question about ladder test results

[dmax1800]

I shot 2 sets of 2 ladders with 2 different primers. Powder and seating depth were the same for each ladder test. I used .3 grain increments for the powder. Caliber is 22-250 and the barrel is factory with an HS Precision stock.

With the first primer, WLR, the point of impact shifted down and to the left with the 2nd ladder.

With the 2nd primer, Fed 210, the first ladder strung the holes up and to the right with the last 3 shots almost touching. The second ladder had the holes basically strung out horizontally.

So my question is: why the inconsistency between the ladders with both primers? I was using a front shooting rest with a sandbag under the rear of the stock. So the rest was the same, same temp, virtually no wind.

 

[Bigeclipse]

I shot 2 sets of 2 ladders with 2 different primers. Powder and seating depth were the same for each ladder test. I used .3 grain increments for the powder. Caliber is 22-250 and the barrel is factory with an HS Precision stock.

With the first primer, WLR, the point of impact shifted down and to the left with the 2nd ladder.

With the 2nd primer, Fed 210, the first ladder strung the holes up and to the right with the last 3 shots almost touching. The second ladder had the holes basically strung out horizontally.

So my question is: why the inconsistency between the ladders with both primers? I was using a front shooting rest with a sandbag under the rear of the stock. So the rest was the same, same temp, virtually no wind.

could you post up pictures? and at what distance were you shooting?

 

[dmax1800]

Distance was 200 yards.

WLR primers:



Fed 210 primers:

 

[Mikecr]

Changing 3-4 things at once doesn't work so well, huh?
What seating depth & why?

 

[dmax1800]

Mikecr
I did 2 ladders each with 2 different primers. I didn't change 3 or 4 things.

 

[bruce_ventura]

Large dispersion is confounding your results. Look at the big picture. Here's what I see in your data:
1. Obvious left to right POI shift in three out of four strings. One string is inconclusive.
2. The low to high POI shift in one string is not supported by the other three strings. Disregard for now.

Are you at the max recommended load or seeing pressure effects at 36.7 gr? If so, switch powders and run a new ladder. If not, explore a higher charge weight with Varget, but only if it is safe to do so. You are looking for the left to right POI shift to stop. That's where you will fix the charge weight and explore COAL dependence.

The large dispersion may not be related to the load, but rather to something else about the gun. Have you shot match grade factory ammo through this gun and gotten smaller groups? If not, look for the usual culprits in the barrel condition, trigger and receiver fit to the stock. Some barrels shoot well clean, others dirty. This may not be a good bullet for this gun. Anything unusual about the brass or headspace?

 

[Bigeclipse]

also, I thought you should ignore horizontal stringing in ladder tests. The purpose is to find a powder range that gives you similar vertical groups which means the load is "stable" in your rifle in that range. You then do seating depth testing in that range to fine tune your group...also ladder tests really need to be completed at 300 yards or greater any less and shooter error can influence results, especially for a newer shooter. If 200 yards is your max range length, you may want to read up on running an OCW test at 100 yards.

 

[bruce_ventura]

also, I thought you should ignore horizontal stringing in ladder tests. The purpose is to find a powder range that gives you similar vertical groups which means the load is "stable" in your rifle in that range.

Although dispersion is large, the data is revealing something useful. To me, the OP's data shows a significant horizontal POI shift with charge weight. I think these results show a barrel vibration effect, not just a MV effect. Barrel vibration can happen in any direction. I would not ignore these results.

 

[Mikecr]

Mikecr
I did 2 ladders each with 2 different primers. I didn't change 3 or 4 things.

You changed at least 2 different ladders + 2 different primers + Spread in powder charge.
What about that seating?

Bigeclipse, bruce_ventura is right.
There is no reason to dismiss horizontal in ladders. Barrels release in every direction.

 

[Bigeclipse]

You changed at least 2 different ladders + 2 different primers + Spread in powder charge.
What about that seating?

Bigeclipse, bruce_ventura is right.
There is no reason to dismiss horizontal in ladders. Barrels release in every direction.

Good to know...I just thought that down range wind could effect shots horizontally and you should not adjust for this during the test itself so horizontal stringing should be ignored since you are not adjusting for it but I missed where he said there was little to no wind.

Also the red dots he used seem quite large to me for 200 yards. Unless he is aiming perfectly at the center of those dots...that could cause aiming issues...not saying that happened here.

 

[dmax1800]

Are you at the max recommended load or seeing pressure effects at 36.7 gr? If so, switch powders and run a new ladder. If not, explore a higher charge weight with Varget, but only if it is safe to do so. You are looking for the left to right POI shift to stop. That's where you will fix the charge weight and explore COAL dependence.

The large dispersion may not be related to the load, but rather to something else about the gun. Have you shot match grade factory ammo through this gun and gotten smaller groups? If not, look for the usual culprits in the barrel condition, trigger and receiver fit to the stock. Some barrels shoot well clean, others dirty. This may not be a good bullet for this gun. Anything unusual about the brass or headspace?

36.1 is book max for Varget and this bullet, so I'm already .6 gr over. But absolutely no pressure signs. Can't go any higher. I've already tried H380, but the results were worse. Sierra suggested RE-15, but it is too temperature sensitive and I can't find it anywhere.

I have not shot any match grade factory ammo. Barrel was cleaned before these ladder tests. Also shot a few foulers (about 10) and to sight in the scope. Trigger is a Timney. Receiver fit is very good. The stock has an aluminum bedding block and the barrel never touches anywhere. Ring and base screws were checked and were tight. Brass is Norma has had a thorough prepping. Nothing unusual about the headspace.

The red dots were the size they are because I've only got a 14x scope.

I've also tried Hornady V-max with a couple of different powders, but they were much worse than the Sierra Game Kings.

A third bullet???

 

[Bigeclipse]

36.1 is book max for Varget and this bullet, so I'm already .6 gr over. But absolutely no pressure signs. Can't go any higher. I've already tried H380, but the

The red dots were the size they are because I've only got a 14x scope.

I've also tried Hornady V-max with a couple of different powders, but they were much worse than the Sierra Game Kings.

A third bullet???

Hmm I only have a 14x scope as well and use dots about the size of a quarter at 200 yards. The guys above are really good shooters and can definitely provide much better knowledge than me so other than the dot size comment I'll let the pros answer

 

[bruce_ventura]

36.1 is book max for Varget and this bullet, so I'm already .6 gr over. But absolutely no pressure signs. Can't go any higher. ...
I've also tried Hornady V-max with a couple of different powders, but they were much worse than the Sierra Game Kings.

A third bullet???

Then I would look at charge weights below 35.2 gr and locate the weight that stops the POI shift on the left side. You might get lucky and find that the node is at or near 35.2 gr. That would be ~100 fps lower than the MV at max load - not too shabby.

Even though you've only begun load development, dispersion seems pretty big to me. How does the muzzle crown look? Any nicks? Seating depth might make a big difference - let's see.

Both are usually good bullets. I assume you're hunting varmints. You could try Barnes Varmint Grenades - I like them in my .223 rifles. I would see how the Sierras work out first.

Good luck.

 

[kahman308]

Have you at least tried a different powder? I had a 270 that wouldn't shoot worth a dang with 4064. I could at best manage 4in groups at 100 yards. Switched to 4831, and am satisfied with the results. I can now under 1in at 100 yards.