Kevin Thomas
Well-Known Member
Well I'd HOPE he was shooting Bergers, not SMKs!
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Meplat trimming & bullet tipping?
- Thread starter joseph
- Start date
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Well I'd HOPE he was shooting Bergers, not SMKs!
HAHAHAHA!! If he shot SMK's then maybe Team Berger could beat Team Sierra.. Why did I know you would comment on this! LOL!!
If anyone wants to know something about this subject ask Kevin! He has forgotten more than most people will ever know on this subject! Sorry Kevin but now you can tell it like it really is regarding trimming meplats.
In wearing out several 30 caliber competition barrels, I've not seen any need to trim the bullet tip on HPMK Sierras to reshape them whatsoever. There's a better way to get bullets to shoot closer to the same hole than meplat trimming.
I'm convinced that unbalanced bullets cause more accuracy problems than anything else when all else is a repeatable as possible. Lowest spread in muzzle velocity, perfect bores and rifle bedding help, but my estimate is that no more than 20% of all the bullets in a box of even the best ones are perfectly balanced.
Back in the early 1970's, a friend of mine and his buddy (I believe the bullet forming die maker at Sierra Bullets) spun some Lapua match bullets in a collet chucked in a Dremel Moto Tool. An amp meter was connected to the tool's power cord. Spinning at 30,000 rpm, bullets that were more unbalanced caused the tool to draw more current; perfectly balanced ones required the least amount of current. The more unbalanced bullets were, the more centrifugal force they put on the bearings and more current was needed to spin the motor up to speed.
A few of the bullets were so unbalanced they flew out of the collet and bounced off the walls and ceiling. No wonder these Lapua 185-gr. rebated base FMJBT .3092" diameter match bullets were notorioius for shooting an occasional bad shot.
About 20% of each box of 100 were absolutely perfect in balance. Several dozen of these "perfectly balanced" bullets were loaded into full length sized .308 Win. cases and tested in a standard SAAMI chambered match rifle at 600 yards. Several 10-shot groups were fired. They ranged from about .700 inch up to 1.5 inches.
I'm convinced that unbalanced bullets cause more accuracy problems than anything else when all else is a repeatable as possible. Lowest spread in muzzle velocity, perfect bores and rifle bedding help, but my estimate is that no more than 20% of all the bullets in a box of even the best ones are perfectly balanced.
Back in the early 1970's, a friend of mine and his buddy (I believe the bullet forming die maker at Sierra Bullets) spun some Lapua match bullets in a collet chucked in a Dremel Moto Tool. An amp meter was connected to the tool's power cord. Spinning at 30,000 rpm, bullets that were more unbalanced caused the tool to draw more current; perfectly balanced ones required the least amount of current. The more unbalanced bullets were, the more centrifugal force they put on the bearings and more current was needed to spin the motor up to speed.
A few of the bullets were so unbalanced they flew out of the collet and bounced off the walls and ceiling. No wonder these Lapua 185-gr. rebated base FMJBT .3092" diameter match bullets were notorioius for shooting an occasional bad shot.
About 20% of each box of 100 were absolutely perfect in balance. Several dozen of these "perfectly balanced" bullets were loaded into full length sized .308 Win. cases and tested in a standard SAAMI chambered match rifle at 600 yards. Several 10-shot groups were fired. They ranged from about .700 inch up to 1.5 inches.
elkaholic
Well-Known Member
Bart...I would tend to agree. In making bullets the last few years, I have noticed that some of the OBVIOUS things make very little difference in poi and for no APPARENT reason, some of the bullets are out of the group. This would give support to what you are stating. Deformed tips are one of the lesser problems, if they are even noticeable? A nick on the heel, however; will throw things off in a hurry. Even a few tenths of grains weight difference doesn't have a lot of affect........Rich
No, I'm not using this method to sort bullets. I just commented on what a friend did years ago. If someone made one and it worked well, he could make some money selling them.
If one looks in a late 1971 (maybe 1970; I don't remember exactly) issue of NRA's American Rifleman magazine, there's a Lapua bullet ad with one of the 10-shot groups shot with some of these bullets. that group's barely under an inch. Lapua though the smallest one shot would be too "unbelievable" for use in advertising.
Not too shabby for a pre-'64 Model 70 action with a 26-inch Hart barrel conventionally epoxy bedded in a wood stock shooting full length sized WCC58 cases. This same rifle and ammo was also used to put 40 consecutive shots into 1.93 inches at 600 yards a week or so later.
I've mostly shot Sierra Match Kings but used Norma 139-gr. 6.5mm match bullets in a .264 Win. Mag. Also have used Berger 155-gr. 30 caliber bullets in a Palma rifle and thousands of military 172-gr. FMJBT match bullets in M118 7.62 NATO match ammo. Tried some Hornady match bullets in a .308, but gave up; they weren't as good as Sierra's.
Regarding bullet trimming and tipping for accuracy, I watched a test comparing Sierra's 30 caliber 190 HPMK vs Berger's 30 caliber 185 VLD bullet. Both were shot in the same .308 Win. rifle through chronographs at 10 feet and 995 yards. Muzzle velocity was about 2570 fps for both. The Berger's slowed down more than the Sierra's did; they lost more speed downrange. Proof that Sierra's had a higher BC. This was done as there was much discussion about the Berger's being a better long range bullet with their Very Low Drag claim. Proof's in the pudding....er, measuring. A good test indeed.
Interesting thread on this on BR central where several tests were done and documented as much as 18" less wind deflection and 3 MOA elevation depending on the bullet. Done by the best LR shooters who know what they are doing and how to win.
Meplat trimming & bullet tipping?
I agree with Boss Hoss, it is an absolute must with the 300 SMks
As far as spinning the bullets, Harold Vaughn built a similar spinner years ago, it is discussed in his book "Accuracy Facts". Vern Juenke used to make his Juenke machines that did something similar and allowed you to sort out those anomaly bullets. Worked for cases also. Sadly Vern quit making those about a year ago and you cannot find them.
BH
Meplat trimming & bullet tipping?
I agree with Boss Hoss, it is an absolute must with the 300 SMks
As far as spinning the bullets, Harold Vaughn built a similar spinner years ago, it is discussed in his book "Accuracy Facts". Vern Juenke used to make his Juenke machines that did something similar and allowed you to sort out those anomaly bullets. Worked for cases also. Sadly Vern quit making those about a year ago and you cannot find them.
BH
Just who are the best LR shooters?
I ask because there's 3 or 4 disciplines who have excellent LR shooters. And there's not a bid of difference in their hardware's accuracy.
Meanwhile, back to meplatting and trimming, I don't think the Juenke tool would be as good as one that spun them upwards of 100,000 rpm or higher. The Juenke tool did a good job of measuring jacket and case wall thickness, but not the mass of core plus jacket spinning about its center of form. This is what the bullet does going down the barrel. Any offset between center of form and center of mass is what causes the bullet to exit the muzzle at an angle to the bore axis.
Surely there's a motor that would spin 'em that fast....somewhere. Even an air dirven one would work. Such as those used to spin rate gryos at ultra high speed.
Kevin Thomas
Well-Known Member
Again, another trip down the past, but Mid and Jim had done something like this at one point. I have no idea what became of the tool they developed to do this, but I'll ask Mid. I do recall them saying that they'd had some good results in spinning/sorting bullets this way, and the results of the testing translated into better results on the range.
Bart
If you read the post, you recognize the names and know they are some of the tops of NRA LR, F Class and 1k BR.
The Juenke was/is different BUT most importantly was the only commercial machine that did something similar that worked, albeit maybe not as good as Vaughns original spinner idea that was never made into a workable marketable product.
I have heard that someone is trying to buy the rights to the Juenke and market it again with some improvements.
Now if someone can just design and market an affordable spinner or something similar.
BH
