A few questions (while trying to develop my 77gr 223 loads)

[jicko]

1) I am trying to establish my seating depth of my 223Rem 77gr Nosler CC HPBT. The current OAL for me is somewhere between 2.258 - 2.260. When I tried to chamber them by releasing from an open bolt and extract them for inspection, I find that there are scratches and markings on the bullet itself. Some of them are quite deep, and i feel them with my finger. Is this an issue? Are those *normal*? Will they affect the accuracy of the bullet? Should I seat it deeper, and will that fix this issue?

(barrel is Colt 5.56 NATO)


2) I'm wondering if I can tumble my non-crimped 223s (after loading them)? Will/can tumbling actually seat the bullet further down? That may raise a pressure issue....


3) Regarding what's the max amount of powder to use, except not getting over the "recommended" max load and that the primer didn't pop out, what are other guidelines and signs to look for?


4) Has anyone do a study on the difference between Nosler Custom Competition .223 HPBT vs Sierra MatchKing .223 HPBT? For all the data I can find on them, they are pretty similar... in terms of dimensions and specifications.... so, basing my start loading numbers on one or the other should be safe, right? (always start low, and work it up.... )

 

[Britz]

I don't load 5.56, however this is what I know:
If your bullets have rifleing marks on them, you are too long and it is only a matter of time before you get a bullet stuck in your rifleing. Also, jamming the bullet agianst the rifle will increase chamber pressure and possibly reduce velocity.
I've never tumbled loaded bullets
Any marks on you bullet can theororeticaly affect the accuracy.
Before compressing loads, try putting powder in the case using a longer drop toob, you can get a little more powder in you case.
If you want to know about pressure signs, get a reloading book and memorize the "reloading steps" section. flatened primers, extractor marks, white rings, stretched cases, tight bolt...
If you are curious about the difference between two similar bullets, look at their website, they will likely give you the BC and the OAL of the bullet. I often use nosler data for a hornady or other brand bullet, but I use similar bullets and never start at the higher loads. It is often helpful to look at the bullet manufacurer's reccomendations for what worked on their gun (just a general guide, each rifle is different).
Hope this helps
Mark

 

[jicko]

Thanks for the quick and detailed reply.

I don't think they are rifling marks... they are more like scratch marks from the feeding ramp :-( I just wonder if they are normal for ARs (I never shot heavy bullets, or bullets that is seated to max OAL)

 

[Asa Yam]

It is normal for semiauto rifles to scratch the bullets - the feeding process isn't gentle, and it isn't silk lined. As you mentioned, the feed ramps on the AR are the culprit in this case. Some shooters take a crocus cloth to the sharp edges to reduce this - personally, I never bothered.

Also remember that a semiauto rifle isn't a benchrest gun. With good quality reloads, odds are the source of inaccuracy is you, not the rifle or ammo. It is possible for scratches, dings, etc. on the bullet to affect accuracy, however, you would have to be a VERY good shot to be able to tell the difference.

One thing to watch out for with compressed loads: Over time, they can push the bullet forward, and no amount of neck tension or crimp can overcome this. Oh, I suspect soldering the bullet to the case might prevent the bullet from being pushed, but this introduces significant problems of its own (i.e., excessive chamber pressure). The practice of soldering bullets to the case is guaranteed to be dangerous, and is highly discouraged.

Re: comparing bullets. The US military compared Nosler, Sierra and Hornady bullets during development tests for Mk 262 ammunition. Ultimately, they chose the Sierra product - for reasons unrelated to the accuracy of the bullet. Other shooters reported bullets from early lots of the 77s (made from J4 jackets - Nosler now makes their own) blew up in flight. Within the past few years, I haven't heard of more such reports.
NOTE: I've never fired a Nosler 77.

Re: Tumbling loaded ammo. The practice is discouraged by most companies selling reloading gear. I have seen several reports saying that a short tumble (about 15 minutes) seems to do no harm. I say why take the chance, when you can tumble brass between sizing and loading. I load using progressive presses, and sizing and loading are seperate operations.

Hope this helps.

 

[Britz]

Asa is obviously far more experienced than I am, but I do disagree with his statement that Autoloaders are not that accurate. I have seen A-R's that will shoot half minute groups pretty consistantly. They are a quality rifle, but one off the shelf probably won't do that. I am all for trying to make the best bullets possible as long as the gun is capable of shooting sub MOA. Why do you crimp such a light recoil shel? Is it because of the Autoloading?

 

[Asa Yam]

Asa is obviously far more experienced than I am, but I do disagree with his statement that Autoloaders are not that accurate.

A friend actually shot a sub-.25 MOA group with an AR-15 in a registered benchrest match - before semiautos were outlawed from such competition. However, he didn't shoot the bullets through the magazine - each round was single loaded.

Benchrest rifles aren't your run-of-the mill rifle. Consistent groups of sub .1 MOA are possible from some, assuming the shooter is up to the task. To date, no AR-15 has been able to duplicate such performance.

Most bullets fired in formal benchrest competition are relatively short, flat based designs - and almost always handmade. A bullet like the 77 grain Nosler simply won't be found at a benchrest match because:

• At short range (sub-300 yards), shorter, flat based bullets shoot smaller groups, and;
• At longer ranges, there are bullets that drift less than the 77s. And shoot smaller groups as a result.

The above is why I say an AR is not the equal of a benchrest rifle. However, I never said an AR was inaccurate - there are lots of factory ones that are consistent sub-MOA shooters.