Hi All. I'm new to the 6x45. Here's what I built as an NRA match rifle (200, 300, 600 yd matches) and possibly for hunting: Lower: Magpul UBR Gen1 stock, Geissele HS Match trigger, Geissele 42 spring, H2 buffer, Tubb grip. Keystone-built 26" 1:7.5 Bartlein 5R stainless heavy-contour barrel, +2" (non-adjustable) gas system, AT3 Tactical 14" free-float handguard, AMBI (cutout) bolt release, Keystone one-piece 30mm scope mount, Minox ZE-5i 5-25 x 56 scope w/German #4 reticle, D&H Tactical 10-round (short magazine)

New Lapua .223 Match brass, neck expanded using an oversized Sinclair 6mm expander mandrel and graphite lubricant. Then, a Redding .223 FL bushing sizing die using wax lube. I don't insert any bushings, as the neck tension is sufficient after using the Sinclair mandrel. Lastly, ream primer pockets and trim to 1.745." In the Whidden gauge, they read 0.000" (Go) to -0.001". Primer: Rem 7-1/2. Powder dispensed with an RCBS Chargemaster and adjusted with an analytical balance for testing. Some preliminary results (LabRadar, 50F, 100 yds):

H4895, 70gr SMK, 2.30" OAL for (cutout) magazine feed
- 26.0gr, 3008fps
- 26.3gr, 3059fps
- 26.6gr, 3070fps
- 26.9gr, 3104fps
- 27.2gr, 3148fps
No pressure signs observed.

H4895, 90gr Berger Match Target, 2.31" OAL for (cutout) magazine feed
- 24.0gr, 2636fps
- 24.3gr, 2685fps
- 24.6gr, 2720fps
- 24.9gr, 2745fps (over-pressure signs: some primer cratering and light extractor marks)
- 25.2gr, 2752fps "
Tough to get more than 25gr in the case and seat this bullet, for a 2.31" OAL

H4895, 95gr SMK, 0.005" back of rifling (single load)
- 24.2gr, 2671fps
- 24.5gr, 2701fps

Varget, 107gr SMK, 0.005" back of rifling (single load)
- 25.5gr, 2615fps
- 25.8gr, 2653fps
- 26.0gr, 2674fps
- 26.2gr, 2689fps (over-pressure signs: some primer cratering and light extractor marks)
Was looking for 2700fps.

Shot a 591-24X in an early Fall NRA M-R match (3x300) with the 25.5 Varget, 107 SMK's. First string was 199-11X (90F that day).

Still some problems with the 90 Bergers and 70 SMK's not going fully into battery (jamming with about 1/8" - 1/16" to go) when mag fed. I know that Lapua brass neck thickness is greater...but they single load just fine, partially inserting them into the chamber then dropping the bolt. Neck turn? Go with thinner brass? Suggestions are very welcome...Tim


Edited by tovaert (12/25/17 10:07 AM)