Range Report 300 WM/178 Amax exploding mid air

[B Man]

My gun:

T/C Encore pro hunter
w/ 28" barrel
1-10" twist

Load:

R-P brass
WLR primer
79gr. H1000
178 gr. Amax
3.495 OAL
.020 off the lands
3020 fps
E.S. 7
3/4 MOA at 100 yds


I pushed this load up to 83gr. before getting pressure signs. The load above was my best overall load. At 82gr. I hit another node but the groups were inconsistant. So I dropped back to 79 gr. and let it ride. I set a target up at 250 yds today to get it zero'd for hunting and thats when I found out why the load was inconsistant with hotter loads. First shot a little high & left. Moved down and over and shot two more rounds. I couldn't find them so I tried again but my hit was high and looked a little big so I then loaded another round to check my self and the paint can I had my target taped to went to flipping in mid air about 5'. I thought I must have hit the top or bottom rim on the can causeing it to go air borne and on my way down there I got to thinking the load was not near as accurate as it looked at 100yds. After getting to the can I could see my problem. Bullets are exploding in mid air after 100yds. I guess it's to much velocity for the 178's.

Has anyone else experienced this?

Kinda sucks after all the time and money spent making this load but I'm glad I checked my zero at 250 before going hunting and wounding an animal.

Here is a picture. It has two 100yds shots showing from zeroing my new scope to compare to the top left 250 and the gapping hole on the bottom right also 250. You can see all the lead splatter on the can and paper.

 

[bohem]

Re: 300 WM/178 Amax exploding mid air

3020fps*720/10tw = 217400rpm

If you went as fast as say, 3200fps from the HOT load then you'd be up to 230400rpm.

That's definitely getting up there for 30cal bullets. I've seen some 208 Amax's blow around 3200-3300fps from a 10tw in 300 RUM so I wouldn't be too surprised to hear that you're getting on the edge too.

I've blown up 123 Amax's from a 6.5-06 around 3400fps from a 8 twist, seems like a much faster twist rate but the forces involved due to the increased bullet diameter are similar.

 

[B Man]

Re: 300 WM/178 Amax exploding mid air

The load above that was blowing up bullets in mid air was the 79 gr. load at 3020 fps. I never shot the hotter loads past 100 yds. But i suspect they had to be pulling apart is why the groups were hit and miss meaning one time it would group tight and next time wild with same load.

Do you think the 178 gr. a max has to thin of a jacket for the 300 WM velocity?

 

[Jig Stick]

Re: 300 WM/178 Amax exploding mid air

How awesome would it be if you found the exact distance that the bullets started to explode. And then shot a deer or ground hog or whateverthefuck at that exact distance. Would it rain bone and fur everywhere from the extreme expansion of the bullet? try it and report back.

 

[bohem]

Re: 300 WM/178 Amax exploding mid air

I think that the jacket's a little thin for your particular setup. I don't know how smooth the rifle barrel is internally and that can have an effect on bullet survival.

I have seen some hot 6.5s and 7s that didn't initially blow up bullets but after about 1000rd the bullets started to periodically come apart in flight.

Can you go to a 190 SMK or a 208 Amax, drop the speed some and still accomplish what you're looking to do with the 178's?

I have a partial box of 208's if you want to try some before investing in a sleeve of them.

 

[RobG]

Re: 300 WM/178 Amax exploding mid air

I used to shoot 7mm 162 amax's at 3170 and blew a few up. Left the same splatter as in your pics.

 

[B Man]

Re: 300 WM/178 Amax exploding mid air

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bohem</div><div class="ubbcode-body">I think that the jacket's a little thin for your particular setup. <span style="font-style: italic"><span style="font-weight: bold"> I don't know how smooth the rifle barrel is internally and that can have an effect on bullet survival.</span></span>I have seen some hot 6.5s and 7s that didn't initially blow up bullets but after about 1000rd the bullets started to periodically come apart in flight.

Can you go to a 190 SMK or a 208 Amax, drop the speed some and still accomplish what you're looking to do with the 178's?

I have a partial box of 208's if you want to try some before investing in a sleeve of them. </div></div>

I think this could be a little of the problem. I just cleaned the barrel really good before putting it in the safe for awhile and noticed after the final cleaning that in the tip of the barrel inside there is a few small pitts in the steel! Also looked the the one of the riflings at the crown was slightly raised like it hit something. If this is true I'm pissed because it has very few shots and is practically new.

But hearing you guys say you have had kinda the same results makes me feel a little better also. Guess I need a tougher bullet. I have some 150 gr. accubonds a buddy gave me for my .308 he sold his but I wanted to stay with around 180's thinking the accuracy would be best around this weight.

I'm suprised the 300 WM pushed it past the limits like this. Seems like manufactures would put a Approx. max velocity on bullets.

Thanks for the replies

 

[JByrd]

Re: 300 WM/178 Amax exploding mid air

178's@83 gr. its a wonder the proj. didnt travel back in time McFly those had to be strokin!

 

[B Man]

Re: 300 WM/178 Amax exploding mid air

Haha, I left the chronny but i'm sure they were cookin in the 28" barrel.

I loaded my first batch to 81gr with no pressure so I loaded another batch to 83gr. I told my friend with me I would never get past 82 gr without pressure but it suprised me. But 83 gr. did show sign so it was a little to hot for my liking and the gun didn't care much for it.

 

[Wardy]

Re: 300 WM/178 Amax exploding mid air

hmmm...this has me a little concerned, although I haven't had any problems with them coming apart...should i say, "yet"??

300RUM,94g Retumbo, 178 Amax, Chronoed at 3175..killed a doe last yr at 300yrds, didnt get the results "Jig stick" is looking for, but, did almost cut her a full flip, lol

 

[JByrd]

Re: 300 WM/178 Amax exploding mid air

more ....more pour it to it wards, chrono find that redline and report back

 

[B Man]

Re: 300 WM/178 Amax exploding mid air

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: procovert45</div><div class="ubbcode-body">more ....more pour it to it wards, chrono find that redline and report back </div></div>

Not to sure how u expect this to help me solve the problem I'm having.....

This is THE first rifle I've ever loaded over max only because it hit another node right at max like I have already posted. So if u want to advise me about limits that's fine but please do so in a better way.

So some constructive advice or troll another thread

Thanks,
Brandon

 

[JByrd]

Re: 300 WM/178 Amax exploding mid air

My point is this.find the node your gun will comfortably shoot.there is no need to flame throw the throat/barrel on a particular round its gonna take alot of heat/powder to make .5mil difference at say 700 yds.in the 300bottom line-you'd be better served running a longer higher bc bullet at long range to get the full advantage of the wm. People get too caught up with speed and hotrod the cartridge.if you want more speed move up a cartridge "ie ultramag" and also choose a proj. Suited for that round

 

[JByrd]

Re: 300 WM/178 Amax exploding mid air

In short,no matter how hard you push the cartridge and how light a proj. Its never gonna shoot a flat line,your still gonna have to know your holds. Appropriate Cartridge proj. Ran at reasonable speeds=consistent

Blowin up bullets,blowin out primers is not where consistency is and at the end of the day that's what a good load is all about.

Don't get caught up in 3000+ speed hype

 

[B Man]

Re: 300 WM/178 Amax exploding mid air

Thanks, That's info like me and others in the future that search this topic will find helpful. Rest assured though I'm one of the last to push anything past a listed max. I like my hands and face the way they are and have found all but one of my rifles at its best around 2 gr. Below max.

I'm going to try some 208 a max bullets soon as they get here and report back. If its my barrel I will expect similar results or if not it will show a close max for the 178 s. I used them mostly because I had a lot on hand from loading my 308 and its for deer hunting so another bullet would have just been one more thing.

 

[JByrd]

Re: 300 WM/178 Amax exploding mid air

208=good choice. Plenty people run the 175's in 308 on here you could always flip em on here an buy your 208's, that's tip top in wm's

 

[former naval person]

Re: 300 WM/178 Amax exploding mid air

Use the 180 Nosler Partition. Problem solved. Cheaper too.

 

[Huckleberry75]

Re: 300 WM/178 Amax exploding mid air

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: B Man</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bohem</div><div class="ubbcode-body">I think that the jacket's a little thin for your particular setup. <span style="font-style: italic"><span style="font-weight: bold"> I don't know how smooth the rifle barrel is internally and that can have an effect on bullet survival.</span></span>I have seen some hot 6.5s and 7s that didn't initially blow up bullets but after about 1000rd the bullets started to periodically come apart in flight.

Can you go to a 190 SMK or a 208 Amax, drop the speed some and still accomplish what you're looking to do with the 178's?

I have a partial box of 208's if you want to try some before investing in a sleeve of them. </div></div>

I think this could be a little of the problem. I just cleaned the barrel really good before putting it in the safe for awhile and noticed after the final cleaning that <span style="font-weight: bold"><span style="text-decoration: underline">in the tip of the barrel inside there is a few small pitts in the steel! Also looked the the one of the riflings at the crown was slightly raised like it hit something.</span> </span> If this is true I'm pissed because it has very few shots and is practically new.

But hearing you guys say you have had kinda the same results makes me feel a little better also. Guess I need a tougher bullet. I have some 150 gr. accubonds a buddy gave me for my .308 he sold his but I wanted to stay with around 180's thinking the accuracy would be best around this weight.

I'm suprised the 300 WM pushed it past the limits like this. Seems like manufactures would put a Approx. max velocity on bullets.

Thanks for the replies </div></div>

You might want to havea gun smith look at the crown and inside the bbl. Several of the guys I hunt elk with run their 300WM's at 3100-3200 and have never had bullets come apart like that. My guess is that if you have some sort of obstruction/burr/issue with the lands/crown, then this is the cause of your problem. I would look here before any further type of bullet testing. Just my $0.02.

 

[bigwheeler]

Re: 300 WM/178 Amax exploding mid air

Hornady's view of things.

http://www.hornady.com/store/30-Cal-.308-178-gr-A-MAX/

 

[Aimsmall55]

Re: 300 WM/178 Amax exploding mid air

I am shooting them out of 700 Police .300 win mag and they are fast. I load 70.0 grains imr4350, Oal-3.555" with wlrm primer. They are doing on average 3100 fps. Shoot them out to 700 yards all the time. But one must consider could it be a defect in that particular bullet? Or is it just sheer drag that is causing them to blow because they are moving so damn fast? I have never had one blow. And my gun loves em.