Totally weird.


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Kachok
February 28, 2013, 08:10 PM
OK so I just got back from the range as you can tell from my last thread, I have been trying very very hard to get my M70 308 FTW to group well with 165s like it does with 150s since I have never used 150s for hunting (not in 30 cal anyway), well today I tried something off the cuff and loaded 180gr SGK over W748 just to see, WOW a .515" group with the first three shots! My jaw about hit the floor! So it shoots 1/2" with 150s, 1/2" with 180s but 1.5" is the best I can do with 165s?!? I asked the reloading guru in the shop and he has never seen anything like that either, had the 180s not grouped I could have chalked it up to the slow twist but this one has me scratching my head, and yes I have tried just about every 165gr bullet/powder combo you could imagine within reason, RL15, Varget, H380, Big Game, 748, BL-C(2), Speers, Sierras, Hornadys, Noslers.....etc, anyone have any ideas?

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c.latrans
February 28, 2013, 08:14 PM
You have tried 165's other than SGK?

Kachok
February 28, 2013, 08:18 PM
Yep Nosler BTs, Hornady SST, and Speer BTSP. Oh and I tried the SGKs in SP and HP versions.

c.latrans
February 28, 2013, 08:23 PM
Probably witchcraft....have you ticked anybody off? Funny stuff happens, doesn't it?!

Kachok
February 28, 2013, 08:25 PM
And to make this whole story even less believable the POI of my 180gr loads is over an inch higher then my factory 150gr core-lokt zero, even the mid load was higher, I don't think barrel harmonics could do that to all powder charges, and I am pretty sure I am not hitting 2850fps+ with 180s that would be a stretch for the 06 on a good day.

Kachok
February 28, 2013, 08:39 PM
Published velocity for 46.5gr of W748 and a 180 SP is only 2610fps, I should be about an inch low, and no I did not hang the target upside down. No pressure signs even at max but it did kick rather stout, nothing like any 180gr 308 I ever shot, dang I need a chronograph.

Rollis R. Karvellis
February 28, 2013, 08:44 PM
The muzzle has more time to rise before the bullet leaves it.

Kachok
February 28, 2013, 08:46 PM
Then why do factory 180s hit low? My 180gr Core-Lokt hand loads hit WAY low with a max dose of IMR4350 too.

James2
February 28, 2013, 08:53 PM
And to make this whole story even less believable the POI of my 180gr loads is over an inch higher

As soon as a bullets starts to move into the barrel, the recoil begins. Recoil that raises the barrel as we well know. Heavier bullet = heavier recoil = more barrel raise. No surprise it may hit a bit higher. This has little to do with velocity nor trajectory, but is a simple matter of how high the barrel kicked up before the bullet left.

Sorry, no theory on the poor groups on the 165s. I would not worry too much about it. Buy what the rifle likes.

Kachok
February 28, 2013, 09:02 PM
As soon as a bullets starts to move into the barrel, the recoil begins. Recoil that raises the barrel as we well know. Heavier bullet = heavier recoil = more barrel raise. No surprise it may hit a bit higher. This has little to do with velocity nor trajectory, but is a simple matter of how high the barrel kicked up before the bullet left.

Sorry, no theory on the poor groups on the 165s. I would not worry too much about it. Buy what the rifle likes.
Oh I am, already working up my next batch of 150s and 180s, I am not too worried about it, but I would like to know what I am missing for future reference. I have seen guns that like the heavy bullet and not the light and vice versa, but never one that likes heavy/light and nothing in between.

TNBilly
February 28, 2013, 09:23 PM
Hate to say it but Quickload calls 46.5gr of W748 an overload running about 70k. You can't get the pressure in bounds unless you're seating out to 3".

Kachok
February 28, 2013, 09:30 PM
Hate to say it but Quickload calls 46.5gr of W748 an overload running about 70k. You can't get the pressure in bounds unless you're seating out to 3".
Not according to the fine folks at Hodgdon.
180 GR. SPR SP Winchester 748 .308" 2.800" 46.5 2610 48,500 CUP
I would think I would see pressure signs at 70k, but then again that thing did kick like it meant business too.
I have shot factory 180gr Power points through that rifle and they did not feel anything like that, nor did they hit that high, if I remember correctly they are supposed to be 2600fps too.

chris in va
February 28, 2013, 10:50 PM
180 GR. SPR SP Winchester 748 .308" 2.800" 46.5 2610 48,500 CUP

Um, better check that formula again.

My Lyman manual shows a 178gr A-max 748 40.0-45.0max at 2662 and 60,500psi. I think you had a dangerous overcharge.

Kachok
February 28, 2013, 10:56 PM
Wow really? Why would Hodgdon post that load if it were dangerous? I am shooting CCI primers don't they show excessive pressure pretty well? I looked the brass and primer over thoroughly, no crater or primer flow and no extractor marks though it is a CRF action so I am not sure if that is the same.

Lost Sheep
March 1, 2013, 12:03 AM
Wow really? Why would Hodgdon post that load if it were dangerous? I am shooting CCI primers don't they show excessive pressure pretty well? I looked the brass and primer over thoroughly, no crater or primer flow and no extractor marks though it is a CRF action so I am not sure if that is the same.
I don't think so. CCI primers are reputed to be made of harder metal than other brands, thus would not flow a whole lot.

About the accuracy thing. Don't discount the effects of barrel harmonics. Also, seating depth can make a difference. A chronograph would probably help you analyze things. Might not help accuracy, but it sure is fun to have the extra information.

Good luck

Lost Sheep

kingmt
March 1, 2013, 12:04 AM
Your not going to see barrel clime in a rifle. You would never shoot .5" groups if it did.

gamestalker
March 1, 2013, 12:19 AM
Without a chronograph the best we can do is guess. As for reading primers, it isn't a real reliable means of identifying high pressures. If anything, primers are easier to identify low pressures. But you did say there were no extractor marks on the case head, so based on your observations alone you are probably OK regarding pressures.
As for accuracy swings, some rifles like what they like. As for those 180's having a higher POI, it contradicts ballistics?
GS

Ky Larry
March 1, 2013, 12:42 AM
I have a CZ-550 Varmint. It shoots 140gr and 155gr Noslers and 165gr Hornady S.P's under an inch at 100yrds with IMR-3031 and TAC. I haven't shot any 180gr bullets.

Kachok
March 1, 2013, 12:42 AM
As for those 180's having a higher POI, it contradicts ballistics?
GS
That is what I said, but I would swear on a stack of bibles it is true, I probably would not believe it had I not shot it myself. The other 180gr loads did not kick that stout and all impacted low, that one kicked like a compressed load 30-06 and grouped high, using Leopold rings/mounts and a Buckmaster scope I highly doubt anything got thrown off zero, my 44gr Varget 150s where hitting just like they usually do. Anyways I need to invest in a chrono of my own so I can check this stuff, while I like the way that load shot, and I don't mind the extra kick I need to do a little homework before trying that one again since everyone thinks it is dangerous.
I have had an overpressure load in that rifle once, flattend the primer like a train ran over it and was leaking around the edges, sadly that was not even near a max load Varget is a funny thing.

joneb
March 1, 2013, 12:53 AM
Probably witchcraft....have you ticked anybody off? Funny stuff happens, doesn't it?!
Only in your sick twisted skull.
As high as the heavens are above the earth, are my ways higher than yours says the Lord.

Kachok
March 1, 2013, 03:00 AM
OK doing a little research and it turns out that load might very well be quite hot despite being a published load from a reputable company and lacking of visible pressure signs, also might have been quite a but faster then I thought, Sierra's max load it 43.6gr at 2600fps seeing as I was running almost three grains more then that I could have very well been in the 2700fps range which while that does not explain the 1" higher POI it gets me halfway there.
I am going to have to error on the side of caution and abandon that one :( darn I thought I had a real winner there, back to the drawing board I guess. Anyone else know a good 180gr powder? My normal Nosler pet loads is letting me down on 308, while I am sure it would be accurate and I don't need 3000fps speeds I was hoping for a little more then 2400fps.

MtnCreek
March 1, 2013, 08:27 AM
Varget w/ 180gr Nosler BT has been accurate for me, but the 165 seems to performs better on deer IMO.

For 165gr Noslet BT, both Varget and 4895 have given good results. Best loads w/ Varget are pretty hot. Best loads w/ 4895 are slower, but a little more accurate. Most deer that I’ve shot have been inside 100yds, so I guess it doesn’t matter much either way.

dagger dog
March 1, 2013, 09:00 AM
Kachok,

" The whip may be extreme enough that the barrel will move both above and below the zero line while the bullet is still in the barrel. The starting movement while usually down, can be either up or down and measurements show that 7 to 15 minutes of angle is common"

This paragraph is the last one on page 58 of 4 pages on barrel whip from ;

UNDERSTANDING FIREARM BALLISTICS
Basic to Advanced Ballistics
Simplified,Illustrated & Expanded

By Robert A. Rinker

Buffalo Arms has this book on sale in their close out section.

It's a great book and can answer questions most experianced handdloader reloader-shooters can ask.

Kachok
March 1, 2013, 12:36 PM
Something other then Varget perhaps? To be honest that stuff scares the goomba out of me, I won't load it over my starting charge with 150s because it made for the worst pressure spike I have ever seen on a mid ranged load! Same rifle, and if it is not flattening out a primer at 70k psi I would hate to think of how much pressure it took to flow those primers like that and cause them to leak. Maybe I just have a bad batch of Varget, but with a starting load it does shoot 150gr Speers and SSTs very well, and the POI is right in line with the factory zero.

MtnCreek
March 1, 2013, 01:00 PM
I wonder if there was something else going on with your Varget load. IME, Varget gives a steady pressure increase and thrives at the upper end of published data. I've pushed some loads a little beyond data and still had good accuracy.

Another powder I've used a lot recently is 8208. I started using it because I wanted a good metering extruded powder in around that rate. I've pretty much replaced all my .223 loads to use it. It does a good job w/ 168 / 178 gr bullets in .308, but did not deliver the velocity that Varget did.

readyeddy
March 1, 2013, 01:14 PM
Max charge in Sierra manual is 43 grains, Lyman is 44 grains at 58,000. 46 grains may be a little hot.

Kachok
March 1, 2013, 01:40 PM
Yeah and if 748 shot as good at 44 or 45gr it would be a none issue, I am not trying to beak any speed records, just want to work up an accurate reasonably quick (2550-2650fps) 180gr load, I got a decent .968" group using 44.5gr of BL-C(2) with a 180g SGK but it was hitting pretty low and now I am scared to use any Hodgdon data since it is supposed to be WAY excessive with W748, my other manuals don't even list that powder for 180gr.
Do you think that Hodgdon load way a typo or do you think that was really safe in their test rifle?

Nevmavrick
March 1, 2013, 07:36 PM
I notice that all the bullets you've used are BTs. Maybe you can try a FB?
You might try to put a bullet back into the case before you resize it. I found I had a slightly short chamber once, and it raised my pressures just enough that the powder-burning got erratic.
I know that WW748 is a very popular powder with the .308,, but you might try WW760 (H414).
Primers MAY not show flattening at 70K. Part of the signs we try to "read" when shooting are common, one way or the other, and are therefor indicative of nothing. I've had several rifles that showed flattening at lower pressures. I've also had a couple that almost won't flatten until some of of the group actually blow by!
One of my rifles craters everything...you ignore it. It just is.
Have fun,
Gene

Kachok
March 1, 2013, 08:14 PM
Yeah a couple of my rifles are hard to read, I have never seen extractor marks on the Winchester even when I had obvious signs of overpressure on the primers, and one of my rifles flattens ever primer every time on any load, I don't worry about it until they start to flow outward and then back them down a full grain. Had one rifle that left a crater on any ol factory load, I think that had something to do with the firing pin. Pressure signs are a funny thing to read, they never appear to be the same rifle to rifle, but every single time I have had outward primer flow I knew to back it off. Have not ruptured a case yet much less a rifle, and I hope to keep it that way.

MtnCreek
March 3, 2013, 03:22 PM
Had one rifle that left a crater on any ol factory load, I think that had something to do with the firing pin.

Probably had a larger firing pin hole or a smaller pin. Newer Remington rifles are this way by design and even a modest load will crater.

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