284 Shehane won't shoot - freebore too short?

[lrgoodger]

Well, after expending 345 bullets trying to get my 32" Bartlein 5R .284 Shehane barrel to shoot, I finally gave up. I tried everything. I suspect my freebore is too short at .189 and the bullets are seated so deep that the base of the bullet is into the area that gets re-formed when necking up the 6.5-284 Lapua brass to 7mm. The Berger 180 hybrids seem like they should be off this area by about 40 thou, but the JLK ogive will not let that 180 grain bullet go as deep into the lands before it touches, so I am certain it is seeing that problem.


After finally concluding I was not going to be able to get that barrel to shoot, I screwed it off the gun and screwed back on the Krieger 30BR barrel. After a half dozen shots to zero the scope and warm the barrel, it was right back to putting five shots in a dime at 200 yards (won my match with it today with a clean shoot on the egg board and 3 out of 3 painballs in the tiebreaker), so I know there was no problem with the BAT action, stock or scope. I'm going to check with Bartlein about sending this barrel back for inspection. I keep ALL of my load development targets, so I have targets with load data for every bullet that was fired through the barrel.

Frustrated.

Ron

 

[Steve Blair]

If you need more freebore, a simple 7mm throating reamer will fix that. I have a .188" Shehane reamer and it is a little short until the throat moves ~.010". I'm going to get a 7mm Uni-throater from PT&G.

 

[RDavies]

It sounds like the same reamer specs I have used on my last half dozen 284 Shehane barrels. This reamer with .189" freebore works well with the 180 Hybrids, leaving the boattail junction just above the neck shoulder junction with up to .020" jump. I used this reamer for my first few 284 Shehane barrels with 180 VLDs before the hybrids came out and had some very accurate 284s back then, still trying to replicate it now. I don't think the freebore will be the total problem. When you say it wont shoot, what sort of accuracy do you mean? What are your loads and velocity?

 

[Erik Cortina]

What size is your chamber neck?
How much neck clearance do you have?

 

[turbo54]

My 284 reamer puts a 175smk on the lands at 3.080" COAL.

It shoots great.

The "short freebore" is not your problem.

EDIT:

However, if you've got donuts, it can absolutely be causing poor accuracy. Because I run my 284 in a short action, any high-BC bullet is seated deeply and I have to be careful about donuts, and I've found the Lapua brass is a donut-nightmare.

 

[lrgoodger]

In my experience, if a barrel is going to shoot you can tell in the first 20 or 30 rounds. I've had screamers and just acceptable barrels, but this is only the second that just plain wouldn't group. I may look around for someone to move the throat out as sleepy suggested, but I don't hold out much hope that it will help.

The reamer is marked .313 nk but it measures .314. Fired cases measure .314 - .3145. I tried .002 clearance first and when I didn't have any luck, I shaved the necks a bit more to .310 loaded round. It didn't help a bit. I tried 4831SC, 4350 and RL17. There were a few tight 4 shot groups but there was always that fifth flyer (not necessarily the fifth shot). I didn't expect it to run with the 30BR at 200 yards, but anything that is going to hold the kind of vertical I'm reading about for the 284 Shehane, it would have to be close.

I'd say the group average is about .8 - .9" at 200 yards. To be competitive at a varmint match it needs to do .5" average or better at 200. I was hoping to have it shooting by Saturday because I have to go up against Schatz and Balding at the Midwest VHA match. I don't think the 30BR is going to cut it for that. It will do great at 100 and OK at 300 but 400 yards is a stretch for that gun. I could get lucky and I don't have much other choice right now except my 6BR with the 105 grain hybrids. That has been accurate enough to snuff prairie dogs over 1000 yards, but I just looked at the bore. I have not shot it since the last trip to Wyoming and the bore looks pretty rough. I'm going to try a few loads tomorrow and see if it will still shoot.

Thanks for all the suggestions, guys.