Hello All,
I have been trying to get a .28 Nosler shooting (it has a 28" 1-8 twist barrel) and while testing at 300m i seem to have lost a couple of shots... no holes in the target.
I set up a target at 60m and started with a clean barrel shot some rounds at it. The speeds chronographed were 3110 fps.
I used 2 different aiming points on the target the first 6 went to the right, the last 6 went above and shots 9 and 12 went astray.
View attachment 102799
Anyone else seen this sort of thing?
Sam
There seem to be a lot of people with 28 Noslers having this issue.
So I going to cut & paste what I posted in another thread for a guy that was seeing the same issues with a 28 Nosler shooting 180 gr. ELD-Ms.
I ran into this with numerous bullets on my 7mm RUM.
With 2 barrels:
1-8.5 34"
1-8.75 30"
180gr. ELD-Ms come out at 3,400 - 3,450 fps depending on load and temp, etc.
Interestingly they hold together initially. I have never experienced any barrel get as hot as quickly as those on a 7mm RUM. This is heavy varmint profile .9" diameter at the muzzle.
By the 3rd shot, taking my time, the barrel is hot. Not enough to burn your hand, but you can't hold it comfortably for more than a few seconds.
Usually by shot 4 or 5 the bullet will now impact the target or berm sideways. This I can only assume is due to the heat in the barrel is causing the jacket to heat up on the way down the tube and blow at least part of the jacket off once it hits the air at the end of the muzzle.
I have tested a LOT of bullets found that unless it's a solid or a bonded bullet like a partition they do NOT hold up at velocities above 3,300 -3,400 + FPS and the above twist rates.
When I chopped one of my barrels down to 22" and the velocities dropped down into the 3,000 -3,100 FPS range on the ELD-Ms, the bullets seem to hold up.
Interestingly, I have run match bullets on my 22-243 with a 1-8 twist, 75gr. ELD-Ms going @ 3,600 fps and have never once had a jacket separation.
Even going to the 40gr. VMAX at 4,800 FPS, I do not experience jacket separation.
Bottom line, with longer barrels, the 28 Nosler is probably able, and the 7mm RUM and 7mm AM are definitely able, to drive many bullets at speeds past their design limitations.
Most 7mms don't come in factory twist rates faster than 1-9, therefore manufacturers have not been exposed to this.
The likely cause is that some 7mm bullets have jackets that are too thin to go down pipe with a twist rate faster than 1-9 at speeds above 3,200 FPS.
