Advice on 223 low velocities versus manufacturer data

[MotoSinge]

I'm reloading .223 exactly as per data from the manufacturer, but consistently getting 200fps lower velocities than the manufacturer data. Any thoughts on why my velocities are so low? Using Viht N135, Lapua brass, 69gr Scenar bullets. Thanks.

 

[davsco]

barrel length and twist the same as their test data?

 

[Snuby642]

Industry standard is 24 inch test barrels.

Sounds like you are shooting a 16 inch?

Estimate 25 fps per inch loss.

 

[spife7980]

Could just be the barrel. Load for your rifle, the manufactures info are guidelines that will never bring up a lawsuit in any barrel basically.

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[Deleted member 181377]

How cold is it where you are?

 

[Another Casual]

Even at the same barrel length some barrels will be slower than others. Some brands (Tikka) have a reputation for excellent accuracy but below average speeds.

Please post some details on your setup and load data and we might be able to shed some more light.

 

[Bmghunter]

Also with the recent threads about powder humidity and velocity, is your powder sitting in a humid environment for long? Lots of velocity lost from high humidity powder.

 

[MotoSinge]

Industry standard is 24 inch test barrels.

Sounds like you are shooting a 16 inch?

Estimate 25 fps per inch loss.

Thanks Snuby642 and all. I had overlooked the barrel length and didn't appreciate the velocity decrease as a result. I'm running an 18" barrel. Test barrel was 25". So that explains the velocity decrease.

 

[Snuby642]

Fyi our 223's averaged 25 fps loss.
308 was 32 fps loss per inch.

Does anyone have a ballpark fps loss for grendel?

Chrono bit it.

I have only found 2 mfg state a different than 24 inch test.
One was a grendel in 20 inch and one was a 16 inch barrel for subsonic 300 blk.

YMMV