Back in January I loaded some rounds for my .270 Win. I primed all my brass and loaded about half of them. I loaded the rest just the other day with 58 gr of IMR 4831 behind a 130 gr. speer sp and went to the range this morning. Well I was a little disapointed because the load wasnt as accurate as it has been in the past in the same rifle. It still shot just under an inch but back in november and December this load would cut holes. I let the primed cases sit on the shelf really unprotected for this long (Stupid i know),could moisture effect the primers causing enough change to drop the accuracy? I am gonna get into detail big time on my next loading for this rifle and see if I cant bring em back down.
I would appreciate some opinions and stories of similar happenings.

Thanks in advance

It is not likely the primers as most primers do not come in airtight containers anyways.Was there a temperature difference between this range session and the one in December?Some loads are quite temperature sensitive.

I find I have good days & better days when I am out shooting. Are these the same lot of bullets? I have recently had a sim. exp. w/ my .338-06. My go-to load of 53.5gr RL15 under the 210grNP usually gives me MOA groups on good days. The last few times out though I have struggled to get 1.5MOA. Can bbl. harmonics change w/ temps., brametric pressure, what?

Gee, lots of variables could lend towards this Russ...

Seating depth from the first group to the second?

Barrel condition? (cleaning solvents or oils, etc)

Temperature or humidity on the two different days you shot?

Scope mountings loose, tight or changed?

Yourself perhaps??? (Too much coffee, mood, distractions, etc?)

You don't say how much of a difference there was between your groupings, but both were under an inch you say.

Personally I know I have "good" days at the range and I have "bad" or mediocre days at the range. It could be as simple as that too.

Jan=cold-P, July=hot+P JMO

Sometimes loss of accuracy is due to copper metal fouling in the bore - an often under estimated and stubborn problem. I had trouble with this, even while using the standard clearner like Sweets. Finally, I stumbled upon BORE FOAM by Gunslick, and IT WORKS WONDERS. Try it! Your variable accuracy problems may disappear.

When shooting for the tightest possible groups with my benchrest rifle in 6 PPC I can notice a change in load preference in as few as a couple of degrees Farenheit, or 10 percent humidity change. While relatively slight, each load shoots it's best for a given specific condition. It does not surprise me that a winter load doesn't shoot so well in the summer... try a little less powder and try again!

quote:

Originally posted by Russ Brumbelow:
Back in January I loaded some rounds for my .270 Win. .... It still shot just under an inch but back in november and December this load would cut holes. I let the primed cases sit on the shelf really unprotected for this long (Stupid i know),could moisture effect the primers causing enough change to drop the accuracy?...

Hey Russ, Yes, "moisture" can effect both Primers and Powder, but normally not very much when kept indoors where the environment is controlled.

But, if that 270win has a termite food stock, it might just be warping. That happens with ALL wood as it's moisture content changes. Of course you can ask any of the wood worshipers and they will say termite food stocks never warp.

Last but not least, if you have not done any shooting since December, there is also an excellent chance the problem is simply a lack of practice. I know "my" shooting form and concentration both show improvement after shooting a lot over the summer. It may be that simple.

Russ ----- I shoot 9 Magnum rifles and a bench rest pistol that will all shoot one hole groups with their respective load. Each took many months or years to perfect. I have to be having a very good day shooting to shoot those groups with any one of them. I know my abilities and the rifles, however on any given day I would never lay down a bet that I could shoot those good groups. By one hole group I mean three shots touching each other, not necessarily a single hole. I never know until I start the shooting process what kind of day I am going to have, somedays the crosshairs seem to dance, on others they are as steady as a rock. I have to leave off caffaine, or I can forget it on the precise groups. Somedays I can shoot numerous one holers with multiple rifles, somedays I couldn't buy one with a million dollars. I am trying to put a tag on it, like "shooteritis", or something like that, but haven't quite hit the right one yet. ----- My experience with lots of shooting over the years tells me that one days shooting will sometimes tell you something, but it may not in the long run. Shoot more times with that pet load before you let one days shooting draw the conclusion, that it should be changed. The same goes for speeds over a chronograph, average several sessions before stating a speed of a respective load. Bottom line, each day shooting is a new adventure, draw your conclusions from many shooting sessions. Good luck and good shooting.

quote:

Originally posted by stubblejumper:
It is not likely the primers as most primers do not come in airtight containers anyways.Was there a temperature difference between this range session and the one in December?Some loads are quite temperature sensitive.

?????? - Agree!

Thanks for all of the response. I think the main variable was time and my lack of patience that day. I went to the range with my LT to tune in our new sniper rifles so I took my deer rifle too. My rifle shot great with Fed match ammo (.5" group). When I finished my zero I went to my deer rifle. I wasnt able to let the barrel cool completely between each shot like I normally would when testing load accuracy. Also I had to change dies. I let a friend borrow my redding dies and I had to use my back up RCBS dies. Seating depth didnt change, I make a "master seating die adjuster" shell for each type of bullet I use in the same gun after I find what depth it likes and I always double check it with calipers. Cleaning isnt the problem as I am a huge fan of Sweets and use it till I see no blue on the patch. Pwder lot, bullet lot, primer lot, case lot, are all still the same. LOL all this, of course, has me anxios to go try again next week end. I will let you know what happens.

Thanks again

Russ

Hot Core came up with the answer first that I would have selected for the average sporter from the information available at that point in the thread.

The name termite food however does not fly. I like wood stocked rifles and find that they please me.

To each his own.

quote:

The name termite food however does not fly. I like wood stocked rifles and find that they please me.

I actually like the name termite food.It is more appropriate than referring to a high quality synthetic like a mcmillan as plastic.Termites do eat wood,but mcmillans are not made of plastic.

I like both wood and synthetic because each has its purpose. My .270 is a REM 700 CDL with a beautiful satin finished walnut stock. It is pillar bedded with Score High's system which also glass beds, and it is glass bedded to about 2" in front of the recoil lug. I think this will stop a warping problem. My step dad has a 22-250 in a wood stock Rem that is over 20 years old. I remember him sighting it in one time in the last 15 years and you can take it out of the cabinet and drive tacks with cheap rem factory ammo to this day.

Russ, join the club, be very pleased with your .5 group, and happy with under moa.
Sometimes I thought I was shooting in perfectly calm conditions, until I noticed some fluffy seeds drifting across.
Another shocker is when I dry fire over the bench and watch the fireing pin fall "jump" the scope this way or that, depending on my hold of the rifle on the bags.
John L.

Most of the rifles I own shoot better groups in the cool Winter and Spring sesions verses our 95-105 degree hot summer days.

You can usually vary the Powder Charge and get them back shooting the way you want but, why mess w/ a load that did so good w/ consistency during the cooler days (Unless you hunt in High temps). The exceptions being the heavy weight barrels, they seem to shoot the same year around as long as the barrel has time to cool.

Good Luck!

Reloader

You may well have let yourself get hurried and shot your groups too rapidly. There's a lot of difference between December and July in terms of barrels heating up. I always feel the rear of the barrel about an inch or so from the action. If I can't comfortably leave my fingers there, I go for a coke, have a smoke or just take a whizz, anything but don't shoot a hot barrel. Just one mans opinion. Best wishes.

Cal - Montreal

Cal,

That's a good point. I often wait 3-5 mins inbetween shots when temps are above 90. I usually only wait 1-2 min when the temps are 50-70 degrees out. The one thing that you just can't help is the inability for the barrel to cool down enough when the temps are 95-100 out. I've let my barrels set for 10 min and they'd still be warm on hot days but, when cool out after just a short wait the steel will be cold to the touch.

I've still found that certain rifles seem to group better in the cooler temps. I do feel that it is the Temp sensitivity of the powder as well as loads that are near max in the cooler temps may need to be backed off in higher temps to achieve the same accuracy. Lots of nit picky differences that only result in a .25" or so difference in group size.

I found the same effect to really amplify when shooting MLers w/ Plastic saboted bullets.

Reloader

I never expect a load to be the same from December to July regardless of powder (like Hodgdon).

That is why I usually never work up loads or shoot at all when it is over 80 degrees.

IMO it is too much to ask of a rifle and load to perform the same when it is cold outside compared to HOT and humid. I know I don't perform the same, so I don't expect it of my equipment.