vertical stringing with 7mmRem mag

[idahoorion]

Hi everyone,
working on a 7mmRem Mag for long range work. previously I have had good luck with other guns in this chamber with H1000 and Rl 22. This new barrel was persistant with vertical stringing with several different loadings of H 1000 so I tried Rl 22 and got similar results. like 1.5 moa stringing. I did my searches here and found that vertical stringing is shooter issues or a few suggested to increase the powder charge till it tightens up.

I just got back from the range between snow storms, I started with rl 22 where I left off before. and in .5 gr increases of powder, shot groups. first was the same, the second loading (1 grain over book max) better. the 1.5 grain increase 66.5 was a cloverleaf under .5moa. these were with 168 smk's

now, my plan is to go back and starting .3 gr. lower work up by .3 increments to see where the node is.

and will this same thing happen (tightening the vertical) if I go back and do this with H-1000? as I was fairly conservative in the load previously that had vertical, I would prefer h1000, as developing a load in the cold with Rl 22 could be a temp issue later.

And is this tightening of the vertical, pressure related, speed related , harmonics or ?

thanks
Idahoorion

 

[tonyb]

Idahoorion, all of the three mentioned at the bottom of your post can cause stringing whether horizontal or vertical. The one thing that I really pay attention to when seeing vertical stringing is neck tension. Just something to think about.

Tony.

 

[dkhunt14]

It could be a lot of things including bedding. If you are using bushing dies try a smaller bushing. Sometimes a tighter grip on bullets can help. How many times were the cases fired? Maybe they need annealed. Matt

 

[idahoorion]

Dkhunt and Tony

thanks for the reply's, I have thought of tension a bit. I am using Norma brass with just one to two firings. I am using a 311 bushing that gives a bout 2.5 to 3 thou tension. When magazine fed I have not noticed any changes in bullet depth but they pull pretty easy compared to my 243. I was going to step tighter and try a 309 and see what if any difference it is.

Bedding, this is the second stock, I tried it first in a Hart laminated pillared and marinetex for the action. so when I saw the vertical, I pulled it out and put it in a Hs precision. where it is now. both have free floated barrel channels. I was shooting another rifle at the same time with out vertical so while some could be do to operator error it shouldn't be all of it.

thanks for the replys, keep the thoughts coming!
Idahoorion

 

[MrMajestic]

You didn't mention your shooting style but if it's off the bags, that can cause vertical if not setup correctly. JMHO

 

[FeMan]

How are you sizing and measuring neck tension? Hopefully the numbers you are referring to are from measuring the sized case before and after seating the bullet. Are you using a sizing button or mandrel? Those are what is going to determine neck tension not the sizing button you use (unless you are turning necks precisely and not expanding them). The reason I ask is neck tension can have a substantial affect and 3-thousandths is a lot. Going to more seems extreme to me.

 

[expiper]

Ida,,,most of the vertical that people encounter is because the powder charge is too low/light,,,and that causes the powder to not burn completely/efficantly and thus gives poor ES/SD #'s,,,,I like the powder charge to be at or near max to give good clean burn ( no soot in the bbl. and short/pointy streaks on the muzzle) which "usually" give good results...IMHO....Roger

 

[dkhunt14]

Most of my match guns shoot best at max. Roger is right, they burn cleaner. Another thing seeing you had it in 2 different stocks. The setup with the wood laminated and pillared with marine tex should of worked. Did you check to see if the scope bases and rings are tight. Maybe the scope is bad. Are all the groups straight vertical. Matt

 

[idahoorion]

Yes, great responses, I am seating at .015 jump. I can fine tune it later..... the two stocks was to eliminate bedding being a cause. Because with a previous barrel/chamber this didn't happen (same reamer) and because both stocks do the same....I think I have put that to bed. lol

neck tension....317 no turn neck on the reamer. 311 was the bushing I ordered on the redding fl bushing die with the first barrel with this reamer. so I just stuck with it. Now.... measuring necks on loaded ammo is according to my calipers. .312 to 313 so going a bit tighter would still not be much compared to some fl die set ups. Bushing die no inside expander button. sized loaded brass is a bit tighter than the 311 on the bushing ave. about 311 to 310 so really only a couple thou tension.

I did check the tightness of the rings/scope etc and discount double checked the action screws.
when I did get the groups tightened I shot at extended range and was consistent in hitting at 400 to 300 to 200 6" steel. that was my scope test dialing back forth and shooting. Yes pretty straight vertical that's how I think this barrel really wants to shoot, take out the vertical and it's going to be consistant. I did try amax 162's the first day and it was the same so I then switched to the smks and have a good amount of em.

received on the bags and that is what I checked the last time. the other gun in same setup had no issues? so some could be me but not all of it both days.
my scope test above was bipod/rear bag

Just ordered that bushing... 8)

Idahoorion

 

[Raythemanroe]

Not to sound dumb, but are you trying the same load also? Try measuring base to give, weight sorting brass and bullets?

 

[ericskennard]

Well I MAY have missed it but what bullet are you using? Usually when I have vertical stringing with VLd 7mm bullets, I have to make them a little longer.

 

[savagedasher]

Vertical can normally adjust with bullet speed. But improper bag hardness can cause the same problem. Thumb pressure will do the same. Change your bags and rest and have someone who shoot good try the gun. Larry

 

[idahoorion]

Ray, norma brass I did not sort it as when I have in the past it's consistent but I could do it. bullet sorting no. measuring base to ogive and seating .015 jump. with stoney pt chamber measure tool and hornaday bullet comparator setup.

I have tried two bullets. amax 162 and smk 168, original rem firing pin spring etc.

bag hardness,.....hadn't considered that. doesn't seem to impact the other gun. but I could shoot these off the bipod or other bags.

Thanks for all the thought. My new bushing is on the way. Plan right now to start where the best load was with the old bushing and reload some with both bushings. and also to have a few with my old standby H1000 load and the new bushing.

thanks
Idahoorion

 

[savagedasher]

Ray, norma brass I did not sort it as when I have in the past it's consistent but I could do it. bullet sorting no. measuring base to ogive and seating .015 jump. with stoney pt chamber measure tool and hornaday bullet comparator setup.

I have tried two bullets. amax 162 and smk 168, original rem firing pin spring etc.

bag hardness,.....hadn't considered that. doesn't seem to impact the other gun. but I could shoot these off the bipod or other bags.

Thanks for all the thought. My new bushing is on the way. Plan right now to start where the best load was with the old bushing and reload some with both bushings. and also to have a few with my old standby H1000 load and the new bushing.

thanks
Idahoorion

Last year I was practicing for our yearly NBRSA match and the same gun with same load that was perfect the year before I was getting 1/2 vertical. Billy Stevens tried it on his bags and rest it was perfect. I changed my rear bag and after he told me he was going to break my thumb my vertical was gone. Larry

 

[Raythemanroe]

Ray, norma brass I did not sort it as when I have in the past it's consistent but I could do it. bullet sorting no. measuring base to ogive and seating .015 jump. with stoney pt chamber measure tool and hornaday bullet comparator setup.

I have tried two bullets. amax 162 and smk 168, original rem firing pin spring etc.

bag hardness,.....hadn't considered that. doesn't seem to impact the other gun. but I could shoot these off the bipod or other bags.

Thanks for all the thought. My new bushing is on the way. Plan right now to start where the best load was with the old bushing and reload some with both bushings. and also to have a few with my old standby H1000 load and the new bushing.

thanks
Idahoorion

I have found Norma brass to be good as of late, Maybe work your load up like some folks have suggested. I like to use H1000 and Retumbo up where it burns better...Opinions on pressure in the bag are good thought to, I found my self shooting better with a different setup (less stringing)

 

[Patch700]

[/quote] Last year I was practicing for our yearly NBRSA match and the same gun with same load that was perfect the year before I was getting 1/2 vertical. Billy Stevens tried it on his bags and rest it was perfect. I changed my rear bag and after he told me he was going to break my thumb my vertical was gone. Larry
[/quote]

Very true lol , I have I rifle that would be considered "nose heavy" in an F-class stock and if it's either too far back or too far forward in the front bag it will do things that will make you accuse the guy shooting next to you that he's shooting at your paper lol..

 

[1 mile]

Std match primers not magnums ...have you ran your loads over a chone....its the std dev. your fps spread. 7mmmag is bad about that...you have to shot big bullets hard.

I shot RL-22 same lot 63 grs with 175 BTHP at 100-1050 and does great...15 -20 fps spread

 

[idahoorion]

!)Hi Guys,

so woke up last night thinking this is a horse issue, lets not go looking for zebras yet. so this AM I unscrewed the brake, and inspected the crown and screwed on the thread protector. then I dismounted the scope and in mounting the other noticed the front base a bit loose. Seems as I used a screw in my kit for a different base and it was too small a head. so got that baby loctited down and solid, (I know, short bus for me) then just for giggles I put it back in the laminate stock bedded for the action. I remember a good thought about the barrels not all being the same diameter on the shank and yes this stock does have a pad for the shank so I demmeled it out prior to putting it the stock, free floated all the way. then I reloaded 10 rounds of ammo. 7 of the old standby 69.5 of H1000 and 3 of 70 grain book max. all with the 168 SMK at 15 thou jump. Off I went to the range hoping the inversion was light enough to see 100 yards.
yep ok at the range. Then, since there was tons of input on the bag.....I shot prone on bipod/rear bag.
with 10rounds I shot three three shot groups.... all three were triangles!! not real tight but about a MOA or a bit less. Ok with that, as now load development begins. and shooting prone with the bipod on ice was not so secure but it put the bag issue to rest.
So lots to do, I'll report back progress, thanks for all the thoughts!

Idahoorion

 

[LKEYES]

So what is the twist of your barrel?
I had the same issue with a 1-8" and ended up going to 180 vld's and
72 grains of Retumbo seated .005's off and it all came together. Also I
switched from Winchester mag primers to Federal GM215M and those
helped as well. It has printed several 1/2" groups at 200 yds so far.

 

[idahoorion]

Lkeyes,

1-9 bartlein, working on getting some retumbo, I think I will try a couple other primers to tighten things up as well.
going to run it over a chrony next time out and will check some fed 215, some 210m and the wlrm that I am using now for ES and SD. using H1000.

thanks
Idahoorion