Thread: Pressure / barrel speeds?

Originally Posted by Shearer

Remember it's winter and pressures can rise as the weather gets warmer. This will vary depending on the powder.
I would stay away from any signs of maximum pressure at the moment. Maybe back off a full grain instead of half.

Mmmm ive lost 40fps since summer with my happy load, is that what would be expected?

Originally Posted by PerazziSC3

Im getting reasonable slap marks on my brass before i get any other signs of pressure with my tikka (norma brass)

Is a slap mark the round extractor mark on bottom of case?

Originally Posted by Gibo

Is a slap mark the round extractor mark on bottom of case?

yep the round one is from the ejector, the squarish one is from the extractor. I get these marks well before the primers are showing signs of pressure. The bolt lift is *slightly* heavier when im getting marks on the cases.

Originally Posted by Gibo

2209 51.5 grns fed 210 norma brass 21 3/4 inch barrel tikka 270 140 grn nosler ab. Been up to 52.4 grns no signs at all



Cheers K, never had trouble opening the bolt yet

Am currently working up loads for a 22" barrel .270 also, on a Weatherby Ultralight action, currently at:
-150 Berger VLD: 58x2213sc@84 fed210 2900fps 3/4" average (no pressure signs)
-140 Berger VLD: 58x2213sc@84 fed210 2900fps 5/8 average (no pressure signs)
Am going to bump the 140 VLD up 2 grains in 1 grain increments to get to 3000fps, and try the 130 VLD Classic Hunter (top BC for a 130gn 270 proj) looking to get to 3100fps, probably the maximum sensible velocity for a 22" barrel, (especially in a 6lb rifle) not able to get the consistancy in accuracy and velocity I wanted from 2209, if 2213 hadn't worked so well I would have gone to 2217

Have tried a few others but the Bergers work so well I'll stop with them.
This rife is going on patrol in a few hours, hoping to find a resting place for a 150 VLD before oh dark tomorrow night!

Is it just me or is the adi manual weak?

Some rifles its very close and others its miles off.
It is only a guide.

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Car pie. I now have a good feel of things. Got a mission sorted for the end of the month. After that its experiment time thanks chaps

In the 708 i can load to 42gr 2208 with no pressure with 162gr amaxes but 41 shows pressure with 150gr lrab. More pressure from lighter projectile of similar design (although suspect more bearing surface but too lazy to measure)

Originally Posted by distant stalker

In the 708 i can load to 42gr 2208 with no pressure with 162gr amaxes but 41 shows pressure with 150gr lrab. More pressure from lighter projectile of similar design (although suspect more bearing surface but too lazy to measure)

Yeah mate I'm the same in everything I have tried them in have to come back a little to. Shoot any good?

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Ok nothing amazing so far. Got a working load already though they were just a curiosity

Hey Gibo,

My take on the Barrel speeds depends on the weight of the projectile. And this is just some food for your thoughts.

I found this is information for the .223 Remington cartridge:

Barrel Twist Rate 1:14" 1:12" 1:9" 1:8" 1:7" or 1:6.5"
Max Bullet Weight 55gr FB 65gr FB 73gr BT 80gr BT 90gr BT VLD
(from http://www.6mmbr.com/223rem.html)

1:7 twist will shoot any .223 / 5.56 bullet up to 77 grains. You can't over stabilize a bullet. If you decide to shoot very thinly jacketed bullets (typically marketed as varmint bullets) weighing less than 55 grains in a 1:7 twist bbl. keep velocity under 2800 fps to prevent tearing the jacket.
(from 223 Bullet weights for 1:7 twist - THR)

Case: Winchester Twist: 1:12" Primer: Winchester SR, Small Rifle Barrel Length: 24" Trim Length: 1.750"
55 grain projectile Min Speed Pressure Max Speed Pressure
Hodgdon CFE 223 .224" 2.200" 26.0 3,133 43,300 PSI 27.8 3,329 51,300 PSI
75 grain projectile
Hodgdon CFE 223 .224" 2.250" 23.0 2,680 45,200 PSI 25.0 2,876 54,400 PSI
(from Take Aim at Rifle Reloading Data | Hodgdon Reloading)

Originally Posted by Gibo

Mmmm ive lost 40fps since summer with my happy load, is that what would be expected?

Hey Gibo,

Did you change any batches of the components or the brands themselves?
Remember the difference between hot air and cold air? Hot air is less dense so it should be faster.

This table is from Hodgdon powder but you might see that somethings back up your Velocity data https://www.hodgdon.com/smokeless/extreme/page3.php#top

Only thing thats changed is the scales ha ha! From digi to balance beam. Il keep an eye on it.

Originally Posted by Gibo

Only thing thats changed is the scales ha ha! From digi to balance beam. Il keep an eye on it.

So what about the crhony ?

I have watched my f1 clime over a hundred fps in 10 seconds as a shadow fell over it.


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Originally Posted by veitnamcam

So what about the crhony ?

I have watched my f1 clime over a hundred fps in 10 seconds as a shadow fell over it.


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Yeah could be, my mates loads were the same as they always are.
Its a pro chrony, are they known for fluctuations?