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Post by tiswell on Aug 17, 2010 7:25:42 GMT -5
I am new to this smokeless stuff, but an idea hit me the other day and I wanted to know if anyone has ever tried placing a shim between the bullet and sabot for a better fit? My Savage has a larger bore (.503"), as I hear many of them do, and I am contemplating placing a .0005" or .001" shim around the bullet to increase the loaded diameter. I thought it might be possible to cut a strip of plastic shim material or cigarette paper about 1/2" wide and wrap it around the bullet so that one end enters and the other end exits the same slit in the petals of the sabot. Bullet would still be centered in the sabot as the ends of the shim would not overlap. I am still playing with different combinations of bullets and sabots in an effort to shrink groups and I will probably try this later this week unless you folks think it is a bad idea.
Thanks, Bill
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Post by smokeeter on Aug 17, 2010 8:12:17 GMT -5
paper patching, been done with some success for some
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Post by edge on Aug 17, 2010 8:26:04 GMT -5
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Post by tiswell on Aug 17, 2010 10:07:39 GMT -5
Thanks for the replies, I will try this out!
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Post by rangeball on Aug 17, 2010 10:22:02 GMT -5
tiswell, have you already tried some of the thicker sabots, like the harvester RCR?
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Post by DHinMN on Aug 17, 2010 13:07:02 GMT -5
Paper wrapping the bullet has been tried. I tried it and it didn't work for me too well but that may have just been my experience. An alternative I use is knurling the bullet with a file. That can increase the diameter of the bullet a couple thousandths of an inch and tighten up the load. This is a common practice with many here.
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Post by Richard on Aug 17, 2010 14:47:43 GMT -5
While the paper patching can work? ?? Its a PITA! Knurling is the way to go. First have a micrometer or caliper at hand to measure the diameter of your bullets. A mic is more accurate but the caliper will suffice. Get yourself about a 10 or 12" mill bastard file. (some use two) lay a bullet on top of a hardwood (or better yet.........one of those nylon cutting boards your wife uses in the kitchen) Take the file and put downward pressure both fore and aft and roll the bullet back and forth. You will see little "knurlies" appearing on the bullets surface. In effect, you are squeezing the copper up while also indenting it. These knurlies will increase the diameter of your bullet. It will also cause a surface which "grips" the inner surface of the sabot so it cannot slip when rotation begins. I can easily increase the size of a .452" bullet to .455 or 56". This gives you a lot of leeway for getting the proper fit. I have found with most Savage ML's that your bullet/sabot should mic around .507 to .509" Clean bores like .508 to 509" while dirty bores maybe .506 to 507". It doesn't matter whether you are using .452 bullets or .458" bullets. Its the combined diameter of bullet and sabot that counts. With the .508 bullets you will obviously use either the orange MMP or Harvester black crush rib. Where the .452's will generally use the mmp12 or Harvester red crush rib. You should have to use two hands to push/pull the bullet/sabot down the bore. Richard
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Post by edge on Aug 18, 2010 7:52:07 GMT -5
While the paper patching can work? ?? Its a PITA! Knurling is the way to go. SNIP. WOW! Lets see, paper is 100% reproducible EVERY time. NO distortions to the bullet. I challenge you to say that every knurled bullet is knurled to the exact same dimensions the first time and every time with no re sizing! Knurling most likely compromises the jacket integrity for terminal performance, but I don't know of any actual performance testing and that would probably take many many shots to guarantee reproducibility of results. BUT paper patching is a PITA..... edge.
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Post by bigmoose on Aug 18, 2010 9:58:49 GMT -5
Edge,
Would you agree that pushing a knurled bullet down the [sabotless} bore more or less makes it the right fit for your bore. At first I was micking each bullet, practise amd hunting, but I realized that the harder a bullet loaded was a postive sign. needless to say, I have no idea why it works that way, but I have put an lot of sabotless bullets down range.
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Post by rangeball on Aug 18, 2010 10:27:33 GMT -5
I think if you are talking sabotless, the less you have to knurl up the better for maximum accuracy potential.
If saboted, it would seem by it's nature knurling lifts up jacket material which would have sharper edges that can dig into the sabot upon loading or firing, negating it's accuracy boosting potential a bit, and possibly paper patching would be more consistent?
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Post by bigmoose on Aug 18, 2010 11:44:33 GMT -5
Rangeball,
No doubt your right about sabotless, I wonder how much better any rifle could shoot, than my RB .45 using 290gr. Barnes TMZ bullets, since it consistently hits dime size objects at a 100 yard. As I stated, in the last 3 1/2 years I have knurled and fired anywhere between 2000 and 2500 knurled bullets, I have had to beat over knurled bullets down the barrel, with a rubber mallet, with no loss of accuracy. I'm sure lots of gents on this site have much more experience shooting sabotless than I have so I'll leave the last word to them.
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Post by Richard on Aug 18, 2010 15:58:25 GMT -5
Edge............Remember, this happens to be my opinion .... which I am entitled to right? You paper patched bullets (when ever it is you shoot paper patched bullets? ) and I will shoot knurled bullets. Members are encouraged to try both and make a decision based on their experience. As far as weakening the jacket You would hard pressed to convince me of that! But again, you are entitled to your opinion as I am mine Remember, we all don't have access to the CNC machinery you have to make those PVC sabots you use. Richard
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Post by lwh723 on Aug 18, 2010 22:03:49 GMT -5
Knurling most likely compromises the jacket integrity for terminal performance, but I don't know of any actual performance testing and that would probably take many many shots to guarantee reproducibility of results. Edge, I was kind of following you to this point. I challenge the idea that knurling has any impact on terminal performance. I find it highly unlikely that a few mils of surface roughness on the projectile is going to make a lick of difference when the payload is delivered.
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Post by lwh723 on Aug 18, 2010 22:10:33 GMT -5
I see Richard's opinion matches mine. (On any impacts to terminal performance) Personally, I'm knurler. Never tried paper patching. I would theorize that there's more tolerance leeway to oversizing when knurling if you're using a sabot since the sabot should be able to absorb some of the inconsistency. So I always try to stay above a certain diameter when I'm knurling and don't really worry about "over" knurling. I'm not a great rifle shot, so I really don't know if my approach is right. Rangeball, I'm not so sure that roughing the bullet doesn't make it perform better in the sabot. I see where you're saying the roughness could be an issue at sabot discard, but I can see where it could be beneficial when the bullet is in the sabot rotating down the barrel. It's really all theoretical. Would need to put a lot of rounds down range to hit anything, but I haven't even had time to work up a load for my new Dtech AR-10 in 7mm-08.
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Post by edge on Aug 19, 2010 5:50:58 GMT -5
Edge, I was kind of following you to this point. I challenge the idea that knurling has any impact on terminal performance. I find it highly unlikely that a few mils of surface roughness on the projectile is going to make a lick of difference when the payload is delivered. I base my theory on the absolute fact that in high performance applications involving most metals that failure occur along any defect in surface finish. IMO, high impact velocities stress the bullets jacket to the max and that cracks my propagate at these irregularities. You take a surface that is relatively uniform in finish and in hardness and you distort, scratch and otherwise make it non uniform in finish and hardness. I would find it more amazing if these acted exactly as their unmodified counterparts. I did not say that they won't work, but did say that you have compromised the jacket to some extent. Will it cause the jacket to grenade, perhaps not especially on the heavier jackets perhaps on bullet already designed with this jackets designed for lower velocities...or perhaps not at all. edge.
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Post by rangeball on Aug 19, 2010 8:55:06 GMT -5
Rangeball, I'm not so sure that roughing the bullet doesn't make it perform better in the sabot. I see where you're saying the roughness could be an issue at sabot discard, but I can see where it could be beneficial when the bullet is in the sabot rotating down the barrel. With sabots, I was thinking more along the lines that knurling bumps the bullet diameter up to provide a tighter fit. It seems possible that the sabot can absorb this bump up due to the irregular sharper surfaces raised from knurling by them digging into the sabot when loading or when fired, with the end result being the effective diameter is the same if one hadn't knurled? One way to test would be to put a knurled bullet in a sabot, measure and record the diameter, seat it, then push it back out (or straight out the breech for you guys that can, my SMI can't) and remeasure. I just wonder if the diameter would still be the same after the barrel compresses the sabot into the sharper knurled edges. That said, lots of folks seem to report increased accuracy with knurled bullets, which is what counts
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Post by rangeball on Aug 19, 2010 8:55:34 GMT -5
Edge, I was kind of following you to this point. I challenge the idea that knurling has any impact on terminal performance. I find it highly unlikely that a few mils of surface roughness on the projectile is going to make a lick of difference when the payload is delivered. I base my theory on the absolute fact that in high performance applications involving most metals that failure occur along any defect in surface finish. IMO, high impact velocities stress the bullets jacket to the max and that cracks my propagate at these irregularities. You take a surface that is relatively uniform in finish and in hardness and you distort, scratch and otherwise make it non uniform in finish and hardness. I would find it more amazing if these acted exactly as their unmodified counterparts. I did not say that they won't work, but did say that you have compromised the jacket to some extent. Will it cause the jacket to grenade, perhaps not especially on the heavier jackets perhaps on bullet already designed with this jackets designed for lower velocities...or perhaps not at all. edge. A barnes bullet would be good insurance in this case, no?
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Post by Richard on Aug 19, 2010 9:39:27 GMT -5
There is nothing wrong with two or more points of view......right? Then let the user decide what works best for him/her Richard
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Post by Al on Aug 20, 2010 2:19:48 GMT -5
I'm up way to early to be asking this....................... but has anyone ever tried paperpatching a 44cal bullet sabotless in a 45, or a 45-475cal bullet paperpatched in a 50cal sabotless?
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Post by tiswell on Aug 20, 2010 8:49:17 GMT -5
regarding knurling with a file, It would seem to me that knurling would allow the bullet to get a much better purchase on the sabot. The sabot and barrel only have a couple of feet to get the bullet above 60,000 rpm. Has anyone tracked any accuracy differences when knurling from different directions? I would guess that any difference may be non existent, but a test on an aluminum rod revealed that when rotating the rod between thumb and index finger after knurling, slightly more friction is felt in one direction. I haven't put it under a microscope yet, but I would guess the file teeth displace more material in one direction than another, so that just like sliding your finger on a file, it would slide more easily in one direction and the teeth would dig in to your finger in the other direction. I am way new to this stuff, and I have a lot of bullet/sabot/powder combinations to try before I go down this road. But when I get to test the knurling out, I plan to try orienting the knurled pattern on the bullet in such a way that the rotation of the rifling makes use of this pattern to grip the sabot better. Many get great accuracy without knurling at all, so knurl direction is probably meaningless.
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Post by Richard on Aug 20, 2010 15:03:22 GMT -5
tiswell.............Your last sentence I believe, says it all ! I don't think the direction of the "knurlies" matter one single bit. It is whether they "grip?" or don't grip!" Check your fired sabot with knurling and without knurling. Look at the inside. If it is slipping, you will see evidence of it as rotational marks on the "slippers" In the case of my .45 PN, I knurl plain .452" bullets (after having sized them down to .448") back up to around .452" to .453". Then, run them thru a sizing die that leaves them right around .4505". So now I still have a total of .0025" worth of knurlies that can grab and impress themselves into the rifling. The same could be done for saboted bullets if you wanted to get them to a standard size. Knurl them "fatter" and then size down to what fits best! Custom sized dies are available from Lee Precision. Once you get the hang of knurling, you can get them pretty close in size to what you want. I never used a sizing die for my saboted .50....just knurling. Al.............Paper patching for sabotless? I would think the pressure would just blow the paper right out the muzzle! May not even ignite the powder? Richard
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Post by Al on Aug 21, 2010 2:32:14 GMT -5
Richard, not sure what it would do. I would think if it took the rifling while loading, it'd come out that way. Might be better to use a wad of some sort under it.
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Post by edge on Aug 21, 2010 6:47:30 GMT -5
Al, yes it works just fine but it requires the proper patching and I always used a wad under it.
The ends are cut diagonally and the paper is wetted so that it will shrink tightly against the bullet. The paper should almost, but not quite go around the bullet twice. Since the ends are cut diagonally there is no straight gap running up the bullet.
If all goes well you will see confetti when shot. Find a piece and it will be cut neatly into straight pieces by the lands.
edge.
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