load question for savage 12 f-class in 6br

[AdamJ]

Been working on loads for this rifle and have hit a problem. The load I started out with was 30 varget and a 107smk at .020 off the lands. This load has shot some nice groups but lately pressure? issues have arose. The cases were FL sized out of the box and have been nk sized with redding .265" bushing since then, about 4-5 firings per case. Last week I tried 10 rds of H4895, 29.5 grns, and noticed bolt lift was quite sticky. Today I shot 30 rds of the 30.0 grn varget and noticed that quite a few, atleast 50%, were hard to chamber and sticky to lift bolt. I examined the primers and while some cratering was there nothing out of line for a factory bolt face was evident. The primers were pushed back flush with the case head, but they still had the slight curvature at the edge of them, not completely flat. On some cases you could see 1 or 2 slight circles on the case head from the ejector, not shiney spots but if held at an angle to light a slight raised portion was there in the shape of the ejector hole. It also seemed like the rifle had more recoil, as it sits it wears a BO 20moa rail,TPS steel rings and a NXS 5.5-22, about 15.5lbs. I pulled out my 243 fast twist that is in a Mcree stock and fired it prone off a bipod; 5 shots- .478, 4 in .277, this rifle weighs 16.5 and drives a 105berger at 2998fps. The 6br definately had more felt recoil then this 243. What is the chance this factory barrel is tight bored and everybodies good starting point load is pretty hot in this gun? Any other suggestions or help would be great. I plan on shooting 10rds of the 30.gr varget and 10 rds of 29.5 gr varget/107 loads over a chrony tomorrow and see what numbers I am getting. load is lapua brass, cci br-4, 30 varget, 107smk(trimmed meplats), and OAL from ogive is 1.770" which is .020" off rifling. I am case trimming each time and barely get a whisk of brass. Rifle is cleaned every 20-30 shots and the chamber mopped and action recess cleaned and a little bolt grease applied. Around 150 rds down tube, bought new

 

[dirtworks5]

Adam,
I have some time behind the savage 6br and it sounds to me that your bushing is too small. I use a .267 bushing in a small base Redding type s. Try to change your seating depth first and then work on the powder measure. I did this with 29 gns of varget to start my test. My particular rifle shoots well at 10 out and at 10 in. Good Luck.
Vern

 

[AdamJ]

Brass is the newer lapua thin neck. loaded nk dia is .267, so only running .002 nk tension. I should have started lower and shot over a chrono before now but have been fiddling with oal and another rifle. The first time I shot this rifle was with smk 010 off and 020 off. 010 off shot a 1/2 group and the 020 off shot a .298. I tried 105 berger touching and 015 jam, they where horrible, so I kept on with the 107smk at 020 off and went up to 30.2 and 30.4 varget. The 30.2 was ok the 30.4 was pretty good but the 30.0 always seemed to shoot good with occasional operator flyer that seems common these days. I settled on 30gr varg and tried .005, .010, .020, .030 off. The difference is night and day, .020 off is always 4 shots really tight, mid .2s with the other 1 shots making it mid .3s. The other OAL pattern into .5-.75 groups with no real shape or flyer that I can call. Loaded nk dia is .267, fired case nk measure .2705. My other br is a custom .271 no turn and I nk size with the same bushing set-up and have not gotten any hard chambering rds in over 15x reloading cylces on that brass. Guess that is the difference between a factory chamber and custom. What gives with the ejector circles and the not quite flattened primers? And what is the chance of a getting a tight bored rifle from savage?

 

[rocketron]

measure the headspace on the brass. hard to chamber would tell me the shoulder needs to be bumped back.

temp change from when loads were worked up?

Ron

 

[k80skeet]

Adam, I will be really interested in what you find out as I am just in the process of having a Savage " F" class built. When I say built is I bought a Savage target action and a Savage "F" class stock and installing a Brux 26" 1.250 full lenght 1 in 8 twist. I am going to have a.268 neck so it should be just right for the new Lapua brass without a lot of turning. I was planning to use Varget 30.0-30.4 grains with 107 Sierras and 105gr Hornady "A" Max's. Thanks Russ

 

[Travelor]

I would hazard a guess that your FL die is not sizing the brass enough to push the shoulder back a couple of thousandths.

I would do as rocketronn said and measure the distance form the base of the cartridge to the middle of the shoulder of both a fired case and a case you FL sized.

If I am right there should be no difference.

The ejector "circles" are a sure sign of excessive pressure.

George

 

[sbrabec]

The cases were FL sized out of the box and have been nk sized with redding .265" bushing since then, about 4-5 firings per case. atleast 50%, were hard to chamber and sticky to lift bolt.

Sounds to me that you need to run through the full length die again. You should bump the shoulder back about .001-.0015. That should take care of the bolt closing hard. If your not seeing any other pressure signs, it should not open hard after full length sizing either. Good luck....
Scott

 

[jlmurphy]

I have a Savage action used in a barrel block rifle, 6mm BR is one of the barrels I use. I had the same problem after neck sizing only for 5 or 6 firings. I bought a body bump die from Redding and with the use of the empty neck bushing die body as an overall gauge, I push the shoulder back about .001" and it also reduces the case above the base. The load never changed, but the cases had become hard to chamber and hard to remove.

 

[JohnMill]

Adam,
Bumping the shoulder a thou is a hard call. If you are measuring it I'd go at least 2 (.002") I use my action as a case guage by taking the striker out and sizing 'til the bolt falls closed. Someone recently gave the dimensions as .002 bump on the shoulder and .0005 on the base (web). At any rate if you can see any ejector marks then you should ( that just means I would ) reduce the load by at least a half grain and prolly a whole. Deal with that pressure first and figure it out after. Another cause of hard bolt opening is skipping the step of degreasing the chamber last thing after you clean, Just a little bore cleaner will break the grip of the case on the chamber wall. I'm just pointing out the things I've done so I know they can be problems.

John

 

[sdneil]

Adam J ---Travelor advice is right on-- I have a 12 F class in 6br, 30 gr of Varget is max in mine, went to RL 15 , life was much easier and more accurate with RL15, you might try it, It works great in mine.

 

[AdamJ]

well was able to finally shoot some here. 30 gr varget and 107 smk ave 2880 fps for 10 shot and had a 10.83 fps SD. The 29.5 gr varget was 2850 fps ave and 14fps SD. To me it looks like .5gr increase would change velocity more then 30 fps if I was getting close to upper PSI limits. The FL sizer resizes it perfectly where the bolt closes great and smooth like butta. I don't like the fact that the chamber is oversize. All my other chambers I can FL new brass and then NK size for 10-15 reload cycles, then 1-2 out of 30 will have slight chambering tension. Then I will run everything through the FL sizer and then be ready for another 10-15 reload cycles. This savage chamber is going to have me working the hell out of the brass, which is $90./100. Not to excited about trashing pricey brass. really looking at a shilen from northlander, for what I can get out of this old barrel and save in more reloads on lapua brass. My smith mentioned recutting crown, swears most savage crowns are not 90* square to bore, and setting chamber back 1/4". Don't really feel like putting 150$ in a factory qaulity barrel. I think I should have done what skeetlee is doing, buying the pieces and assemble.

 

[k80skeet]

Adam, I bought a LRPV in 6mmBR 1 in 12 twist throat was so long I couldn't touch the lands with 68gr-70gr bullets and still have any of the bullet in the case. I had my gunsmith cut .350 off chamber and rechamber with a reamer that was made for 68gr bullets and a .268 neck and recrowned it. I haven't shot it yet so I can tell you how it works. Savage barrel are pretty good as I have a couple other LRPV that shoot very well with the Savage factory barrels. I also bought a Brux 1 in 8 twist 1.250 full lenght 30" that I was going to make a switch barrel but ended up buying a Savage "F" class stock from this site the bought a Target action right port right bolt from Jim Briggs at Northland Shooters Supply and decided to build another whole rifle which I haven't completed as the barrel hasn't arrived as of yet. The gunsmith will complete the project as soon as the barrel arrives. He is going to put a .268 neck in this rifle as well. So I will end up with both 1 in 8 and a 1 in 12 6mmBR"s.

 

[fm1947]

Adam,

What tool did you use to touch lands or what method I am loading now to your OAL of 1.770 in my F Class gun and I am doing some at 1.780, since I do know Savage uses same reamer all the time.

 

[AdamJ]

I have always smoked bullets to find the just at the rifling point. With this method I came up with 1.790"ishat the rifling with 107smk. My hornady oal 6br case finally showed up and after 4 tries the average kiss the rifling length was 1.792". I played with the load at 1.785,1.780, 1.770, and 1.760. The 1.770 always shot tight. I had a chance this past weekend to shoot at 400 with this load. All prone as I am more of a position shooter then bench. The wind was FV 2.5-10mph gusts that were changing constantly, but managed 2 5 shot groups in the 2.5" range, not great but both groups had 4 shots in 1" and 1.5" groups. All goups showed more horizontal then vertical. The ave vertical was 3/4". I shot a good group the other day at 100 first shot was out of a clean cold bore and landed 1/2"to the right of the bull the next four piled into a hole on the bull that measured c-t-c .157", I wish I would have had another rd to try to put 5 in that hole instead of four.

 

[fm1947]

okay, I use a hornady modified case also , but I am getting much longer readings then you are I am assumeing when you say 1.770 that you are useing a bullet comparator and measuring from ogive to the end of case.

Sierra shows a COAL of 2.347 on their data so I set a dummy at that length just so I could get a comparator reading and it was 1.808. I am not getting around very good today had a operation yesterday and I just cant get to my notes I remember being around 1.850 or 40, I hope to keep comparing notes with you and if there are others in here with same gun I would like to know what measurement there getting., I also have a varmint action with Shilen barrel that has a shorter throat by about .010 or so.