Switching Bullets

This one is hard for me to understand, had very good performance using a horandy 40 grain vmax and have worked a load the barrel likes. Picked up some 39 grain sierra just to try and assumed they would be similar. Nope...all over the target. They are loaded with identical powder charge, cases, primer and oal. Did notice they are shorter bullets than the vmax.

This has been a monkey on my back leaning to load. Had this happen with the .243 but not to this extream. It was more forgiving than this .20 caliber. What are the physics of this? Alchemy? Hate wasting time and doe.

while the bullets are close in weight, the shape is different. I dose not take much to change everything.

Whenever I switch any component I start the process all over and work up from starting load data. Different bullets, even of the same weight can have significant differences in pressure due to bearing length and composition and probably a few other things as well. As an example one of my "standard" .270 bullets for many years has been the 140 grain Hornady Interlock, it has given good accuracy in several different rifles. My Ruger #1A will not shoot this bullet under 2.25" (5 shots @ 100 yards) with any load I have tried but will slide 5 of the Nosler 140 grain Ballistic tips in under an inch every single time and it will go under.75 with boring regularity.

Bob

I just want to start by saying I am not a bullet expert, I am in no way a ballistic technician, or a bullet-smith. I find that bullets are still a mystery to me. I will try to explain bullets the best that I can. There is many others that are far more qualified on the subject than me.

There is different parts to a bullet, you have the meplat or the tip, you have the ojive where the transition starts of the bearing surface, you have the bearing surface where the bullet ride on in the bore, you have the back of the bullet which can be flat or boat tailed, and you have the heal the rear part of the bullet. ( I am sure there is other parts that I am missing.) The outside of the bullet is the jacket, and the inside is the core. Some company's use lead wire and cut it to length to make a core, and some take soft lead and swedge them through a die to make cores.

Now when bullets are made they start with a jacket, and they insert the core, and then they are ran through dies. Because of difference in components used, and different machines that the bullets are made on, bullets are made in lots. Bullets can very from lot to lot. There is a number on the side of the box that stats what lot number the bullets are from. (Something with powder, cases, and primers.)

Each manufacture has different has different dies, machinery, different component's. Sierra and Berger makes their own jackets and both company's sell there jackets to other company's and individuals that make bullets. then company's have different designs in bullets as well. You also have pattens and copy rights involved.

So the moral to the story is, even bullets from the same company can be different. Bullets from different company will be different. In the parts of a bullet there can be a change in any one and/or all parts. Company's play with design to change the characteristics of the bullet, such as BC. (Ballistic Coefficients) Different bullets will have different characteristics. Be carefully with bullet jump when switching bullets, for example where you would be touching the lands on a 22 cal 52gr SMK, you would be jamming the bullet hard on a 52g Nosler comp, and probably could not get the bolt to close. This is why you need to measure ojive.

Will step back from 18.8gr to 17.5gr and shoot my way up from there with the 39 gr sierra. Funny thing, puts two in same hole and then spreads the last 3 almost identically. Did this on four targets of 5 shot rounds. Haven't measured these two bullets for comparison. Maybe it's a red tip versus green tip thing! Also got some br primers to try.

Hornady 40 grains are zapping small groups at higher velocities.

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Be carefully with bullet jump when switching bullets, for example where you would be touching the lands on a 22 cal 52gr SMK, you would be jamming the bullet hard on a 52g Nosler comp, and probably could not get the bolt to close. This is why you need to measure ojive.

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What is the correct procedure to measure bullet depth?

I have a OAL guage which will measure the bullet when it touches the lands, and I use the ojive measurement.

Some say partially load a bullet in a fired case and chamber/lock the bolt twice in your gun. Use this measurement for the correct length.

You need to find where the bullet just touches the lands, there is a ton of different ways on doing this. (Using a oal gauge, fired case partially sized, fired case with a cut in the neck, using a match to blacken a bullet, ETC)

The method you have described people have used it.

Once you have found where the bullet is touching (Not jambed) the lands you can measure from the ojive of the bullet to the rear of the case. (As long as your using all the same brand of cases) Then you set your seater to reproduce this measurement. Now that you have the base line set you can move the bullet in or out to find where it shoots the best.

Hey Guys! Don't forget the possibility of that pesky carbon ring that could be formed from numerous rounds of the same bullet over a long period of time. I had a problem switching to a longer bullet,[got the answer on this forum]. I suppose the same thing could affect the shorter bullet. Quick

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Once you have found where the bullet is touching (Not jambed) the lands you can measure from the ojive of the bullet to the rear of the case.

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The OAL guage with the comparator is the "ONLY" way to go! Especially on small calipers.

My 243 measurements follows using the comparator:

NOTE: Three bullets used for averaging

107 SMK's avg 2.261

70 gr Nossler Ballistic Tip's 2.270 every time I measured it.

55 gr Nossler Ballistic Tip's: won't go in the case, I will go by the book on this round or one of my Federal 55gr rounds (COAL).

And striaght out of NOSSLER&#39;s reloading manual; Seat at a depth of <.015 or more if required.

Therefore:
The 107 SMK&#39;s should have a lenght of 2.246
The 70gr NBT&#39;s should be 2.255

I have several reloading books, just bought the Nossler (recommended) and it&#39;s about the best overall!

in order to avoid confusion, isn&#39;t the correct term ogive and not ojive? or am I confused.

you are right mike, one is how it is spelled (ogive) but it sounds more like the other (ojive). Both good I guess, long as we all know what part of the bullet we&#39;re talking about!

Yes you are correct it is spelled ogive, but it is pronounced ojive.

We are on the same page . . .

Worked up from 17.5 in 2-3gr intervals. Cleaned after 20 rounds. When load hit 18.6gr, fired another rapid 20 rounds. The first 6 walked all around, then 3 grouped tight, then the last 11 rounds cut a ragged hole of about 1/2" dia at 100yrds.

OAL was kept the same, Devin chambered the barrel and sent me several dummy cartridges for reference at 1.92." Bullets differ little in length, the sierra has even taper from rear to tip while the hornady has a straight rear to mid section and heavier taper from mid to tip.

Two things interest me, first the 39gr load is only 3 gr off powder from the 40 gr hornady and the targets look almost the same with the 40 gr a bit tighter. Second, both loads acted the same on the target after cleaning needing 7-10 shots to tame down, then shot the lights out.

Only 100 rounds fired through the barrel, all new brass being fire formed, may switch to br primers and shoot the fire formed brass now for comparison. Also, there was almost no copper fouling during the 100 round break in period, so may cut back on cleaning to see what happens.

Don&#39;t have a good front rest or bag, am using bipod, recoil is shifting poa. Barrel contour is mag sporter at 24," considering cutting back 2" and installing break...could be a dumb idea with accuracy potential showing during breakin.

Just curious....why rapid fire?

Put this rifle together as a repeater with det/mag to shoot fast at crows, have a farm close by that gathers hundreds+++ in winter barley fields, shots from 100-400 yrds.

Like shooting a full box of 20 at a time, it is cheap to shoot excepting bullets, and it keeps one of the neighbors interested. (Only 5 of us in the head of the valley, that&#39;s counting when one is out of jail).

Just a bit more curious.................

WHY put a muzzle brake on a .204 of any kind?? Have
not heard of a single one in which the shooter cannot keep
scope on target during firing.

Most factory Savage barrels shoot better dirty over clean, this is normal.

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Originally Posted by DannoBoone

Just a bit more curious.................

WHY put a muzzle brake on a .204 of any kind?? Have
not heard of a single one in which the shooter cannot keep
scope on target during firing.

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Injury prohibits recoil, near zero preferable.

High velociteties move poa around off bipod, not a varmint taper, Sin Arms custom shoots great! No copper fouling after 40 rounds, needs more firing, less than 200 so far, should only improve. Just doesn&#39;t like 39 Sierras.