Posted on 05/27/2012 5:48:19 AM PDT by FLAMING DEATH
Thanks for that. I’ve pretty much standardized on 62 grain projectiles be they FMJ, HP, or SP. I cant expect real distance accuracy out of an M-4gery anyway. That is what the M1A and the bolt guns are for.
Anytime, glad I could help, that’s just a general rule but I have heard guys shooting up to 75 gn and 77 gn projectiles out of their 1:9 twist rates just fine, it depends on the rifle really. If you already have 77 gn projectiles, load them up and give it a try, your rifle may shoot them fine or it won’t. You can see if your target has some funny holes in them if the bullet is tumbling or if there is a nice round hole.
Twist Rate Calculator (Green Hill Formula)
http://kwk.us/twist.html
my bad for not reading the whole article and i haven't shot it in awhile so they may very well be/prolly are clean steel now, but hitting it with a blowtorch would burn off lacquer on the case(if it was there) and i doubt anything would be visible coming off as it's burned up in the process of torching it i do know it was a problem in the past and the article makes a strong case for mixed brass/steel to keep it the chamber clean...
good article
I picked up a few boxes of moly costed 77 grain HP a while back. I fired a few at an indoor range at about 75 feet. No key holing evident, but I was wondering if that would hold true at longer distances.
Guess I’ll just have to take the 90 minute drive to the nearest outdoor place and give them a try. I will probably just stick with the 62 grain stuff just so I can standardize.
Thanks for the help. Have a nice holiday.
Ping - interesting
I can’t even begin to help you with that...since I bought my AR, I haven’t kept up with who’s selling what.
I’ll tell ya, though...if I was getting an AR, and I wanted to go the budget route, I’d get the parts and build my own.
Not saying I’d go this direction, but I’m intrigued by the Plum Crazy/New Frontier complete polymer lower, with trigger, grip, and buttstock installed for around $100. You can get a Del-Ton complete rifle kit with everything but the lower for $469 from Classic Arms. Says they’re in stock right now. You could swap out any of the parts in the lower with the better ones in the kit, and you’d have spares in case something broke. You’d be in under $600 for the whole thing. That’d be sweet.
Plus, you wouldn’t have to “build” anything...just pin the upper to the lower and you have a gun.
I think it’d be good for someone who needed a budget AR, or as a backup/truck rifle. Or, you could even get a dedicated .22 upper or conversion kit and have a great practice rifle.
Not sure how durable for the long term the polymer lower is, but the people who have them like them. And, they’ll take a lot of abuse.
http://www.youtube.com/watch?v=NaFevpTka-I
http://www.youtube.com/watch?v=_qpnmi3XPP8
http://www.youtube.com/watch?v=CEAYW_2y4VU
Thanks for the ping, I learned a lot. If things are ever so desperate that only steel-cased ammo is available, I'll remember to mix in some brass-cased in a 1-and-9 mixture. It would be a good, but desperate, use for all my PMC 5.56mm, which except for the brass case, is about the crappiest western-bloc ammo I've ever seen.
Soviet-style weapons were designed from the ground up for steel cases with a large amount of taper. They also have very large gas ports so there's plenty of energy to work the mechanism. My guess is they don't have the institutional "memory" of making ammo for western weapons the way the original designers intended ammo to be made.
The fairly violent functioning of an AK or SKS makes for greater reliability under adverse conditions, but at the cost of battering the weapon. No big deal in a political system where the rifle's user wasn't expected to have a long service lifetime, either.
Doesn’t explain why mine jams on the first round and every round after. Got a pile of steel cased .223? Buy an AK chambered for it.
The one thing the author never does (and which many gun owners never do) is *measure the cases and rounds*.
For starters:
Get a set of calipers (good ones, not the PRC crap out there for $15, but B&S, Starrett, Mitutoyo) and measure the over-all length of the round.
Then measure the diameter of the neck of the steel vs. brass cases.
Then measure the diameter just forward of the extractor rim on the case.
If the case starts out at the wrong size (too large) (which isn’t unknown with cheap, steel-cased ammo), then guess what? It ain’t gonna feed into the chamber correctly. Too small at the neck means it won’t seal the chamber against blow-back. Wrong OAL means that the bolt might not go into battery.
And so on.
Now, what is your rifle expecting?
You could start with a chamber print (available from the SAAMI website, or you could get a Pacific Tool & Gage chamber print book for $50, or you could look at a reloading manual for what the SAAMI spec for the ammo is supposed to be... or you could go to the extent of casting your chamber with Cerrosafe and measuring the cast.
http://www.brownells.com/.aspx/pid=384/Product/CERROSAFE-reg-CHAMBER-CASTING-ALLOY
I find it odd that so many otherwise intelligent shooters would spend so much time and trouble pondering these sorts of issues when a little application of actual measurement would likely tell them as much or more.
I appreciate your suggestions, but I tend to always start with the simplest explanations first and work your way up. Doing so in this case seems to have fixed the problem.
Occam’s razor is my friend.
Mine did too if I didn’t start with a clean chamber.
Otherwise, you might have a tighter chamber that what I do. I’d recommend what NVDave said and check the specs of the chamber.
Didn’t even know that they made “chamber casting alloy” and I have to say that is pretty cool.
Or, get a .223 AK. Never hurts to have more guns.
I learned a lot from this thread. Thanks for posting it.
Occam’s razor would indeed fix this problem. The nut of said proverb is the “simplest explanation is usually the correct one” and the nut of most problems in semi-auto failures to feed are magazine issues, and failures to extract are usually ammunition problems. Most ammunition problems stem from the fact that the ammunition is out-of-spec in relation to chamber dimensions. That’s taken across the whole of semi-auto firearms, not just the AR platform.
Thanks for reminding me about the CZ-82. Might have to look into one of those.
Also, if you ever chrono any Wolf or Tula, please post back with your results. I’d be fascinated to see what kind of consistency it exhibits.
For the price get two. Then you have one for parts.
Right.
If my problem had been that every round had exhibited the same issue, I’d probably have started by measuring the steel cased ammunition (or just throwing it out altogether). When I noticed that the problem only occurred after a certain number of rounds (more or less, about 50 rounds or so), regardless of any other factors, then I knew that it had to be a result of some condition changing with the gun.
When my buddy stated it was a dirty chamber issue and suggested I run a brass round every so often, I almost dismissed it as being “too simple”, therefore ignoring Occam’s Razor altogether. I had considered checking chamber dimensions, and perhaps even changing the chamber dimensions with a reamer if necessary, but to my surprise, mixing in the brass seemed to work. I still need to do more testing, though.
The more input and suggestions the better, though, especially for people who might be experiencing problems that aren’t exactly like the ones that happened to me.
That’s the cool thing about opening a gun thread on Free Republic. There are a bunch of knowledgeable people here. Every time I’ve shared information about something I’ve discovered, I end up picking up more new info that what I shared.
Thanks.
Can’t argue with getting two, but Mrs. FD would claim one and there’d be virtually no way she’d let me cannibalize one for the other, unless I was donating MY parts for fixing HER gun.
Fortunately, my dad has machining tools and can make virtually any part I might need, short of a barrel.
LOL.
I run into the same issue with Mrs. L. When I acquired our first Mosin rifle I was showing it to her. She said “I like it. Where’s yours?”.
I should have mentioned this about measurement:
If I sit down with high quality ammo (never mind Russian or ChiCom cut-rate stuff) and measure them, I’m going to find variances. There is almost no manufacturing process that can maintain super-tight tolerances down to, oh, less than one-thousandths of an inch without huge inspection/maint/culling protocols and expenses. There are variances on the length of the case, the thickness of the neck, the concentricity of the bullet in the neck, the roundness of the case, the diameter of the case, etc.
In ammo, I’ve measured brand-new cases from US high-quality manufacturing plants of as much as .003” in areas like length, neck diameter, etc. I’ve seen variances in weight between cases as much as 3 grains. Again, this is the good stuff. The best stuff will be tighter yet, but the price starts heading for the moon. Instead of buying the very best, I’ll often buy bulk “good stuff” and then measure/sort brass, sell off what I don’t want, etc.
You’ll see some plants and companies have more and less variance. What’s more is that as tooling and machines wear, sometimes the mean of the measurement starts to drift upwards... so that some of the stuff that is on the outside statistical edges will fall outside the allowed bounds of the chamber.
So not every case or round where the tolerances are out of spec will fail to feed because not every round will be out of spec. If the reloading plant’s dies are getting worn, hey, maybe one-in-ten rounds is out of spec, maybe more if they’re a foreign outfit and they don’t have to listen to complaints.
Part of why there’s a designed-in slop between the chamber size and the SAAMI max ammo dimensions is to allow for dirt, ammo dimensional variance, etc. That’s also the reason for allowances in go/no-go headspace dimensions.
Interesting you should mention that.
My wife got me a sweet, apparently unfired Nagant on our first Valentine’s day.
She’s somewhat recoil-sensitive, though, so she never fought me for it.
Nothing says love like cosmoline and 7.62x54R.
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