Pressure signs at 31.5gr of Varget in Alpha 6 Dasher.

[cp255]

I recently got a Proof Research 6 Dasher barrel (274 neck) for my TL3 action along with 200 pieces of Alpha 6 Dasher brass. I finished fire forming all the brass and started load dev.

I was using 31.5 gr of Varget to do a seating depth test on the 108 ELDM which I thought would be a moderate load. I had worked up there during fire forming and figured now I would have a little more case capacity now. Most the cases with 31.5 looked fine but I had a few with heavy bolt lift and an ejector mark. My velocity was around 2830fps. From what I have read many people can get above 2900fps and load in excess of 32gr. Was kind of surprised I was getting pressure signs at 31.5 and now I want to drop down to 31.

I think the reason for this is lower case capacity than what most people run. I measured the volume of the fired Alpha cases and got around 40.5gr H2O. I think Lapua cases are supposed to hold 42gr. Also I have to seat the 108 eldm a bit deep into the case which further restricts capacity. Could probably use some more freebore. Plugging these parameters into GRT and calibrating in measured velocity, 31.5gr of Varget puts me just under pmax.

Anyone here want to share their load using Alpha 6 Dasher brass?

 

[Nowhere Man]

Clean your chamber. What you described can be caused by oil in the chamber.

 

[Fclassfool]

33.2 varget cci 450 105 barnburners alpha brass gets me around 3080fps with no pressure signs

 

[jaybray]

Clean your chamber. What you described can be caused by oil in the chamber.

It is so important to clean the lube of the cases and chamber. I was sloppy cleaning my cases for quite some time a few years back and could not figure out why I was having major pressure issues at even the lowest of charges until
I started cleaning my cases and chamber with brake clean. Prior to that I was just wiping them off with a rag. No good. My sloppiness caused me very much grief to say the least.

 

[cp255]

It is so important to clean the lube of the cases and chamber. I was sloppy cleaning my cases for quite some time a few years back and could not figure out why I was having major pressure issues at even the lowest of charges until
I started cleaning my cases and chamber with brake clean. Prior to that I was just wiping them off with a rag. No good. My sloppiness caused me very much grief to say the least.

That might actually be my issue. The way I clean my brass is I rinse them in alcohol and then Tumble them. The alcohol removes most the lube and I reuse the alcohol between batches of brass. However I did notice my brass was kind of greasy this time. Maybe it's time for some new tumbling media and alcohol.

I wonder if the oil and lube actually causes that much more pressure or if it just increases the bolt thrust and therefore make it look like there is more pressure.

 

[jaybray]

That might actually be my issue. The way I clean my brass is I rinse them in alcohol and then Tumble them. The alcohol removes most the lube and I reuse the alcohol between batches of brass. However I did notice my brass was kind of greasy this time. Maybe it's time for some new tumbling media and alcohol.

I wonder if the oil and lube actually causes that much more pressure or if it just increases the bolt thrust and therefore make it look like there is more pressure.

Oh no there is for sure more pressure with lube still on the cases. I actually had the primer blow out on one case and burn a small divot in my Bat bolt face and wrecked a bunch more cases. Huge ejector marks also. Lube on cases is bad news. For me I found brake clean was the most effective at removing the lube. Excess lube may or may not be your problem but hopefully it is as it's an easy fix.

 

[joshb]

Every gun is a little different.

 

[cp255]

I washed my bass in some clean alcohol and made sure there was no lube. Loaded 31.5gr and tried again. Still seeing the same issues. Most cases were fine but Maybe 25% had heavy bolt lift or an ejector mark. Primers looked fine. I chronographed every shot and I was getting a low SD and ES. Velocity was 2830.

I'm thinking now maybe I didn't bump the shoulder enough during sizing. I remember I was seeing all kinds of pressure signs on my 308 with neck sized lapua brass. When I full length sized them the issues went away. Going to try resizing my dasher cases with more bump. I had used a +4 redding shell holder before so now I might try a +2.

 

[Archer79]

Are you sure your barrel is clean...without a borescope there is no way to really tell...but my pressure issues were caused by carbon I thought I was getting out but wasn't....I got a borescope and my problems went away

 

[Bottom Fodder]

Remember how deep you seat the bullet can effect case capacity To a Certain degree and to much neck tension can someone affect pressure. Just rambling

 

[Ryan66]

@cp255 do you have any pics to illustrate better how deep that 108 eld is in the case ? Any other bullets to compare the same?

I’m very interested in how this works out for you as I have alpha brass and 108 eld on the bench and waiting for a proof prefit in 6 dasher myself!

 

[FeMan]

When it first came out (pre OCD), I bought some Alpha brass to try. It was great, so I bought 300 pieces a while later. The new stuff was thicker and had insufficient neck clearance. It shot poorly. I didnt want to turn necks, so I loaded up some 115 VLDs with RL16 and jammed them. I have since gone back to Lapua brass but here is my confirmation target with the Alpha brass, 115 VLDs jammed and RL16:

 

[R.Morehouse]

Alpha 32.5 Varget 106 Weber 3050ish. 104fb.

My chorno. isn't the latest greatest.....But my es & sd are good.

Regards
Rick

 

[cp255]

@cp255 do you have any pics to illustrate better how deep that 108 eld is in the case ? Any other bullets to compare the same?

I’m very interested in how this works out for you as I have alpha brass and 108 eld on the bench and waiting for a proof prefit in 6 dasher myself!

There is not enough freebore to seat the 108 fully within the neck. I tried the 107 SMK and that fits better.

 

[Ryan66]

Much appreciated! Please let us know how it works out for you with your early pressure signs.

 

[cp255]

So last night I decided to measure my brass. I had sized my once fired cases using a +4 Redding competition shell holder and a Redding Type S FL bushing die. I measured the shoulder on 5 fired cases and 5 resized cases. Looks like my brass is still 5-6 thousandths short when using a +4 shell holder. I confirmed this by adding a piece of making tape to the back of a sized case which adds 4-5 thou and was still able to close the bolt on this although it felt kind of snug. I decided to double check my head space so I took out the extractor (no ejector on a TL3) and it does not close on my PTG no-go gage which is good. I guess not I am going to have to use the +8 shell holder. I wonder if my die is a bit small or something. Have never had to use a +8 before.

 

[Liven The Dream]

I don't shoot Barn Burners at all.
6 Norma Dasher and Norma Brass 30" 1-7.5 Brux Varget 31.7 450's 105 Berger HB around 2870.
Win's F/Class Matches at 300, 500 and 600 yards , Shoots well at 1000 yard 15 shots 148-5X ??
Speed Kills little holes (6mm)in Barrels.

 

[EEP]

My chamber is a 274 neck 140 fb. I’m shooting 105 hybrids in an 8twist at 32.2gr Varget. 109 hybrids in a 7.5twist at 32.6gr Varget. Light jam on both barrels. The above is my cold weather loads and different lots of Varget I must disclose. I clean my brass with a clean rag and 90%alchohol after one shot lube FL sizing with a Harrel’s Precision die bumping back 0.003”. Im very near pressure loads here on both barrels. They both shoot pretty good out to 600yds. Sub 2” groups not uncommon depending on conditions and cleanliness of barrel. My velocity’s are in the mid 2900’s.

 

[K22]

Notes of lube and chamber:

It is important to remove all lube residue for the case after sizing. I use a simple method of wiping the cases with a Scott shop rag containing a light coat of mineral spirits.

Most store the rifles in the safe with the muzzle up. Most coat the bore with some form of rust prevention preservative after cleaning. This can result in the preservative draining into the chamber and accumulating. I always use a bore mop, lightly coated with mineral spirits and run through the chamber of a cleaned rifle before shooting the rifle. I also run a patch down the bore to remove any oil.

Yes, both conditions, if not addressed, can create increase pressure.

 

[CA_Shooter]

For reference, 108 ELDs and Varget and alpha brass

At 31.2 I averaged 2871
32.1 2986
32.4 cratered primers at 3014