The 35 XCB, the sledgehammer I've been waiting for

[runfiverun]

I just caught back up with this thread and need to apologize for the delay but work has kept me far from anything computer related.

CJR is giving some very good advice as to what could be happening here.
some time back Tim and myself had a discussion about mechanical and static fitment of a boolit.
and how the designs need to differ from each other.
if the collapse occurs in the mechanical stage and the design doesn't support that, it can lead to results like discussed above.
CJR gives the explanation on how the cog/cop relationship can give you fits when it flip flops mid throat so to speak.

[35 shooter]

Bjornb i was glad to see the 35xcb boolit come together for you a bit there. That's the best group i've seen from it so far. I've been shooting it in the whelen with 54 to 58 gr. of imr 4350 and 54 to 54 1/2 gr. usually shoots most any cast boolit well from this rifle. That's a bit over 2200 fps. depending on boolit weight...so right about where you are with the aa4350.

Think i'm getting too much contact in the throat when seating to the rifling in the whelen with this boolit. I'm going to back off a bit and give it a run at the rifling.

Since you did so well at about the same speed, i'm hoping that will be the charm. Oh well, i didn't name my rifle "ol contrary" for nothing.

Thanks for posting your results on it and that was good shooting!

[Bjornb]

Yeah like I said earlier, the 35XCB was never given the thorough workup that we gave the 30 cal. version. That will be changed once the weather cools down a little; my winter project is to get this cartridge to shoot well in both bench and hunting rifles.

Leaving for moose tomorrow (I shouldn't say that and jinx myself), and I decided to go with my Marlin 1895 GBL (completely gone through by Goodsteel, cycles like butter), loaded with the 350 RD GC bullet over RL7. As a backup rifle I'm bringing the Ruger Gunsite scout with jacketed ammo.

I'm getting the Mihec 359-220 hunting bullet in the GB that just closed; that will give me another design to try against both the NOE 360-200 FN, the 35 XCB and the 358009 (minus nose sizing).

Experimenting at the range is half the fun!

[taco650]

Yes indeed! Good luck on the hunt!

[OnHoPr]

May I ask what is the time frame of the 10 shot string, 5 , 10, or 20 minutes? Oh, was it fun hauling all that moose meat out?

[swheeler]

Yeah like I said earlier, the 35XCB was never given the thorough workup that we gave the 30 cal. version. That will be changed once the weather cools down a little; my winter project is to get this cartridge to shoot well in both bench and hunting rifles.

Leaving for moose tomorrow (I shouldn't say that and jinx myself), and I decided to go with my Marlin 1895 GBL (completely gone through by Goodsteel, cycles like butter), loaded with the 350 RD GC bullet over RL7. As a backup rifle I'm bringing the Ruger Gunsite scout with jacketed ammo.

I'm getting the Mihec 359-220 hunting bullet in the GB that just closed; that will give me another design to try against both the NOE 360-200 FN, the 35 XCB and the 358009 (minus nose sizing).

Experimenting at the range is half the fun!

So how did the moose hunt go? Pictures?

[Bjornb]

So how did the moose hunt go? Pictures?

No moose; only saw cows and calves. The 50-inch plus bulls got the memo and stayed away. We had visitors at the cabin:


No open season on these, so we'll be trying again next year.

[swheeler]

It happens! Hope the stars align for you next year.

[taco650]

Bjornb,

Sorry to hear you had bad luck with the moose. Why didn't you get a caribou tag too?

[Bjornb]

Bjornb,

Sorry to hear you had bad luck with the moose. Why didn't you get a caribou tag too?

I had a caribou tag (and both brown and black bear tags), but this Game Management Unit would only allow for taking bulls. The visiting caribous were a cow with her calf.

[taco650]

I had a caribou tag (and both brown and black bear tags), but this Game Management Unit would only allow for taking bulls. The visiting caribous were a cow with her calf.

That's a bummer! Hope you enjoyed the trip anyway.

[kens]

Bump on this thread
Any more news on the 35XCB testing?

[Mauser 98K]

there is one little problem with wanting to go with a very slow twist with a long bullet, and this might explain why the groups is so large.. a slower twist imparts less gyroscopic forces upon the projectile leaving room for destabilization and degradation of accuracy, the same goes with slower velocities.. to remedy this one must either push the bullet harder in a slower twist barrel to get adequate stabilization or increase the twist rate to compensate for the slower velocities.. the longest bullet of that cal at 2250fps will usually stabilize with a 1-14 twist barrel is 1.5in long, at the 1,300fps the max length is 1.165in long in a 1-14 twist. longer bullets or slower bullets will not effectively stabilize enough to get the groups to 1MOA or less..

i went through this myself a while back when i started swaging and casting my own bullets.. the longer the bullet got the more unstable it got in the slower twist barrel and the slower the velocity the more unstable it got for a long bullet. this caused the group to open up or in extreme cases the bullet would start to tumble as soon as it left the barrel and it would keyhole and do other strange things.. to figure out if your bullet will stabilize in your barrel you must know the length of the bullet, the velocity you plan to use, and the twist and do some fancy math called the "Greenhill equation". or you can use this little calculator.. http://kwk.us/twist.html

this is the largest problem with a lot of people who think longer or heavier bullet is the way to go without really knowing what the laws of physics are or any knowledge of how rifles really work. the problem with this is that you can only push a long heavy bullet so fast b4 you grenade your rifle with the chamber pressures so one must either shorten the bullet for a given velocity and caliber or increase the twist rate to enable the bullet to stabilize enough for accurate flight at the slower velocities. there is a reason the old mauser with 0.323 bullets had a twist of 1-10 or faster, it was because the slower twist would not stabilize a long heavy projectile at any real range. the further the range the slower the bullet and it would start to wobble and yaw. this sounds like what is happening out at 200m as the bullet is now too slow to be stable with that slow a twist or length of bullet. barrel twist and gyroscopic stabilization and its effects on accuracy was figured out over a hundred years ago..

but for a lead bullet i would also not under any circumstances resize the bugger as long as it was within 0.003in. it is lead and the barrel resizes it. i use .310 bullets in my .308 target rifle at velocities down to 1,000fps and can get under 1MOA all day and im using the Lee dippers and not weighing a thing.. i have actually went as far as to put 15rounds in a hole i can cover with a nickle with lead round nose bullets at 50m. you must tailor the bullet as well as the other components to the rifle if you want to tighten the group up. shorten the bullet a bit and see if that is better if you can..

[Nrut]

The 35 XCB will easily stabilize in a 1/16" twist down as low as 1000 fps..

http://noebulletmolds.com/NV/images/...GC)_Sketch.Jpg

Berger Twist Rate Calculator:
http://www.bergerbullets.com/twist-rate-calculator/

In the day when the 98 Mauser was a main battle rifle the jacketed bullets were new and of lower quality, read less balanced than today, hence the faster twist..
There was a thread sometime ago on 24hr. Campfire that discussed the twist rates of the old military rifles...

Cast bullets are more delicate than jacketed bullets and must be started straight and square with the bore or they become mangled, and out of balance..
Throat and bullet design, BHN and pressure along with pressure curve play a big role also..
A slower twist is more gentle on a cast bullet and is why it is prefered over a fast twist if goal is high velocity..

[GARD72977]

In intrested in this caliber. I dont care whats new or old when a case has a good ne k for cast bullets its intresting.

[Mauser 98K]

an unbalanced bullet will not stabilize no matter how fast you spin it. if anything it will wobble faster around its center of gravity and the groups will open up even further.. but if you want to get into the older bullets not being as good as today. a lot of the bullet manufacturing equipment that is being used these days is the old EW Bliss press systems or equivalent that were built over 50 years ago. it is the same equipment used way back then. in fact Mr Hornady started with one of the old surplus presses. as far as making bullets go not a lot has changed in the actual creation of the bullets. the materials might be a little different and the inspection process might have went computerized but the way they are made is virtually unchanged..

but back to the stability and twist... ya can do what you want in that department. there is no reason that a rifle cannot get sub MOA with cast bullets other than the thing is not stable or the loading is inconsistent..the other reasons would be shooter error, ammo is low quality, or the rifle has issues. but something has to be off with the stability if the groups cannot be brought to 1MOA or less and the groups keep going to **** at longer range. the only logical explanation from the observations is that the bullet is losing stability at longer ranges as the velocities drop and the bullet spin is less and that is what is causing the group to open up like it does. the way to rule out shooter error is to put the rifle in a cradle and set it up where it is mounted solid and do a group with it mounted solid, only then can you tell exactly what the rifle is doing..

another thing it could be. i see there is no cheek pad on that rifle.. accuracy will also suffer if you cannot get your head in the same location every time. this is why i got a raised section on my stock to rest my cheek on that ensures a exact cheek weld every time.. also is the barrel free floated or does the stock touch it anywhere. if there is varying pressures on the barrel that will cause problems also.. you want to be able to slide 2 playing cards all the way to the action for best results. this insures there is no chance of anything touching the barrel.

all i can do is put out the information, i cannot make anyone do it. and information is useless unless it is used..

[Larry Gibson]

Unbalanced bullets do in fact, stabilize.

Please, let us not confuse bullet stability with the decreases in accuracy unbalanced bullets can have. Unbalances in bullets is the primary reason why we shoot groups instead of all the bullets going into the same hole. The reason many old rifles shoot so much better these days is because the quality (read that; uniformity of jacket thickness and balance) of the commercial jacketed bullets is much better.

[Mauser 98K]

what causes the decrease in accuracy with an unbalance bullet then? while it is true the bullet will rotate along the center of gravity as soon as it leaves the barrel it does not necessarily mean that it is stable in flight as the gyroscopic forces will tend to want to yank the bullet one way or the other as the bullet wobbles around the center of gravity. a truly stable bullet will rotate along the center of gravity that is in the exact center of the axis of the rotating bullet. if it is rotating outside that exact center then it will not be stable enough for perfect accuracy.. there is a reason that unbalanced bullets result in accuracy problems, if it were stable then this would not be the case..

but we can demonstrate this effect by filing a notch or drilling a small hole in one side of a hand full of bullets to throw them off balance and then shooting that at the target.you can also swage the bullet core with a small plastic bead to one side of the core to create a void of lighter material that will also throw off the bullet. the more unbalanced you make the bullets the more erratic the grouping will become till you can no longer even hit the paper. and it does not matter how fast you spin or drive these bullets you can never get them to stabilize enough for a good group. but as i said, while it will stabilize around the center of gravity, while it wobbles around the center of gravity it will get a differentiation of the air pressures on different parts of the bullet and this will also create turbulence in places you would normally not have them and that also effects the trajectory. there is a whole slew of things that happen to a unbalanced bullet, not just rotational stabilization along the axis of the rotating mass.

the biggest reason for lead bullets to become unbalanced is due to air cavities in the lead, you might not be able to tell it by looking at the bullet but one side would be heavier than the other and these will cause fliers.. uniformity in the jacket thickness is only part of the equation with a jacketed bullet. if the base is at an angle or the core is not swaged in the jacket correctly there might be air trapped between the jacket and core and that will throw the bullet off and cause accuracy problems..

http://bisonballistics.com/articles/...llet-stability

[Larry Gibson]

You've all the right parts there. Problem is your not understanding what bullet stabilization is. Bullet stability is simply that the bullet has enough rotational spin to fly point forward. Bullets can be very stable yet inaccurate.

It is the centrifugal force of the RPM acting on the imbalances that causes the inaccuracies. The higher the RPM the greater the inaccuracies.

[Mauser 98K]

yea, stable enough to fly point forward is a kind of stability.. and i agree that there is such a thing is too much spin.. they tried different twist with the .223 back in the day. one twist they had was so fast that the bullet was on the verge of flying apart and would detonate when it hit a blade of grass.. accuracy was out the window also.. as with everything there is a happy medium there where things work good... but that is what i would do though, id try a shorter bullet just to rule that out as a factor. what is there to lose? and b4 id go whittling off parts of the barrel id juggle the ammo weights and lengths a bit. always try the simpler stuff first because it is hard to add metal back after you machine it off or cut it off.. but if it was capable of 7 bullets in the same hole as outlined in the opening post then it is not the rifle and i can bet you it is the ammo.. if that is the only factor changed then it is something worth looking into.. id try to duplicate the load that did the good 7rnd group..