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Big 30's
demo-dan
Member Posts: 109 ✭✭
First of all, thanks for the help with the pegasus ammo. I was really curious as to what barrel and length no nonsense went with his 30-378, along with the twist. I've got a sako 995 warbird that shoots the factory 180 nosler partition on a string. The barrel has a 1-12 twist. I've read that guys are using 1-10 and even 1-8 twists to shoot some of the heavier rounds. I also had some 180 accubonds loaded to 3420 and they were quite accurate but after just two rounds I noticed copper in a couple grooves. After cleaning, I went back to some unplated 180 partitions at over 3500 and there isn't a hint of copper. Is the twist rate that touchy to load weight and velocity, is the copper a little softer with the accubonds? Or is it possible that the higher velocity powder is actually to some degree burning the copperright off.
Comments
Both of my .30-378 WBY barrels are 1:12" twist with one being 34" and the other being 40" in length. Note that these are specialty benchrest rifles and have no bearing on being carried in the woods for hunting![:D]
I shoot the Berger 210 VLD and I'm testing the Hornady 208 Match AMP.
I'll write something on the twist and coppering later.
Best.
The 34" barrel is running between 3300 and 3400 FPS depending on powder. The 40" barrel is off of the action right now while I fabricate a new tuning system for the barrel.
If a barrel is all over the place than settles down for a few shots then goes back to being poor, get rid of the gun or have the thing rebarreled with a good barrel.
The other hyper-velocity barrels probably need to be lapped sufficiently to improve the performance and decrease the copper build up. This is something that will require a gunsmith to do because the muzzle will need to be cut back slightly after lapping. These rifle need to be very important to you to go through with stuff like this because it costs money and the process of cleaning/polishing can be tedious when done correctly.
On the other hand, you could spend some time cleaning the barrels thoroughly then slugging each a couple of times, being sure to measure both slugs very accurately, not using any old calipers... Pay close attention the actual slug as it goes through the barrel. You might detect slight loose spots and tighter constrictions as the slug is moved from the chamber to the muzzle. Obviously the slug will reflect the size of the tightest constriction and won't yield any information about the looser areas other than the fact that they exist. You can mark both types of spots with a china marker on the outside of the barrel if that will help understand what's taking place.
There are some bore polishing compounds that are applied to patches and run through barrels which can help occasionally just don't push the patch out through the muzzle then try to draw it back into the barrel. This damages the crown to the point where it will have to be re-done.
I don't have much interest in the .30 caliber offerings anymore except for the .30-378 WBY and one new cartridge I'm working on for a supposed hunt this fall. The 7mm RUM will go along as well since I have secured a large supply of Matrix 190 gr. VLD hunting bullets.
Let us know how the project progress.
Best.
Which barrel maker did you choose?
Best.
The other question I had was with regards to your 190 grain 7mm. I've had a gentleman that has used a 7mm remington for decades now out of his stand where he hunts exclusively. He has always used the 175 grain rounds. His reasoning years ago has been the fact that his max distance is only 175. He's not a big balistic nut and 9 chances out of 10 he will never change stand locations. He really does like his heavier rounds and I was thinking of having some really high quality rounds loaded up for him. How well would the 7mm remington throw the 190's without showing a variation of much in the recoil, compared to the stock 175's? He's posessive with his gun/ammo combination so I usually avoid the subjects with him. We both know that the heavier rounds are far better choices for long range but don't tell him that. He only has about 200 feet to walk where he could cover a valley out across 40 acres (440 yards) he just refuses to due to the range. In any event I respect him keeping his shot distances reasonable but he's really passed on some bruiser the last couple of years. Does berger make a 190 hunting load for the 7 remington? What do you think. Showing him a book doesn't help, I'll definately have to get him out on the range.
By the way I don't mean to confuse or clutter you with all my gab, but i do thank you for your time. Thanks