I just got back from the range with my new CZ550 bolt-action rifle in 9.3x62. I had an assortment of loads and all of them showed vertical stringing. A couple of the groups were practically vertical lines, leading me to believe they would have made one ragged hole if it weren't for the vertical stringing.

The barrel is not free floated. The rifle came with steel spacers ("pillars"?) that go between escutcheons in the stock and the action, around the action screws. The barrel has an additional small recoil lug a few inches in front of the action. There is a plate set in place in the stock behind the large recoil lug on the front of the action. Despite the spacer around the rear action screw, the rear of the action is sitting on the stock (it looks like the spacer is about 1/32" or more too short to reach the bottom of the action).

What is my best course of action to try and cure my vertical stringing? I've glass-bedded and free-floated a rifle before, but it didn't have the spacers like this one, or the extra recoil lug on the barrel. What is the proper approach to deal with this stuff?

Thanks for any advice, or links to information I need.

Good shooting,
desmobob

First put a folded credit card under the barrel in front of the first recoil lug (the one closest to the action). tighten down everything and see how it shoots. This will tell you if free floating is the answer. This will lift the barrel up so it does not touch the barrel.

If this works then I'd remove enough wood from the barrel groove to float the barrel. I've not dealt with the extra recoil lug either.

My recommendation would be to piller bed the action along with a good glassbed job. This includes bedding both recoil lugs and floating the barrel from the second recoil lug forward.

I've had really good luck stabalizing stocks by cutting grooves in the forend (I use a radial arm saw) then glassing the lengthwise cuts in solid. This helps with any forarm warping.

I like to bed the whole action in along with the piller bedding and I also bed in the floorplate. Piller bedding kits can be had from Brownell's or Midway.

Before you do a lot to your rifle you need to check a couple of things. My thoughts are about a Mauser action. One thing to try first is the tension on the action screws. Loosen both screws so they are loose. Now tighten the front screw first and make it tight. Then tighten the rear screw but just so it is snug but not as tight as the front screw. Sometimes over tightening the rear action screw will effect accuracy, most times it will not. If you find that accuracy is affected by adjusting the rear screw you need to re-bed the pad under the rear action screw.

Vertical stringing is usually caused by too much upward pressure on the barrel from the forend of the stock. Look at the forend bedding in the last few inches of the stock. You might see a bedding pad that puts pressure on the barrel. If the pad is there you need to relieve the pressure with a scraper. I would not remove the pad completely but just remove a slight amount and then see if it helps the stringing. The manufacture felt this was the best way to bed the rifle and I would try to keep it.

Now, if there is no bedding pad in the upper forarm, you are getting pressure from some other place. You will need some inletting blue/black and paint the bottom half of the barrel. Very carefully place the barrel/action back into the stock and tighten the front action screw. Now remove the barrel/action trying to lift straight up. When you look at the forend inletting you will see inletting blue/black every where it touched the stock. If there is a high spot, it will be quite obvious. Take a scraper and remove the high spot.

If there is no high spot you need to do the same procedure (inletting blue/black) around the action recoil lug and the axillary recoil lug. Make sure the recoil lugs are not touching any where but the face that butts up to the stock. Both sides, the front and the bottom of the recoil lugs should have clearance. If you do any cutting or scraping on the inletting, you need to apply finish on the spots.

The front axillary recoil lug is used in high recoiling rifles. I used them in 375H&H on up to help distribute the recoil energy to the wooden stock. A really high recoiling rifle usually has a screw through the forend into the aux lug to hold the barely into the barrel channel during recoil.

Frank

Thanks very much for the help! I appreciate it. I'll post my results and "before" and "after" groups when I get finished.

Thanks again,
desmobob

Thanks very much for the help! I appreciate it. I'll post my results and "before" and "after" groups when I get finished.

Thanks again,
desmobob

Hi desmobob,

How are you making out with your 9.3x62. Have you found your problem with your stringing?

Frank

Hi desmobob,

How are you making out with your 9.3x62. Have you found your problem with your stringing?

Frank

Hello Frank,

The rifle is bedded, loads are ready, and I'm waiting for some decent weather! We had a heck of a storm here in the Northeast this weekend, so I wasn't able to get out and shoot.

I'm hoping to sneak out tomorrow after work. If I don't get a chance to, I'll certainly get to the range this weekend (if the weathermen are right....).


Thanks again for your help with the bedding information.

The rifle was pretty bad off. I thought I had some simple fore end pressure. It turned out to be a more serious bedding issue. First, I tried just free-floating the barrel. I borrowed the proper tools and went to work. I'd get some clearance, but it would disappear when I tighted the action screws. This confused me, as the stock appeared to be very nicely inletted and I could see where the action was sitting perfectly in the stock at the tang and at the front of the magazine well -- the bottom of the action was grooved at these areas and the stock inletting was left high in the corresponding spots. The stock showed the grooves from the action sitting very nicely on the two high areas.

BUT... the front action screw goes into the bottom of the main recoil lug, which was about an inch forward of the front area where the action was bedded. The action would sit solidly into the stock, but as soon as I tightened the front action screw, the action teeter-tottered; it rocked the barrel down and the tang up. Tightening the rear screw would draw the tang back down and the barrel back up, and put a whole lot of stress on the action and stock, I'm sure!

My quick fix was to bed the area from the front of the action to the recoil lug, and from the recoil lug to the auxillary recoil lug. CZ had done such a nice job bedding the tang and front part of the action, I decided to leave it as it. I might hog it out and bed that part later, if needed, or just "skin bed" it for piece of mind.

Now, the action sets in the stock solidly and doesn't move when the action screws are snugged up. The barrel is well-floated all the way back to the auxillary recoil lug.

I just need some time off from work and good weather to try her out! I'll post the results.

Thanks again for you help; I appreciate it,
Bob

Hi Bob,

It sounds like you did a good job. I hope it shoots better for you. Looking forward to your results.

Frank

Washers worked for me just two days ago but in a .Winchester pre 64 model 88 in 308. A 88's mounted to the wood by slipping the rear of the action into a metal piece bolted to the rear of the stock and by one screw to the barrel about a foot in front of the action. mine has been a good shooter for ever till all at once groups went nutso.8 inch vertical strings to all over, even off the paper at 100 yds at times. checked and rechecked every thing, evern trying different scopes, and finally add two tiny ,thin copper washers between the mounting screw and the barrel till I could slip a folded dollar bill between stock and metal. first shot hit the bullseye, but three had a 2 /1/2" group or so. After letting her cool completely I ran a clip full ,4 , and shot the best group that gun has done for me in 20 years I have had it. 13/16" 4 shots by 5/8's wide. darn like a ok bolt. and all I did ,besides fret a lot first, was add two little washers that fit perfect. Sometimes get lucky.

Hi Bob,

It sounds like you did a good job. I hope it shoots better for you. Looking forward to your results.

Frank


I got to the range yesterday... the results weren't what I hoped for. The groups, using Speer and PRVI bullets and Ramshot Big Game powder, were all 1.5" and up (sometimes way up).

The vertical stringing is gone. All the loads with the Speer 270g. bullets were extremely consistent and had low Standard Deviations (10.8-17) so I'm thinking the groups should have been better. The groups shot with the much cheaper Prvi bullets had SDs from 23.5-40.

Before I get too upset, I'll go back and try some other loads. I have a Model 70 in .300 Win Mag that just would not shoot anything I loaded up for it. I free-floated and glass bedded it. It still wouldn't shoot. I was convinced it was just not that accurate. Years later, I pulled it out and started experimenting again. I found a 180gr. bullet load that it will shoot into .75" at 100 yards. Needless to say, I no longer consider it a lemon and will be hanging on to that one.

I also have a new scope that I can swap for the one on the CZ, just to remove the possibility that it could be causing a problem.

MarlinF:

One of the first things I did when I was looking at the CZ was hunt around the shop for a pair of washers to put on top of the action screw spacers. I couldn't find any that were suitable. Maybe I should have kept looking!

Thanks again,
Bob

Hi Bob,

It sounds like you did a good job. I hope it shoots better for you. Looking forward to your results.

Frank


Frank,

I finally got some good groups today. I was very relieved. A mild load with IMR3031 and a Speer 270gr. bullet cloverleafed the first three shots! That made me very happy. Another load using 3031 putt four shots in 1-3/16".

Now I can stop worrying and start fine tuning those loads.

Thanks for the help,
Bob

Frank,

I finally got some good groups today. I was very relieved. A mild load with IMR3031 and a Speer 270gr. bullet cloverleafed the first three shots! That made me very happy. Another load using 3031 putt four shots in 1-3/16".

Now I can stop worrying and start fine tuning those loads.

Thanks for the help,
Bob

Hi Bob,

I really like it when a plan comes together :p. Glad it workded out for you. I am sure you will come up with a good load. You thought it would group if you could get away from the stringing.

It seems to me that IMR3031 may be too fast for your 9.3x62. You might want to try IMR3050 or even IMR4831. IMR3031 is better suited for 308win.

Frank

Hi Bob,

I really like it when a plan comes together :p. Glad it workded out for you. I am sure you will come up with a good load. You thought it would group if you could get away from the stringing.

It seems to me that IMR3031 may be too fast for your 9.3x62. You might want to try IMR3050 or even IMR4831. IMR3031 is better suited for 308win.

Frank


Frank,

This cartridge seems to thrive on faster powder; much faster than you'd expect it to use. Would you guess that 4831 is too slow for the 9.3x62? Even 4350 is so slow that you need a compressed charge to get mild velocity, and the pressure is still far below max. (These figures are for the Hodgdon varieties, the IMR burning rates are almost the same.)

Here's some data from the Hodgdon page:

270 GR. SPR SP 270 H4350 .366" 3.280"
63.0 2322 38,500 CUP
67.0C 2438 44,600 CUP

270 GR. SPR SP 270 Varget .366" 3.280"
55.0 2290 40,100 CUP
59.5 2440 48,100 CUP

270 GR. SPR SP 270 BL-C(2) .366" 3.280"
60.0 2338 39,600 CUP
66.0 2548 47,400 CUP

270 GR. SPR SP 270 H335 .366" 3.280"
54.0 2283 40,700 CUP
58.0 2411 47,600 CUP

270 GR. SPR SP 270 H4895 .366" 3.280"
52.0 2244 39,800 CUP
56.5 2406 48,000 CUP

Hodgdon's data would lead me to believe BL-C(2) might be the most efficient powder choice for the 270gr. bullet. And BL-C(2) IS .308 powder. This 9.3x62 really interests me... and the more I learn about it, the more interesting it gets!

Thanks again,
Bob