Scope, rifle or bullet?

[old #7]

I have been worlikg on a load for a 7mm rem recently and I am a bit confused after my latest trip to the range.
The rifle is a Ruger M77 markII. The barrel is free floting and the scope is a 3x9x40 Zeiss conqest
I started out loading 140gr bt's with rl-22 and had decent results but wanted better. I loaded some 140gr bt's with IMR 4831 and the groups shrank to a quarter at 100yds. I played with that powder bullet combo again and also loaded some 160gr ab's with rl19. I shot the 140 bt's first and had decent results and had the group centered on the target about 2.5" high at 100yds.
Here is the confusing part.
I thought that I might have better results with the 160gr ab because of it''s higer BC. I shot one group of four. Two of the four were in a ragged hole the other two were close by but the grouping was three inches to the left and two inches lower than the 140 bt group.
I was under the impression that BT's and AB's were ballisticly equallivent. What is your reasoning why the group shifted like that.

 

[SakoSteve270wsm]

Some rifles seem to prefer a specific weight of bullet.Not sure if it has to do with barrel harmonics or rifleing?I have a Remingotn VSF in 22-250 that groups 50 grain bt's great but won't group 55's at all.
My only suggestion would be adjusting seating depth perhaps?As far as BC of the bullets,I don't think that will effect accuracy at all just the retained velocity down range and the wind deflection of the bullet.

 

[Desert Fox]

Shifting of your group has nothing to do with your bullet BC. Two different brand or type of bullet even with identical BC could have different point of impact. Steve got it right. It has something to do with your barrel harmonics or sometimes refer to as barrel whip. The best illustration of this is to unwind a garden hose and open the water spigot. You'll notice that the hose will whip from side to side, or move up and down. Increase or decrease by adjusting the flow of water in a spigot, and you'll notice a change in the hose movement. The barrel of your rifle acts the same way, when bullet is traveling through it except, in a very minute frequency, invisible to the naked eye, but it's there. Now you wonder why we want our handload to be very consistent. That's because, a consistent handload will result in a uniform barrel whip which usually makes good groups. Hope this help. RJ

 

[remingtonman_25_06]

Different weight of bullet and different powder is why there impacting different places. A 160g isn't going to be any more accurate then a 140 or 175 for that matter, BC has nothign to do with accuracy...When you even change somethign so slight as a primer, it will change the harmonics of your barrel.

You probly need to tinker more with the powder charge and fine tune with seating depth.

 

[Britz]

ANY change in your handloads will result in point of impact shift. I was loading 300 wsm 165's and testing the OAL for accuracy (everything was identical from brass brand, weight, powder, primer, sizing) except seating depth. I was amaized to watch the poi shft over 1 inch during the tests.

Also, Just because one bullet hit higher on the target doesnt' mean that it is going faster or ballistically superior. Simply that your scope needs to be adjusted because of barrel harmonics. Once your sighted in, then you can rely on your range charts based on velocity and BC. Chrony your shots some time too. They never go as fast as the books say.
good luck, Mark

 

[cloverleaf]

If I understand you correctly you had improving luck with the first couple loads you tried. With the third load you got two shots in one hole and then things started to deteriorate. Just my experience, but my rifle is floated as well but as it starts to heat up it still "walks" right. Is Parralax a possibility? I have a bad habit of canting my head. Maybe its recoil or laziness, but that shifts my POI. My barrel also starts to loose accuracy quickly once it getas to a certan "dirty point". I dont have answers for you just some thoughts you may or may not have ruled out. Personaly, I cant get my rifle to shoot as well as I did one timesince I had it re blued. I can still get sub MOA groups but no clover leaf one hole groups. I'm goingf to have a friend who is an ex-marine sniper shoot some groups with my favorite load and see if he can do it. CL

 

[old #7]

I don't have problems dealing with recoil. I was brought up as a child at the shooting range and learned very early how to pull a trigger. I shoot at a bench with a rest and I see the muzzle flash through my scope. If the round is fast enough I see the impact of the bullet through the scope. I always let the barrel cool between shots and I keep a surgicaly clean gun.
I think that Britz hit the nail on the head with the barrel whip theory and desert fox's discription of the garden hose makes it hit home.
Since I changed bullet weight the barrel harmonics would change also.
I was suprised because I have not seen a change that drastic in my other rifles.
I disagree with remingtonman 2506 about BC. The higher the BC the better the bullet preformes in wind, humidity and elevation or air density. To me that would make the higher BC more accurate.
I mentioned the pionts of impact only to illustrate the sudden change. I purposly sighted in 2.5" high at 100.
This is a new gun and maybe it isn't fully broke in yet. Most of you have said in a different thread that the newer Rugers aren't as accurate as the early 1970's rifles.
I shot 40 rounds through it, cleaning between each round for the first ten. Removed all coper. Cleaned after every third round for the next twelve. Removed copper. Shot five cleaned, shot five, cleaned, removed copper, shot eight.
I appreciate all of your responses, they all have great recomendations in them.

 

[remingtonman_25_06]

BC is important for longer range shots yes, but 100 yards NO. Plain and simple. You can take a Round nose bullet and it can very well shoot .5" groups at 100 yards, but take it to 600 yards with its low BC and compare it with a VLD, the VLD will shoot better groups everytime.

You were talking about 100 yards and so was I...

 

[steve4102]

I have yet to see a Ruger rifle that was not very picky about it's ammo(harmonics). IMO they are "Hit and Miss" in the accuracy dept. and the slightest change in ammo or components can make a huge difference. More than any other rifles I have loaded for.

 

[old #7]

I think this may one of those Rugers that just won't group but, I have not exausted my efforts yet.
I agree that at 100 yds a higher or lower bc won't make that much difference. I usualy do a rough sight in and load development at 100yds but, do most of my shooting at 300 to 400 yds. those distances are a bit more fun and challenging to me.
I also live at the coast and my elevation at the range is about 100ft above sea level.

 

[Alaska]

the Gameking 160gr BTHP in the 7mm Mag excellent bullet with

RL 22 and Fed 215GM primers

 

[Britz]

Rem 2506, With all due respect, I would prefer a low BC accurate bullet over a mediocarly accurate vld any day for any thing.

You are correct in saying that the VLD's will preform better at range in tradjectory and will be affected by wind less due to their higher velocity. but (and this is important) your rifle needs to shoot the bullet accuratly and consistantly first. If your barrel is whipping the bullets out inconsistanly, it doesn't matter if your BC is .01, or 1.0, you will miss with either.

 

[Britz]

Old #7. In my humble opinion, you should just try to find a bullet that shoots well even if it has a less than desirable BC. I too try to find a higher BC bullet, but the truth is that the BC doesn't impact your tradjectory that much out to 400 yards. It will make a difference if you are trying to find a bullet that you will not have to raise or adjust your sights for.

but if you want to make a good kill shot, you should use a rangefinder and create a tradjectory table.

 

[old #7]

Britz,
Trying to find a bullet, powder combo that shoots well is exactly what I'm trying to do. I am just trying to get the best of both worlds with the AB.
The application will be hunting, but I still love to target shoot. I am "shooting" for a good point blank range out to 300 yds that will stay in the kill zone of a deer without any compensation.
The trajectory table is the reason I rough sight in 2.5 high at 100yds durring load development.
Thanks.

 

[remingtonman_25_06]

Well Britz, take what you want, and I'll take what I want...

I'll take a 162g AMAX or 168g VLD with BC"s of .625+ any day vs a "hunting" bullet with BC's that are in the .5's...At long range, you need every advantage you can get...

VLD's are 9 out of 10 times more accurate then standard hunting bullets anyways, so not real sure what you mean by your comment about barrel whipping and not shooting them well or being inconsistent, are you serious??....

My 7 RM shoots the 162 amax and 168g VLD awesome...As well as a few other "hunting" bullets. I"ve got targets with the 168g VLD shooting 3.5-5" groups at 700 yards. I doubt a round nose is gonna give you groups like that at those kinda distances...

Different strokes for different folks I guess..

 

[Britz]

Rem 2506, I'm not trying to start a fight or anything. Some rifles just may not like the vld. Just like My rifle likes Sierra 168 matchkings and 150 grain NBT's but hates 165 grain nbts. I am not disputing that the VLD is an excellent bullet. I am disputing that every rifle will shoot them well! Believe it or not, harmonics plays a big role, and just because the bullet is better made and has less drag doesn't mean that it will be more accurate in every rifle.

However, You are right, you take what you like and I will take what I like. Talk to ya later, Mark.