I would like anyones opinion on this.

I have a brand new Marlin 917 M2S which is a bolt action stainless steel heavy barrel rifle in .17 HM2.

It is arguably the top of the Marlin range in that calibre and sold as a varmint rifle.

The barrel in mine is 22 thousands of an inch off centre, meaning the bore is 22 thou off centre to the outside of the barrel.

My concern is after firing a few shots and the barrel is heating up that it will warp unevenly and shift the point of impact.

I concede that the .17 HM2 is a samll case and it may take a while to heat up a heavy barrel and that the shift in POI may be small but nevertheless it is supposed to be a varmint rifle.

Is this normal for Marlin?

Am I being unreasonable by expecting a much closer standard of machining in a factory rifle?

Any comments or advice most welcome!

I have not even fired this rifle yet and also concede it may shoot very well as is.

This is NOT a bad mouth Marlin post, overall I am quite impressed with my first ever Marlin and am looking forward to shooting it.

You would be surprised at how far off center most factory barrels bores are. Find one where the bore is centered and cut it back a few inches and you will likely find it off center. Take it out and shoot it.

I don't think that you need be concerned.

If it shoot good there isn't a problem.
If you did some research, I think you would find that .0022 was within specs.

Let us know how it shoots.

quote:

If you did some research, I think you would find that .0022 was within specs.

Rusty.....he said .022 ...not .0022

but I agree.....see how it shoots......don't go solving problems before they show themselves.

How did you get that measurement?

I barreled up an action with a Krieger that was worse than that. They are all off some and there has never been a straight bore from any maker. Shoot it and don't let it worry you.

Thanks guys!

Malm hit the nail on the head, I had the barrel shortened 3" and threaded for a silencer which is legal here.

When threading for a silencer they usually also supply a threaded collar that is knurled on the outside to protect the thread when the silencer is not in use. When screwing the collar on I noticed there was a high spot on 1 side and thought the thread was off centre to the bore.

I should add that I am a trade qualified machinist although I havent worked in the trade for about 20 years. Going by some of the work I have seen recently I think I should go back on the tools!

I then sent the rifle to a gunsmith I usually use and who specialises in varmint and benchrest stuff. He put the barrel in a lathe chuck and centred the barrel on the bore and confirmed that the thread was centred around the bore which was good. He then used a dial guage on the outside of the barrel to measure what is run out.

Yes, it was 22 thousands of an inch, 0.022, NOT 0.0022. In other words about a thumbnail thickness, or half a millimetre which we work in.

The NZ importer for Marlin replaced the brand new unfired rifle and today I received the replacement. The importer had his in house gunsmith shorten and thread the barrel per my old rifle and it seems as bad. Worse, the thread has been cut incorrectly and is rough and I cant fit my silencer. If it goes wrong it just seems to keep getting worse!

I now wonder if I am being unreasonable in expecting the bore to be more centred than what it is after reading all your comments.

I rang several respected gunsmiths around NZ and some said the same as Malm, that when you shorten a barrel you find all sorts of run out.

Keep the comments coming, Thanks!

If you were starting with a custom, uncontoured, barrel you could reasonably expect it to appear to have the bore dead nuts in the center when finished and fitted to your rifle...it is a natural and standard procedure to suspend the barrel between centers when tapering them in most all custom shops.

I am not sure however, that is how it is done in all the large manufacturing facilites today, though. Even so, it is likely not to be any sort of mechanical accuracy problem.

It could have a very small pyschological effect at first, due to a loss of confidence in the gun based on its appearance.

So, shoot it, as suggested above. It will likely be almost scary accurate for a rimfire. The .17 HMR seems to be one of those fortunate occasional designs which is just plain going to shoot like gangbusters in any reasonably assembled rifle. And, as you shoot it you will gain confidence in it, and then it will shoot even better as you get it broken in and learn how it likes to be held.

Enjoy, and don't worry....

AC-

not sure what custom gunmaker shops you have been visiting, but I do not know anyone who does things as you describe. Unless a premium is paid, the customer picks a profile from a barrel maker, the smith cuts the breach and muzzle end where it needs to be for the specified finished length, and the bore just winds up where it winds up in relation to the outer diameter. They are all off center to some extent and it is no big deal. As stated above, every time you cut the barrel, you get a different runout.

Any custom tapers buy the gunmaker result in a premium charged to the client. Even then, the taper is usually turned with the blank full length so you can grab the barrel with a dog, and it finishes shorter. WHen cut to that shorter length, the bore will be off center to some degree.

quote:

Originally posted by Marc_Stokeld:
AC-

not sure what custom gunmaker shops you have been visiting, but I do not know anyone who does things as you describe. Unless a premium is paid, the customer picks a profile from a barrel maker, the smith cuts the breach and muzzle end where it needs to be for the specified finished length, and the bore just winds up where it winds up in relation to the outer diameter. They are all off center to some extent and it is no big deal. As stated above, every time you cut the barrel, you get a different runout.

Any custom tapers buy the gunmaker result in a premium charged to the client. Even then, the taper is usually turned with the blank full length so you can grab the barrel with a dog, and it finishes shorter. WHen cut to that shorter length, the bore will be off center to some degree.

If I read it correctly, AC was talking about starting with an "uncontoured" blank. In which case he is accurate in that a person could reasonably expect the bore to be centered on the ends. Of all the manufacturers barrels I order in preturned, Lilja is the one whose bore is most consistantly centered when they arrive. However, by the time you cut them to length, like the bore, all bets are off. But not by much!

Malm, is 22 thou reasonable after cutting of 3 inches?

This is a brand new unfired rifle, not a blank.

Thanks also to all who replied so soon!

quote:

Originally posted by malm:

quote:

Originally posted by Marc_Stokeld:
AC-

not sure what custom gunmaker shops you have been visiting, but I do not know anyone who does things as you describe. Unless a premium is paid, the customer picks a profile from a barrel maker, the smith cuts the breach and muzzle end where it needs to be for the specified finished length, and the bore just winds up where it winds up in relation to the outer diameter. They are all off center to some extent and it is no big deal. As stated above, every time you cut the barrel, you get a different runout.

Any custom tapers buy the gunmaker result in a premium charged to the client. Even then, the taper is usually turned with the blank full length so you can grab the barrel with a dog, and it finishes shorter. WHen cut to that shorter length, the bore will be off center to some degree.

If I read it correctly, AC was talking about starting with an "uncontoured" blank. In which case he is accurate in that a person could reasonably expect the bore to be centered on the ends. Of all the manufacturers barrels I order in preturned, Lilja is the one whose bore is most consistantly centered when they arrive. However, by the time you cut them to length, like the bore, all bets are off. But not by much!

Thank you Mr. Malm, you are exactly correct. That is why the very first words in my post were "If you start with a custom, uncontoured blank..." Perhaps I should have capitalized the "IF".

Marc, I am well aware that most shops install blanks that are already contoured, by the manufacturer, to one of perhaps 7 or 8 standard contours, on most of the actions they are hired to barrel. Some folks DO, however, have barrels both tapered (contoured) and installed by custom shops, particularly if they want them fluted, or cut with integral ribs, etc. Or maybe they just want a taper different than they had originally ordered. In those instances, as my post suggested, they are usally done between centers, I believe.

I also am aware that anytime you cut a barrel back AFTER it has been contoured will usually result in the bore being slightly out of apparent center. Until one of us someday develops perfectly straight deep-hole drilling, that will likely always be the case. (I hope I live that long, but somehow I doubt it.)

Anyway, be that as it may you will note, I hope, that I suggested the same thing to our Aussie friend that you and others have...that the amount his barrel contour is apparently off of absolute bore-center will likely be of no consequence to the accuracy he can expect from the rifle.

Take care, and best wishes,


AC

quote:

Originally posted by Kiwi Vince:
Malm, is 22 thou reasonable after cutting of 3 inches?

This is a brand new unfired rifle, not a blank.

Thanks also to all who replied so soon!

.022 is more common than you think. Shoot it, if there is a problem then you will have some data to back you up should you need to contact the manufacturer.