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Post by epanzella on Oct 7, 2015 11:31:40 GMT -5
My 458/450/18 McSavage has been done a few months and shoots saboted .40 XTP's well out to 200. However, I built the gun because I wanted to shoot 300gr sabotless and I can't get this to work for me. I've tried 458's, 452's, knurled & not, all full formed with a swinglock. Although saboted bullets load beautifully with consistant resistance, any sabotless load I try goes down the first 10 inches of barrel nicely and then jams in the bore. I've been able to shoot them via a rubber hammer and brass rod hoping for a break-in but it's not happening. I don't want to crank down the swinglock to fit the tight spot and leave the bore loose for fear of hurting the die. Any ideas on how to lap the tight spot out? Being as the sabots load well I'm guessing the tight spot is only a tenth or two smaller than the outer half of the barrel.
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Post by rangeball on Oct 7, 2015 12:29:10 GMT -5
Is it tight in just that spot or does it stay that tight once you hit it until the load is seated? If you push a saboted load all the way through and examine it is there a tear in the sabot, possibly indicating a burr in the rifling?
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Post by epanzella on Oct 7, 2015 12:36:20 GMT -5
No, the sabots go thru smoothly. With sabotless the bore gets tight about 10 inches in from the muzzle and seems to loosen up a bit about 2 inches before seating. I'm guessing the tight spot is about 10 inches long.
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Post by 7mmfreak on Oct 7, 2015 12:45:29 GMT -5
I sent mine back with full-formed bullets and had them re-lap it.
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Post by Deleted on Oct 7, 2015 12:45:42 GMT -5
I had a "tight" spot on my McGowen barrel near the muzzle. I used JB Bore b paste to clean barrel and worked the "tight" spot more than the rest of the barrel. From what I've noticed you end up with allot of fowling near the muzzle end and by cleaning it the way I did I got all the junk out. After I cleaned the barrel with jb it seemed allot smoother than before when posting the bullet down.
JB isn't a lapping compound and is just a cleaning material. You could lap the barrel where the tight spot is but I didn't want to do that and ruin the barrel.
Have you tried smooth form or ask you can do is full form? I only run smooth it's easier I can full form but haven't figured out how to make it work for me.
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Post by hemicuda on Oct 7, 2015 21:13:40 GMT -5
Full form size your .458 300gr. bullet until it just goes thru the tight spot then work that area with JB bore cleaner. If that doesn't do it use a very fine lapping compound. toothpaste? Those barrels can take more than you realize and still shoot well. Maybe better after you're finished
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Post by 7mmfreak on Oct 8, 2015 3:59:35 GMT -5
By the time you buy what you need to get the job done, try to learn how to do it, then attempt to do it well how much time will you have invested in this and what is your time worth to you? I chose to pay one way freight, have it fixed under warranty, and sent back to me.
I do a lot of DIY gun work but JB isn't going to lap out a tight spot, nor toothpaste, and Clover is a valve lapping compound that isn't as consistent as I'd like for cutting metal in my barrel.
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Post by cuda on Oct 8, 2015 6:32:06 GMT -5
Why not try fire lapping it? That would take care of any tight spots and not do much to rest of the bore.
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Post by Dave W on Oct 8, 2015 7:42:55 GMT -5
My .442 McGowen had a small tight spot right before the bullet would hit the powder column. Had to size for the tight spot which meant the bullet was pretty much in free fall for all but a couple inches. Shot great, but the annoyance was more than I cared for so it went down the road.
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Post by epanzella on Oct 9, 2015 7:47:58 GMT -5
Why not try fire lapping it? That would take care of any tight spots and not do much to rest of the bore. I might try fire lapping if it wasn't a ML. I'm concerned about pushing an abrasive laden bullet in from the muzzle when that's the area that already has the loosest fit with the bullet.
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Post by epanzella on Oct 9, 2015 7:52:08 GMT -5
By the time you buy what you need to get the job done, try to learn how to do it, then attempt to do it well how much time will you have invested in this and what is your time worth to you? I chose to pay one way freight, have it fixed under warranty, and sent back to me. I do a lot of DIY gun work but JB isn't going to lap out a tight spot, nor toothpaste, and Clover is a valve lapping compound that isn't as consistent as I'd like for cutting metal in my barrel. Sending the barrel back to McGowan is probably my safest option but I'll have to wait for after hunting season. I'll contact them to see if they'll do it under warrantee. Thanks, Ed P
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Post by cuda on Oct 9, 2015 10:00:10 GMT -5
To do it right you would put the bullet in from the breech. By removing the breech plug but make sure not to get powder into the threads reloading. You would push the bullet in a little farther than the it would be from the seated spot towards the muzzle by an inch or two. And then add powder then breech plug and tighten it then seat the bullet tight onto the powder before firing it. You would need to do this 4 or 5 times to see any real results. So if McGowen will not help that is just what I would do. I would check fit from the muzzle every 5 or more shots just to feel the fit. And I would use 500 or finer just to kinda polish it out slowly.
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Post by 7mmfreak on Oct 10, 2015 5:31:57 GMT -5
When barrel makers lap I'm pretty sure they don't go finer than 400 grit because too smooth causes copper fouling issues.
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Post by Richard on Oct 10, 2015 11:38:06 GMT -5
If I were to use the Clover valve grinding compound, as 7mm says, I would first mark on my rod where the tight spot was. Then push the tight patch with the 400 grit to that point and then "short stroke" that area only..........then retrieve the patch, re impregnate and go back to that spot and short stroke. I don't feel the trip in to the spot and out will be that much detrimental to the bore and it will/should loosen that tight spot. Make sure you thoroughly clean the Clover out when through and before re-checking the bore.
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