Yesterday was a beautiful day. I pulled 3 rifles from a safe and went to my range which used to be my horse pasture. My objectives were to Fire form brass for the Lapua chamber, check zero & pressures on my 6mm Alpha (chambered with Alpha reamer), and check zero on my 6 GT lightweight hunter rifle.
Summary: This was done on my 104 yard range. I’m limited to 300 yards on my range. The rifle chambered with Alex Wheelers reamer that I was fire forming Lapua 6 BR brass using 105 Berger hybrids over 30.0 Varget repeated shot groups that equaled my best ever. I’m calling the .25. Just barely bigger than the bullet. They might be .2. All shooting was done on a bench using just a tripod & no rear bag. No pressure signs.
The rifle chambered with Alpha’s 6 BRA reamer shot good, but not as good. I’m calling the groups 1/2 - 3/4 moa. I was using 30.4 Varget under Berger 105 hybrids. Pressure was indicated by a heavy bolt lift and ejector marks, plus 1 pierced primer. I’ll post a pic later. It looks like from bolt blow back to me. I’ll also compare the 2 chambers using pin gauges. All primers used in all 3 rifles were CCI 450s.
The barrel with the Wheeler reamer fire forming Lapua brass exceeded all expectations with zero signs of pressure. The barrel chamber with the Alpha reamer disappointed with the serious pressure indicators. I need to decide if I’m going to pursue this barrel or not with the pressur. There were no carbon rings. I clean after every shoot whether 15 rounds or after a PRS match. I use a borescope to verify a clean bore.
Details:
Rifle with Wheeler chamber fire forming brass.
Impact 737r, MDT ACC Elite, TT Diamond, Bartlein 28” HV .237, .104 freebore, .272 neck, 8-7.75, 4 groove. 30.0 Varget & Berger 105 hybrids fire forming Lapua brass. Round count at 140. No pressure signs at all & beautiful groups.
Alpha rifle. Impact 737r, Manners T2A Gap, TT Diamond, Krieger 27” M24, .236, .272 neck, 7.5, 4 groove
Rifle with Alpha BRA reamer and Alpha BRA brass shot good groups (not as good as other rifle).
Question:
With pin gauges showing correct size at .200 line why do you think I’m getting pressure at 30.4 in the Alpha chamber with Alpha brass? Is below 30.4 Varget the ceiling with the Alpha chamber?
Velocity FFing brass with 30.0 Varget = 2845 fps. Barrel might speed up a little more.
Velocity with 30.4 Varget in Alpha barrel = 2882 with pressure signs.
Humidity on both powders are 40-45% (controlled environment).
Neither rifle is bedded. I always bed my chassis after I get a baseline on precision without bedding and am sure that I am keeping the chassis.
Summary: This was done on my 104 yard range. I’m limited to 300 yards on my range. The rifle chambered with Alex Wheelers reamer that I was fire forming Lapua 6 BR brass using 105 Berger hybrids over 30.0 Varget repeated shot groups that equaled my best ever. I’m calling the .25. Just barely bigger than the bullet. They might be .2. All shooting was done on a bench using just a tripod & no rear bag. No pressure signs.
The rifle chambered with Alpha’s 6 BRA reamer shot good, but not as good. I’m calling the groups 1/2 - 3/4 moa. I was using 30.4 Varget under Berger 105 hybrids. Pressure was indicated by a heavy bolt lift and ejector marks, plus 1 pierced primer. I’ll post a pic later. It looks like from bolt blow back to me. I’ll also compare the 2 chambers using pin gauges. All primers used in all 3 rifles were CCI 450s.
The barrel with the Wheeler reamer fire forming Lapua brass exceeded all expectations with zero signs of pressure. The barrel chamber with the Alpha reamer disappointed with the serious pressure indicators. I need to decide if I’m going to pursue this barrel or not with the pressur. There were no carbon rings. I clean after every shoot whether 15 rounds or after a PRS match. I use a borescope to verify a clean bore.
Details:
Rifle with Wheeler chamber fire forming brass.
Impact 737r, MDT ACC Elite, TT Diamond, Bartlein 28” HV .237, .104 freebore, .272 neck, 8-7.75, 4 groove. 30.0 Varget & Berger 105 hybrids fire forming Lapua brass. Round count at 140. No pressure signs at all & beautiful groups.
Alpha rifle. Impact 737r, Manners T2A Gap, TT Diamond, Krieger 27” M24, .236, .272 neck, 7.5, 4 groove
Rifle with Alpha BRA reamer and Alpha BRA brass shot good groups (not as good as other rifle).
Question:
With pin gauges showing correct size at .200 line why do you think I’m getting pressure at 30.4 in the Alpha chamber with Alpha brass? Is below 30.4 Varget the ceiling with the Alpha chamber?
Velocity FFing brass with 30.0 Varget = 2845 fps. Barrel might speed up a little more.
Velocity with 30.4 Varget in Alpha barrel = 2882 with pressure signs.
Humidity on both powders are 40-45% (controlled environment).
Neither rifle is bedded. I always bed my chassis after I get a baseline on precision without bedding and am sure that I am keeping the chassis.
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