Slower then expected speed from SK std+

[King_beardsly]

I tested out my tried and true SK Std+ through a new barrel and it shot pretty solid but when I choreographed it was a lot slower then I expected. I was getting an average of 1066 out of my 20” 16tw GM barrel but only 1025 from the PBB 23” 12tw, now I don’t know if the weather being roughly 32*F would cause the lack of speed or the length/twist rate but just seemed odd.

 

[RTH1800]

Cold weather, cold ammo, new barrel, rough bore, looser chamber and longer barrels shoot slower.

 

[Cowpokey]

^^^That^^^

Cold weather has a big effect on .22lr. 1,066fps out of a 20" barrel isn't really that slow, I get 1,068 out of my 20" Vudoo when it's much warmer than 32ºF

 

[King_beardsly]

Cold weather, cold ammo, new barrel, rough bore, looser chamber and longer barrels shoot slower.

It’s a pretty tight chamber, but you’re probably right with the temp having an effect on the speed. I just wasn’t expecting a 41fps difference between the two barrels, but then again I’m so used to centerfire logic and the world of the rimfire is still new to me.

 

[King_beardsly]

^^^That^^^

Cold weather has a big effect on .22lr. 1,066fps out of a 20" barrel isn't really that slow, I get 1,068 out of my 20" Vudoo when it's much warmer than 32ºF

The 1066 was pretty good, since I think the published speed is around 1070. I just didn’t expect the 40fps difference is speed going between a 20” and 23” with similar round counts, maybe I’ll check speed after a few matches to see if I gain anything.

 

[ma smith]

I don’t know if the weather being roughly 32*F would cause the lack of speed ...

View attachment 8084804View attachment 8084805

SK ammo performance degrades pretty noticeably in the cold.

 

[Defender32]

This is why a good temp table in velocity on the ammo you are shooting in your kestrel is a necessity. Every 15*-20* for a difference.

Every barrel will be different as well. the length will shave some speed, but most of it is the temp.

 

[King_beardsly]

This is why a good temp table in velocity on the ammo you are shooting in your kestrel is a necessity. Every 15*-20* for a difference.

Every barrel will be different as well. the length will shave some speed, but most of it is the temp.

I noted the speed and temp when I was going through filling out my spreadsheet and in the ballistic software.

 

[grauhanen]

There are several factors that explain why SK Standard Plus or any .22LR match ammo MV averages differ.

1. As noted above by others, temperature plays a significant role. MV averages for ammo from the same lot rise or fall with temperature.
2. Different bores, even of the same length, may produce different average MVs for the same ammo. Bore characteristics matter.
3. With entry level ammo such as SK varieties, average MVs for the same lot of ammo can vary from one box to the next.

 

[Hi-NV Shooter]

I tested out my tried and true SK Std+ through a new barrel and it shot pretty solid but when I choreographed it was a lot slower then I expected. I was getting an average of 1066 out of my 20” 16tw GM barrel but only 1025 from the PBB 23” 12tw, now I don’t know if the weather being roughly 32*F would cause the lack of speed or the length/twist rate but just seemed odd.

View attachment 8084804View attachment 8084805

Temperature affects the powder burn rate colder temperatures cause a slower burn rate. so logically lower MV

Lee

 

[RTH1800]

Bore finish seems to play a role as well.

 

[King_beardsly]

Bore finish seems to play a role as well.

Bore was lapped, so it should be pretty smooth but I’m sure after a few hundred rounds will smooth it out a bit more

 

[justin amateur]

What are all the variables that affect muzzle velocity?

These are what I can think of...

1) Primer chemistry and amount/moisture content
2) Powder chemistry and amount/moisture content
3) Bullet dimensions and weight
4) Seating depth and crimp tension
5) Brass volume and hardness
6) Chamber dimension/brass expansion
7) Bore finish and dimensions
8) Atmospheric conditions
9) Bore surface (combustion deposits/lubricant/metal deposits)

What am I forgetting?

 

[RTH1800]

Barrel length if not included in the bore finish and dimensions.

 

[King_beardsly]

What are all the variables that affect muzzle velocity?

These are what I can think of...

1) Primer chemistry and amount/moisture content
2) Powder chemistry and amount/moisture content
3) Bullet dimensions and weight
4) Seating depth and crimp tension
5) Brass volume and hardness
6) Chamber dimension/brass expansion
7) Bore finish and dimensions
8) Atmospheric conditions
9) Bore surface (combustion deposits/lubricant/metal deposits)

What am I forgetting?

So pretty much everything and the kitchen sick will have an effect on the speed.

 

[grauhanen]

Bore was lapped, so it should be pretty smooth but I’m sure after a few hundred rounds will smooth it out a bit more

Bores can remain different even after lapping. For example, two lapped bores can produce different results with the same ammo -- even if they are the same length.

The main causes of different average muzzle velocities for the same lots of ammo start with temperature and bore characteristics.

In the case of entry level match ammo, box-to-box variation within a lot must also be considered. Entry level lot sizes are so large that such variation is unavoidable.

 

[King_beardsly]

Bores can remain different even after lapping. For example, two lapped bores can produce different results with the same ammo -- even if they are the same length.

The main causes of different average muzzle velocities for the same lots of ammo start with temperature and bore characteristics.

In the case of entry level match ammo, box-to-box variation within a lot must also be considered. Entry level lot sizes are so large that such variation is unavoidable.

I didn’t even think about that, just because one bore is slick as eel snot doesn’t mean the one done right after it will be the same due to possible differences in material.

I only tested the speed on the SK because I’ve got a lot of it, and you can really see the difference within the same lot. One group is like .25 and the next open up to .5 and at distance it’s like a shotgun pattern, with the SD of 12 and ES of 45.

 

[usafa77]

I would agree Kidd all the way. My current go to rifle is a full Kidd build, and am very happy.
however thinking you can get repeatable 1/2 moa accuracy at 100 is a tall order. I honestly haven’t group tested mine at 100, but it is pretty hard to get that kind of performance even from a high end bolt gun.
my use has been prs and nrl22 events, and my dope starting with a solid 50 yard zero has held true projected out as far as 300 yards.

Didn't know about Aguila subsonic. Would love to buy a case, but not at today's price. I can get the TAC22 so much cheaper.

What are all the variables that affect muzzle velocity?

These are what I can think of...

1) Primer chemistry and amount/moisture content
2) Powder chemistry and amount/moisture content
3) Bullet dimensions and weight
4) Seating depth and crimp tension
5) Brass volume and hardness
6) Chamber dimension/brass expansion
7) Bore finish and dimensions
8) Atmospheric conditions
9) Bore surface (combustion deposits/lubricant/metal deposits)

What am I forgetting?

Didnt Eley post an article about the number of variables- like 400 different things. Humidity of powder the day it was produced- thinks like that.

 

[1588]

Isn't SK Standard Plus rated at 1,073 fps? 1,066 fps is close to factory specs and it's what I am seeing with my Savage MKII.

My lot of SK Standard Plus was purchased several years ago and it groups well at 100 yards. It shoots better through my Savage MKII than Wolf Match Target. I shot a 1-3/16" group at 100 yards on a light wind 41-degree day. Worst group of the day was 1-9/16".

 

[King_beardsly]

Isn't SK Standard Plus rated at 1,073 fps? 1,066 fps is close to factory specs and it's what I am seeing with my Savage MKII.

My lot of SK Standard Plus was purchased several years ago and it groups well at 100 yards. It shoots better through my Savage MKII than Wolf Match Target. I shot a 1-3/16" group at 100 yards on a light wind 41-degree day. Worst group of the day was 1-9/16".

The 1066 was out of my old barrel I pulled off in favor a heavier contour and a faster twist rate.

 

[Boxerglocker]

Those results are pretty typical. I get 1066 out of my 20 inch 16T with SK Standard +. Using the same lot my Lothar 22 inch 12T gets 1040 when used for practice ammo. My standard match ammo is SK LRM which gets 1090 in the Lothar. All speeds at the same pressure and mid 40s temps.

 

[King_beardsly]

Those results are pretty typical. I get 1066 out of my 20 inch 16T with SK Standard +. Using the same lot my Lothar 22 inch 12T gets 1040 when used for practice ammo. My standard match ammo is SK LRM which gets 1090 in the Lothar. All speeds at the same pressure and mid 40s temps.

I was hoping someone with a 12T would chime in with their experience, so my speed is pretty much what’s to be expected with the twist and length.

 

[DeathBeforeDismount]

You wont see the velocity boost until the barrel is seasoned. Same shit with both Standard + and RM in my vudoo. It shoots around 1045-1050.

 

[King_beardsly]

You wont see the velocity boost until the barrel is seasoned. Same shit with both Standard + and RM in my vudoo. It shoots around 1045-1050.

I’ve got 175 through the barrel after a quick “lot testing” session with a bunch more ammo to test. Also have a match this weekend, so figure another 150 through it and I’ll be a little over half way to seasoned.

 

[DeathBeforeDismount]

You are going to need closer to 1k through it. Thats when things tighten up.

 

[King_beardsly]

Couple more test sessions and a match or two, then I should be right around 1k