high velocity bullet failures?

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fmj357

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I tried to search this but couldn't come up with the right keywords somehow.

I loaded my M700 7mm Rem Mag with 100 gr Hornady HP and 70 grains of Accurate Arms 3100, 2 grains below their max load, so they should probably have been around 3200 FPS.
Confirmed with a single shot on a 25 metre target that I "should" have been ok on paper at 100 and then could not put a single shot on the paper. I fiddled with my scope and finally ran out of daylight thinking my scope was way out of whack.

I am wondering now, is it possible these bullets were failing? 3200 doesn't seem excessive to me. I have read stuff in the past about bullets coming apart if they are fired at velocities they were not designed for but this seems unlikely at a velocity that has published data.
Maybe it was my scope, but I thought I would get some feedback.


I have had my rifles in the gun safe for a few years while I shot pistols and shotguns, so I haven't done much rifle loading for about 20 years, but I am not a novice reloader.
 
Maybe your twist rate is not right for such short bullets - I just checked a chart and in .284" 1:9 is ideal for 140gr and up and 1:11 is suggested for lighter bullets. I don't know of any 7mm RM with a 1:11 twist. Most have 1:9 or 1:9.5, so that may very well be your problem.
 
I just want to get back into the swing of rifle shooting-some trigger time. I have this old BDL which was my Dad's hunting gun, a .303 P14 and an early mini 14. Not exactly precision equipment, but I haven't decided what new rifle to buy yet.

I know the heavier bullets will shoot better in the 7mm, but frankly, they loosen my fillings. I shot lots of game with this rifle in the past. I have owned heavy barrel .308s and .223s which were target rifles, but I don't have one now.

Right now I just want some trigger time and NOT to develop a flinch before I even get started.

It's probably just me. I will go back to the range and shoot some more before I get my panties in a knot about this. :) Thanks for the comments.
 
Why don't you try a lighter charge of a faster powder with some inexpensive 140 or 150gr bullets? There are a variety of powders that will provide usefull velocity with a 55 - 57gr charge.

For example Nosler #4 lists 50.0gr of IMR4895 with a 140gr Ballistic Tip at just over 2900 fps - it also happens to be the most accurate charge for that powder. Or 52.0gr IMR4064 with the same bullet for just under 2900 fps.

Those loads will be very mild in the recoil department but deadly on deer sized game. Switch to Partitions or Accubonds and it will be enough for moose.
 
I have no plans at all to do any hunting with this rifle again. It is a 1967 BDL that I inherited from my Dad 30 years ago and plan to keep in the family. I hate to let it just gather dust so I wanted to shoot it some while I try and decide whether to buy a target .223 or a 6BR or a 6.5x.284 or something else I haven't read enough about yet.

The reason I am starting with such light bullets is that for me the subjective level of recoil with this load is similar to what a .243 feels like and I thought it might give me a rough sense of what shooting the 6BR would be like. I have 120 gr, 140 gr and 168 gr bullets that I am planning to work my way up to so I can gauge my own tolerance for recoil over a long day of competitive shooting-a lot different that just sighting in for hunting. I am not sensitive to recoil-"yet". I don't want to get there either. :)

I have a plan, but having these 100 gr bullets just "disappear" surprised me and I wondered if the combination of the fast twist and velocity might be an issue.

I looked on the Lilja barrel site and they actually recommend a 14" twist for 100 gr and 12" twist for 120 gr and they actually will make those barrels. So now I am really confused. Who would need a 14" twist 7mm barrel? Really small (like .223 size) cases? The recommended bullet weights I found, even for the 7mm TCU were in the 140 gr range.
So who needs a 14" twist barrel and who, besides me, would even buy 7 mm 100 gr bullets?
 
By the way, 1899 and Juster, I don't actually live in Vancouver. I'm in Cloverdale, so since you guys are so close, why don't you just come over for a beer and we can talk about this around the campifre? :):):)
 
Juster said:
50 m target would be worth a try. See if there are funny lookin' holes.
Click to expand...

x2

And then 75 if it looks good at 50.......

I would imagine your bullets aren't stabilizing, you could see groups gettting wider and wider the further down range you get as the bullet could be tumbling and or flying in an ever increasing spiral down range....

Its amazing what can happen with light bullets and impropper twist....... I once tried some new to me bullets that I new were improper to my twist. my groups went from 3/4" at 25y to MOSS (Minute of Stop Sign) @ 75. Heavier bullets stabalized no problem in the rifle, but REALLY light ones..... Not so much.

Cheers!
 
bedrock said:
Why would you piss around with 100 grains in a 7 mm?
Click to expand...

ahem... 3200 feet per flipping second
id do it too if i had a 7 mag.
close your eyes and you can just see the gopher parts flying.

to the OP. i would think anyone who designs a 100 grain 7mm bullet would know that its going to be going really fast, so i doubt the bullet itself is to blame. but stranger things have happened.
 
I loaded up a bunch of 150 gr hornady sst's for my old man's Ruger 77 .300win to see what charges it liked. Well due to the terrain we had only 30 and 150 yard sets. He
was shooting pie plate groups.. He can shoot, but he was so frustrated. We did t know if his scope was screwed, he was at fault or what. Could it have been that his rifle just didn't like those bullets? Mine was liked them just fine. The other
day I loaded up a bunch of 180gr noslers and he shot some excellent groups with no other changes.
 
I have a centuriy arms surplus barrel on a custom 7 mm Rem mag, and it has an 11 inch twist. I can stabalize 175 gr bullets, at close to 3000 fps. I know it is beyond what book says should work, It also works well with 150's, I have not tried anything lighter.
 
Thanks for the input guys. I have done some more research and I think I have a few possibilities in mind.
No doubt the bullet manufacturer knew that these bullets could be sent out at that velocity, but all bullets have a maximum rotational velocity beyond which unexpected things may happen. :) On the Lilja barrels site, optimum twist rate for the 100 gr bullet is 14". My M700 is 9.25", optimal for 165-175, which do shoot well in my rifle but thump the crap out of me. Yah I know some of you guys will say the 7 Rem Mag is a good gopher gun and I'm a pussy if I don't want the big recoil, but I am not trying to kill bull elk anymore at 300 yards. I only want to kill paper with little squares on it. :0

MAYBE, maybe the bullets are over rotating and failing. PROBABLY it is just me and my scope.
I will be back to range this weekend and will start at 25 meters and work my way out until I know for sure what is happening. Will report back.
 
It is unlikely that your velocity is a problem with the bullet, unless your rifling is really bad and damaging the jacket.
I have only seen .22 bullets self-destructing, and at 25 yards you could see a swirl of grey around the bullet hole showing where the lead was coming out. If your short range target does not have any such indicator it is unlikely the bullet coming apart.
Shoot a group at 25 yards, and then work out slowly and see where the bullets are going.
And, you are not going to 'over-stabilize' the bullets with your twist. A good bullet will continue to work despite what the books say about optimum twist. Remember the .30-06 will shoot 110 to 220 grain bullets, and mine has been hunting accurate with all weights (one of the most accurate loads was with 110 grain HP at 3400 fps). Your 7mm should not be any different.
 
Just to put this one to rest. My first shot on the first day at 25 was a couple inches high at 25m so I cranked a few clicks on my scope, maybe about 4, and went from there to 100m. Nothing on paper and couldn't get back to the 25 that day. That led to this whole thread.

Back to the range yesterday and my scope had somehow managed in 4 clicks to suddenly be almost a foot low at 25 meters. Well, that explains the 100. Maybe I should think about a new scope?

Got it on the paper and shot the last of my 3200fps 100 gr bullets at 100 meters. I had a very nice vertical string, very well centered, no more than 1/2 inch off center about 3 1/2 inches high over 8 shots.

Now why would 70 grains of AA 3100 heat my sporter barrel up? :) Thanks for all the help. This has always been a great hunting rifle and I think I will stick to that and find something else for targets.

Now, what to buy.........................
 
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