.223 loads too slow.

[cjp45]

I loaded 27.3gr of H335 behind 5 different brands of 50 gr. bullets. I chronographed them and found that they were 700 fps less than what Sierra manual said I shoud be getting. There was also 300 fps difference between the high and low averages for these loads. I came up with the 700fps differeance buy taking the high average compared to manual. What could be the problem?

[billc]

I think at one time some reloading books listed 223 data assuming military brass. The smaller internal volume due to thicker brass generated higher pressure than civilian brass with the same powder load. I don't know it that is your problem. I would check a couple of different books. I would also check my scales to ensure I was loading the correct amount.

[cjp45]

Billc,
Thanks for the answer to my question. I'm just getting ready to send my scale back to PACT for a complete inspection.
CJP

[billc]

CJP,

Sorry to hear your scales had to go back to the shop. I would be interested in what you find out about the problem.

Bill

[wilmsmeyer]

I am new to the electronic scale game. However, so far, I love my PACT.

One thing I do is calibrate it before each use. Then I set my RCBS powder thrower for the charge I wish. I throw 4-5 charges and weigh them on the PACT. Then I weight them on my RCBS balance beam scale. I find that when they both are showing the same thing, my confidence is higher then just trickling powder onto an electronic devise alone.

Additionally, with a good flowing powder, the thrower can be set and relied on to throw charges within 2-3 tenths of a grain! Weighing every 10th charge verifies that things are still going well with the thrower.

[big6x6]

Never hurts to have a balance beam scale to verify every once in a while. Velocity variations from book are common and the .223 Remington is one of the worst ones. Reason ONE is BARREL length...Longer the barrel the more the velocity within reason. Common for .223 Rem barrels to vary from 16 inches to 26 inches! That's a LOT of velocity difference there! Also action type. A bolt action or single shot will always have a higher velocity than the corresponding auto all things being equal.. Then you have new brass vs. once fired brass... New brass will almost always shoot a slightly higher velocity...

Back to the powder charge of H335...your powder charge should have pretty much filled up the case and maybe up into the neck slightly.....

BTW...what velocity were you getting?

[cjp45]

Big6X6,
The high was 2,700 fps and the low was 2,400 fps. My rifle is a single shot with a 24'' barrel. I was useing once fired brass.

[big6x6]

Man...When you say too slow, you mean too SLOW! ;D

I have one .223 Rem that has a 24 inch barrel and it is a Remington VS. Here are some of the velocities I get:

Sierra 52gr MK
26.0gr H335 high-3246fps low-3206fps
26.5gr H335 high-3344fps low-3313fps

Compare that to some factory velocities out of that rifle:

Win Super-X 55gr PSP ave velocity-3126fps
Winchester 50gr Ballistic Tip 3386fps

I sure suspect your chronograph.... When you load 27.3gr H335 do you do a visual inspection of how much powder is in the case? If it all looks the same it probably not the scale... Did you try weighing some of the 50gr bullets? They should weigh 50gr =/- not more than 1gr... How were the GROUPS?

[cjp45]

Big6X6,
I also shot Rem. 55gr hollow points over my chronograph at the same range session. Thy averaged 3,200fps. Thats why I suspected my powder scale. I sent it in along with my powder measure that I want upgraded so it runs faster.