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Problem with Barnes TSX in my 25-06
ltmlt
Member Posts: 25 ✭✭
I have just reload some 115grs TSX bullets in my model 70 in 25-06 (1-10 twist),and I am getting Keyhole.Had no problem before with 120grs.Grand Slam,or the 110grs ballistic tip and was getting less than one MOA.The groove and crown are OK.
Any idea what is causing this problem with the Barnes TSX.
Thank you
Any idea what is causing this problem with the Barnes TSX.
Thank you
Comments
How much is the bullet keyholing? Is it full profile or is the hole just slightly elongated.
You need to check a couple of things:
Check the twist rate of your barrel accurately. Do it more than once. The potential is that it isn't a 1:10" exactly and when you're at the maximum of some extents, every little bit hurts or helps.
Is it cold yet where you're shooting?
Clean your barrel thoroughly especially in the area just in front of the throat. There might be a build up of carbon or fouling. If the barrel is fouled, the bullet can skid and throw everything out of whack.
What velocity is the bullet leaving the muzzle? Did you chronograph it or are you guessing because of the book load data? Insufficient velocity with bullets that approach maximum length or maximum length due to construction can cause bullets to keyhole.
Your 115 gr. TSX bullets should be in the area of 1.225" in length and if they were a standard construction of copper jacket and lead core, you wouldn't have a problem until the velocity dropped below 2800 FPS. Being a mono-metallic construction though, combined with lower velocity could require a 1:9" twist. The solution obviously is to boost the velocity.
Now, in my 25-06 and my .257 Roberts Ackley Improved, this same bullet flies straight and true but I'm loading at the upper range of the velocity curve.
We await your findings and comments.
Best.
Thank you for your help,Included with this reply a link to a photo of my target with 2X3 shots before and after ajusting my scope.As you can see it looks like between ovalhole and keyhole.My rifle is a Winchester model 70 with a 1-10 twist,temp. was about 80 degres,I had check my velocity with my chrony and had an average speed of 2800 fps.little less than I was expecting by Barnes data.My reload was 50grs. of RL19, COL 3.155,bullets seating around .050" off the lands.
http://img233.imageshack.us/img233/9360/barnes115grstsxoy0.jpg
Thank you
Here is the image of your target:
Yes, they are keyholing just not a full profile.
I understand that Winchester says that your barrel is a 1:10" twist but in many cases you need to measure that twist rate for yourself by using a tight patch on a worn brush on a ball bearing cleaning rod. I do this with every barrel that I haven't made or had made by a custom shop. Make these measurements more than once to be sure as well as accurate.
The temperature is good and your velocity is what I thought it would be. Your O.A.L. is where Barnes wants you to start to preclude pressure problems.
Are you seeing any signs of pressure?
If not, I would start by making small increases in the load to see if that increase helps with the keyholing. You don't have to shoot groups here but simply increase the powder in each consecutive cartridge by maybe 0.3 grain. In essence 50.3, 50.6, 50.9, 51.2, 51.5, etc. Shoot from low to high and examine each cartridge case and primer carefully for signs of pressure before moving on to the next higher load. If your bolt starts to feel sticky when you attempt to eject a fired case, stop and examine everything for pressure problems.
If the bullets stop keyholing, stop and shoot some groups at that load, so long as the case and primer aren't showing signs of pressure and the bolt lift isn't sticky. You may want to continue going higher to be sure you have enough velocity for the colder weather. Make sure your barrel is clean before starting this part.
Best.
Thank you very much for your help.My model 70 is a true 1-10 twist.I sent a email at Barnes asking their help for my problem and to see if they had some problems before,gave them any details they ask me including twist rate,my load data,day temperature,gun maker,velocity and elevation over the sea that I took with my GPS.They said they were going to simulate my load and give me a report.I just receive that report and guess what,I think I have to move because they said the problem comes from my elevation.Included a copie of their anwser.Funny anwser because I shoot similar bullet in weight and size like the Hornady 120grs SP and no problem.So the real problem comes from their bullets not my gun.
Thanks again for your time
I suspect the elevation is the issue, We are shooting them here and they are working fine at that velocity. You can try to get the speed up another 100 fps and it may help but I suspect you may not be able to get it to go even then. The 100 gr TSX may be a better bullet for you.
Dave Card
Barnes Bullets Inc.
Customer Service/Sales
800-574-9200 ex 103
Fax 801-756-2465
davec@barnesbullets.com
"I suspect the elevation is the issue,"
Well golly gee whiz! Why does their answer not surprise me?
I shoot their bullets and a large number of others from various manufacturers at every altitude from a few feet below sea level to just above 10,000 ft. The method used to accommodate the change in atmospheric pressure is to vary the velocity. How does this person think that we can compete or hunt at disparate locations across the country, when they are all at different altitudes?
If you want to continue to test these bullets, I'd suggest using the method that I detailed above. If not then go with his suggestion and switch bullets. Not everyone needs to have a Barnes bullet in their set of tested projectiles.
Good Luck!
Best.
As Nononsense suggested in his first response, the bullet is to LONG for the twist rate in your rifle, coupled with the lower velocity you are driving it at. You must remember that lead is heavier than copper, and since the Barnes bullets are all copper, and have no lead core, any given bullet weight for caliber will be longer than it's conventional lead cored counterpart.
The advantage to this, if you have the proper twist rate, and/or velocity, is usually an increased ballistic coefficient, providing the bullet is stabilized, and not wobbling. You can drop down in weight to the 100 grain TSX, and enjoy near the same ballistic coefficient as the 115/117/120 grain lead core bullet, and be able to drive it faster to boot. Imagine that...fly faster, and flatter, plus no lead core to seperate from the jacket, which means it holds its weight well, and penetrates. It is hard to beat a Barnes for hunting. The 100 grain TSX will do as much or more than either the Grand Slam, Partition, Accubond, ot Ballistic tip of the 110/115/117 or 120 weight.
Best