Temp sensitive??? Powder or gun????

[AlaskanGuy]

Ok, i went to the range today with my K31 that I sighted in yesterday. Rifle was sighted in for 1 in high at 150 yds.... Saw something I have never seen quite so dramatically...

98914

First shot was top of the string, with each shot dropping from top to bottom with things settling down to the place where I sighted in to yesterday.... Here is the load data...

7.5x55 k31 swiss brass twice fired, full length szed
Lee 160gr boolit lubed with 50/50 jpw and beeswax and gas checked
Alloy was range scrap water dropped for a bhn of 18
20gr of 2400, cci #200 LR primer
Each charge was individually weighed, and a tuff of Dacron added.
Temp was 18f
Wind 0 mph sunny morning but shooting in the shade.
Range to target was 148 yds

Now, is this an issue with the gun barrel warming up??? Or the rounds being cold??? Or the powder being temp sensitive... That drop was almost 7.5 inches.... This is kind of a problem as where do you sight in for hunting here in alaska where the weather is cold durring deer season... Would you sight in for the first shot or the last... All shots point of aim was the black dot..

Any opinions ?????

AG

[runfiverun]

top shot.

if you repeat the test you'll probably get similar results. [if so definitely top ole]
OOOR you could try a quick swab with an atf patch then shoot to see if the first shot comes down.
some of us have dropped the first shots powder load [about 4-5%] and had it land in the group from a fouled cold barrel too.....
some of the stuff we learned running through the quest [lube] thread.

[AlaskanGuy]

interesting Fiver... I have made up batches of Lube with atf, would that help???

[waksupi]

If they will chamber, I would advise sizing your projectile .001 larger.

[runfiverun]

atf is good stuff in lube and it is definitely a top player in the cold.

I think what you are fighting is the c.o.r.e. principle here at it's outermost swing.
a combination of the fouled barrel, and a first shot "flyer".
the rifle itself could be coming into play too if it's still in full wood trim.
that front band on the 31's is problematic on some of the rifles.
it causes a little rubbing right there on many of them [I think it's because of how they are carried by their sling]
the one I bubba'd for hunting I cut down all the wood, then opened the barrel channel and full length bedded it in the stock.

[AlaskanGuy]

Well, the barrel is completely clean, and I mean spotless, i really went at it to make sure there is 0 copper fouling in the barrel. This gun is only gunna shoot cast for the rest of MY life...lol .

I have some jpw/beeswax with a couple tablespoons of ATF that I could try on the next batch of boolits.... This did not happen the first time when it was warmer and i sighted the gun in...

Waksupi, why size the boolit larger??? The gun slugged at 308, boolits sized at 310... With the almost non existent tight throat, wouldn't that make things harder to chamber? Making me have the boolit seated too far into the cart? Just wanting to understand your line of thought on the sizing.... No argument intended.... Just wondering...

AG

[btroj]

Didn't happen when warmer. Classic signs of a first shot flyer due to a cold barrel.

That is one of the big reasons for the entire extreme lube quest.

[RobS]

Clean barrel from first shot?
I have to shoot 3 - 5 down the tube before the barrel settles down and it becomes consistent.

[KYCaster]

I had the same problem with my Marlin 336 in 35 Rem.

Bullets lubed with Thompson's Blue Angel would shoot nice repeatable groups as long as the temp was above ~40F. Below ~30F the first shot from a cold barrel would consistently be 8" high and take five rounds to settle into POA, same as your target. Subsequent shots would stay in the group even after letting the barrel cool, up to about 24 hrs. later. Let it sit longer than that then the first shot would shift again.

It's enough to drive you nutz!

Changed to Bullshop Speed Green and the problem went away.

Jerry

[runfiverun]

in the cold I have had to shoot 11 shots to see a lube star appear.

the carnuba is a killer in the cold. [starts at about 40-f]
eutectic has had some good luck using a mostly carnuba wax lube in - temps, but he highly modifies it with some other oils.
poe's, as I recall.

what happens is the carnuba gives you that just buffed floor look in the barrel.
it also dries out to a glazed alligator skin look in the down time.
then you have to get the barrel back to the glassy smooth condition.[1 to 4-5 shots depending on the ambient temp]
once you do it settles in and shoots well again.

[waksupi]

Well, the barrel is completely clean, and I mean spotless, i really went at it to make sure there is 0 copper fouling in the barrel. This gun is only gunna shoot cast for the rest of MY life...lol .

I have some jpw/beeswax with a couple tablespoons of ATF that I could try on the next batch of boolits.... This did not happen the first time when it was warmer and i sighted the gun in...

Waksupi, why size the boolit larger??? The gun slugged at 308, boolits sized at 310... With the almost non existent tight throat, wouldn't that make things harder to chamber? Making me have the boolit seated too far into the cart? Just wanting to understand your line of thought on the sizing.... No argument intended.... Just wondering...

AG

I was just thinking barrel heat expansion, if the boolet was marginally sized. I had a couple rifles do it over the years.

[madsenshooter]

My guess would be pressure of the handguard on top of the barrel. As the barrel warms, shots go down. I have a Krag that does the same thing. I've loosened the front band on my K31, put a rubber washer on the band screw. My handguard will rock a little side to side. Just try loosening the front band screw before you shoot another group. No sense getting overly complicated. You likely had the barrel warmed up before yesterday's final sighting shot.

[madsenshooter]

Here's where I found the accurizing tip: http://www.swissriflewebsite.com/tuningforAccuracy.asp My forearm is warped, for now I just loosen the band, but eventually I'll file the barrel channel so that the barrel is free floated even with the bands tight to the wood.

[AlaskanGuy]

I am a member there too... That is some great info sir...

In my case, i dont think this is the same issue though.... I am positive it is a case of the wrong lube... I took the plunge and started reading the quest lube forum..... Wow, is that a lot of reading.....

AG

[Changeling]

Hi AG, The first thing I would look into and DO would be to free float the barrel from 4 to 5 inches from the action forward to the muzzle. This can be acomplished by using a woden dowell of the proper diameter with sand paper wrapped around it. Plus bedding compound for those first few inches.
If this is a well dried stock forend ! If it is not well dried , good luck.

[popper]

You might try PC. I've shot from 30F to 80F, no change in POI. Would tell you if it's the barrel or lube.

[Larry Gibson]

As mentioned it is from the cold temperature of the barrel, hardness of the fouling from such and cold ambient temperature of the lube in unfired rounds (lube gets pretty hard with rounds below freezing). I also have seen this many, many times in NE Oregon when shooting cast in the winter with temps form -8 - 40 degrees F. Note your temp was 18F, well below freezing.

A softer lube formulated for the winter (Bullshop Speed Green) will work better like or BP lubes such as SPG and Lyman's BP lubes. For hunting in cold weather I found Javelina (no longer available) lube worked well from a cold clean barrel most of the time for hunting accuracy. The 1st shots went close enough to group. However, most of my hunting was not in the "teens" and below like yours may be. For that try the lubes mentioned and use a clean barrel.

Larry Gibson

[AlaskanGuy]

I wonder how Bullshop Speed Green would work durring our super hot summers of 65F?

:lol:

[runfiverun]

Dan did develop it in Alaska.
if you are looking at 75-85 f and below temps [much like I do here]
you want to swing to a thinner lube.
you end up with a lube that fits into a temp window, the temp areas seem to run closer together in the cold.
the thinner lith greases [white lith or #1] and ATF do well in temps down to minus 20 or so.
neats foot oil, and many of the 2 stroke oils are good too.
it's the various waxes we use that start to give us trouble in the lower temps.
as you read the quest thread you'll see us start to talk about modifiers and middle modifiers those are the things we were working the waxes over with trying to manipulate and better control their flow characteristics.

[KYCaster]

I wonder how Bullshop Speed Green would work durring our super hot summers of 65F?

:lol:


You'll be happy to know that BSSG will perform very well at temps well beyond your "super hot summers of 65F".

Our summer temps often exceed 100F and I haven't had any problems with BSSG, but that's also with very high humidity. I don't know how it will perform in dry conditions.

Jerry

P.S. I once saw the National Weather Service site report 115% humidity at the Fort Knox station that's ten mile up the road from me. It started raining later that afternoon and the RH went down to ~85%. I just couldn't stay dry that day.