A Short Throated Handi!!

[Fred M]

MT Glass Quote.
I'm still perplexed as to what to do about this barrel.  There is a .001" constriction just ahead of the throat.  The grooves are .286 here and .287 at the muzzle.  I still haven't shot it waiting for some decent weather.

How did you get these measurements? Did you use a bumped up lead slug?

If these dimensions are correct you have a way out of spec barrel, worse still with the one thou restriction at the throat. I would consider this barrel a reject.

You will have severe blow by and a great deal of lost velocity, even though your chamber pressure is up to snuff. To get more velocity is not safely possible without raising the chamber pressure beyond safe limits.

I had a similar barrel in a 25-06 Handi but not nearly as bad as what yours is and lost 100ft vel. with every load.

[MTGlass]

Fred,

To get these measurements I used both LBT push through slugs and egg shaped lead sinkers.

First, after cleaning the barrel I pushed an LBT slug through, chamber to muzzel.  I didn't like how it felt; tight at first then sloppy loose the rest of the way out.  I posted about it here a few weeks ago.  On Quick's suggestion I slugged both ends.  At the muzzel I pushed in anoter LBT slug just far enough to get a good engraving of the lands then scratched an index mark on the slug before pulling it back out.  I did the same with a sinker, pushing it back out with a rod from the chamber.  At the chamber I did essentially the same thing, but I couldn't make the index marks.

My mesuremens were done with a dial caliper.  I really do need to get a micrometer.  At any rate, the diameter difference across the grooves is readily discernable on the caliper.

After taking the measurements of the LBT muzzel slug I reindexed it in the muzzel and gently pushed it all the way through.  After pushing it through the tight spot just ahead of the throat it came out with the smaller ~.286 groove diameter rather than the ~.287 it started with at the muzzel.  I wish I knew someone with a bore scope.

I too have wondered about what kind of pressure curve this would produce and whether bullets would have a rattle fit the rest of the way down the barrel.    I hadn't considered blow by.  I'll bet you're right on that one too.

I don't know if I can, and haven't tried to get a measurement across the lands.  I would expect that to be .284 or less.  The wife's out of the house for another hour.  I'll see what I can come up with.  I should repeat the muzzel to chamber process again too.

I dread having to send this rifle back to the factory and have been dragging my feet on making the call.

[Fred M]

MT Glass.
It looks like they way you do it you will be a tad shy of the real size. You need a slug about a .290 x 1/2" long and dive it into the muzzle with a wood dowel.
It should be soft lead.

Then you put a rod against the slug from the chamber end and use a brass punch and drive the slug against the rod.

Push the slug out a bit and index it, then push it  out and take your measurments.
Lube your barrel put the slug back in excactly as it came out and push it down the barrel you can feel when it gets tighter mark the spot and push the slug out the chamber and measure it again.

Anyway I can see your barrel is over size at 287 by three thou. The lands are only two thou x two. So across the lands you only have 283. That means a 284 bullet will only engrave a 1/2 thou on each side or not at all on one side.

I would send it back to the factory, and get a new one. It is too bad that H&R
sends out a barrel like that.

I have a bore scope but that wont tell you anthing about dimensions, but would tell you a bump. Measurements across the lands are meaningless too when the grooves are out of spec. Sorry about your barrel.

I have explained before why H&R makes a lot of poor barrels.

[MTGlass]

Fred, thanks.

I apologize for hijacking Quick's thread.  After this post I'll probably be off line for most of the week & will start a new thread "Daugher's oversize 7mm-08 bore" with any further discussion.

These numbers have had me shaking my head.  Your posts started to clarify things for me but I had to see for myself.  I dug up a slug of my Model 7, 7mm-08 from several years ago.  Sure enough, it's .284 across the grooves and about .280 down in the lands.  Now I realize this H&R barrel is actually worse than I first thought.  Best case, it's .002 oversize and at the best I can measure the lands are .284.  At least the bore seems to be centered in the barrel.

[quickdtoo]

I haven't slugged the bore of my 7mm-08, but it shoots the 140gr Fusion into about an inch, but the first one from a cold barrel is always away from the next 2 which are almost touching, so I think it will shoot real well with a little forend "tuning"!!

Not a problem MT, it's all good to learn. Overbore Handis isn't just a problem with you rifle, it seems to be consistent with a lot of em, but they can still be made to shoot good usually, with the right loads, it's just a matter of finding it.

Tim