Gunsmithing Weird problem, .284 Win chamber with .188 freebore

[Mike_in_FL]

I'm pretty sure my chamber was cut with a PT&G reamer with that freebore dimension. This is for a Savage pre-fit barrel and I headspaced it fine using a Forster gauge. Here is where things take a dump. My brand new Winchester brass doesn't want to fit very well. The problem seems to be about less than 1/2" above the case head. Measuring my cases shows them to be around .494 just above the case head and around .490 where it gets tight in the chamber.

I thought I was having a problem related to the extractor but I removed it to test. Now it just makes it easier to force the case into the chamber. It's stuck well enough that I have to knock it out with a cleaning rod from the muzzle.

I don't own any, but my first thought has been is it possible that this is a dimensional issue between Winchester and Lapua brass with this reamer? Any help would be appreciated at this point.

 

[buffybuster]

Did you tried FL resizing the brass first and chamber check just the empty cases?

 

[Mike_in_FL]

Yes, same thing. I have a question in to the person that chambered the barrel for me. I've been doing some reading and what is weird is that from what I've read the Lapua brass is supposed to be thicker? I also have the Hornady case to use with their OAL tool, same thing have to force it into the chamber. And it's made from Win brass, to make matters even stranger I also have a 6.5-284 Hornady case made from a Norma. It chambers and falls right out with no extractor in the bolt. It almost looks like an OAL thing, like the brass needs to be trimmed. And again I find one piece of Win brass that chambers fine and it's close to max case length. JUST WEIRD.

 

[Turd in the Pool]

Sounds like his reamer is just tight at the base. What do the Norma cases measure at the base and around the .490" mark on the Win?

 

[stockdoc]

It isn't the case body that is giving you problems. It's the case neck. They are too thick. Seat bullets on each piece of brass and measure the necks. Note the difference. Neck turn the brass to the dimention on the brass that will chamber with no issues. Had two 6.5x284s and had the exact same issue. Neck turning fixed it

 

[300sniper]

i agree with stockdoc about it being the neck. although i have a hunch it is the bell mouth winchester 284 brass is notorious for. if you are running a fairly tight neck, the winchester brass really needs the outside of the mouth chamfered/deburred. sometimes this is hard to see but you can rub your thumb nail along the neck towards the mouth and it will hang up just before it drops off. i haven't personally measured it but i would think that lapua would have a thicker neck and a chamber would have a larger neck diameter if it were specifically designed for it. unless your chamber was designed for neck turned brass, i think it's probably the bur on the winchester brass.

 

[buffybuster]

Sounds like a tight neck issue. If you can check the reamer print dimensions against your brass. Or better yet make a chamber cast and take direct measurements.

 

[Mike_in_FL]

i agree with stockdoc about it being the neck. although i have a hunch it is the bell mouth winchester 284 brass is notorious for. if you are running a fairly tight neck, the winchester brass really needs the outside of the mouth chamfered/deburred.

I believe you and stockdoc are correct. I know you have a lot of experience with this cartridge so I appreciate you taking the time to reply. The reamer cuts the neck at .313 so I may have to turn them.

Since the Savage uses a barrel nut wrench I RTFM and followed their directions. Which are odd from how I've watched a chamber being headspaced on quite a few 700s, that is you cut and check the chamber with the bolt and the go gauge. The instructions stated hand tighten the barrel nut on the go, remove it, make sure it won't close on the no/go, remove and torque the barrel nut.

I never had an issue with not being able to close on the go gauge, but I went ahead and pulled it apart to torque it up again. The only difference was that this time I left the go in the chamber, and I was considering sticking a layer of scotch tape on the end of it. I tried chambering the cases and it was the same thing. I then tried a chamfer/debur, same thing. Better, but not perfect. I ran them through the FL die and they chambered fine. The neck issue I can understand, but the body was definitely a problem as well. Some of the cases I attempted to chamber before sizing actually have some marks on them now, never did this with new brass before BUT this is the most specified chamber I've ever asked to have cut. I didn't know the neck dimension offhand because I went with the reamer they had. Everything else ever done for me was just with a Clymer generic to the caliber.

I did make up one dummy round intentionally seated long to use in lieu of the Hornady tool. I didn't bother to pull out the stuff to measure to the ogive, but OAL with the 162 AMAX is right about 3.205. I think this is what I expected.

Thank you all and buffybuster for your help.

 

[turbo54]

.313" is quite tight for 284.

Loaded WWSuper cases measure ~.312-314", AFTER removing the gnarly bur.

My .317" neck chamber wouldn't accommodate WW cases until the but was removed.

A "Lapua" 284 chamber is larger down by the case head, so I doubt your chamber is too small for the WW cases.

I have a .319" neck reamer if you'd like to punch it out a little. A .313" neck **will** require neck turning for **all** head stamps.

 

[300sniper]

A .I need a good Mai tai recipe!313" neck **will** require neck turning for **all** head stamps.

Absolutely.

I'd have it opened up to .317-.318" for Winchester brass (making sure to remove the bur on the of of the case mouths). I haven't used or measured loaded lapua brass so I don't have advice on neck diameter for that off the top of my head.

 

[turbo54]

I know how to make Mai Tai's, actually...

But as for brass...

Lapua 6.5-284 that's been necked to 7mm and bullet seated measures ~.311-.312, so normally about .002" smaller than WWS.

Still, I contend you want at least .004" diametral neck-chamber clearance for a field rifle. More won't hurt.

 

[300sniper]

I know how to make Mai Tai's, actually...

But as for brass...

Lapua 6.5-284 that's been necked to 7mm and bullet seated measures ~.311-.312, so normally about .002" smaller than WWS.

Still, I contend you want at least .004" diametral neck-chamber clearance for a field rifle. More won't hurt.

lol, no idea where that came from!

 

[Mike_in_FL]

You gentlemen know your .28 calibers that's a fact. I have just measured two dummy rounds I threw together and they are running .312 - .315. It looks like I'll be acquiring the tools to turn the necks. I have been looking at the Forster setup which is their trimmer and the neck trimming attachment. I know I have to also buy the pilot, but Brownells shows 2 different pilots, one is longer? I think I want to go this route before I consider opening up the neck. Thanks again for all the help.

 

[colchester]

The long pilot is the one you want for the neck turning attachment

 

[RugerSlinger]

I have the Lyman Neck Turning tool and it works great. I was a little skeptical at first when using it but it does produce very uniform neck thickness.