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Topic: New BRA (Read 5101 times) previous topic - next topic

New BRA

I posted up the target in MOA all day but I'm going to run a thread here on load development for the new stick. I find it helps me sometimes to go back through it for a number of reasons.

The gun is a Borden action, McMillan LRB stock, Jewel trigger and a 28" Krieger Heavy profile 1:8  with a Vortex golden Eagle in Nightforce rings. Built by Shawn Williams of Northridge Rifles in Helena MT. Shawn is a very accomplished shooter in Benchrest and F Class and I feel fortunate to have got to know him.

I started out with 300 pieces of Lapua 6 BR brass that I sent to DJ's for FF. Upon getting them back I culled of maybe 6 pieces that I didn't especially like the look of the shoulder. From there i started turning necks and had a malfunction on the turning tool that screwed up a few pieces. I ordered a new tool but not being able to be patient and wait for it I "fixed" the broken tool and went back to turning again and after about 20 pieces decided I decided it wasn't holding a good enough tolerance and waited for the new tool. In all I wound up with about 10 pieces I won't use, another 10 that were trashed by the turner and another 10 that will be fouler only rounds for various reasons. So approximately 270 rounds out of 300.

I pulled the firing pin out of the bolt and bumped every case until the bolt would almost fall closed on its own. This ain't no Savage I can replace galled lugs with for $40.

Loaded them all up with 29.5 g H4895 and a CCI 400 primer with a 105 seated .020 into the lands. I used Alex Wheelers stripped bolt method to find the lands and it worked flawlessly.

     https://youtu.be/TWmIwPwLyyg   

My plan was to go to my range with all 270 rounds, break in the barrel and explore seating depth while FF the brass. The HF comes blown out but the shoulder body junction is still round and needs FF.

So i started in with the shoot one clean, shoot one clean, shoot one clean program and the barrel caught the tiniest bit of copper on the first shot and none on the second. Barrel break in is easy on a nice barrel, sucks on a bad one! Nice little 2 shots touching one just off group. Made a scope correction and shot 3 and cleaned, 2 touching one just off.

I started seating the rounds in deeper. I had them into the lands and used the softer 400 primers so I wouldn't get any FTF from the shoulder bump allowing the firing pin to push the case forward in the chamber. I started at .020 in then went .015 in for a group, then .010 in then .005 in then touch - .002 off. The bullets were NOT sorted so I was getting some Base to Ogive variance from the same seater setting.

I got through 130 rounds on tuesday and the remainder on wednesday. The goal here was to FF all the brass and explore seating depth. Not waste a bunch of time trying to test powder on FF cases in a fresh barrel that would be climbing in velocity.

Pic one is the whole set from tues. The groups have a numer of order to the lower left of the bull and number of shots in the group to the upper right. Every shot including the first 3 is on there.   
Dave

Re: New BRA

Reply #1
Day two i focused solely on seating depth, cleaning every 30 rounds or so. .004 off .005 off and .006 off appear to be where its at. That is where my Savage runs also. Day one was at 100 yards but I moved out to 200 for these.

The split group in picture 2 was a lack of tension on the windage on the Sinclair rest. It shot 8 into the lower right then 4 into the upper left. Conditions were horrible by then with a 15 mph wind quartering into my face and I was chilled down pretty good.

 These are all .006 off, .004 & .005 off were not touching like these but were sub 1" @ 200 yards.  Pic one and three are 5 shots. Pic 2 is 12

It tightens up at .004 & .005 then really tightens at .006 and blows up at .007
Dave

Re: New BRA

Reply #2
Coming along nicely Dave!  Isn't the Borden action nice?  Smoooooooth...  So easy to pull the fire control and check touch length and case clearance.  One tip on the Wheeler method.  If you have some eccentricity of the seated test round at the leading edge of the bearing surface (more than 0.0015"), it can lead to a false or inconsistent feel of the 'stick' at the top of the extraction cam while testing.  I use my gauge and finger pressure to true up my dummy round prior to checking touch length with Alex's method.

Re: New BRA

Reply #3
Coming along nicely Dave!  Isn't the Borden action nice?  Smoooooooth...  So easy to pull the fire control and check touch length and case clearance.  One tip on the Wheeler method.  If you have some eccentricity of the seated test round at the leading edge of the bearing surface (more than 0.0015"), it can lead to a false or inconsistent feel of the 'stick' at the top of the extraction cam while testing.  I use my gauge and finger pressure to true up my dummy round prior to checking touch length with Alex's method.

Thanks Robin, high praise from a guy who can shoot small. I woke that MOA thread up from the dead and here you come posting up those really nice shot marker targets. I gave up trying to one up you years ago!   :))

I hear you on finding the lands but I really don't think its life or death finding the exact measurement. All I need is a number to adjust seating from. If I'm calling it .005 off and it's really .007 off it doesn't really matter. The target trumps all other info IMHO. 
Dave

Re: New BRA

Reply #4
Nice logical, steady, work up going on there Dave. I like your approach. And your results. 😊

Re: New BRA

Reply #5
Nice logical, steady, work up going on there Dave. I like your approach. And your results. 😊

Thanks Jerry, we've got wind for another day or two then I'll get to testing some full house loads. I ordered the rest of the auto throw gear yesterday and Adam said it would ship on Monday so I should be fully automated next week.
Dave

Re: New BRA

Reply #6
The autothrower has a little learning curve as to sequence and adjusting the 'drum' but I was glad I pulled the trigger.  I am with you on determining the touch length.  Once I get a bullets best seating depth I keep the same CBTO until it stops shooting small, then I may add a thou' or two or three.  If it does not come back to me I will recheck the touch length.  I know the erosion rate of my loads in Bartlein steel but it is showing up different on a Brux I am working with so I have to recheck touch length more often as I have faster erosion in this Brux.  You are lucky to have such great resources in your neck of the woods in the way of Shawn and Alex.

Re: New BRA

Reply #7
Dave......What rests are you using ?

Re: New BRA

Reply #8
Dave......What rests are you using ?

It's a Sinclair Competition with a Field & Cave  aluminum base plate to increase the footprint size. Edgewood Gator rear bag and a 4" Edgewood front bag.

I've got a Field & Cave Windage Tensioner for the rest that I haven't installed yet but obviously should have after seeing that split group.

 https://fieldandcaveoutfitters.com/

This is a great company with some really unique products you can't get anywhere else. Top notch craftsmanship, fast service and great prices. I met Travis at a match in Montana last summer. I've never had a bad deal with him or ever heard of anyone else having one!
Dave

Re: New BRA

Reply #9
Thanks Dave !!   I asked  this because we rarely mention
this part of the equation when a group gets posted. If I post
something up, it will be off a bipod and no rear bag. It's just
the way my head is wrapped for shooting. The older I get
though, I know it's getting to be time to invest in a good
bench anchor. The joke at our range is me shooting without
a rear rest. I tell them it's a matter of pride, and a good way
to see if my heart is still beating.....LOL  We have our junior
rifle shooters hunkered down on Bald Eagles and Edgewood
bags.....I wonder if we could snooker Grant into doing a Farley
or Seb review.....LOL

Re: New BRA

Reply #10
I can review the green Caldwell bags if you like.. 😁
Grant

Re: New BRA

Reply #11
@Fuj

" ...........and a good way to see if my heart is still beating.....LOL "

Very true, until I got on a good rest and bag I could always see my heartbeat on the target!
Dave


Re: New BRA

Reply #13
I use an Atlas bipod up front with an Atlas monopod on the back mostly. I get settled in until I feel the heartbeat in my shoulder, the one in my cheek and the one in my trigger finger. Then I twist the knob on my pacemaker 'till they are all in sync, that's when it's time to yard on the ole Timney :)
Chris

Re: New BRA

Reply #14
Did better than I thought 290 pieces of brass decapped with the Frankford Arsenal decapper.

Had to turn down the pin for the small flash hole. Worked great but the spent primers can fall out of the cup if you don't keep it pointed down.

Worth mentioning I trashed 3 pieces of brass in the FF process by not keeping the chamber clean and dry. It's a thing!
Dave