Ultra-light load development

  • 4.9K Views
  • Last Post 03 January 2011
beetrix posted this 24 December 2010

I have been working on developing a sub-sonic (950fps) load in a G2 Contender rifle using Beartooth 120gr. plainbase bullet. (originally developed for .270 REN). There is very little data for cast bullets in the 6.8, i.e., (mini .270 Win)., especially in the 950fps range.

So far, I'm using 2400, however, my research says Red Dot. Any charge suggestions? Yes, I'm using specially prepared cases and magnum primers and all the precautions, accuracy at 25 yards is one ragged hole. The whole thing comes down to load density and powder choice.

Attached Files

Order By: Standard | Newest | Votes
DAMRON G posted this 24 December 2010

red dot at about 2g will be a good start .I should clarify this is if you are looking for an ultra silent load.

Plainbase under 1000 have worked well for me to about 50 yards.When i go to 100 i find 1200 a sweet spot.I have never gotten ultra accurate plainbase loads above 1400.Sometime a group or two,but they seem to deteriorate after about 10 shots.

George

 

eidited becase i misread you post

Attached Files

RicinYakima posted this 24 December 2010

If you have a good 2400 load in the 1400 - 1600 f/s range, about 20% of that in Red Dot could be a good place to start.

Question, why magnum primers? That would be the last thing I would use in a rimless case for light loads, due to high primer pocket pressure. Unless you are using lubed cases?

Ric

Attached Files

DAMRON G posted this 24 December 2010

RicinYakima wrote: If you have a good 2400 load in the 1400 - 1600 f/s range, about 20% of that in Red Dot could be a good place to start.

Question, why magnum primers? That would be the last thing I would use in a rimless case for light loads, due to high primer pocket pressure. Unless you are using lubed cases?

Ric

Ric i have used std pistol  primers up to Fed 215's in 1200 fps 30-06 plainbse loads and havent had any problerms.I fired one case 500 times with RP 9-1/2 with no ill effects.

George

Attached Files

RicinYakima posted this 25 December 2010

George,

I haven't either except for WW's in 30/06 with light loads. The primers would push the case into the chamber to the extractor lip, and the primer push out to the bolt face. But to use them by choice? I was just wondering. During the primer shortage of a couple of years ago, I was using Fed 215's from the 1950's and FA corrosives in plinking loads in rimmed cases. RP's 9&1/2's are my favorite in light loads, high heat and low flash and no powdered aluminum in the priming compound. Plus they are cheapest ones around now. Ric

Attached Files

beetrix posted this 25 December 2010

Yes, the quieter the better. Fifty-seventy five yards would be good.

I will try Red Dot, my current 2400 load is 5gr.

As for the magnum primers,I read a report on the internet stating that: “SEE is the result of slow or incomplete ignition of small amounts of powder. The powder smoulders and releases explosive gasses which, when finally ignited, detonate in a high order explosion.” and, finally, all reduced loads should start with a magnum primer. The hotter and longer the flame duration insures the charge is fully ignited. Their testing also claimed accuracy improved 8% with magnum Primers.

Interesting to was the suggestion to find a cartridge with similar load density and volume to use as a starting point. The .44 Spl. with 120gr RB recommended start is 2.2gr. Red Dot.

I found this site by searching for: Developing Sub-sonic loads.

Attached Files

RicinYakima posted this 25 December 2010

beetrix,

The 2.0 - 2.2 grains of Red Dot is probably a very reasonable starting load. A2400 would not be my first choice for loads below 1200 f/s in the 30 Remington based case, just for the chance of sticking a bullet in the bore. The double based flake shotgun powders or WW231 would be better choices. I have used these at 4.0 grains in the 7.62 X 39 with 200 grain cast bullets for quite sub-sonic loads.

The SEE theory has been around since the early 1970's and is originally, I believe, from research done for howitzers by the US Army. It does not apply to the faster powders we are discussing. If they are ignited by the primer, they will be consumed before the bullet starts to move from the case. None of the reloading companies have ever been able to duplicate this SEE in their labs. This was well reported in the better gun magazines in the '70's and 80's.

However, Norma was able to have pressure spikes high enough to damage small arms. In their pressure guns, smaller charges of slow igniting powders could cause problems, in about 25% of the tests. Their theory is that a combination of fouled throat, light bullet pull, heavy for bore size bullets, and hard to ignite powder would allow the force of the primer to move the bullet into throat and jam the bullet against the lands. As the pressure rises, the powder burns faster and faster. Since the bullet is basically a bore obstruction, pressure spikes before the bullet can be engraved and start down the bore.

In my personal experience, I have only found better accuracy with cast bullets and hot LR primers in the 45/70 with 11.0 grains of Unique and Green Dot. Everything else has done better with mild LR primers or LP primers.

Best wishes,

Ric

Attached Files

beetrix posted this 25 December 2010

OK, Thanks ... I'm glad to put that theory to rest. I'll work with Red Dot.

It will be a week or two until I can test and Chrony, but it sounds good. 2400 was what I had on hand to start with.

I have cast bullets since 1965 (oops!)9mm,.45acp, .45/70, and a lot of time with a Gonic Arms muzzleloader and the Gould 330gr. HP.

Now, I'm retired, have a sheltered 25 yard range inside my barn and can shoot off my porch to 50 yards before going to the range.

Any comments, remarks or insults will be greatly appreciated.

Thanks again,

Attached Files

DAMRON G posted this 25 December 2010

If had to pick a go to plainbase powder for 1200 or under it would be Bulleye or Unique and pistol primers.I shot both last year with 30 cal plainbase and couldnt pick a clear winner.

Your 25 yard indoor range is my envy.

George

Attached Files

DAMRON G posted this 25 December 2010

RicinYakima wrote: George,

no powdered aluminum in the priming compound.

I use Win LR that have the aluminum in PB loads and cant see an accuracy or velocity difference.If anything they may give a bit more uniform velocities (but no better accuracy i i will admit)If they were cheaper and in stock all the time i'd use them exclusively.

Why do you see the aluminum as  a problem?

 

George

Attached Files

RicinYakima posted this 25 December 2010

George,

As you know, I usually use A2400 and SR4759 for my rifle loads and usually in a 1903 Springfield, of some conformation. From match benchrest shooting with them, I have developed the habit of holding the base of the cartridge down on the follower so that the bolt will slide over the ledge of the follower. This means my powder charge is generally laying spread out on the bottom of the case. I don't want those 4000 degree pieces of Al flying around the inside of the case.

I will admit that the hottest primers will give the smallest velocity spreads and SD of velocity, if the firing train has enough energy to fully detonate the primer. But I am not convinced that it has much to do with accuracy up to 200 yards. It doesn't make it worse but it doesn't make the groups better either.

Maybe if I was trying to ignite a compressed block of black powder, like the BPCR guys, or a compressed load of 50 BMG powder, it may make a difference. Again, the only time I have had better accuracy, at least in my loads, is the 45/70 in the trapdoor with minimum loads of shotgun powder. Then the Fed 215's and WW LR primers gave me better result, especially in winter.

Ric

Attached Files

DAMRON G posted this 26 December 2010

RicinYakima wrote: George,

As you know, I usually use A2400 and SR4759 for my rifle loads and usually in a 1903 Springfield, of some conformation. From match benchrest shooting with them, I have developed the habit of holding the base of the cartridge down on the follower so that the bolt will slide over the ledge of the follower. This means my powder charge is generally laying spread out on the bottom of the case. I don't want those 4000 degree pieces of Al flying around the inside of the case.

I will admit that the hottest primers will give the smallest velocity spreads and SD of velocity, if the firing train has enough energy to fully detonate the primer. But I am not convinced that it has much to do with accuracy up to 200 yards. It doesn't make it worse but it doesn't make the groups better either.

Maybe if I was trying to ignite a compressed block of black powder, like the BPCR guys, or a compressed load of 50 BMG powder, it may make a difference. Again, the only time I have had better accuracy, at least in my loads, is the 45/70 in the trapdoor with minimum loads of shotgun powder. Then the Fed 215's and WW LR primers gave me better result, especially in winter.

Ric I haven't seen a difference in accuracy with low SD loads of say 5-10 over ones that were in the 20 -30 range at 1500 fps either .When i shoot plainbase at 1200 or so seldom do i get top accuracy with wide velocity variations.I shoot pistol primers in all of my plain base loads lately.

I always liked the idea of the aluminum flying around to help ignite the charge.

I am going to try Dacron wad next time out.A Schuetzen i know guy swears it gives him best accuracy in big cases with little charges.The uniformity is about the same he says,but it protects the bullets base is the theory.Worth a try.

George

Attached Files

RicinYakima posted this 26 December 2010

I've never done any real work with plain based bullets in rifles, except for the one Trapdoor project. You, Molly and the schuetzen guys are way more advanced than I am in that field.

That may be a field I will explore with the new 30 Sharps (wildcat of the 30 Johnson wildcat) that I will hopefully work on next summer.

Ric

Attached Files

DAMRON G posted this 26 December 2010

RicinYakima wrote: 30 Sharps (wildcat of the 30 Johnson wildcat) that I will hopefully work on next summer.

Ric

It sounds like fun.I'd always wanted to build a .30 Schwartz.(short tapered 30-30  based)What alteration of the Johnson did you guys do?

George

Attached Files

RicinYakima posted this 26 December 2010

George,

  1. full diameter of 30/30 rim, not reduced for working with a 30/06 bolt face

  2. rim thickness 0.005” less than SAMMI (could not find brass that was even close to SAMMI spec's max rim thickness)

  3. the neck and throat reamer appears to cut a longer neck than Johnson's published spec's in the test chamber so don't know what the fireformed case length will be

It should finish up a little shorter than the Schwartz by about 0.10” and with a larger shoulder, 0.370". The neck is large enough to seat a 0.3095” bullet in the test chamber with an unfireformed case, but neck turned to about 0.015” thick neck wall.

Attached Files

DAMRON G posted this 26 December 2010

Load of 2.5 of Unique,Fed pistol Primer and 150g RN plainbase in 7.62 x 54 Russian Rifle has a1.3X pistol scope in Scout mount. Shot at 100 yards because my chronograph was set up.I Didn't expect much more than chronograph data,but once i found the bullets impact it surprised me.It was about 24” low from a dead on at 10 meter setting.It took 6 shots to find my 24 x 24” paper.I had to  hold on a dirt clod on the bank to land them on the paper.Lower group has 6 shots.At first I thought most hadn't even made it there so i went down to find almost a group.!The three shots above were the last three i had in the box holding on a bit higher clod to see if they grouped.i dont think I'll shoot 100 yards with them again,but it was interesting.

588 fps-----25.5 ES----10.4SD

George

Attached Files

beetrix posted this 31 December 2010

More on the 6.8 ... I switched to 2.5gr. Red Dot at 760fps and began experiencing vertical stringing. No more magnum primers, now using CCI Benchrest large rifle primers. And, before anyone asks I position the powder before each shot.

This project is still in the development stage. I'm trying eliminate the variables before getting serious.

Increase the powder charge and velocity, try pistol primers, etc. ????

Attached Files

DAMRON G posted this 31 December 2010

beetrix wrote: More on the 6.8 ... I switched to 2.5gr. Red Dot at 760fps and began experiencing vertical stringing. No more magnum primers, now using CCI Benchrest large rifle primers. And, before anyone asks I position the powder before each shot.

This project is still in the development stage. I'm trying eliminate the variables before getting serious.

Increase the powder charge and velocity, try pistol primers, etc. ???? How much vertical and at what distance? I shoot most of mine at 10 meters and 50 feet and cant see vertical if it was there!

I like pistol primers.i don't think you need to go any faster.I dont position the powder though i am told it is a sin with all that airspace.Try loading only one case without resizing the neck,it has worked for me very well lately.De-cap, Re-cap,dump powder, finger seat the bullet and shoot.The low pressure doesn't expand the neck very much and you have enough neck tension for quite few shots. It makes a nice pace for offhand.

George

Attached Files

DAMRON G posted this 31 December 2010

Here is my set up for gallery shooting.It cant get much simpler.And yes the bullets you see don't have any lube.I don't seem to need any at this low velocity. The primers are a mystery,they were bought at a show loose in a box marked “CCI Military"

George

Attached Files

DAMRON G posted this 31 December 2010

three 5 shot groups at 10 meters.last group was the smallest.

7.62 x 54 Russian ,91-30 1.6X scope

308241 150g no lube

2.5g Unique

CCI mystery primer.

George

Attached Files

nimrod posted this 01 January 2011

After reading and seeing this thread develope I decided to give this a try and see. Using my TC Encore in .223 loading the 225415 unsized, lubed with LLA, seated in the same case like DAMRON G, old CCI green box primers small pistol primers. Started with .5 grains of Bullseye and shooting across my basement at 33' the velocity wasn't fast enough to stick in a 2 X12 pine board. Very quiet but the bullet bounced off the board “NOT GOOD” don't know where it went, somewhere in the basement. So after that I angled the board foreward pointed downward so that any more bouncing bullets would hit the floor if it happened again. I then upped the charge to 1 grain of Bullseye big difference. That one went throught the board and hit the steel plate that I normally use which is angled at a 45* with a catch box under it. A bit too loud so dropped back down to .7 grains of Bullseye much better. Quiet about like a .22 air rifle still penetrates the pine board and I can shoot groups much like DAMRON G is getting.

This is some good trigger time when the weather is cold and nasty outside and cheap too. Great fun!

Attached Files

Show More Posts
Close