Mean radius and inaccurate hunting rifles

[Mr. B]

I have just discovered the theory of Mean Radius and have conducted 10 shot, 200 yard testing on handloads for a remington 742 woodsmaster in .30-06 that I inherited.

My first load was 49 grains of IMR-4350 with hornady brass, speer 150 gr. spitzers and cci primers. This load had an extreme spread of 9 inches, and a mean radius of 4 at 200 yards. R95 of 4*1.3=5.2. This gives a 95% confidence of landing your shots in a 10.4 inch circle. This seemed too big for deer hunting so I moved on to the next load.

My second load was 48 grains of IMR-4895 with federal brass, speer 150 gr. spitzers and cci primers. This load had an extreme spread of 7 inches, and a mean radius of 2.48 at 200 yards. This is a tried and true M1 Garand powder and bullet weight. The 95% confidence level or R95 = 2.48*1.3=3.224. This means that a high percentage of shots will land in a 6.5 inch circle at 200 yards. I don't hunt anywhere that would offer a 200 yard shot I think I will use this load.

Testing was conducted on windless days, from a lead sled, with 3 minutes between each shot.

I think this method is generally thought of as relevant only to accurate, long range rifles, however, it seems that it is just as relevant for the short range, less accurate deer hunting rifle. You get some very useful data from this method that 3 shot groups can't provide

• scope adjustment based on 10 shot group center (the more the better when the rifle is inaccurate)
• an actual way to evaluate accuracy based on intended target size
• some sort of actual confidence level that the large 10 shot group you are staring at can be directed to the intended target
• in this case an accurate handload in an inaccurate rifle for only 20 shots. Especially important in a rifle where every shot brings it closer self destruction!
• With a chronograph (I don't have one) you have all the information you need to get your zero angle in 4DOF.

I will be using this method of load development for accurate as well as inaccurate rifles going forward.

 

[Fast14riot]

It is a decent method, however in my hunting rifles I want to see how a true cold bore shot does. After my load development I clean the rifle then put 25 rounds on target and put it away dirty. I never go into the field with a cold, clean bore. I will shoot another day (usually too busy to wait an hour to shoot same day) and confirm my cold bore zero.

 

[dellet]

Mean radius provides great information for paper targets and evaluating a load. But applying that to live game, an extreme spread of 7”, gives you 100% confidence that 20% of your shots will miss the vitals completely on a broadside shot.

Depending on the size of the game and degree of quartering, with the average miss from point of aim being 2.5”, you should have the confidence that 100% of your shots will miss the vitals.

Kind of a harsh way to interpret the same information. The truth is that 100% of the shots in a 10 shot group, has a 10% chance of being the shot you take on game day.

None of that says you won’t kill a deer, but it might give an indication of how long to expect to track.

 

[dryhumor]

I would repeat the test on your chosen load without the lead sled. Unless you are going to use it in the field, you have introduced a variable you have not factored into your results.

 

[fkimble@charter.net]

A hunting weight 30-06 in a lead sled sounds like a good method to destroy your scope.

Frank

 

[William Vogel]

The 742 isn’t a great candidate for 200 yard shots because of its barrel to receiver fitting and it’s fore end stock attachment to the barrel/gas system. Front rest consistency is very important to shrink group size. I too have a 742 and while it’s historically important to me ( my mother bought the rifle for my dad just after their marriage), it’s a short range rifle at best. 2 moa is what I get from it with my load of 42.3 IMR 4064 with Speer 150 boattail PSP bullets. Watch out for velocity over 2600 in this gas operating system. I can make 600 yard shots on steel targets but it’s a 100 yard hunting rifle. It’s an awesome gun for 100 yard shots but I wouldn’t have confidence past that for deer. I laughed at the name “WoodsMaster” and agreed that its best use is in heavy cover. I deemed it the powerful Remington AK improved.

 

[Webster]

I have just discovered the theory of Mean Radius and have conducted 10 shot, 200 yard testing on handloads for a remington 742 woodsmaster in .30-06 that I inherited.

My first load was 49 grains of IMR-4350 with hornady brass, speer 150 gr. spitzers and cci primers. This load had an extreme spread of 9 inches, and a mean radius of 4 at 200 yards. R95 of 4*1.3=5.2. This gives a 95% confidence of landing your shots in a 10.4 inch circle. This seemed too big for deer hunting so I moved on to the next load.

My second load was 48 grains of IMR-4895 with federal brass, speer 150 gr. spitzers and cci primers. This load had an extreme spread of 7 inches, and a mean radius of 2.48 at 200 yards. This is a tried and true M1 Garand powder and bullet weight. The 95% confidence level or R95 = 2.48*1.3=3.224. This means that a high percentage of shots will land in a 6.5 inch circle at 200 yards. I don't hunt anywhere that would offer a 200 yard shot I think I will use this load.

Testing was conducted on windless days, from a lead sled, with 3 minutes between each shot.

I think this method is generally thought of as relevant only to accurate, long range rifles, however, it seems that it is just as relevant for the short range, less accurate deer hunting rifle. You get some very useful data from this method that 3 shot groups can't provide

• scope adjustment based on 10 shot group center (the more the better when the rifle is inaccurate)
• an actual way to evaluate accuracy based on intended target size
• some sort of actual confidence level that the large 10 shot group you are staring at can be directed to the intended target
• in this case an accurate handload in an inaccurate rifle for only 20 shots. Especially important in a rifle where every shot brings it closer self destruction!
• With a chronograph (I don't have one) you have all the information you need to get your zero angle in 4DOF.

I will be using this method of load development for accurate as well as inaccurate rifles going forward.

All you need is group size. No math involved. Sounds like a crappy riifle. I never had a factory rifle that shot worse than 1". Hows your shooting skills. Did you ever shoot a group under .5" with a rifle.

 

[HandgunHTR]

I would repeat the test on your chosen load without the lead sled. Unless you are going to use it in the field, you have introduced a variable you have not factored into your results.

Exactly. I would repeat the test using bags rather than the sled. In fact, you should toss the sled or put it in a place where it isn't accessible to you any more. All they are good for is destroying scopes and stocks.

I would also give your optics system a good going over as well before doing the test over. As I said above, lead sleds have a history of shearing off optics screws, and damaging scope internals, especially in lower end scopes (not saying that is what you have, but you didn't specify).

 

[SeabeeKen]

A hunting weight 30-06 in a lead sled sounds like a good method to destroy your scope.

Frank

Never damaged a scope on a lead sled. I've heard of it but never had it happen. Not even hundreds of rounds of 9.3x62. I have had to shoot more using one since my shoulder has been giving me trouble.

 

[6.5 forever]

A hunting weight 30-06 in a lead sled sounds like a good method to destroy your scope.

Frank

I am a range officer. I see this lead sled all the time and it makes me shutter. What a waste. They still can't hit anything with it

 

[6.5 forever]

I would repeat the test on your chosen load without the lead sled. Unless you are going to use it in the field, you have introduced a variable you have not factored into your results.

I wonder what the difference is in the POI between the lead sled and a hunting shot (off hand, rested on a stand, bipod, etc). I've never seen a shooter verify it after "sighting in" on a sled.

 

[dryhumor]

I wonder what the difference is in the POI between the lead sled and a hunting shot (off hand, rested on a stand, bipod, etc). I've never seen a shooter verify it after "sighting in" on a sled.

I’ve never used a sled. I’ve watched people a couple of times use them, and it seemed to me that it puts an unnatural hold into play. I’d want confidence in in the bodies ability to shoulder, weld, align, squeeze, and follow through. Being able to do that, with the added variables of heartbeat, breathing, and adrenaline gets tough some days.

I am curious now about the POI between a sled and the others though.

 

[jelenko]

I’ve never used a sled. I’ve watched people a couple of times use them, and it seemed to me that it puts an unnatural hold into play. I’d want confidence in in the bodies ability to shoulder, weld, align, squeeze, and follow through. Being able to do that, with the added variables of heartbeat, breathing, and adrenaline gets tough some days.

I am curious now about the POI between a sled and the others though.

My experience is there's a bunch of difference in POI.

The idea behind using a 'sled' is it takes much of the variables of a human out of firing the rifle so easier to determine the accuracy of a load.
My experience is also that there's a whole nother learning curve to getting consistent results from a sled.
From watching others use a sled, I've seen them print groups in the MOA range. But, for my application, I need to be able to differentiate between 1/2 MOA and 3/4 MOA groups.

I've gone back to using a front rest and rear bag.

 

[6.5 forever]

My experience is there's a bunch of difference in POI.

The idea behind using a 'sled' is it takes much of the variables of a human out of firing the rifle so easier to determine the accuracy of a load.
My experience is also that there's a whole nother learning curve to getting consistent results from a sled.
From watching others use a sled, I've seen them print groups in the MOA range. But, for my application, I need to be able to differentiate between 1/2 MOA and 3/4 MOA groups.

I've gone back to using a front rest and rear bag.

I'm with you!

 

[6.5 forever]

I’ve never used a sled. I’ve watched people a couple of times use them, and it seemed to me that it puts an unnatural hold into play. I’d want confidence in in the bodies ability to shoulder, weld, align, squeeze, and follow through. Being able to do that, with the added variables of heartbeat, breathing, and adrenaline gets tough some days.

I am curious now about the POI between a sled and the others though.

Has any one compared the POI

 

[SD guy]

Mr B:

I would try a different load. IMR 4350, may be a poor choice for down loading. In one fashion you have strived for a lower pressure load & I commend you for that. Though I have seen no load data for 4350 with that low of charge as a starting load. Not sure what else you have available for propellants or bullets.

Nosler offers data that may steer us in a direction for a starting point. Personally I do not handle high recoil well, thus I would look at Nosler load data offered that has an asterisk indicating an accuracy node at a lower velocity.

When I looked, IMR 4320 & VV N150 stand out for the 150 grain class projectile. With 125 grain projectiles H414 & IMR 4895 are a couple propellants that stand out to me. H4895 May also be a consideration as this one that often does well w reduced loads.

Then, I would ditch the lead sled & give an adjustable front rest and an appropriate rear bag a try. We are just looking to get an idea of what the rifle is capable of at this point. If it surprises you & does well, then perhaps you may consider a stiffer load or different projectile.

link for reduced loads if interested. https://www.americanrifleman.org/content/handloads-reduced-recoil-30-06-springfield/

 

[dryhumor]

When I shoot from a bench, plinking or load development, I use these bags. Depending on the stock, I may or may not need to add a spacer under the front. Seldom for the rear, but I do have different small squeeze bags if I need them.

When in the field, I use an Armageddon bag every chance I get. They work right side up, upside down, even standing up sideways. In many cases it will hold a rifle balanced in a ready position.

 

[Coyotefurharvester]

I saw the POI difference between a lead sled and bags/bipod while testing 338wm loads. The TC venture synthetic stock was too flexible. I used epoxy to reduce the forend flex. This reduced the poi change between rifle rest changes, still was about 2" at 100 yards. The groups however still had different shapes, for my rifle the sled turned nice clover leaf shapes into vertical strings. Having a brake installed later, allowed me to end the sled testing. And I was able to find a good sub moa load(tested to 400 yards) that maintained poi off bags,bipod which for hunting was all I needed.

 

[Spoonbill]

I have just discovered the theory of Mean Radius and have conducted 10 shot, 200 yard testing on handloads for a remington 742 woodsmaster in .30-06 that I inherited.

My first load was 49 grains of IMR-4350 with hornady brass, speer 150 gr. spitzers and cci primers. This load had an extreme spread of 9 inches, and a mean radius of 4 at 200 yards. R95 of 4*1.3=5.2. This gives a 95% confidence of landing your shots in a 10.4 inch circle. This seemed too big for deer hunting so I moved on to the next load.

My second load was 48 grains of IMR-4895 with federal brass, speer 150 gr. spitzers and cci primers. This load had an extreme spread of 7 inches, and a mean radius of 2.48 at 200 yards. This is a tried and true M1 Garand powder and bullet weight. The 95% confidence level or R95 = 2.48*1.3=3.224. This means that a high percentage of shots will land in a 6.5 inch circle at 200 yards. I don't hunt anywhere that would offer a 200 yard shot I think I will use this load.

Testing was conducted on windless days, from a lead sled, with 3 minutes between each shot.

I think this method is generally thought of as relevant only to accurate, long range rifles, however, it seems that it is just as relevant for the short range, less accurate deer hunting rifle. You get some very useful data from this method that 3 shot groups can't provide

• scope adjustment based on 10 shot group center (the more the better when the rifle is inaccurate)
• an actual way to evaluate accuracy based on intended target size
• some sort of actual confidence level that the large 10 shot group you are staring at can be directed to the intended target
• in this case an accurate handload in an inaccurate rifle for only 20 shots. Especially important in a rifle where every shot brings it closer self destruction!
• With a chronograph (I don't have one) you have all the information you need to get your zero angle in 4DOF.

I will be using this method of load development for accurate as well as inaccurate rifles going forward.

If it works it works. Its nice to have a really accurate rifle but not always necessary to kill a deer.

 

[Mr. B]

Mr B:

I would try a different load. H4350, may be a poor choice for down loading. In one fashion you have strived for a lower pressure load & I commend you for that. Though I have seen no load data for 4350 with that low of charge as a starting load. Not sure what else you have available for propellants or bullets.

Nosler offers data that may steer us in a direction for a starting point. Personally I do not handle high recoil well, thus I would look at Nosler load data offered that has an asterisk indicating an accuracy node at a lower velocity.

When I looked, IMR 4320 & VV N150 stand out for the 150 grain class projectile. With 125 grain projectiles H414 & IMR 4895 are a couple propellants that stand out to me. H4895 May also be a consideration as this one that often does well w reduced loads.

Then, I would ditch the lead sled & give an adjustable front rest and an appropriate rear bag a try. We are just looking to get an idea of what the rifle is capable of at this point. If it surprises you & does well, then perhaps you may consider a stiffer load or different projectile.

link for reduced loads if interested. https://www.americanrifleman.org/content/handloads-reduced-recoil-30-06-springfield/

I agree with you on the IMR 4350 being a poor choice. Going forward I will be considering IMR 4895, BL-C(2), and H4895. I have these powders and they are more suited for semi auto rifles.