Author Topic: EXTREME .308 "Whiteout and Alpha 30 wins 1st & 2nd at EBR 200 yd event! (Read 24656 times))

rsterne · « **Reply #80 on:** October 11, 2015, 12:49:35 PM »

I have found that proper tuning is just as important with a regulated PCP as an unregulated one.... While reducing the hammer strike may not drop the velocity at all, it will save air.... and you can save half the air over the "wrong" tune or even more, getting double the number of shots or more at the same velocity.... If you want the ability to shoot a few shots untethered, you can even come up with a tune that will allow say 3 shots off tether with an extremely tight ES (1% or less) and when you are tethered, you are shooting the first shot of that 3-shot string, and hence on the "efficient" side of the curve.... If you need to get away from the tether (eg. for the EBR), you can fill from the regulator and get 3 shots before refilling.... Not only that, when properly done, you can be within a few percent of the maximum the gun can shoot if power is what you need....

Stew, if you want a bullet design similar to the Whiteout but lighter, I already have three done, 133 gr., 154 gr. and about 172 gr.... The 154gr. needs, in theory, an 11" twist, the 200 gr. Whiteout uses an 8", so I would think the 172 gr. would need about a 9", but might work in a 10".... Boattails require a faster twist than the same length flat-based bullet.... Send me a PM or email if you want a drawing....

Bob

bluethunder · « **Reply #81 on:** October 11, 2015, 08:23:25 PM »

Until someone is actually shooting extreme spreads averaging lower than 7 fps for a 10 shot string I'm not going to fiddle with the hammer spring. I've had 10 shot strings as low as 4 fps extreme spread. There's not a lot improvement left in this arena. And I'm not going to worry about shot count. I already get 80 shots per outing (2 bottles) and it's always been more shots than I needed. I am interested in improving the B.C. of my bullet. And lock time. That's where I will focus my improvement efforts.
I think the EBR rules need to be re-evaluated. I mean, if an individual is charging an air rifle for "every" shot-- what's the difference in allowing it to be regulated and tethered to obtain the same effect. Is the EBR implying that tethered/regulated rifles have no relevance in the hunting world while charging a rifle for every shot does? Get real. Neither is relevant to a hunter. The tethered/regulated rifle is going to work just fine in a hunting situation un-tethered for 1 shot. If we are going to recharge every shot in the field we are going to have to be carrying buddy bottles everywhere we go. Just acknowledge that both systems are unrealistic for the hunting world and allow regulation and tethering for the big bores. They need to re-evaluate their rules. Our sport is still in its infancy. We'll learn.

C.ALLS · « **Reply #82 on:** October 11, 2015, 09:47:53 PM »

Our extreme spreads our WELL UNDER %1 and we're refilling every shot so there's human error with the reading of the gauge ect. If we shot tethered WITH a good regulator I'd be surprised if our ES was anything over 4-5fps. That wouldn't be a big deal over your already low 7 fps spread but I guess I just don't understand putting all the time and effort into a long range rig and not spend a little extra time to set it up for the best efficiency. To each his own I guess.

Now on the lock time we're experimenting with the best setup and by shortening the lock time and decreasing the hammer travel the gun is becoming even more efficient and I have to believe the less extra air trying to blast its way around the bullet when it's exiting the barrel the better.

rsterne · « **Reply #83 on:** October 11, 2015, 10:20:31 PM »

I agree, not allowing a tether at the EBR, but allowing you to fill after every shot, makes NO sense, as functionally they give the same results, and neither is great for a lot of hunting situations.... However, shooting from a tether IS practical for shooting/varminting at 200 yards, and a lot of the big bore guys here do just that.... IMO they should either allow a tether, or restrict you to shooting each 5-shot target with a single fill.... The latter you can get around by hanging a large tank on your gun, so just allow a tether and be done with it, IMO....

Anyone who hasn't played with a preload adjuster on a big bore (or any PCP) really needs to get with the program.... Here is what happens with my .284 cal Hayabusa, tethered at 2900 psi....

The gun uses about half the air per shot at 4 turns out than it does with the preload maxed out, and the velocity is the same.... The ES is much tighter at 4-5 turns out as well.... Also, the gun is so much quieter at 4 turns out you would think it was a different gun.... Efficiency matters, even when on a regulator.... Why big bore manufacturers don't install a preload adjuster on their guns I will never understand.... Regulated or not, it's a necessity, IMO....

Bob

bluethunder · « **Reply #84 on:** October 12, 2015, 09:28:18 AM »

Maybe someone out there in the aftermarket air gun world could make a threaded end cap with an allen screw that could move a spring guide/plug fore and aft for our Extremes so that it would be easy to try different pre-loads. As it is, you either cut coils or keep swapping out springs. Brent are you listening?

rsterne · « **Reply #85 on:** October 12, 2015, 12:21:31 PM »

Chris and Mike made them.... but I'm not sure if they will work with the stock stock.... (do I hear an echo?)....

Bob

C.ALLS · « **Reply #86 on:** October 12, 2015, 02:10:32 PM »

Quote from: bluethunder on October 12, 2015, 09:28:18 AM

Maybe someone out there in the aftermarket air gun world could make a threaded end cap with an allen screw that could move a spring guide/plug fore and aft for our Extremes so that it would be easy to try different pre-loads. As it is, you either cut coils or keep swapping out springs. Brent are you listening?

They're available but as Bob said the factory stock needs modified slightly.

C.ALLS · « **Reply #87 on:** October 12, 2015, 02:11:26 PM »

Quote from: rsterne on October 12, 2015, 12:21:31 PM

Chris and Mike made them.... but I'm not sure if they will work with the stock stock.... (do I hear an echo?)....

Bob

Wish I could take credit for that creation but that was all Mike.

TPL · « **Reply #88 on:** October 12, 2015, 05:13:50 PM »

1-8" twist? I find it pretty tight comparing those generally told before. You guys found any keyholing due to fast spinning?

moorepower · « **Reply #89 on:** October 12, 2015, 05:48:14 PM »

A keyhole is yaw from not spinning fast enough.

C.ALLS · « **Reply #90 on:** October 12, 2015, 06:21:35 PM »

While there is a possibility of over stabilizing a shorter/lighter bullet the effects wouldn't be seen till the bullet was way outside the range we would be shooting them. The 1:8" twist managed to stabilize the 200 grain BBT (most of the time) that was built to the wrong specs and ended up 1/16" longer than designed. So once the mold is corrected and the bullet is the correct length I feel we'll be able to easily hold 2.5" or better groups at 200 yards.

C.ALLS · « **Reply #91 on:** October 12, 2015, 06:22:30 PM »

Double post.

Tofazfou · « **Reply #92 on:** October 12, 2015, 08:41:24 PM »

At only 970 fps and 8" twist, the bullets definitely are NOT over stabilized. Push em faster "FORWARD" and that stability/yaw might be corrected. Wow, 8" twist is superfast and seems to restrict forward speed even using helium IMO. I've heard of you guys testing in the near future using plain ole HPA but i wonder..............

My question is though, is a 1/16" shorter bullet gonna correct the yaw issue. Thats really minute in OAL........

I say a little lighter of a bullet will help cause you will have more forward speed which helps SPIN the bullet FASTER along with that twist. I'm just assuming here though and really don't know the answer............

Bullet RPM = MV X 720/Twist Rate (in inches)
87,300 RPM for the 200 gr WHITEOUT (roughly)

I'm really interested in this and how its going to turn out. The more CONCRETE info, the better. I can't wait to read the future progress once the corrections are all made up and tested........

C.ALLS · « **Reply #93 on:** October 12, 2015, 09:10:05 PM »

I'll admit I'm no bullet expert but the original 200 grain boattail design required a 1:8" twist and I have to imagine adding 1/16" to the length can't help. The thing you said about pushing them faster makes sense. My gun pushes the bullets about 60 fps faster than Mike's and his gun suffers from flyers more so than mine. I have a little more power available. Maybe I should send them out the barrel closer to 1100fps?

rsterne · « **Reply #94 on:** October 12, 2015, 10:28:17 PM »

The stability decreases with velocity until you hit Mach 1, where it is the worst.... beyond that things are completely different, but we can't launch bullets fast enough to stay above Mach 1 out to 200 yards, and if we did, they would have MUCH more wind drift, so what's the point....

The Whiteout shoots 5 holes touching at 100 yards, but some of the holes are showing yaw at 200.... To me that means it is VERY close, so that extra 1/16" in length could make the difference.... it destabilizes the bullet by about 8%.... Only testing that idea will tell for sure....

Bob

hunter457 · « **Reply #95 on:** October 13, 2015, 01:19:48 AM »

Nice work! I like the camo.

KnifeMaker · « **Reply #96 on:** October 13, 2015, 03:15:19 AM »

Simple enough to check the theory. simply make a jig to hold the bullet in a mill, and mill the desired amount off the nose.

I did this before modding any of the NOE Molds here in my shop. this allowed for through testing before any mod's to the mold's were done. That is how I settled on a 80 gr. Spitzer for the .250 with it's 1-14 twist barrel. I sent a bunch to Doug to use at the EBR as they are very accurate bullets, however, Doug had problems with the Reg. on the .257 and switched to the 30 cal for the event. A shame, as the .257 is more accurate than the .30 Doug is shooting.

As far as Tethering goes, We Americans are far to proud,and down right stubborn to pay attention to how is being done in other parts of the world.

As I explained to Doug, Bench Rest is all about the very best accuracy obtainable from both the shooter, equipment, and gun. Not whether it translates to any perceived Hunting arena.

Not allowing tethering, which
is just about necessary in a big bore match, is foolish in my opinion. and in the opinion of match rules all over Europe. For some reason, the EBR seems *(&^ bent on making it difficult for Big Bore Shooters. Not that it surprises me in the least!

In fact, it is exactly what I would expect them to do, either out of disdain for Big Bores, or willful ignorance. Either- or, if not both. .

Knife

Rizen 1 · « **Reply #97 on:** October 13, 2015, 07:51:45 AM »

One thing I think we need to remember is that this was the very first year the EBR had a bigbore category..... There is a learning curve when stepping out into something like that... AOA did a great job with the event, and I am sure there will be changes next year, as the bigbore market continues to expand.

Extreme Big Bore · « **Reply #98 on:** October 13, 2015, 07:58:08 AM »

I think that everybody did a great job the group from the EBR shoot set the rules that everyone new before hand and one rule was no tethering which I think is a great idea it puts more on the shooter if the shooter can not fill his rifle exactly the same they will not have the same point of impact for each shot. Especially for big bore rifles they are for most of the people that own them they bought them with hunting in mind and I would have to say in most cases for hunting tethering is not practical I am not saying that some people do not tether while hunting but would have to bet most do not. Like I have stated before I have raced snowmobiles professionally for 18 years and believe me I hate some of the rules we have to follow but any competition without clearly defined rules and enforced will eventually fail I have witnessed this time after time over the years with different racing organizations the organizations that did not set and enforce the rules did not last very long.

Brent Hoag

bluethunder · « **Reply #99 on:** October 15, 2015, 08:16:58 AM »

Tethering for a prairie dog shoot would probably work out. Especially if there's an air stripper and you are not spooking them too much.

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EXTREME .308 "Whiteout and Alpha 30 wins 1st & 2nd at EBR 200 yd event!

Author Topic: EXTREME .308 "Whiteout and Alpha 30 wins 1st & 2nd at EBR 200 yd event! (Read 24656 times))