As a "serious" and relatively experienced reloader when working with a new powder in a known rifle: How far above a "book load" would you venture?

Specifically the .223 Rem using 77 grain Siera MK's and IMR 8208 XBR powder.

Book (Hodgdon's website) published maximum 23.2 grains for a velocity of 2792.

The known rifle is chambered in 5.56 Nato.

Sorry also posted in the small caliber forum.

I find that most everything I have shoots more consistently a little under max loading, and I look for velocity deviation and group size more than just velocity.

Not to say I didn't load up and look for pressure signs at one stage in life, but as I've, ahem, *matured* I tend to look at velocity less and less.

I would not "venture" above it at all unless you can measure the psi reliably (sorry HC, your CHE doesn't cut it) particularly if the "known rifle" is an AR.

Larry Gibson

My AR is a 5.56 Chamber.
Buddies is a .223 Chamber.
With 52-55 grain bullets I have to back my loads off a full grain to avoid pressure signs in his rifle.

Some books like Nosler #6 list both chambers. You might want to see what they recommend for a 77gr bullet and a 5.56 chamber.

One book is never enough. It takes about 5 or 6 to get an idea what's going on...

quote:

One book is never enough. It takes about 5 or 6 to get an idea what's going on...

You got that right!

I use 77 gr. bullets in my AR (5.56 chamber) all the time. I can't get to max listed loads without pressure signs and accuracy isn't quite as good so I don't go there. With the 77's you usually have a compressed powder charge. I try to hold that to a minimum if possible. I am getting 2740 fps with Varget from an 18" bbl.
C.G.B.

The way to find that out while being safe is to shoot some kind of a pressure/velocity test. I've done it just loading 1 round at each designated charge weight starting at the book start load and move up slowly with some sort of predetermined charge weight increment. Say .3 grains for big cases or .2 grains for smaller case cartridges.

I'll load to the book listed max and go over it sometimes by as much as 1 full grain.

A good idea is to shoot these loads at about 300 or more yards at the same point of aim on a larger than normal target starting with the lowest charged case and moving up. When you do this, carfully examine the target through your spotting scope and on a mock up of the target at your bench, mark and number each shot in its unique location. Record the velocity as well if you have a chrono.

What's neat is that you will see some consecutively fired shots "group" or at least be on the same horizontal plane. That is telling you what charge weight range your barrel "likes" for the components for accuracy.

As you continue to shoot the cartridges, look for signs of pressure as you approach the book max. Sticky bolt, nice shiny ejector marks on the case head, etc. Stop shooting any more of the loads once you notice this, even though you may have more cartridges loaded. You can pull the bullets.

You have just found the max load for your rifle.

But wait!!

This is called an Audette's Ladder! It can find the max load for your rifle AND the accuracy nodes AT THE SAME TIME!

What will they think of next?

Velocity and inferred pressure are not a great way to do things but I'd say that 2792 fps is a pretty good velocity for a 20 inch AR. The M262 load with 77 SMK is in the neighborhood of 2810-2830, that's using TAC and will loosen primer pockets after a couple of loads. Ramshot actually lists a max load that is faster at 2900 fps. I haven't used 8208 yet, but 2792 fps will get you where you need to go. My load for 77's is 24 grains of Varget at 2700 fps, 24.5 runs 2750 if I remember. The 24 grain load will hold and X ring at 600 and is 1 MOA, 2 clicks with 1/2 minute sights, under the M262 round at 600 yards. Asa reference to the how far over part of your question, Sierra loads for the .223 not 5.56 and maxes out Varget at 23.8.

quote:

Originally posted by 308Sako:
As a "serious" and relatively experienced reloader when working with a new powder in a known rifle: How far above a "book load" would you venture? ...

I use the only two Pressure Detection Methods - that actually work, and eliminate guessing - good old, never fail, always reliable, time proven CHE & PRE. I let them tell me where the Upper Pressure Limit is located, because they always work.

But, you should use whatever Method you want.

quote:

Originally posted by cgbach:
I use 77 gr. bullets in my AR (5.56 chamber) all the time. I can't get to max listed loads without pressure signs and accuracy isn't quite as good so I don't go there. With the 77's you usually have a compressed powder charge. I try to hold that to a minimum if possible. I am getting 2740 fps with Varget from an 18" bbl.
C.G.B.

I cannot achieve that velocity with Varget and accuracy in my 24" Colt 6724, but have gotten to over 2900 ft/secs with XBR. Still no pressure signs consistant with this rifles history, accuracy is under 3/4 MOA at 300 yards.

I am not looking to find velocity at any cost, nor am I looking to venture into the totally unknown regions with my original post. I have tried TAC, as well as Varget, H4895, IMR 4064, 4320, 4007 SSC and various VV 133, 135, 140, 540 & 550 and some very hot factory loads, and this IMR 8208 XBR powder does not give any of those indications in this rifle.

I see some folks continue ignoring published data for safe reloading ,in their quest for additional velocity or accuracy !.

When choosing a powder check CUP or PSI for max loads , such as IMR 8208 XBR 23.2 2792 55,000 PSI


The .223 Remington is a sporting cartridge with the same external dimensions as the 5.56x45mm NATO military cartridge. It is loaded with a .224" diameter, jacketed bullet, with weights ranging from 40 up to 90 grains, though the most common loadings by far are 55 grains.

The primary difference between .223 Remington and 5.56 x 45 mm is that .223 is loaded to lower pressures and velocities compared to 5.56 mm. .223 Remington ammunition can be safely fired in a 5.56 mm chambered gun, but the reverse can be an unsafe combination. The additional pressure created by 5.56 mm ammo will frequently cause over-pressure problems such as difficult extraction, flowing brass, or popped primers, but in extreme cases, could damage or destroy the rifle. Chambers cut to .223 Remington specifications have a shorter leade (throat) area as well as slightly shorter headspace dimensions compared to 5.56 mm "military" chamber specs, which contributes to the pressure issues.

While the 5.56 mm and .223 cartridges are very similar, they are not identical. Military cases are made from thicker brass than commercial cases, which reduces the powder capacity (an important consideration for handloaders), and the NATO specification allows a higher chamber pressure. Test barrels made for 5.56mm NATO measure chamber pressure at the case mouth, as opposed to the SAAMI location. This difference accounts for upwards of 20,000+ psi difference in pressure measurements. That means that advertised pressure of 58,000 psi for 5.56mm NATO, is around 78,000 psi tested in .223 Rem test barrels (SAAMI .223 Rem Proof MAP is 78,500 psi so every 5.56mm round fired is a proof load, very dangerous). The 5.56 mm chambering, known as a NATO or mil-spec chambers, have a longer leade, which is the distance between the mouth of the cartridge and the point at which the rifling engages the bullet. The .223 chambering, known as the "SAAMI chamber", is allowed to have a shorter leade, and is only required to be proof tested to the lower SAAMI chamber pressure. To address these issues, various proprietary chambers exist, such as the Wylde chamber[2] or the Armalite chamber, which are designed to handle both 5.56 mm and .223 equally well.

Using commercial .223 cartridges in a 5.56-chambered rifle should work reliably, but generally will not be as accurate as when fired from a .223-chambered gun due to the excessive leade. [3] Using 5.56 mil-spec cartridges (such as the M855) in a .223-chambered rifle can lead to excessive wear and stress on the rifle and even be unsafe, and the SAAMI recommends against the practice.[4] Some commercial rifles marked as ".223 Remington" are in fact suited for 5.56 mm, such as many commercial AR-15 variants and the Ruger Mini-14, but the manufacturer should always be consulted to verify that this is acceptable before attempting it, and signs of excessive pressure (such as flattening or gas staining of the primers) should be looked for in the initial testing with 5.56 mm ammunition.

6mm BR article

223 Remington vs. 5.56x45--Chambering and Throat Considerations
Is the .223 Remington the same as the 5.56x45? The answer is yes and no. There ARE differences between the .223 Remington as shot in civilian rifles and the 5.56x45 in military use. While the external cartridge dimensions are essentially the same, the .223 Remington is built to SAAMI specs, rated to 50,000 CUP max pressure, and normally has a shorter throat. The 5.56x45 is built to NATO specs, rated to 60,000 CUP max pressure, and has a longer throat, optimized to shoot long bullets. That said, there are various .223 Remington match chambers, including the Wylde chamber, that feature longer throats. Military 5.56x45 brass often, but not always, has thicker internal construction, and slightly less capacity than commercial .223 Rem brass.

Should you be worried about shooting 5.56x45 milspec ammo in a .223 Remington? The answer really depends on your chamber. 5.56 x45 ammo is intended for chambers with longer throats. If you shoot hot 5.56x45 ammo in short-throated SAAMI-spec chambers you can encounter pressure issues. The new long-throated 'Wylde' chamber allows safe use of military ammo. Wylde chambers are quite common in Rock River guns. Other manufacturers, such as Fulton Armory, offer modified "match chambers" with extended throats that allow safe use of 5.56x45 ammo in .223 Remington rifles. For a complete discussion of the .223 Rem vs. 5.56x45 question, read this Tech Notice from Winchester, and this GunZone Commentary by Dean Speir. Without belaboring the point, we'll repeat the official SAAMI position: "Chambers for military rifles have a different throat configuration than chambers for sporting firearms which, together with the full metal jacket of the military projectile, may account for the higher pressures which result when military ammunition is fired in a sporting chamber. SAAMI recommends that a firearm be fired only with the cartridge for which it is specifically chambered by the manufacturer.

Bottom line why proof your rifle's chamber an barrel on every shot !. If your looking to impress someone purchase a Larger Bore !!!.

quote:

Originally posted by Hot Core:

...But, you should use whatever Method you want.

Very kind, diplomatic, non-feather ruffling, etc...

The New, non-abrasive, Neutered HC!

I hate that...

Doc, thank you for that most learned response.

I feel that several of the above posts reflect very well my own belief that each rifle is a law unto itself, and since dealing with a 5.56 Nato chambered rifle with .223 data was the origin here, All saftey precautions would apply.

I also concur with the bigger bore if that was a requirement for the intended use.

Thanks for your response!

quote:

Originally posted by rcamuglia:

quote:

Originally posted by Hot Core:

...But, you should use whatever Method you want.

Very kind, diplomatic, non-feather ruffling, etc...

That is why EVERYONE has ALWAYS refered to me as "Amiable Hot Core".

1/10th of a grain over .223 Rem data, but fired in a Colt 5.56 NATO chambered Colt 6724.

Absolutely not a hint of pressure (other than velocity ) in this rifle.

Excellent Shooting!

I could not care less what the MV is --the group is what counts and using the published data from the Hodgon website
I have had some excellent groups using IMR 8028 XBR in the ,223 rem. I will have to say also that I will not be buying any more of it since I get the same or better results using N-135 of which I have a lifetime supply and it works better in several other cartridges I shoot.

quote:

308Sako

I didn't mean to single out anyone in particular I simply posted that as general info .

I also agree 100% a rifle is an entity unto it's self , in regards too accuracy Not sure about metallurgical however .

quote:

find that most everything I have shoots more consistently a little under max loading, and I look for velocity deviation and group size more than just velocity.

Not to say I didn't load up and look for pressure signs at one stage in life, but as I've, ahem, *matured* I tend to look at velocity less and less.

I would also agree with the above statement 100%




I simply don't wish to see anyone hurt reloading or firing !!. It's one of the main reasons I've always been so insistent ,on persons using loading manuals !. Some pretty remarkable experiments and a ton of collaboration between manufactures ,has in fact been done on the reloaders behalf . Pressure peaks time curve with resulting accuracy consistent with favorable velocity's , all to avoid possible injury's too the reloading shooter's community .

I know most all of us at one time or another ,has had pressure signs resulting in a , WOW or HOLY Shit stuck round hard extraction Etc. An I least of anyone should point fingers ,because once upon a time I batched powders for Hercules . Now with that said How many of us have read about AMMO recalls from MAJOR manufactures as of late !. Yea they SCREW UP just like everyone else !.

Many Powders are different today then they were years back ,an I'm guilty as charged of using older powders an old loading data !.

Now imagine new data with old powder or vice versa which is worse , an I myself have SCREWED UP more than once !.

Be safe be sane and enjoy the art of single hole pursuits !. Nice Groupings as well as Shooting !!!.

PS ; That picture of a S&W 629 isn't mine , an I only heard a story of what happened . It was due to improperly reloaded cartridges !.

God forbid that happens to anyone on this forum !!!!!!!!!!!!!!!!!!!!!!.

Velocity 2845, 2861, 2874

5.56 chambered Colt 6724

As one, who, although not new to handloading, am still learning, I appreciate very much the posts in this thread, especially the information submitted by Doc. All these posts have been helpful to me and I will certainly heed the advise offered.
Thanks to all!

Doc - Glad to see your post. I hadn't seen any from you for a while and really missed them and you.

I share your view that newer batches sometimes are significantly different than those from years ago, even though they still have the same names.

When my wife forced our move here I had to give away over 400 pounds of various powders...no way I was going to risk transporting that batch in a rental truck, especially as we had to drive through California! And NONE of the commercial carriers I contacted would touch it.


Anyway, I am not only out whatever all those good powders were worth (and many can't be replaced at all), but now I have to work up loads for all my rifles again (over 100 different cartridges).

Best wishes, AC