A very useful calculator.

[450BM]

Twist Rate Stability Calculator

Our newly updated Twist Rate Stability Calculator not only tells you what your SG is, but it also lets you know if you are reaching your optimized BC.

bergerbullets.com

A buddy of mine sent me his 22 TCM with all the components to develop a load for. I figured that with a 1-16 twist I needed a short light bullet pushed as fast as possible. This calculator is backing up my theories. He sent me 3 different bullets, all Hornady, 45 gr Hornet, 45 gr HP Bee and 40 gr VMAX. So far the most accurate has been the 40gr VMAX shortened by pulling out the plastic tip. I’m pushing these to 2900 which is as fast as I dare but playing with the calculator shows the velocity has little effect on stability compared to bullet weight/length and twist.

I really think a 30gr VMAX, which I suspect is their 22 magnum bullet, would be perfect for this gun. For now though, going to keep pulling the tips from the 40gr VMAX’s. (That and I don’t have any of the 30gr VMAX’s…)

Powders he sent are Accurate TCM, the best metering powered I’ve ever used, H110 and LilGun. I’ve decided to concentrate on the TCM (9.6gr) since the velocity averaged 20 fps faster than H110 (11gr).

The last set of groups were odd…. When I held the gun tight the groups were pretty bad, 1.53” and 2.19 at 50 yards. When I held it with only my trigger hand laying in the bags, I had groups of 1.1”, .42”, .925”, .8” and 1.145”. Pretty significant difference…

For the life of me, I can’t figure out why a fairly modern rifle, I think made in 2012, would have such a slow twist in it. A 1-8 would have easily stabilized any bullet you’d likely shoot in this cartridge and they had how many years of 22 Hornet history to look at!

Anyways, the Berger twist rate calculator is pretty handy and easy to use.

This chart comes in handy too giving bullet lengths… https://jbmballistics.com/ballistics/lengths/lengths.shtml#Speer

 

[Webster]

Twist Rate Stability Calculator

Our newly updated Twist Rate Stability Calculator not only tells you what your SG is, but it also lets you know if you are reaching your optimized BC.

bergerbullets.com

A buddy of mine sent me his 22 TCM with all the components to develop a load for. I figured that with a 1-16 twist I needed a short light bullet pushed as fast as possible. This calculator is backing up my theories. He sent me 3 different bullets, all Hornady, 45 gr Hornet, 45 gr HP Bee and 40 gr VMAX. So far the most accurate has been the 40gr VMAX shortened by pulling out the plastic tip. I’m pushing these to 2900 which is as fast as I dare but playing with the calculator shows the velocity has little effect on stability compared to bullet weight/length and twist.

I really think a 30gr VMAX, which I suspect is their 22 magnum bullet, would be perfect for this gun. For now though, going to keep pulling the tips from the 40gr VMAX’s. (That and I don’t have any of the 30gr VMAX’s…)

Powders he sent are Accurate TCM, the best metering powered I’ve ever used, H110 and LilGun. I’ve decided to concentrate on the TCM (9.6gr) since the velocity averaged 20 fps faster than H110 (11gr).

The last set of groups were odd…. When I held the gun tight the groups were pretty bad, 1.53” and 2.19 at 50 yards. When I held it with only my trigger hand laying in the bags, I had groups of 1.1”, .42”, .925”, .8” and 1.145”. Pretty significant difference…

For the life of me, I can’t figure out why a fairly modern rifle, I think made in 2012, would have such a slow twist in it. A 1-8 would have easily stabilized any bullet you’d likely shoot in this cartridge and they had how many years of 22 Hornet history to look at!

Anyways, the Berger twist rate calculator is pretty handy and easy to use.

This chart comes in handy too giving bullet lengths… https://jbmballistics.com/ballistics/lengths/lengths.shtml#Speer

What do you mean by my trigger hand on the bag? I shoot with a bipod and a bag. My trigger hand doesn't come near the bag. Recoil starts as soon as the bullet moves forward. How you hold the gun effects how it moves while the bullet is still in the barrel. Before I start, I slide the rifle back and forth about an inch and watch how the cross hair moves on the target. I rotate the bag so the cross hairs only moves verticality. If there is side movement the bag grove is not aligned. With my trigger hand, my finger is on the trigger, the other 3 fingers only touch the small of the stock lightly pulling it into my shoulder. The stock butt should be in the hollow of the shoulder. If It rest on the bone the stock will roll off the bone a little under recoil. The more body parts you have touching the gun the more variables you have. I never shoot free recoil. It's a varmint hunting rifle and I am happy with the results I get. If you don't flinch you can see how the cross hair moves on the target under recoil. There's probably something to learn from that movement.

You comments tell you that your bench manners are affecting the groups.

 

[450BM]

What do you mean by my trigger hand on the bag? I shoot with a bipod and a bag. My trigger hand doesn't come near the bag. Recoil starts as soon as the bullet moves forward. How you hold the gun effects how it moves while the bullet is still in the barrel. Before I start, I slide the rifle back and forth about an inch and watch how the cross hair moves on the target. I rotate the bag so the cross hairs only moves verticality. If there is side movement the bag grove is not aligned. With my trigger hand, my finger is on the trigger, the other 3 fingers only touch the small of the stock lightly pulling it into my shoulder. The stock butt should be in the hollow of the shoulder. If It rest on the bone the stock will roll off the bone a little under recoil. The more body parts you have touching the gun the more variables you have. I never shoot free recoil. It's a varmint hunting rifle and I am happy with the results I get. If you don't flinch you can see how the cross hair moves on the target under recoil. There's probably something to learn from that movement.

You comments tell you that your bench manners are affecting the groups.

I didn’t write that very well.

The gun is laying on the front rest and rear bag with me holding it just enough with the my trigger hand to pull the trigger. I’m basically holding it like you described.

I know my bench manners are sometimes pretty terrible, I could never be a bench rest competitor, I get distracted too easily.

The barrel is free floated, I checked it yesterday.