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Posted: 12/29/2005 6:28:35 PM EDT
[Last Edit: 12/29/2005 6:30:46 PM EDT by tyler2you]
I just put together a build with Denny's Guns 16" Recon barrel. The barrel is stainless and has a Wylde chamber. It comes from WOA with a headspaced bolt.

I took it to the range yesterday and did the break-in routine by firing a shot and then cleaning. I started out using some Black Hills .223 68 grain match ammo (blue box remanufactured). The first round chambered and fired with no problem, but when I dropped the mag and tried to unchamber the round, it was very difficult to pull back the charging handle. It was so stiff, I almost couldn't get the bolt back. When the round did eject, it had a couple of lengthwise scratches on the bullet. The gun ejects the .223 empties normally.

I also fired a couple of variants of 5.56 (55 and 77 grain) and had no problems at all. Manually extracting rounds was easy and felt normal.

Any ideas what could be causing the problem?

Thanks

Link Posted: 12/29/2005 7:17:24 PM EDT
Link Posted: 12/29/2005 7:21:47 PM EDT
Are Black Hills using Wolf cases these days ?
Link Posted: 12/29/2005 8:01:05 PM EDT
Tweak:

There was some slight primer cratering on the fired rounds, but not what I consider excessive.

When I manually eject rounds, it does create some scratches and slight dents on the extractor side of the case. The extractor is also scraping up the case head and extractor groove.

What are you thinking? Is it a headspace issue? The barrel was supposed to be headspaced to the bolt it came with.

I hand cycled some 77gr 5.56 ammo as well. There were some scratches on the projectile, but nothing on the case like with the .223.

Here's some pictures that probably don't show much.







Link Posted: 12/29/2005 8:13:48 PM EDT
[Last Edit: 12/29/2005 8:16:18 PM EDT by Dano523]
The long straight scratches that you are seeing is not caused by the chamber, but being caused by the tips of the lugs on the barrel extension as the case is being removed (ejector caming the brass over against the lugs).

As for Black hills ammo over the other ammo sticking in the chamber when still live, could be that the chamber is either short reamed (brass being slight longer on the BH ammo) or the ogive on the BH ammo is engaging the throat of the bore (bullet mark on photo 1 just after the neck ends).

My suggestion would be to check the headspace, then use a sharpie to smoke a BH round and see if the bullet is engaging the lands.
Link Posted: 12/29/2005 9:02:29 PM EDT
It looks like the cases may be a bit long, or your barrel has a shallow throat.
In the 3rd, and 4th pic, the end of the case neck appears shinier than the rest of the case. Like it was squeezed into a tight spot. I don't think this is from factory crimping.
Do you have any rounds that have not been chambered, for comparison? It would be interesting to see if the necks look the same.
Link Posted: 12/30/2005 4:50:45 AM EDT
Here's about the best I could do with the picture. The one in back is unchambered.




Thanks everyone for the help so far. If I do have a short chamber, what do you recommend? Should the barrel go back?

Link Posted: 12/30/2005 7:42:12 AM EDT
Short chamber yes,
Short throat, not if you’re going to reload. This short throat will allow you to load match type ammo to both fit into the mag, and just kiss the lands (read my guess why you bought the Wylde chamber).

Note: looking at the last photo, I can see the bullet embedment scrap line caused by the throat. If you have a bore scope, check the beginning of the throat. Since this is a new barrel, could just be that there is a high step reamer bur that may just need to be knocked down.
Link Posted: 12/30/2005 10:42:48 AM EDT
[Last Edit: 12/30/2005 3:56:25 PM EDT by Tweak]
Link Posted: 12/30/2005 8:53:45 PM EDT
I'm confused.

I would have thought that I would have these kind of issues with 5.56 ammo in the Wylde chamber due to the thicker case walls. Isn't the Wylde chamber technically .223?

Why would the 77 grain 5.56 stuff extract easily yet the 68 grain .223 ammo will barely come out of the chamber?

Could it be an issue with how Black Hills resizes the cases on their remanufactured ammo (neck not pushed far enough back)?

I'd like to shoot some of the more accurate loadings in .223. Will this still be possible?

Thanks again for all the diagnosis.
Link Posted: 12/30/2005 9:05:53 PM EDT
Link Posted: 1/1/2006 7:22:00 AM EDT
[Last Edit: 1/1/2006 7:25:15 AM EDT by imcoltsguy]

You've gotten some good suggestions from some of the most knowledgable people on the board. I doubt that I can add anything but the bottom line is that you are getting pressure signs with some ammo but not others. Black Hills is good ammo but your chamber doesn't like it. Suggest you don't shoot that ammo and it wouldn't be a bad idea to have your chamber checked either. Have you contacted Denny's to see if they have any other complaints about barrels from this maker?

Link Posted: 1/1/2006 9:07:00 AM EDT
Thanks imcoltsguy--that's what I plan to do--just not shoot the BH stuff.

I haven't sent anything to Denny yet--I plan to take the gun to a local shop and have them take a look first.

Thanks.

Link Posted: 1/1/2006 12:03:26 PM EDT
tyler2you,
If you are anywhere near Denver, We can get together some weekend when I am home and load you up a few cases of ammo for the barrel/rifle. As stated, the barrel has a shorter throat than a USGI chamber and to get the most out of it, you will need to reload.

If you haven't noticed by now, each type of bullet has a different ogive, which is the section from which a given bullet will be .224, then step down to the point/end. Since different ogives mean that the different bullet needs to be set in relationship to the throat of the chamber, and not the OAL of the round to fit the mag, some loads will need to be loaded shorter than the max mag allowed lenght. This is a good thing since if the barrel is a 1/8 twist, the 68gr bullet can be loaded to both fit the mag, and to kiss the lands (throat).

To sum it up, a shorter throated barrel is ideal for a tack driver that you plan to run ammo out of the mag, but it involves that you reload for the barrel. On the other hand, if you are going to run production ammo, you will need to pick a single round type, and then have the throat cut for it for the kiss needed (.003 off the lands). As of now, it does sound as if the throat is cut for the 77gr round, but you will need to gauge the throat to be sure of this.
Link Posted: 1/1/2006 12:09:31 PM EDT
To add, if you want to do some more reading, do a search on the Oly SUM barrels.
Here the barrels are chambered in tighter 223, and also with a shorter throat. Not only do you see signs of overpressure caused by trying to run Nato ammo in the tighter 223 chamber, the bullet embedding take the over pressure problem two fold when the wrong factory type of ammo is used.
Link Posted: 1/1/2006 5:20:08 PM EDT
When cycling a few mags of m855 through my new Stag Arms upper with .556 chamber I had to slam the stock agaist the floor while pulling on the charging handle to remove several of the first few rnds. They had scratches very similar to yours plus one deep scratch on a bullet. I just made sure to have my safety glasses on when I went to fire the rifle. I fired 120rnds with no problems and inspection of the brass showed no major scratches or high pressure signs. Maybe you need to carefully break in the rifle before sending anything back.
Link Posted: 1/1/2006 8:24:25 PM EDT

Originally Posted By HP40:
When cycling a few mags of m855 through my new Stag Arms upper with .556 chamber I had to slam the stock agaist the floor while pulling on the charging handle to remove several of the first few rnds. They had scratches very similar to yours plus one deep scratch on a bullet. I just made sure to have my safety glasses on when I went to fire the rifle. I fired 120rnds with no problems and inspection of the brass showed no major scratches or high pressure signs. Maybe you need to carefully break in the rifle before sending anything back.



+1
Just did this with my Superlite I built,... about the 6th round I tried to fire, which was fresh out of a box of XM193, stuck so badly I had to repeatedly slam the CH and FA to loosen things up. (I didn't want to be seen on the range cam slamming my stock down to the ground with a live one in the pipe... ). My issue was that the bolt didn't completely close upon chambering the round, so I couldnt even break the weapon open! It was far enough for the hammer to fall, though.

When I finally got the bolt closed (cam engaged), the bolt was still stuck shut. I opened the rifle, cocked the hammer, and (probably stupidly) let it fly. Gun fired, case ejected, and had no odd markings. Rifle functioned fine after, shows no ills now at this point.

+1 for longer break in!
Link Posted: 1/1/2006 10:23:33 PM EDT
Thanks for all the great input--I want to get the headspace checked just for my piece of mind.

I'd thought about reloading, but always figured it was more difficult for an autoloader--small base sizing dies, crimps, etc. I've been reloading for my Remmy 700 VSSF for about 6 months with decent results, but the bolt action is very forgiving. May have to give it a try.

People on the range do start to give you funny looks when you start pounding your buttstock on the ground.

The 77 grain 5.56 stuff shoots sub MOA, so maybe I should just call that good. The Black Hills stuff sure is a bargain though at $13 a box of 50. Heck, 55 grain surplus shoots very close to MOA as well.

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