25-06 rifle twist question

C

cdoc42

New member
I was reviewing information about rifle twist rates today and I happened to come across a list of calibers and twists from Brownells that provides the reason for this question.

I have a 25-06 with a 26-inch Hart barrel with a 1:10 twist. According to the Brownell list, a 1:10 twist is for bullets up to 105gr, and anything over 100gr should use a 1:9 twist.

I have been shooting 117-120gr bullets and achieved my best groups with Hornady 120gr HP (4 shots, 100yds=0.27") and Sierra 120gr HP (4 shots, 100 yds 0.36").

These were both using H-1000 50.0gr with the Hornady bullet seated 0.015" and the Sierra at 0.020". I later discovered I most likely made an error in developing these loads as the Hodgdon manual lists 52 gr (2772 fps) as a starting load; I think I used that as the Max load, and loaded 2 grains down to start.

From what I understand, a heavier bullet needs a faster twist (as in Brownells recommendation). What might explain this nice accuracy with a slower load with a heavier bullet?

Is the 1:9 twist really that critical that it forces me to use bullets less than 105gr in my 1:10 twist?
 
I have the reamers for 25-35, 250 Krag Ackley, 250 Sav, 257 Roberts, and 25-06.
I borrowed the reamer for 257 Roberts Ackley and built a couple rifles for myself: 257RAI and 257RAIR.

My real experience with stability has been:
1)
25-20 14" twist 75 gr Sierra #1600 will stabilize and get great groups at 2350 fps

2)
257RobertsAckleyImprovedRimmed 10" twist 115 gr Nosler Ballistic Tip will stabilize at 3050 fps and get great groups and broke the shoulder of an oversized mule buck.

I have ordered and received some more 257 barrels.
One of them is a Shilen Stainless Select match #3 taper 257, 9" twist.

Why I got a 9" twist, I dunno. The 10" twist is working great.
Maybe I was thinking 115 gr NBT is a wimpy cartridge.
That must be it.
THe 250 Krag Ackley is not as fast.
 
How can the 10 twist "force" you to use bullets lighter than 105 grains when you are already shooting 117 grain bullets accurately?

I suggest not making stuff up to worry about.
 
What I meant by "forcing" me is if I had not yet had the experience with the heavier bullets, following the literature would be the driving force keeping me at 105gr or less.

It would still be interesting to see an explanation for the apparent contradiction between Brownell's recommendation and my experience with 177gr and 120gr bullets.
 
In my standard version 25-06 I have had excellent accuracy nearly since I purchased it with the stock 1-10 Remington barrel that came on the rifle close to 20yrs ago.

When Nosler came out with the BT I begged them to release a 115gr version against all of their arguments that it would not stabilize even though the 115gr Barnes X was getting me 1/2 - 3/4" groups day in and day out. Now it is one of their best sellers. Go figure.

I settled on the 115gr Partition in that rifle simply due to I was able to get a bit better velocity from them than out of the 120's. Granted it might not make a hill of beans to someone else but it mattered to me and I stuck with them. They shoot more than accurate enough to head shoot a fox squirrel at 200yds and thats plenty good for me.

I also built an Ackley version as well using a 1-9 Broughton 5C 4.1 Magnum Sporter finished to 28" expressly to get the best velocity and to shoot the heavier weight 120, 125, and 130gr bullets I had purchased several years back. The original one version I have shot them plenty well enough to hunt with, but I wanted to get a bit more velocity in order to reach out across my back pasture with them for feral hogs and coyotes. The 1-9 shines with them out to further than I have wants to shoot on a regular basis.

The two most used bullets I shoot in it are the discontinued 120gr Nosler Solid Base, and the 120gr Remington Core Lokt's over a copious dose of Ramshot Magnum. Either of them will do all I need getting done as far out as I can hit anything with it. I also use the Hornady 120gr HP, for fireforming cases when I need some. They shoot exceptionally well, but are a bit more destructive than I would want to unleash on a deer or hog. For coyotes though, they are a red mist adventure akin to something you might see with a 22 cal and a prairie dog.
 
Stability calculators like JBM give a "known good", "marginal" or "known bad" answer when you add in the variables.

It is my experience that the "marginal" zone answers are likely to be stable if the numerical value is closer to the "known good" portion. But, sometimes they aren't, and people just have to find out what works in their own rifle.

So I wouldn't avoid a bullet because the predicted stability factor would be "marginal."

Jimro
 
I bought some 6mmPPC 14" twist benchest take off barrels off Ebay for $50.
I can change the threads and change the chamber and change the taper, but I cannot make them longer nor can I make them a faster twist.

They would be great barrels, if they had a faster twist. That is why Hart, Lilja, Krieger, Shilen barrels are $50. They are nearly worthless.

A 75 gr Vmax at 3000 fps with 6mmBR with one of those short barrels is a stability factor of ~ 0.75 using the Berger calculator on line
http://www.bergerbullets.com/twist-rate-calculator/

Sometimes 0.2 moa
Sometimes keyholes

I thought that one would want as little stablity as possible without keyholing.
Then someone, who calls himself a ballistician and does experiments to calculate the real ballistic coefficients and not the published ones, says that under stabilized bullets have a hard time with wind.

That would be a deal killer for me.
A 500 yard shot at animal as the sun is coming up and there is no wind, is easy.
A 500 yard shot at an animal at noon when there is 7 mph wind, is a much harder shot.
 
Bullet stability is also a factor of velocity. Your 26" barrel may be giving you just enough velocity advantage to make those heavier bullets work. I use a 25/06 w/24" x 1/10 twist barrel and the 100 grain bullets are the winning combination. I also have a Savage 110FP with a 1/10 twist (IIRC) that shoots cloverleafs with Remington 100 factory loads but 2-3" w/115 grainers.
 
Simple motto: the faster the twist is. In most instances. It will prefer heavier bullets.

Same applies to a slow twist: The slower the twist is. In most instances It will prefer lighter weight bullets.
 
Note how often we say "in most instances". ;)

Rifle barrels shoot how they shoot, what they shoot depending on many factors, twist rate is ONE factor.

As an example, I have a Win Model 70 Varmint in .22-250. Book says its 1-14" twist. It shoots 52, 53, 55gr bullets into about 3/4". Sweet varmint rifle.

It shoots 63gr semi spitzers into about 2" groups. Not so good for long range Pdogs, but good enough for small deer.

Whatever the book (or online table) says, YOUR rifle may shoot a little different. Or, it may not. The only way to know is to shoot it with your loads, and see what it does.

Also, Hart barrels have a reputation for high quality, which might explain why it seems to shoot better than the "twist list" indicates it should.
 
I thought the Brownell list was interesting because, in many calibers, it advises just like it does for the .270 Win: "1:10 twist: all bullets."

At the same time I recognize some truth to the statement and confirmation to the post above about all rifles differ. I have a Rem Model 700 in .270 that shoots 1 MOA or less with a Hornady 150gr Spire and has the same point of impact at 100yds with the Hornady RN; a newer Rem Model 700 stainless that does the same with only Hornady 140gr SST; my son's Model 70 Sporter in .270 shoots 1" at 200 yards with a Speer 130gr FLAT base but the Boat tail and all others don't even come close. A Sako top-of-the-line in .270 doesn't come any closer than 1.5" with ANY bullet- 130-140-150gr in Remington CoreLok, Hornady Spire, SST, Sierra spitzer/HP, Barnes,and Speer.

Then, of course, we shouldn't forget the Browning "BOSS" which can "tune in" any bullet with some experimental turns at the muzzle, which apparently eliminates the concern about twist rate and bullet weight.......
 
Make sure that the twist you got is what you think it is. I bought a new stainless steel benchrest barrel from a famous barrel maker, chambered it and when shooting it found my bullets key holed at 100 yds. After bringing it home put a patch in the cleaning rod and got it started into the barrel and made a mark on the rod at the beginning. Then pushed it in until the rod showed a complete 360 deg rotation. This proved that the twist was too slow and the barrel maker apologized and sent me a new barrel.
 
the Browning "BOSS" which can "tune in" any bullet with some experimental turns at the muzzle, which apparently eliminates the concern about twist rate and bullet weight.......
Click to expand...

The BOSS doesn't do anything about the twist rate of the barrel, if the twist is completely wrong for the bullet, the BOSS won't help. What the BOSS does is allow a "tuning" of the barrel harmonics, to (hopefully) find the "sweet spot" to get the best groups from a given load, AND to allow it to be done again at need, for each different load used.

or so I understand, never had one myself.
;)
 
My presumption is, for 25-06 the standard twist is 1-10. Mine shoots 117 gr. Hornady BTSP just fine. And 110 gr. Nosler Accubonds too. Strange that Brownells makes that recommendation. :confused:
 
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