Problem @ 1000 yds - ES, Scope, or Shooter?

[vh20]

I'm hoping you guys can give me some advice on what you think may be going on here. Although I've been an avid shooter and reloader for many years, this is my first rifle set up for 1000+ yards. It is a stock Savage 110FCP .338LM. Load is 89.9gr Retumbo, WLRM primer, 300gr SMK, Lapua brass. I'd rather not mention the scope brand at this point until I rule it out as a possible cause, but suffice to say it is one that enjoys one of the better reputations here on the forum.

So the problem: at 100 yards, with this load the rifle will put three rounds into .30 MOA every time. At 500 yards, I was still getting a solid .50 MOA. However, on the three attempts I've made to shoot at 1000, the rifle starts out shooting at least sub-MOA where it should, but after a few shots, they begin to climb successively higher - up to a couple feet or more. I can then return the scope to zero, go back to 100 yards, and put another three rounds into .30 MOA, dead-on zero.

Now, I know that having a high ES can cause a load that shoots tight at 100 yds to break down at 1000, and I wasn't running a chrono when I was shooting at 1000, but on my earlier tests with this load I got an ES around 33 (avg - 2711). Not great, I know, but this load grouped much better than the same load with a CCI 250 at 500 yards, despite the CCI giving an ES of 21 - so I succumbed to the lure of the tighter groups at 500. Even so, if I plug in loads with an ES of 50 into the Shooter app, it only shows a difference in drop of about 12 in. from highest to lowest. PLUS, half of those would be ABOVE the aim point, and half would fall BELOW. With my current problem, the rifle starts out hitting where it would be expected for the avg. MV, then begins to climb higher and higher, but never lower - and WAY more than the extreme calculation of 12 inches.

Winds have been very light in each of these sessions, and are not a factor. The only three causes I can think of are 1) A high ES causing vertical stringing, but this is more severe than predicted; 2) A scope problem that drifts POI at the higher elevation (8.1 mil), but not at the lower, 100 yd. zero (Geez, is that even possible??), or 3) A problem with shooting technique. My ability to shoot consistently at 100 and 500, plus my first few shots of each session at 1000 would seem to indicate I'm doing my part, but I'm open to suggestions.

In the pic below, you can see my first shot (labeled "F" = clean/cold bore fouler) just to the right of the edge of the white paper, and close to the proper elevation (I over-compensated for a 4 mph wind from 90 deg.). I reduced my windage adjustment by half, and fired my next shot (labeled "1"). I felt pretty good about hitting dead-on elevation and only two inches right at 1000 yds on the first shot after the fouler. However, shot numbered 2-5 all did as in previous sessions, and climbed up, up, up. Having seen this happen twice before, I moved up to 100 yards, set the turrets to Zeros, and fired shots 6,7, and 8 into a 0.278 in. group (typical for this load), essentially dead-on zero.



Here's a close-up of the 100 yd. group (shots 6,7, and 8).

So what do you guys think? Can ES of 30, or even 50 make THAT much difference between 100 and 1000?

 

[vh20]

The first time I noticed this was the first time I backed out to 875 yds. I was shooting jugs filled with colored water so that I could see the hits. After shooting one fouler on an cold/clean bore, I made a first-round hit at 630, then backed off to 875. I fired several shots as a group, but scored no hits. When I drove to the target, I found a group size small enough to all be hits, but the windage was off just a smidge:



I corrected the Windage, and fired the next six rounds, expecting every one to be a hit. Instead I found the following: (all high, though I did not touch the Elevation)

 

[arnie19]

I would try a different scope .It looks like when ever you turn the turrets for any thing more than 100 yards ,things are moving but not in a steady secure manner .

 

[vh20]

My next session started by reconfirming my zero - one fouler on a clean/cold bore, followed by a three-round group:


Next was a single, first-round hit at 875 yds. using Elevation calculation for MV of 2710 and range of 875 (near-miss, but hit the lower right corner):



Then moved to 1000, recalculated Elevation for MV of 2710 and range of 1000. This took two rounds for a hit, but first shot was CLOSE (by cap):



After that, put up a new jug, taped over previous holes, and same thing as before - no turret changes, but rounds climbing higher and higher. The last three rounds (6, 7, and 8) actually went above the board and don't even show. These shots are labeled 1-5, but I started over labeling shots when I put up the new jug. :

 

[vh20]

I would try a different scope .It looks like when ever you turn the turrets for any thing more than 100 yards ,things are moving but not in a steady secure manner .

I wish I could, Arnie, but I don't have access to one. I've even considered buying something like a SWFA SS fixed-power just for that, but that is an expensive "test". Do you (or anyone) think an ES of 30, or even 50, could account for the huge disparity in group size between 100 and 1000 yds seen here?

Thanks

 

[Dan Newberry]

I kinda doubt it's the load. And the rifle obviously shoots well enough to make a TRG-42 blush...

I agree with arnie, the scope may be the culprit. I'd try this, however: Run the scope's turrets end-to-end a couple or three dozen times. This will help the erector move more freely, and hopefully will uniform the movement. I've seen the most expensive scope on the market ignore a turret adjustment every once in a while... then they'll be jolted by recoil enough to finally go where they were actually dialed to.

 

[blurry6]

Hmmm,... Given the contour and length, I can't imagine that the barrel on a Savage 110FCP would heat up THAT much to start throwing 'em off, but who knows,... However, I've talked to several high-dollar barrel makers about their process and each has said that the key to getting a great barrel is the steel. Most of the quality barrel makers can all deliver 0.0015" tolerance in their barrels, so that's not really an issue. While all profess the steel to be the same spec, they have seen plenty evidence of certain 'batches' of steel blanks yielding superior barrels,... and others not cutting it,... just a thought. At first glance, it would seem that yours is a little too sensitive to heat,... but there are other things to consider, as follows:

Given that all the environmental variables are consistent, I'd guess powder charge variation (doubtful), primer inconsistency (doubtful), bullet inconsistency (possible, but doubtful), neck-tension (possible). Considering you're shooting so well at 100-yards, I don't think there is much to say about your shooting. How are you sizing your brass? Are you full-length resizing it with one die? Personally, I'm a fan of splitting up the variables for more control. I use Redding 'S' type dies. I only bump the shoulder .001-002" and size the neck .002" dimensionally (bushings) and only 2/3's of the way down the neck - the idea being to eliminate any potential donut formed by sizing the neck all the way to the shoulder and interfering with the neck tension - yes, it's a real issue. While Lapua brass is as consistent as it gets, you might try turning the necks to get ultimate consistency and testing them out.

At 1000-yards any and all defects/inconsistencies are going to start to show themselves,... Just a thought.

Ry

PS - What is your SD (Standard Deviation) for the rounds you shot? Try getting the SD around 10 to 15-fps variation for each string of 10-shots. If you can get it to that tight of a control, and you're still stringing them up/down,... you know it's that stock barrel.

 

[vh20]

Blurry, most of these shots were made 3 or 4 at a time, then drive 1/2+ miles across the pasture to check the result, then drive back to the bench, etc. By that time a good 10-15 minutes had passed since the last group was fired, and before the next one commenced. Also, the 100 yd. group in the first post was fired under those same circumstances, at the end of the session when the barrel would have been at its worst as far as heat or fouling go. Nevertheless, it is a "factory" barrel and I do not expect it to perform like a high-grade custom barrel, and your point is well-taken.

Regarding powder charge, the RCBS 5-10 scale that I've had for over 30 years now is capable of registering the difference in one kernel of Retumbo if you pay close attention. A half of one-tenth grain is easy to tell, and 0.1 grain is blatantly obvious. I am using a Redding S-type full-length die, bumping shoulders .001-.002", and using a bushing for .002" neck tension. I have not turned necks or tried sorting cases, bullets, etc.

The SD (and ES) that you mention is my only area of concern. I don't have a good answer for you because I had some problems with my chrono readings on the day that I was chronographing that load. I had some outliers that didn't make sense, and I think it was due to being too late in the afternoon to get good light. I was not running a chrono on the days I was shooting at 875 or 1000. I will be running one the next time I shoot, though. My best guess is that the ES on the load is around 30, but the weird outliers made it more like 50. Even at that though, it doesn't account for such a large group, according to the calculator, but I don't really know what to believe. Thanks for the suggestions. I'll have better numbers on the load after the next session.

 

[blurry6]

Hmmm,... That's what I figured - hard to mess up a powder charge of 90gr to be of significance. Good to hear that you're using the Redding 'S' dies. Try neck sizing them only 2/3's of the way down the neck,... it's important - you will probably see your SD and ES tighten up. That donut that forms at the neck/shoulder junction can really mess with your velocity if the bullet is seated well into the case i.e. past the junction,... as might me the case with a 300gr SMK

Ry

 

[vh20]

Hmmm,... That's what I figured - hard to mess up a powder charge of 90gr to be of significance. Good to hear that you're using the Redding 'S' dies. Try neck sizing them only 2/3's of the way down the neck,... it's important - you will probably see your SD and ES tighten up. That donut that forms at the neck/shoulder junction can really mess with your velocity if the bullet is seated well into the case i.e. past the junction,... as might me the case with a 300gr SMK

Ry

OK, dumb question time - how do you do that and maintain your 1-2 thou shoulder bump? Leave enough space above the bushing so that it can ride up? I think the normal setting for the die is to back-off 1/16 turn on the cap to give the bushing just a little space to float. To do what you're saying, you just back off more? Thanks

 

[blurry6]

Ahh, I see the trouble. You're using ONE die to do your FL sizing and neck sizing. I use the 3-die set: a body sizer, a neck sizer (allows for various bushing inserts and the ability to dial in the depth of the sizing), and a seating die. You might try backing off the top adjustment on the sizing die in order to give the bushing more play in the ONE die you have,... it might allow you to do that. Othersize, you have to cheat it by sizing the body without a bushing, then dialing the whole die off, putting in a bushing and sizing the neck 2/3's of the way down. I'm not sure if that will work.

Ry

 

[Dan Newberry]

If you're loading and feeding from the magazine, and you're using bushing dies... you may not have enough neck tension to keep the bullet from slipping forward in the case necks under recoil. This will really mess things up... just thought I'd mention that.

In order to rule out the barrel getting hot, and being the culprit, you should allow more cooling time between shots next time out as well.

Lastly... try 89.3 grains of Retumbo with the 300's. This is a steady, repeatable node--especially for the Savage guns. If you're not on a good, repeatable accuracy node, the slight changes that will come to the system due to a heating barrel or changing outside temperature, odd brass case--in short, anything that will alter the pressure of the load a bit--will move your POI more than you bargained for. This wouldn't be evident at 100 yards, but velocity spreads will increase vertical more and more as range increases, of course.

Dan

 

[Mad_Charlie]

Ahh, I see the trouble. You're using ONE die to do your FL sizing and neck sizing. I use the 3-die set: a body sizer, a neck sizer (allows for various bushing inserts and the ability to dial in the depth of the sizing), and a seating die. You might try backing off the top adjustment on the sizing die in order to give the bushing more play in the ONE die you have,... it might allow you to do that. Othersize, you have to cheat it by sizing the body without a bushing, then dialing the whole die off, putting in a bushing and sizing the neck 2/3's of the way down. I'm not sure if that will work.

Ry

It should, I do much the same thing by using a .070 spacer ground to size, that way I don't have to change the die adjustment.

 

[blurry6]

If you're loading and feeding from the magazine, and you're using bushing dies... you may not have enough neck tension to keep the bullet from slipping forward in the case necks under recoil. This will really mess things up... just thought I'd mention that.

In order to rule out the barrel getting hot, and being the culprit, you should allow more cooling time between shots next time out as well.

Lastly... try 89.3 grains of Retumbo with the 300's. This is a steady, repeatable node--especially for the Savage guns. If you're not on a good, repeatable accuracy node, the slight changes that will come to the system due to a heating barrel or changing outside temperature, odd brass case--in short, anything that will alter the pressure of the load a bit--will move your POI more than you bargained for. This wouldn't be evident at 100 yards, but velocity spreads will increase vertical more and more as range increases, of course.

Dan

Listen to Dan,... he's the man Slipping bullets in the mag while under recoil is a definite possibility, especially with a .338 Lapua. If you're single feeding them,... well, that's probably not it. Dan's definitely on to something with dialing back your load. You might be on the edge of a node with your current load and any/all shifts in environmental variables will really show up at long range.

Ry

 

[vh20]

Blurry - D'oh! Regarding the neck-sizing, of course, I see it now that I re-read it. The first time I read it (your first post), I thought you were saying you use a single Type-S/Full Length die. I was thinking trying to do that might cause more problems than it fixes. However, if I understand Mad Charlie's modified method, that might work just fine.

Dan - although I CAN load these loads from the magazine, I typically don't when I'm testing. These were loaded singly, but I appreciate your point because it is something I will remember in the future. Regarding 89.3 gr., I have found that I need to adjust my load every time I've changed powder lot numbers. Retumbo seems very consistent over a wide range of outside temps as long as it's from the same lot, but my MVs have changed every time I change lots (more times than I've wanted due to having to take what you can get during the shortages). There was a time during my load development that I found 89.3 to be working, changing lots changed the load. Regardless of the charge weight, the rifle always seems to start shooting best when MVs are in the low 2700s (say 2710s-2720s). With the current lot I'm using 89.9 gr. to get the same MV that I was getting from 89.5 gr from the previous lot. Fortunately, this is an 8-pounder so I have some to work with. How much time would you suggest between shots? Shoot 3-shot groups and wait for "x" minutes, or shoot singles with "x" minutes between shots?

Mad Charlie - if I understand, you are putting a .070 spacer beneath the bushing to raise it up and keep it from going all the way down to the shoulder? The o.d. is the same as the bushing, and the o.d. slightly more than the fired case neck?

Thanks, guys.

 

[Rprecision]

Something that is pretty cost effective is to do a tracking test on the scope. Shouldn't cost you more then about 20 rounds (although that's like 4lbs of powder)

 

[Mad_Charlie]

To vh20

No, I use the spacer between the die lock ring and the press, raises the whole thing up.

When I take the spacer out it bumps the shoulder, when I use the spacer it neck sizes all but the lower .070 of the neck.

This is with Redding type S FL die. I just leave the bushing out to bump the shoulder.

Clear as mud? ;-)

 

[vh20]

Very clear, MC. I see now - you're doing a two-step like Blurry but using only one die. Seems like it would work quite well, though. Thanks