Two distinct groups with the same load - what's happening?
 

I was testing some loads in my Weatherby Vanguard 270 Winchester in preparation for deer season. While I'm not going to be shooting it, my younger cousin and sister will be taking it during rifle season. I've been having quite a few issues with the gun lately, though, and today was no different. Here's what's happening:



130 grain Hornady SST - 3.405" OAL
Remington case
53.0 grains IMR 4451
Federal Large Rifle primer
3,020 fps average, 6 fps s.d.



130 grain Hornady SST - 3.405" OAL
Remington case
55.0 grains IMR 4451
Federal Large Rifle primer
3,141 fps average, 18 fps s.d.

As you can see, I'm getting two distinct groups quite some distance apart. However, the individual groups are somewhat tight. In the top picture, the three-shot group was .835", while the three-shot group on the bottom was .740", both at 100 yards. On their own, they would certainly be groups to be proud of, but with the other two bullets grouping elsewhere, I can't be comfortable with these loads yet. There was no real pattern to how the bullets hit, either, and I let the barrel cool between shots, so I don't think barrel heating was the issue.

My question is, what could be causing this? I'm wondering whether I'm not holding the rifle consistently enough between shots. Additionally, I was using a Lead Sled, which I've heard isn't conducive to the best shooting. The way I see it, I have two options: make some loads I've confirmed are accurate and see what happens, or test these loads for accuracy again using my pistol rest and a sandbag to rest off of.

BS.

Some people have fear or anger with lead sleds. It just a rest. If you don't use a rest for checking loads or sighting in scopes, you are just arrogant fool.

Today I was sighitng in 45-70. Only 50 yards, I realize difference would be multiplied at longer ange. But I did my final shot with sand bags, Touching. I realize at longer ranges it may different.

Only difference is length of pull. Same as jacket, or not. But I hear so many people say you shouldn't use them, that probably have not used one, and may use some other rest themselves or sand bags.

Myself, I am behind my rifle, looking forward, shouldering the rifle.




I bought mine to check loads, leaving my ego aside. Saying that, I was dissapointed, that it was not rocksold steady. You still have to do your part. Is just a rest.

Mine only hold 25lb, depite claim of 50. But I like that, still gives you recoil.

All that aside, things effect grouping. I was having high shots with my new 45-70. My theory is heavy trigger is causing me to lift. When I shoot 30-06, I only support with one hand, often. With my 1895 I need to hold the forearm, or it seems to go high. Which I adjusted lower, only to be really low when shouldered tight.


No answer, just saying lot of factors

Next time use a marker and number the brass and keep track of where they hit in the groups !

What do you think that will do? They measured the same, and same brand of brass.



Re-reading this in the daylight. Two groups, two different amoutns of powder. Hit 2 different spots. So? You would think it would just be elevation, in perfect linear world.

Ya I would expect a linear spread. Maybe pressure spike causing something different. Primers look good on both? High chargers racks out fine?

I have notcied groups tighten up at with certain charges in some rifles. My 45-70 actually changes elevatio with charge at 50. My 30-06 and 243 do not at 100 yards. They tend to change accuracy. 45-70 is more accurate then people realize. Doesn't seem to care how many grains, udner max of coarse.




Keep a log book, and document how your charges work for you. Find the best grouping. With a chrono people also look for consistent speed if shooting long ranges. Then sight your rifle in for the load you decided on. Just my opinion. But I am only on 2nd cup of coffee, in vacation.:woot:

TNLW,

I have seen something similar when someone was loading a bit too close to the lands and probably getting some pressure spikes. Also, sometimes different lots of bullets have very tiny variations from previous lots which can change max coal.

Your coal if fairly long, so I would try pressing the bullet deeper and see if that has any effect. Sometimes a bit of jump is not a bad thing.

Are you showing a six shot group with mixed results, or two three shot groups with different POI?

Five shots for each load to be tested, with two of the shots hitting one place and three hitting someplace else. The other loads I tested weren't as accurate, but they had definite fliers.

I would hold the fore end during firing to see if you are having a simple problem with bag jump. If that is not the problem I would revisit the seating depth of the loads.

Good luck with it.

Before I would go and change anything as both those loads shoot good I would try a couple things. Next time out take another rifle along. Shoot this one then play with the other until you're good and sure this rifle has cooled down. Then fire another group and see where it hits. Should be the same as the first group. If not, give the barrel a good cleaning there at the range and try shooting again.
IMO its one of a couple issues: Either heating of the barrel or barrel fouling. (If its barrel heating make sure your barrel is free floating) It may also be that the action screws are not tight.
Maybe a bedding job is in order but try the simple things first.

winner, winner, chicken dinner. group within the group syndrome can almost always be helped by adjusting seating depth.
RR

How much deeper should I seat them? Suggested OAL is 3.210", and my current OAL is 3.405", so should I seat them to the suggested OAL or something like 3.300" instead?

Also, I'll check the action screws and clean the barrel, too.

Why load them long in the first place? Not trying to be a smart a$$ but curious if you had a thought on loading so far outside of the recommended length.

How much jump were you trying to allow at 3.405"? What's your jam length for that rifle with that bullet?

Better accuracy. I seat bullets similarly long in my 300 Win Mag and 221 Fireball Encore pistol barrels, and it noticeably improved the accuracy. The 300 shoots 1 MOA, while the 221 is capable of about .5 MOA when I do my part.

I was trying for about .02".

I start at .030" off the lands, they shoot faster at less pressure if given some jump. best group I ever shot measured .04 MOA at a lazer ranged 752 yards, was .030 off the lands. also keep runout to a minimum will help also, the straighter you start your bullet into the lands the quicker it stabilizes.
RR

Why would his seating depth be different? Did he take his dies apart and set them again?

I though powder charge was different. If its the same, I say human error. Possibly the way he is grabbing trigger. This is more prevelent in hand guns, for me though.

As said closer to the land is often more accurat.


One of my theories as as way some cheap guns are accurat is the lands are very close. My old 700 very far away. Savage, close.

Having them close may restrict the amount of powder you can add, if you want to go beyong published data. Obviouly may make the rifle a single shot too.


I am not sure it will account for lateral movement. Maybe others have seen it.

As I said, since they are grouping, just a different spot, I say human factor. Maybe someone has seen different.

Some long range shooter vary the depth before working on loads. I vary loads and bullet first, but I am not a long range shooter, or a pro.

wrong! why not just stick with what you know.
RR

Here's what I'm thinking: load 30 to 50 rounds with 55.0 grains of powder and the bullet seated to 3.405", clean the bore, and tighten the action screws. Fire five rounds off my Lead Sled, holding the rifle the same way every time. If they're still double grouping, I'll shoot five rounds off my specialty pistol rest and a sandbag. If that doesn't work, I'll run inside and adjust my seating depth. Lather, rinse, repeat until I find the answer.

what powder ya loading?
RR

IMR 4451. It's one of the new Enduron powders close to 4350 in performance.

My favorite 270 load was 54 gr of IMR4350 under a Nosler 130 gr Ballistic Tip. Just about every 270 that shot this load found it to be extremely accurate. So if that Enduron powder equals 4350 then you should be well within the ballpark for a decent load.
IMO if I were you I'd listen to RR. He seems pretty knowledgeable.

I wouldn't load them that long, jamming only sometimes helps with VLD type bullets.

Shorten them up and you'll be much happier...

ok just checked the msds for 4451, its a double based powder, this means it contains nitrocellulose and nitroglycerine, its more temp sensitive than single based powders (4350 or 4831) would also try H4350. single based powders are harder on barrels than the double based but not much of a difference till you get big jugs. you won't see a difference in a 270.
RR

I will group shots with a clean barrel, and then have POI move after 3 or 4th shot.


More rounds, just to make sure you don't have some outlyers. Even with lead sled it can happen.

Not sure if you need to do 30-50. But I would fire some more. Letting barrel cool 10 minutes between shots, if you want the most accuracy. Fire a 10-20, and see what it looks like.

Another option, is to try another load or bullet.


If loaded the same, I don't believe it is actually producint 2 groups. You just got 2 bullets near each other, out of 5. Shoot some more.


I also say to watch how you are grabbing the trigger. Square your finger with it. Make sure not pulling it to one side. Again, I notice this more in handguns. But same idea.

Speaking from my bowels, I think seating depth is a different discussion.

Clean barrel. shoot 3 rounds. Then shoot 10 or more and see what you got. I like to number mine, more so for fouling shots, and as things get dirty.

I was reading Lyman 47th. Different approach to test hunting loads. Fire 4 shots kinda quick. Cool down. Then put target over old, and do it 10 more times or so. This is more extreme then what I do. But the idea is to learn what your hunting rifle and load will do.

LOL! most insane pile of BS I have read in awhile
RR

Which paticular pile of BS?

... when it's so bad you don't even want to ignore list because that would prevent refutal of bad advice with proper advice and preventing someone read it and think it's good...

posts # 27 and 28, did you ever load any ammo before last week? your reasoning makes no sense, none of it, wanna argue point by point? we can not only will you lose but you already have anybody have the feeling Topgun is back?
RR

You don't think clean barrels fire different? I have had groups that moved.

You don't think you should pull the trigger square?

You don't think trying another bullet or load is good?

You don't think practice is good?





Take it up with Lyman. Bt they have been in business a long time. I do get what they are saying. Which shoot, shoot, and shoot. THey cover one target over the over to look at a large sample.

I don't have the patience. But I definitely think it would tell you a lot about your gun, load, and skil. The flyers would show up.

I have never shot 4 times at an animal. Only once have I fired a 2nd shot, because snow was 4 feet deep and slowed him down. But I get the idea of firing 2 or 3 to see what your rifle will do in real world conditions.

When checking loads I wait 10 minutes between shots or so, but I am looking for accuracy in the load, not the rifle.


An intelligent man can debate things. A fool just says you are wrong.

I have gleamed from other posts you guys are Edited by JW Rule 1, and will address both at same time.

You say you are smart, but do not back it up.

You just say the other person is wrong, but again, do not back up.


Edited by JW Rule 5.

Just as much of an internet expert as you.

From the little bit of searching I did I see that the OAL in a couple places list the .270 at 3.340" making your 3.405" .065" longer than a factory cartridge. This is fine unless your accuracy suffers or if they won't fit your magazine.
Try loading 10 bullets at different lengths from your 3.405' reducing the length by .010" for each set of 10. Then shoot 5 shot groups and see how or if your accuracy changes.
If the length is the issue you should see your groups tighten and hit same basic POI then begin to open up again. I wouldn't go below the 3.340" recommended OAL though.
Please keep us posted. I'd like to know your results.

This thread is why i would not ask a question on any site .
If i have a problem i just start doing research in books and so on ? Trial and error are my best problem solvers .
I always have ideas when i read of a problem on site but i keep my thoughts to myself.
One thing i will say is i have seen the quality of bullets,brass and powder go down hill in the last 10 or 15 years ! Quality control at the factory's seems to gone by the way side.

Hi Folks,

This thread has brought out some very spirited opinions. I always learn something new from these sorts of discussions.

I recently reviewed some of my old targets and found a similar problem (two distinct groups within the same load) in some of my reloading efforts. Please see my thread called "Unexplained Fliers". I have been reading a lot about bullet seating depth lately. And along with the thoughts presented in this thread, I think one possible cause of my problem was that the jump distances of some of my loads were approaching zero. That is, the Cartridge Base To Ogive (CBTO) length was getting too close to the jam length. There is always some error in any measurement or any operation such as seating a bullet. So... I might have inadvertently had a few rounds within a particular batch where the bullet's ogive would touch the rifling when it was chambered. When the round was fired, this would have caused a larger than normal "pressure spike" and would have changed the way the rifle barrel vibrates as the bullet travels down it. It's like two different loads within the same batch. I am now seating my bullets slightly deeper.

Thanks for you thoughts on this subject,
Ron

The reason I ask here is that while researching the issue, I came up with a multitude of potential fixes suggested by people on other websites, not all of which are practical to test. For instance, people have said double grouping can result from loose scope mounting screws, bad scopes, improperly bedded barrels/actions, improper grip on the forend, loose action screws, excessive OAL, fouled bore, etc., and that's not even the full extent of the proposed solutions. While I'll certainly try different solutions myself, the reason I asked here is that there are several far more accomplished rifle shooters here whose opinions I trust to help me narrow down the potential causes of my problem.

I'd have shot it again yesterday, but it rained all yesterday afternoon and continues to today. Looks like I'll have to wait until next weekend.

TN, try this, back them off .030, also if you use standard dies, do this when seating, hold bullet in the case, and seat it just a bit, back the ram off, spin your case 60 degrees, seat a bit more, back off spin it again, and fully seat your bullets keeps run-out to a minimum if your using a standard FL sizer.
RR