300Rum Bullet Depth Test

baydog

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I ran accross this older awesome tread that I'm finally going to make the time to try. My question is how far should I do these testing? 50yrd or 100yrd?? And if I'm reading it right start .010 off the lanns. So touching the lanns gives me a O.A.C.L. of 4.000. Just want to be sure I'm doing this right. The first group should have a O.A,C.L of 3.990 is this right?
Then 3.950
then 3.910
then 3.870

The i guess suggested O.A.C.L is 3.600 Should I work my way all the way down to this length? Here is the thread I'm talking about..
Thanks
Scotty


Getting the Best Precision and Accuracy from VLD bullets in Your Rifle

Background

VLD bullets are designed with a secant ogive. This ogive shape allows bullets to be more efficient in flight (retain more velocity = less drop and wind deflection). While this result is desirable for many rifle shooters the secant ogive on the VLD bullets produces another result in many rifles. It can be difficult to get the VLD to group well (poor accuracy).

For years we encouraged shooters to use a base of cartridge to end of bearing surface OAL (I will use the term COAL to represent this dimension) which allows the VLD to touch the rifling or to be jammed in the rifling. This provided excellent results for many shooters but there were others who did not achieve top performance with the VLD jammed in their rifling. These shooters were left with the belief that the VLD bullets just won't shoot in their rifle.

Other groups of shooters were discouraged by our recommendation to touch the rifling. Some of these shooters knew that at some point during a target competition they will be asked to remove a live round. With the bullet jammed in the rifling there was a good chance the bullet will stick in the barrel which could result in an action full of powder. This is hard on a shooter during a match.

Yet another group of shooters who were discouraged by our recommendation to touch the rifling are those who feed through magazines or have long throats. Magazine length rounds loaded with VLDs could not touch the lands in most rifles (this is the specific reason that for years we said VLD bullets do not work well in a magazine). When a rifle could be single fed but was chambered with a long throat a loaded round that was as long as possible still would not touch the rifling.

Until recently, shooters who suffered from these realities were believed to be unable to achieve success with VLD bullets. Admittedly, we would receive the occasional report that a rifle shot very well when jumping the VLD bullets but we discounted these reports as anomalies. It was not until the VLD became very popular as a game hunting bullet that we were then able to learn the truth about getting the VLD bullets to shoot well in a large majority of rifles.

After we proved that the Berger VLD bullets are consistently and exceptionally capable of putting game down quickly we started promoting the VLD to hunters. We were nervous at first as we believe the VLD needed to be in the rifling to shoot well and we also knew that most hunters use a magazine and SAMMI chambers. Our ears were wide open as the feedback was received. It was surprising to hear that most shooters described precision results by saying "this is the best my rifle has ever shot."

We scratched our heads about this for awhile until we started getting feedback from hunters who were competition shooters as well. Many were the same guys who were telling us for years that the VLDs shoot great when jumped. Since a much larger number of shooters were using the VLD bullets with a jump we started comparing all the feedback and have discovered the common characteristics in successful reports which gave us the information needed to get VLD working in your rifle. We were able to relay these characteristics to several shooters who were struggling with VLD bullets. Each shooter reported success after applying our recommendation.


Getting the Best Precision and Accuracy from VLD bullets in Your Rifle

Solution

The following has been verified by numerous shooters in many rifles using bullets of different calibers and weights. It is consistent for all VLD bullets. What has been discovered is that VLD bullets shoot best when loaded to a COAL that puts the bullet in a "sweet spot". This sweet spot is a band .030 to .040 wide and is located anywhere between jamming the bullets into the lands and .150 jump off the lands.

Note: When discussing jam and jump I am referring to the distance from the area of the bearing surface that engages the rifling and the rifling itself. There are many products that allow you to measure these critical dimensions. Some are better than others. I won't be going into the methods of measuring jam and jump. If you are not familiar with this aspect of reloading it is critically important that you understand this concept before you attempt this test.

Many reloaders feel (and I tend to agree) that meaningful COAL adjustments are .002 to .005. Every once in a while I might adjust the COAL by .010 but this seems like I am moving the bullet the length of a football field. The only way a shooter will be able to benefit from this situation is to let go of this opinion that more than .010 change is too much (me included).

Trying to find the COAL that puts you in the sweet spot by moving .002 to .010 will take so long the barrel may be worn out by the time you sort it out if you don't give up first. Since the sweet spot is .030 to .040 wide we recommend that you conduct the following test to find your rifles VLD sweet spot.

Load 24 rounds at the following COAL if you are a target competition shooter who does not worry about jamming a bullet:
1. .010 into (touching) the lands (jam) 6 rounds
2. .040 off the lands (jump) 6 rounds
3. .080 off the lands (jump) 6 rounds
4. .120 off the lands (jump) 6 rounds

Load 24 rounds at the following COAL if you are a hunter (pulling a bullet out of the case with your rifling while in the field can be a hunt ending event which must be avoided) or a competition shooter who worries about pulling a bullet during a match:
1. .010 off the lands (jump) 6 rounds
2. .050 off the lands (jump) 6 rounds
3. .090 off the lands (jump) 6 rounds
4. .130 off the lands (jump) 6 rounds

Shoot 2 (separate) 3 shot groups in fair conditions to see how they group. The remarkable reality of this test is that one of these 4 COALs will outperform the other three by a considerable margin. Once you know which one of these 4 COAL shoots best then you can tweak the COAL +/- .002 or .005. Taking the time to set this test up will pay off when you find that your rifle is capable of shooting the VLD bullets very well (even at 100 yards).

Regards,
Eric Stecker
Master Bulletsmith



gun)
 
LOL! I see what your saying, its a looong ways back to 3.600 isn't it.

A big determining factor here is your magazine length and if you desire/need to be able to load from the mag or if single shot is ok. The numbers you quoted are correct as per the recommendation in the doc. I would use those numbers, and if the number that works best fits in the mag great. If not, I would then try some loads that are to mag length and see how they work. I really don't see a need to load in .040 increments all the way back to 3.600.

For what it's worth. I shoot 210 VLDs in my 300 RUM at .020 off the lands. It shoot great there. I think, more than likely, you will find that sweet spot within. 070 of the lands.
 
Thanks Barrelnut,,,LoL...and yes it is a long ways back to 3.600 that's why I wanted to be sure I was doing the math right,hahaha...but I'm willing to do what ever it takes to get the beast shooting better. You think I should shoot this test at 50 or 100 yard? The gun I'm shooting is a Remington Sendero and I had a gun smith extend the mag box so I could extend the bullet out of the case futher and still fit in the mag box. I can actually load up to 4 inch rounds that will fit in the mag box and chamber well..I went throught all that to find out that I really don't think it shoots as good extended as far out as I can get it and thats what brings me to this test..I'm still on the fence on the best powder for me..Retumbo and the H1000 seem to be real close. I've shot some 208 A-max and some 215 VDL and it seems to knock a 2 inch hole in the paper at 50 yard with 93gr of powder but when I step back to 100 yard the group opens up and 200 yard i'm lucky to hit a pie plate! And that just ain't why I bought this gun...Hoping to get the time to do more shooting to figure this thing out..Between working till dark and this stuipd time change just can't get the daylight time to buckel down and git-r-done!
Thanks
Scotty
 
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Yes, your math looks right. Its amazing how far out the rifling can be in some barrels! 100 yards is ok for testing. I like to do my load testing at 200 yards most of the time. Gives the bullet a bit more time to "settle down" as well as amplify any changes from load to load. Its easier for me to spot group differences if I test at longer ranges. The good loads will still be good and the poor loads will be even worse.
 
I've shot some 208 A-max and some 215 VDL and it seems to knock a 2 inch hole in the paper at 50 yard with 93gr of powder but when I step back to 100 yard the group opens up and 200 yard i'm lucky to hit a pie plate!

Baydog,

Those are some horrid groups. The rifle should probably shoot better than that without seating depth tuning at all. Did the rifle shoot better before you had the extended box installed? Is it possible the smith didn't torque action back down on the stock well enough after the box was installed? You might want to run thru it and tighten everything down again. Stock, scope bases and rings and see what happens. After that you could try something like 180 Nosler ballistic tips. It is easy to get them to shoot well in a 300 RUM. Also consider trying another scope, if you have one. If nothing makes it better, consider talking to the smith again. A Sendero should shoot way better than that.

Good luck
 
Torqued the action to the stock 65 inch pounds and have rechecked the scope mounts..It's a new Leupold VXR- 4x12x50mm scope but that don't mean that nothing can't be wrong with it either..I have own a 7 mag Sendero for 11 years and love it..I be liking me some Sendero... it took me a little while to get that gun dialed in but I did...and I will get this one dialed in too it's just the time in between that sucks or is fun not sure which one comes first..lol..Time, patients, powder, bullets and a lot of questions ..it will come but I'm sure I will always be looking to beter this gun and all the other ones I own.. It's a never ending thing that will probally go on with me long enough to pass it on to my son..But I'll have everything worked out and all the load data for him to just say Thanks Dad!!
 
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