Tight 223 brass in my AR15. Is it ok?

[RodneyDowns]

1st a little background (then my problem):
I just got my AR15 recently and unfortunately the range is only open ONE day a week so load development is rediculously slow.

Heres the rifle, Bushmaster Upper 24" Varmint HVY match barrel, LAR grizzly Lower w/ RRA LPK, Stark E-2 grip, Nikon Buckmaster 6-18x scope, Primary arms 1 piece scope mount.

Anyway, the 1st trip to the range was using several brands of factory amo just to see how the gun shot. Here are the four best 100yd groups.

Everything else shot .75 or bigger so I didnt even bother with them. This was better than I had expected with off the shelf ammo even though th ereview I read had a 1/4" 100 yd group (with NICE ammo. I was very excited to think I could get sub .5 moa with factory ammo. I couldnt wait to try out some nice reloads.

I have searched everywhere I could find for best loads for the AR15 223. I found several and decided to try 6 of them for the 1st test run using 50gr sierra blitzkings? (green tips),55gr vmax, and 69gr SMK's. I seated the bullets back off the lands a few thousands.
I have several brands of brass (range brass) sorted by brand but right now I dont rem which brand I used for these tests. I do know is was 223 brass not 5.56 brass.
When I 1st started to reload for this AR I used the standard RCBS FL die but noticed the bolt wouldnt copmpletely close on this brass if I closed the bolt slowly with the charging handle. It closes just fine on new factory ammo. My friend said he knew what the problem was. I needed a Small Base die. So I bought one and tried it.
The bras still wont close all the way if I close it slowly. Is that ok? If I just pull the bolt back and let go it slams the bolt closed just fine. but with factory ammo it closes fine even going slow. Is that normal?
I have the SB die just barely touching the shell holder to get the most I can from the die.
I measuered the factory brass and the only difference is the factory brass is .003-.004 smaller than the fully resized brass at the base. Length is right at 1.750, neck and shoulder measurements match the factory loads. just the base is off a few thousands. I'm assuming that is why the bolt wont close slowly all the way.
#1 - Is this something I should be worried about?
#2 - Does it have any effect on accuracy?

The reason I ask #2 is that I took my handloads to the range and they all 6 shot horribly. Not one group under 1". I was totaly diqusted. I dont know if i was just having a terrible day or the loads for some reason sucked in my gun even though MANY people claim they are the best loads theyve shot in their AR15's. The only 2 things I can think of are I need to find the right OAL and that the reloads dont feed a easily as the factory stuff.

I've used the SB die on several different brands of bras with the same results. I guess the bushmaster upper chamber just has very tight tolerances? But if I cant shoot reloads that are more accurate than cheap factory stuff with it I dont want it.

And ideas? Its supposed to rain all week so no range time this week it looks like.

frustrated,
Rodney

 

[turbo54]

Re: Tight 223 brass in my AR15. Is it ok?

Use your non-SB FLS die and size a few pieces of brass

Use your SB FLS die and size a few pieces of brass

Remove your upper from lower, tip the muzzle to the floor.

Drop sized cases into the chamber, push on the case head to "force" it into the chamber with 1 or 2 lbs of force.

Tip the muzzle up. Does the brass fall out? No? It should, so the cases need more sizing.

For an autoloader to work properly, the cases need to be a nice easy fit into the chamber.

You should buy a case gage so you can properly set your sizing die. The "lower die until it contacts shellholder" is close, but not 100%.

 

[turbo54]

Re: Tight 223 brass in my AR15. Is it ok?

Other possibilities:

Chamber dirty or rough.

Maybe your COAL is too long.

Maybe your brass is too long.

Maybe your bolt is really tight to the locking lugs in the barrel extension. Ease your carrier (with no cartridge) home into battery nice and easy. Does it go right in and lock up?

 

[RodneyDowns]

Re: Tight 223 brass in my AR15. Is it ok?

Turbo- Im resizing the brass down as far as it will possibly go. I cant resize it any smaller.

I thouroughly cleaned the gun last night. (completely field stripped) still a problem.

COAL is fine. bullets are backed of the lands a few thousands.

Ive tried it with resized but unloaded brass. Still a problem and the neck and shoulder both measure the same or smaller than the loaded rounds.

I tried resizing with the decapping pin out to make sure the button didnt effect the neck. still a problem.

As I stated, the brass is 1.750 (its all newly trimmed to the suggested trim length, max 223 brass lenght is 1.850).

Bolt is fine. Works perfectly with no round in the chamber and also with factory rounds in the chamber. The ONLY difference I can see is that the factory brass is .003 smaller than the resized brass right at the base where the brass is in the shell holder and I cant resize that small part.

 

[turbo54]

Re: Tight 223 brass in my AR15. Is it ok?

Try the sized brass in the chamber technique I mentioned before - and you shoud get a case gage.

If your press/die setup won't get the brass small enough, you'll have to grind the top face of the shellholder or the bottom face of the die to size the brass more.

 

[RodneyDowns]

Re: Tight 223 brass in my AR15. Is it ok?

Turbo54-
I tried what you mentions and more and even using a small base die and contacting the shell holder with the die the brass is still just too tight.

Soory it took so long to reply but I set the AR in the safe for a while and finished building my 1000 yd gun and have been consumed with getting it set up and shooting, testing dope, etc.
Its all good to go now so back to the AR.

I HAVE talked to several people since my last post and a couple have had the same problem. I was told by one guy he had a few thou taken off the back of his chamber and that solved it. Others say just to ream it to 5.56 dimensions. (I didnt buy the tighter tolerance chamber for better accuracy just to ream it out)
I'm sure that the problem lies in the extremely tight tolerance of the bushy chamber. Tonight I will blacken a SB sized case and feed it in and extract it. I'm pretty sure I'll find the shoulder, and possibly the base, needs to be bumped down just a few thousands. (which I cant do even with a SB Die and a standard shell holder. )
I know you can buy Competition Shell holders that are a set of 6-8 shell holders with the top part milled to different hights in I think .002 increments for I think $30.00- $40.00. I think I'll get a standard shell holder for a few bucks and have a friend mill a few thou off at a time and see how that works.

I;ll try this 1st before messing with the chamber.

 

[9H_Cracka]

Re: Tight 223 brass in my AR15. Is it ok?

Buy a Wilson case gauge. Learn to use the case gauge. Gauge your sized brass to see where it is dimension-wise. This will help you isolate the problem to be either reloading related or rifle related.

 

[aojones]

Re: Tight 223 brass in my AR15. Is it ok?

What brand of dies are you using, I found that some are not as good as others. I perfer Dillion for semi autos, they make a 3-die carbide set that works great for auto loaders. Just a thought....

 

[RodneyDowns]

Re: Tight 223 brass in my AR15. Is it ok?

aojones- I have always used RCBS dies. I DO have a some NICE Redding and Forster dies for my 1000yd gun but the rest are all RCBS with no complaints.

I Found the problem!!!

I was searching the net to find a solution and last night I started checking to see just where the case was not being sized down enough to fit easily.
I set my small base die so that it just touched the shell holder when the ram was all the way up.
Sized a case, and it still didn’t fit.
I blacked a case with a match to see where the die was contacting the case so I could tell what was and wasn’t being resized. I pushed the case all the way into the die and noticed there was a slight gap between the shell holder and die. Took out the case, raised the ram and they touched. Put the case back in and there was the gap.
I use a rockchucker and have always been very happy with it. I was very suprised to see there was a .003 gap after making sure the die touched the shell holder when empty.
SO, apparently the rock chucker has a few thousands difference between no resistance and a case giving resistance.I'm sure its the play in the pivot pin.
Anyway, I adjusted the die down about .002 leaving .001 gap when the ram is up all the way and a case is in the shell holder and tried that. Now the resized cases feed perfectly in the AR. It was just that .002 extra that was the problem.
NOW I can start working up loads soon for the AR and hopefully they will do better.

 

[Kiba]

Re: Tight 223 brass in my AR15. Is it ok?

FYI... I have the same upper and it absolutely shines with 50gr V-max over N133 powder and a 7.5 primer. Many a ground squirrel and coyote has fallen to that upper... makes great groups on paper too.

For my semi-autos I use a Redding Type-S bushing FL die and bump the shoulder back .002-.0025" from a once fired case measured using a shoulder gauge. No issues with tight cases/chambering problems and I haven't found the need for a small-base die even after 6 loads on LC brass.

For easier tweaking of die height I really like the shim packs that Sinclair sells. I setup the die & locknut with about .008" shim at nominal and then in the future it's very quick and easy to adjust a few thousands in either direction if necessary without ever having to dink with the locknut on the die. Also works great for using the same die for multiple rifles with slightly different chambers-- just add or subtract the shim stack to achieve the correct shoulder setback. Simple, easy, and cheap.

http://www.sinclairintl.com/.aspx/pid=33197/Product/Skip_s_die_shim_kit____7_8_14_

 

[Prairie Wolf]

Re: Tight 223 brass in my AR15. Is it ok?

I was going to say the next step might be to polish off a little bit on the base of your die. I don't know what RCBS's setup instructions are, but my cheap Lee dies you are supposed to set them so the press "cams over". I don't do that, but I usually have pretty solid contact with the shell holder.

 

[RodneyDowns]

Re: Tight 223 brass in my AR15. Is it ok?

Kiba- Thanks for the tip. Those shims will help when switching from my 223 bolt brass to AR brass.

 

[MitchAlsup]

Re: Tight 223 brass in my AR15. Is it ok?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Rocca</div><div class="ubbcode-body">I Found the problem!!! </div></div>

Actually, you had identified the problem in your first post::
"When I 1st started to reload for this AR I used the standard RCBS FL die but noticed the bolt wouldnt copmpletely close on this brass if I closed the bolt slowly with the charging handle. It closes just fine on new factory ammo. My friend said he knew what the problem was. I needed a Small Base die. So I bought one and tried it.
The bras still wont close all the way if I close it slowly.<snip> I have the SB die just barely touching the shell holder to get the most I can from the die.
I measuered the factory brass and the only difference is the factory brass is .003-.004 smaller than the fully resized brass at the base."

The factory ammo is shorter "on the shoulder" that the resized brass. There is the problem.

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">I was searching the net to find a solution and last night I started checking to see just where the case was not being sized down enough to fit easily.
I set my small base die so that it just touched the shell holder when the ram was all the way up.
Sized a case, and it still didn’t fit.
I blacked a case with a match to see where the die was contacting the case so I could tell what was and wasn’t being resized. I pushed the case all the way into the die and noticed there was a slight gap between the shell holder and die. Took out the case, raised the ram and they touched. Put the case back in and there was the gap.
I use a rockchucker and have always been very happy with it. I was very suprised to see there was a .003 gap after making sure the die touched the shell holder when empty.
SO, apparently the rock chucker has a few thousands difference between no resistance and a case giving resistance.I'm sure its the play in the pivot pin.</div></div>

As far as I have seen, all cases have such "self aligning" clearances. This is what complicated die-set-up for the uninitiated.

This is also why the budding reloader should have a means to measure the shoulder position to the 0.001 accuracy required for precision work.

 

[Tioga]

Re: Tight 223 brass in my AR15. Is it ok?

I will also use N133 with 50 VMAX in 24" varminter shoots real well in all my AR's

 

[RodneyDowns]

Re: Tight 223 brass in my AR15. Is it ok?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Tioga</div><div class="ubbcode-body">I will also use N133 with 50 VMAX in 24" varminter shoots real well in all my AR's</div></div>
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Kiba</div><div class="ubbcode-body">FYI... I have the same upper and it absolutely shines with 50gr V-max over N133 powder and a 7.5 primer. Many a ground squirrel and coyote has fallen to that upper... makes great groups on paper too. </div></div>

How many grains of N133 are you using? an dwhat about seating depth? Are you touching the lands/ .005 off lands? or what?

And when you say shoots great, what kind of groups are you getting.

I was planing on waiting for Hodgens new AR powder but maybe I'll try some N133.