of your stock design and caliber (IE recoil). But without the above information I am just assuming.

 

[CJ6]

Dryer sheets F/R . Try it

 

[whiskey08]

Id check the position of the stock on your shoulder, and your body posistion. Sometimes a bench makes it hard to get behind the rifle.

If you have an adjustable buttplate then you can use that to help take out jump.

Also what helps me with the .308 is a hard hold. I pull it in to my shoulder fairly hard and that helps control recoil so i can see impact of bullet on target.

 

[richard_123]

definitely having problems (40 plus years on the ground) getting use to a bench. Will try dryer sheets F/R, getting more behind the rifle, and holding tighter to shoulder. Also going to setup my video camera and observe the rifle and me as it fires. Thanks for the input.

 

[fdshuster]

Had a similar problem with a 308, and even with a hard hold got a lot of jump and torque/twisting recoil. Had a muzzle brake installed and recoil now is like a 243, and straight back to the rear without the "jump and twist". Groups shrunk by a significant amount.

 

[artbosco]

new to discipline of benchrest. what would cause rifle to jump (up) in front bag when fired? seems to slide well. Rifle balance? Hardness of front bag? Weight of rifle? Facts are: rifle is 14.5 pounds., 24 inch number 7 contour lilja barrel in 308, 3 inch front flat, edgewood front bag with 3" spread, Caldwell rock be front rest (don't like it--but what i have right now) , edgewood rear bag and donut. Does it regularly. need to solve before i start load testing

Did you remove the sling swivel studs from your stock?

Did you over tighten the sides on the front rest?

Are you using stock tape?

Are your bags hard as a rock?

Are you using a front end stop for consistency?

How far from the ends of the stock, fore and aft are your bags placed?

Are your front and rear bags aligned in a straight line?

These are some of the things you might want to look at.

Also, here is a very good article worth reading: http://bulletin.accurateshooter.com/2009/11/benchrest-tip-optimize-your-rifle-position-on-the-rests/

There are all types of benchrest, but here is how "B"enchrest is defined by us diehards: http://video.google.com/videoplay?docid=9194636798795391569# Expand the view!

 

[LHSmith]

Note: use only "used" dryer sheets.
You preface this thread with "new to discipline of benchrest".
Not sure where your intentions lie with that rifle....pt. blank or LR? If pt. blank with the 3" fore-end your looking at VFS or group in which a brake is not permitted, also the max. wt. is 13.5 #.
Up to several years ago it was common to see a .308 on occasion in the score game, especially Hunter Class. Most have given up on that chambering for the reasons you are experiencing.... heavy recoil causes bag upset, and 40 or more shots with heavy recoil in serious competition usually takes it's toll on anybody.

 

[richard_123]

answers to questions:
Did you remove the sling swivel studs from your stock? none ever installed.

Did you over tighten the sides on the front rest? how much tension is needed to side of stock?

Are you using stock tape? no

Are your bags hard as a rock? front bag pretty hard

Are you using a front end stop for consistency? yes

How far from the ends of the stock, fore and aft are your bags placed? fore is three inches and aft is one is from the 4 way adjustable butt

Are your front and rear bags aligned in a straight line? yes used a string to align as best possible

 

[DCRYDER]

Is your front bag leather or cordura. I like cordura MUCH better, feels like rubbing 2 pieces of silk together. And I like sides tightened just enough to eliminate side to side motion but really no resistance sliding front to rear. Again if you're shooting with a cordura front bag this is easier to achieve.

I'd like to try microfiber, heard its even better.

 

[artbosco]

answers to questions:
Did you remove the sling swivel studs from your stock? none ever installed. Good!

Did you over tighten the sides on the front rest? how much tension is needed to side of stock? Enough tension to ensure no lateral or horizontal movement. However the tighter it gets, the harder all three sides of the bag are going to become. Not good. There's a fine line here.

Are you using stock tape? no. Recommend you buy some or use USED dryer sheets. If you have Cordura ears, just keep'm clean.

Are your bags hard as a rock? front bag pretty hard. If you have to, take a little sand out. I squeeze mine with my thumb and index or forefinger to fluff it a little, and I mean just a little. You can also overdue soft. I fluff mine between competitive relays.

Are you using a front end stop for consistency? yes Outstanding!

How far from the ends of the stock, fore and aft are your bags placed? fore is three inches and aft is one is from the 4 way adjustable butt. I've seen them, but not that familiar with the 4 way. [Nothing is sticking out that could catch on the rear bag?] If you have one continuous flat that rides the rear bag, all the better. Put some stock tape on it also. If Cordura ears on rear bag, again, just keep it clean. Three front, and one [from the end of the butt] is OK! Experiment per article. All this depends on your rife's balance. Mine are 1 1/2" and 1" but I'm shooting a 6PPC.

Are your front and rear bags aligned in a straight line? yes used a string to align as best possible I use an old golf shaft. Go to Home Depot and get a "straight" piece of wood dowel or metal rod, and use that. After you're done establishing where the rifle finally rides smoothly, set the tip of the rod or dowel in the front stop and then measure to the point on the butt, where you want to place the end of the rear bag's rabbit ears each time you set up, then mark the dowel. This will ensure you separate the bags the SAME DISTANCE each time you set up THIS RIFLE. This will make it a fast and easy process.

 

[richard_123]

thanks for the input----I will work with the suggestions---- thanks again

 

[alf]

Kind of a fact of life with a 308. I assume you're shooting bigger bullets, as it for 600/1000, which makes the condition worse.

My first Hunter gun was a full length 308, brakes not allowed. About like a buckin' bronco with it's jumpin' and twistin'. Made worse because of the 10# weight limit and 2 1/4 forend width.

Pound the butt into the rear bag and squeeze the piss out of the sides on the front bags. It still needs to slide, but you need to eliminate the side play. I pin the forend into the stop with my shoulder, but try not to steer the gun with it. Hang on with both hands, pulling it tight into your shoulder straight back. If you take your hands off in that position, your gun should be still close to your POA, which shows you're not muscling the gun off track.

Consistency is king......

 

[Dennis Keefer]

richard_123; Outdoorsman has given you very good info. I had lots of vertical jump in my Groundhog bench gun. It turned out to be two main items, front bag rock hard, and, front rest ears so tight that the forarm was popping out of the bag when fired. This was a stock profile issue. I now wipe the forearm of my rifle with a silacone cleaning rag after each group of 5 shots. My front bag is a Protector leather bag. IMHO cartridge is less of an issue than stock profile, hardness of front bag, and front bag ear tightness. My rifle is a Savage Model 12 BVSS in .223 Rem shooting 75 grain Hornady match bullets. Good shooting!

 

[BulletShooter]

Well recoil is always a thing with rifles, been shooting for 20 years. I have a 308 and I just said that is enough. So I had a muzzel brake put on and guess what. no recoil. shoot's like a dream come true. I can even see billets hit steel at 600 yards.
Little loud but I was tired of that recoil and when I hunt I use elect, ears any way, I can hear things better so when I shoot I just grin.