Piercing Primers, again !

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Ronnie3

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Does anyone have a Rem XR100, 6 BR with a Pacific Tool & Gauge Bolt thats shooting 108 Bergers, Varget , CCI 450 primers, & Lapua brass ?
If so, are you having any problems with pirecing primers ?
We have 2 identical rifles , only differences are one has the Pacific Tool and Gauge Bolt which is the one thats piercing primers with as low as 30.1 grs of Varget, the other gun we have loaded 30.6 grs of Varget without a problem. I realize that Varget can vary a lot between different bottles & lot numbers, I did conograph it after the first time I had problems and it was only 2880 FPS, that was with 30.6 grs, this time I loaded it down to 30.1 grs and it still pireced primers, I will conograph this load too as soon as I get a chance.
Info appreciated.
Ron
 
Ron do you notice the primers flowing around firing pin on loads that did not pierce primers. This has been a common problem with remigton lately, i sent back a 223 police for that reason. Hole in bolt face for pin is to large.
manitou
 
Thanks, not sure what you mean by primers flowing, there is a little cratering, very little, hardly catch your finger nail on it. This is not a remington bolt, its a Pacific Tool & gauge bolt, but I did compare the size of the firing pin hole with our other brand new XR100 ( which is working fine ) and its pretty much identicle.
Thanks, Ron
 
Maybe get the bolt face bushed Ron and see if that fixes it. Dennis Sorenson does them as well as Bill Leeper. I know you shouldn't have to since it is a custom bolt, but he probably made it to spec rather than for a smaller firing pin.

My XR's both crater (1 more than the other) but never pierced a primer in the thousands of rounds I have put through them. 31.2 in the "Purple" one and 30.8 in the Brown one.

Are you shooting new brass again?
 
What is the Bore/land diameter on the 6mm barrel you are piercing primers with? Is it a .236 or a .237? X .243? Was it one of Mick's reamers or was it your own?

I think I asked you about which powder lot as well. I have had more than 1 grain differences between powder lots of Varget, and I do know many guys that are getting 2850-2875 with sub-30 grain loads.
 
I assume you have addressed any neck clearance issues?

Have you measured the pin protrusion?
 
Thanks, Richard, I guess getting the bolt bushed or going to a much light load is about all I can do ( that I know of anyways ), Ian, both the barrels, the one thats on it and the first one that was on the gun when I bought it from Steve B both came from you so I'm assuming they are both the .236 dia, and Mick chambered both barrels and he said he used the same reamer. X-fan, yes I have checked the neck clearance and the pin protrudes .051. Thanks,
I did email PT&G and they told me to dress the firing pin back to .055, but its allready at .051, they mentioned other than that they really don't know. So, I guess I could allways look for another XR100, or just keep shooting the old back up Green Machine ( Rem 700 ), it seemed to do allright at the Farky.
Thanks all,
Ron
 
I'm not trying to hi-jack this thread, but at the Farky I had 6 completely pierced primers and all cases showed severly cratered primers in my 223.
Only new unfired brass had pierced primers....cases used several times did not. Further to that, the same load tried at home before and after Farky showed no crater and only mild sign of pressure.
According to most load manuals the load is under max.
Surely the difference in elevation from home to Kamloops wouldn't cause that ?? Failing that I have no idea of why.... :confused:
 
Kevan & Ron,

New Brass has a smaller capacity than fired brass and as such a high-pressure load that may work well in fire-formed brass may be above the safe pressure mark with new.

I have seen this phenomenon personally, and I know Ron had the same problem last year. I Have since learned i must fire-form any new 6BR brass for the high-speed node I like to use in long distance shooting. I do only get this with factory actions. My custom has a tight FP hole and little FP penetration, your PT&G bolt should be the same, but it is opposite..... weird.

It just goes to show what a fine line one can walk with maximum pressures and how few variables it takes to cross the line from safe to unsafe.

Ron, I am stumped. Everything I sell in 6 1:8 is .236 unless requested otherwise and I know for a fact that it is not an inconsistency in barrel diameter.

Out of curiosity, if you were to use identical loads in the two rifles using identical powders, bulets cases etc. Is there a marked velocity difference between the two rifles?




Ron:

Are you still having to bump your cases after each firing?
 
6mm Shooter said:
Try wolf small rifle magnum primers. They have a very hard cup. My brass is flowing into the ejector pin hole before the primer shows any sign of pressure.
Click to expand...

Odd.....Paul Reibin tried these a couple of times and each time he did (in 2 different cartridges on 2 separate occasions) he put the rifles away because everyone of the rounds was piercing the Wolf primers.
 
Ian, I will try that test with conographing identical loads in both rifles and let you know , probably tommorow. I would say I usually bump the brass about every second or third time, but we do have 4 6 BR's, so I'm going to have to keep better track of things.
I did get another email from Dave Kiff and he suggested sending the bolt in and they would have a look at it.
Thanks, Ron
 
Ron, what are the chances you can try some H4350? This might delay the peak pressure long enough to stop primers from breaking. Has worked for me in the past. Moly could also be an aid here - let me know if you want some bullets coated.

Not a slag on Krieger as this applies to ANY barrel manf. Tolerance on the smaller side of the barrel plus bigger on the bullet side could be all there is to push over the top pressure wise and busting primers. This assumes there isn't a mechanical problem with the rifle.

We are talking variance at the 0.0005" to 0.001" level.

My 6BR from years ago had this issue. Was on the tight side and some brands of bullets simply wouldn't shoot (these were on the big side of 243). However, when I made the adjustment to account for these differences, it shot amazingly well.

At the peak pressures we tend to run at, any little bit can push you over the top. I would back off the loads a couple of grains and work up but shoot over a chronie. Shoot the other rifle that is not causing any troubles at the same time and alternate to ensure the chronie data is reliable.

When I work up, I see that velocity increases at a steady rate given increases in powder. Near max pressures, the velocity changes very little, if any, even when powders are increased a few 'increments'. I have even seen it get SLOWER.

BUT pressure signs on the primer and case show themselves.

Kevan, I am really surprised at the trouble you were having. If using a powder like Hodgdon Extreme, the difference in temp and atmospheric conditions shouldn't cause that type of issues.

In general, new brass is smaller then fireformed brass and is certainly more ductile. I usually find pressures to be LOWER in new cases as some of the energy is spent expanding the brass to the chamber.

I really have no idea why you would have no issues at home but a bunch in Kamloops.

Was the bore heavily fouled at Kamloops? That could push pressures.

I think you may have to come up more often and do some R&D :)

I know of a great place to do some testing...

Jerry
 
Just finished conographing some loads, the Rem XR100 6BR that I was piercing the primers, it has a 28" Krieger barrel (.236 ) and a PT&G bolt, and I just shot ammo from the same box that I was using when I pierced the primers,108 Bergers, 30.1 Grs Varget,.030 jam, CCI 450 Mp's, Lapua Brass ( fired twice ). fired one cold shot first and here's the results,
Avg = 2854
ES = 7.41
SD = 2.64
Temperature was plus 6 degress celcius, where as in Kamloops it was in the mid 20's . Both guns were just cleaned.

Then I tested the other ( new ) Rem XR100 6 BR with a 30" Krieger Barrel (.237 ) stock bolt, ammo also left over from the Farky, 108 Bergers, 30.3 Grs Varget, .010 Jam, CCI 450 Mp's,Lapua Brass ( Fired once ) also fired one cold shot before conographing, here's those results ,
Avg = 2895
ES = 6.24
SD = 2.44
There was about 5-10 mph winds out back and the group I got while testing this gun was one of the best groups I have ever shot at 100 yards, it was 5 shots = .160 ( 1/8" ) looks like one hole, funny, I wasn't even really trying for a good group, concentration was on the conograph.
 
Thanks Jerry, yes I have some H4350 and I was also going to try some VV 540, the moly coated bullets is also a good idea, I'll try them.
Thanks, appreciate that info.
Ron
 
30 thou jam will produce high pressures in the BR. If you don't believe me, try loading bullets starting at 30 thou jump and seat them out in 5 thou increments. You will see the shots climb the paper as the pressure increases. Increased pressure does not always result in increased velocity.

30 thou jam on a non VLD bullet is my guess at to the culprit. I don't have any 108's to measure either.

236 is SAAMI and the use of 237's is generally used on light flat based bullets with the pressure ring on them (such as with ppc's). 237's work absolutely fine, but there will be differences in the 30" 237 over a 28" 236. The use of 237 is a fad thing.

H4350 is a very slow burning powder relative to Varget. I've dismissed ever wanting to experiment with it on that basis, but whatever spackles your crack. 540 is an excellent BR powder.
 
Ron,back off your loads below 30.1gr and see what type of speed you get. If my hunch is correct, you will see little to no speed difference but pressures will fall nicely.

My SWAG is something around 28.8gr will solve your problems. Likely a speed of around 2835fps. compare primers and I would expect the lower load to have less pressure signs. From my mucking about, I find that with Hodgdon Extreme extruded powders, the pressures increase linearly until after magnum pressures. Then things get real peaky in a big hurry.

With the difference in bore diameters, it again confirms my thoughts on this being a pressure issue not a mechanical one. 1 thou can make a world of difference on the pressure curve and how high the spike gets.

If you have an accurate micrometer, measure the diameter of a few of your lot of 108's and compare to some 105's. You want to measure to the 0.000X"

Be interesting to see what diameters you have...

Jerry
 
Shooting the same action, .236 barrel, brass, primers etc and my load is 31.2gr of Varget (as well as others I know) my bet would be on a bolt issue and not the load.

30.8 is a fairly tame load for the 6BR in fact 30.5 is my start load with this caliber.
 
Richard, aren't you shooting 105 Bergers ? I'm shooting 108's, probably a little difference there. I do plan on sending the bolt to PT&G. so they can check it out.
Thanks, Ron
 
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