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Topic: Varget 135 Grain Berger Hollow Point Hybrid Load Data (Read 348 times) previous topic - next topic

Varget 135 Grain Berger Hollow Point Hybrid Load Data

I have a question about loading Berger Hybrid 135 grain hollow points in my Creedmoor using Varget. I followed published loads starting with 34.5/35.5/36.5 grains, 2.795 with a light crimp. At 36.5 the primer blew out a hole. Went to 35.5 and the primer blew out a hole. Decided enough was enough and ended up pulling them all and will reload with Varget again, if I can find reliable load data. I got the data from the manufacturer, so I can't understand what happened. Using a 24" Ballistic Advantage barrel, muzzle brake. Any ideas on what happened?

Re: Varget 135 Grain Berger Hollow Point Hybrid Load Data

Reply #1
The load seems reasonable (haven't looked up load data) so I'd begin by checking the firing pin for irregularities. Looking for a nice rounded tip. Next look at protrusion of the pin and research how much you should have.

Is your barrel clean? Is there a chance it's coppered or carboned up? Could you have a carbon ring?

Most of us don't crimp and that could be causing you to pressure. What primers are you using.
Don't back down in the powder to far. If blowing primers below book max I have to think you have equipment, bore, firing pin issues.
Dave

Re: Varget 135 Grain Berger Hollow Point Hybrid Load Data

Reply #2
Who published a Varget load for that bullet? I'm not seeing it in Bergers data.
Dave

Re: Varget 135 Grain Berger Hollow Point Hybrid Load Data

Reply #3
This is the data I used: https://www.shootersreference.com/reloadingdata/65-creedmoor/   No discernable damage by eye exam of the firing pin tip, S&B store bought ammo worked fine, as well as some I reloaded with XBR 8208, same bullet, data from the Hornady manual. What could be bore issues/chamber issues? I am stymied so far. Thank you for your help. The barrel and build are both new, it's a Ballistic Advantage barrel. Originally the gas hole was way too small, had to drill it out to .86, or drill bit #44, and now it cycles perfectly. No adjustable gas block needed.

Re: Varget 135 Grain Berger Hollow Point Hybrid Load Data

Reply #4
I didn't realise it is a gas gun and have very little experience there.

If the pin looks good and the barrel is new and or unfouled I'd probably take a look at seating. Are you seated off the lands, in the lands or at touch.
In the lands or at touch can cause pressure as well.

Did I miss what primer you're using? A mag primer could be causing pressure combined with a crimp especially and some primers have thinner cups than others.
Again I have limited gas gun experience but I think I'd want a primer with a thicker cup for a gas gun.
Dave

Re: Varget 135 Grain Berger Hollow Point Hybrid Load Data

Reply #5
Small rifle primer. I don't know exactly, but I did load about two thousandths less than the 2.800 standard length, so it most likely is not quite hitting the lands. It's brand new Lapua brass too.

Re: Varget 135 Grain Berger Hollow Point Hybrid Load Data

Reply #6
According to QuickLoad you should be well within safety margins, unless I missed something.

Quote
Cartridge          : 6.5 Creedmoor Hornady
Bullet             : .264, 135, Berger Classic Hunt G1 #26571
Useable Case Capaci: 45.756 grain H2O = 2.971 cm³
Cartridge O.A.L. L6: 2.799 inch = 71.09 mm
Barrel Length      : 24.0 inch = 609.6 mm
Powder             : Hodgdon VARGET *T

Predicted data by increasing and decreasing the given charge,
incremented in steps of 1.0% of nominal charge.
CAUTION: Figures exceed maximum and minimum recommended loads !

Step    Fill. Charge   Vel.  Energy   Pmax   Pmuz  Prop.Burnt B_Time
 %       %    Grains   fps   ft.lbs    psi    psi      %        ms

-10.0   81    32.85   2416    1749   39244   7769     98.1    1.447
-09.0   81    33.22   2439    1783   40337   7848     98.4    1.428
-08.0   82    33.58   2462    1817   41459   7923     98.6    1.409
-07.0   83    33.95   2485    1851   42609   7997     98.8    1.391
-06.0   84    34.31   2508    1885   43788   8069     99.0    1.374
-05.0   85    34.68   2530    1919   44998   8138     99.2    1.357
-04.0   86    35.04   2553    1954   46238   8205     99.3    1.340
-03.0   87    35.41   2576    1989   47511   8270     99.5    1.323
-02.0   88    35.77   2598    2023   48815   8332     99.6    1.307
-01.0   89    36.14   2621    2059   50154   8392     99.7    1.291
+00.0   89    36.50   2643    2094   51527   8450     99.8    1.275
+01.0   90    36.87   2665    2129   52935   8505     99.9    1.260
+02.0   91    37.23   2687    2165   54380   8557     99.9    1.245  ! Near Maximum !
+03.0   92    37.60   2709    2200   55862   8607    100.0    1.230  ! Near Maximum !
+04.0   93    37.96   2731    2236   57383   8654    100.0    1.215  ! Near Maximum !
+05.0   94    38.33   2753    2272   58943   8699    100.0    1.201  ! Near Maximum !

Results caused by ± 10% powder lot-to-lot burning rate variation using nominal charge
Data for burning rate increased by 10% relative to nominal value:
+Ba     89    36.50   2732    2237   59740   8181    100.0    1.198  ! Near Maximum !
Data for burning rate decreased by 10% relative to nominal value:
-Ba     89    36.50   2516    1897   43390   8436     96.5    1.376
Chris

Re: Varget 135 Grain Berger Hollow Point Hybrid Load Data

Reply #7
No experience with 6.5CM gas guns,
No experience with Varget. 
No experience with those Berger bullets. 
BUT, I do have experience with popping small rifle primers in SRP 6.5CM brass (Peterson in my case).  I had to switch to small magnum rifle primers (CCI 450s) for the harder cup to contain the pressure.  If that hadn't worked, I would have had to look at getting my bolt bushed so the firing pin was a tighter fit and would support the softer standard primer cups better.

Re: Varget 135 Grain Berger Hollow Point Hybrid Load Data

Reply #8
@hdmunger, I should probably know about bushing a bolt, and I've heard of it before, just never connected the dots with respect to primer popping. If you don't mind sharing what causes a bolt to pop primers, and how bushing the bolt fixes the problem, I'd appreciate the education. Always willing to learn :)
Chris

Re: Varget 135 Grain Berger Hollow Point Hybrid Load Data

Reply #9
No experience with 6.5CM gas guns,
No experience with Varget. 
No experience with those Berger bullets. 
BUT, I do have experience with popping small rifle primers in SRP 6.5CM brass (Peterson in my case).  I had to switch to small magnum rifle primers (CCI 450s) for the harder cup to contain the pressure.  If that hadn't worked, I would have had to look at getting my bolt bushed so the firing pin was a tighter fit and would support the softer standard primer cups better.

This is what I was getting at. Cheaper thin cup primers could be the problem.
Dave

Re: Varget 135 Grain Berger Hollow Point Hybrid Load Data

Reply #10
This chart shows the different primer cup thickness

Dave

Re: Varget 135 Grain Berger Hollow Point Hybrid Load Data

Reply #11
If everything on your rifle is good to go along with the primers likely being one of the thinner varieties you may also be dealing with a fast lot of Varget.

If it were my situation I'd get an accurate distance to the lands measurement and seat .020" off using br4s or 450s and start off again just above book starting load.
CCI 41s and Federal 205 ARs are specifically designed for AR gas guns with the thicker harder cups but If your firing pin is getting too much protrusion through the bolt I doubt it will matter what primer you use. Something else to look at.

You are going to have to establish a "baseline" of what works to get to the bottom of this and know how to safely proceed in your gun.

Wish I could give you one exact answer but there may not be one
Dave

Re: Varget 135 Grain Berger Hollow Point Hybrid Load Data

Reply #12
@hdmunger, I should probably know about bushing a bolt, and I've heard of it before, just never connected the dots with respect to primer popping. If you don't mind sharing what causes a bolt to pop primers, and how bushing the bolt fixes the problem, I'd appreciate the education. Always willing to learn :)

Um...to be honest, my comment stemmed from my research into solving my original issues with standard small rifle primers 2 or 3 years ago, at least.  At the time the solution that seemed to be easiest (if it worked, and for me it did) was to use magnum primers, but another solution I saw was to bush the firing pin.

At the time I believed the problem was the cratering in the primer cup, which showed a rounded concave indentation from the firing pin surrounded by raised wall that protruded above the surface of the primer and was the same approximate diameter of the firing pin hole in the bolt face.  This lead me to believe that that "flow" into the small gap between the firing pin and the hole in the bolt face was responsible for weakening the primer cup in that area enough to allow for failure.  Hence, bushing the bolt to close that gap would better support the softer primer cups.

Or it was all BS...I don't know because I never had to go there...

Re: Varget 135 Grain Berger Hollow Point Hybrid Load Data

Reply #13
That is exactly why they put a bushing in the firing pin hole.. to take up the slop between the pin and the hole it goes in. Therefore not allowing the primer cup to flow inbetween the two..
Grant

Re: Varget 135 Grain Berger Hollow Point Hybrid Load Data

Reply #14
Thanks guys, hated to beat around the bush, figured I'd just bolt right in and ask :)
Chris