Causes of Low pressure -223

Muzzle blast giving you erroneous results?

Edit to add:
Hodgdon shows 23.0 as a starting load for 55 fmj at 3000 fps from a 24" barrel so I'm not sure how 20.8 gr would net 2900 fps.

That may be your issue.

Try 24.0 grains and see what happens.

(Hodgdon's) on-line/similar data is run from a 24" barrel
What length are you running?

Looking at the data on the Hodgdon site I see they use a 24" barrel to test the ammo. I'm guessing your barrel is below 18" which will account for a lot of velocity loss. The current Hornady manual reports a 26" barrel and the current Speer manual uses a 24" test barrel. Your rifle with a 16" to 18" barrel can't match their numbers.

You are probably doing nothing wrong. BTW, with 55gr bullets I usually charge 25.0gr H335 and that produces accurate and clean ammo for me.

OAL too short (compressing load or allowing pressure to sneak by before projectile hits lands?)??? Max OAL for 223 is 2.260. I usually load from 2.210 to 2.245 depending on the rifle. You're loading at 2.191 to 2.192 which is pretty short for a 55gr. Where is the cannellure on that Hornady bullet? It should not be completely buried.

If you plug H335 and a 55 grain bullet into the Hodgdon reloading sit, it gives you a load of 21.3 to 22.7 grains, with a COL of 2.180.

My only other thought would be to ask what your trim length on the cartridges is?

berettaprofessor said:

If you plug H335 and a 55 grain bullet into the Hodgdon reloading sit, it gives you a load of 21.3 to 22.7 grains, with a COL of 2.180.

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That data is for the Barnes all copper TSX bullet. For a standard 55gr SP bullet the H335 charge range is 23.0gr to 25.3gr max. which would apply to the bullet the OP is using.

Your problem is too slow a powder for a short barrel:

QUICKLOAD:
16" barrel
H335/21.6gr
55gr FMJ
2.190
33,577psi/2,524fps
Only 85% burn

(if actual barrel is only 14" -- then 2,422fps)


For a short barrel, use one of these powders:
Alliant AR-Comp
IMR 3031
Accurate 2495
Accurate 4064
Winchester 748
Accurate 2520

gifbohane said:

Well I went to the range to check my first 223 loads. Used 55Gr FMJ-BT Hornady (#2267)

Fired some factory rounds as a baseline. They chronoed an average of 2901 FPS.

First batch of 10 rounds of H 335 at 20.8 grains chronoed an average of 2300.

Second Batch of 10 rounds of H 335 at 21.6 grains chronoed and average of 2364.

Now the Hornady manual says that 20.8 grains should get you 2800 FPS and the 21.6 should get you 2900 FPS.

So the factory rounds were dead nuts on but mine were low pressure by a lot.

I guarantee that the loads were exact, I measured them twice before loading. All the rounds were 2.191 to 2.192 COL. The cartridges were same headstamp shot previously by me and had the military crimp removed by me. All the carts shot by me were purchased in bulk from midwestern retailer.

They all shot and ejected well. Nothing strange.

Ideas? Or Suggestions.

Thanks Gif

Click to expand...

I've run into that before with Hornady data. Hodgdon's or Sierra were a lot closer in what I actually got. I never could get those bullet to shoot anywhere near accurate no matter what powder I used in the 18" Wlyde 1:8 barrel I had. The long leads just kill that short bullet. 2" at 100 yrds was the best I ever got and it was with CFE-223 powder.

Your charges are waaaaay too low.
I load 25.0g H335 with a 55g fjmbt and get about 3030 fps out of a 20" AR

The very lowest chronographed data I have is 24.0g H335 which gave me mid 2800 fps. I doubt you'll get anywhere close to that with 21g

Many times, the load data will state that the barrel tested was 24". If you're shooting with a 16" barrel knock off a couple hundred fps of the published data.

The important thing is, are your loads accurate and do they cycle the gun properly?

Hodgdom pistol data.

Again, see Post#10
Use one of those powders for short barrels.

gifbohane said:

Now the Hornady manual says that 20.8 grains should get you 2800 FPS and the 21.6 should get you 2900 FPS.

Click to expand...

Hornady's generic load data should not cover 5 different bullets. IMO. Each bullet will have different bearing surfaces. Or in other words, some bullets make less contact with the bore. Less contact, less pressure, less velocity.
I would guess the 55Gr FMJ-BT Hornady (#2267) makes less contact.

Example of different bearing surfaces. https://www.thehighroad.org/index.php?media/bearing-surface-224-bullets.485/

Some bullets will have a pure lead core, lowest pressure. Other may have a harder alloy. Sierra has 5 different alloys.

Ball powders do better with a magnum primer. IMO.

I would like to see some one run each (5) Hornady bullets over a chronograph, with other components being the same.

I don't use 55gr bullets but I do use a lot of 60gr loaded at 24.1 with h335. When looking for more speed I go with CFE.
Oal just short of mag length.
Load manuals should be used but keep in mind that a lawyer was looking over their shoulder when max loads were determined.

MEHavey said:

Again, see Post#10
Use one of those powders for short barrels.

Click to expand...

I disagree, H335 is not slower than most of the powders you listed in Post #10. All but IMR3031 are slower and 3031 is just barely faster. I'm not sure why you think H335 is a slow powder but it's not. It was the powder used by the military in the form of WC844.

Fast powders for high velocity in short barrels is an old wives tale with no bearing. The better velocity powder in a Long barrel will still be the better velocity powder in the short barrel.

I’d echo the sentiments above - the barrel is short, so the velocity is low. The powder charge could be higher, depending upon the data you choose to follow. Both Hodgdon and Hornady pressure test all of their data, so discrepancies are either bullet type or test-equipment variance, both are safe.

Different bullet but Lyman Start 24.3gr Max 27gr with a 55gr Sierra Soft Point.
Note: Lymans data is quite a bit higher than Hodgdons.
Edit: I think 27 maybe to high, proceed with caution using Lymans data.
Color added.
Would need to check my notes but off the top of my head somewhere around 24.5gr of H335 was sweet spot for me with a 55 FMJ. (a little above the middle of Hodgdons range which is for .223 pressures not 5.56 pressures)

Interesting that Quickload says H335 is to slow but then suggests other powders that most burn rates charts list as slower than H335,
Of course burn speed charts do not necessarily reflect how a powder will behave in a given cartridge. Also of course Quickload is a model, I understand it to be a very good model, but still not the real thing.
I prefer TAC or BLC(2) for my AR/Mini14 over H335 but H335 seems to work well for a lot of people, hard to argue with what works well for lots of people.
OPs charges appear to be on the light side compared to Hodgdons charges and his barrel is shorter than the test barrel so of course lower vels.

I'm going to once again state that H335 is too slow for the OP's reqm'ts -- if he wants best performance -- notwithstanding ButEverybodyElseUsesIt defense.
That's one of the advantages of QuickLoad... as a significant number of other powders (already listed) are far more efficient, at lower pressures, for higher velocities, with that barrel/bullet combination.

But y`all press on, now, heah ?






* for you QL users, plug in the bullet/OAL/barrel/52ksi and ask it for an ordered list of velocity-prioritized powders
Incidentally, 108% fill is where a settled powder charges starts to compress. So one of the powders is out.

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