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338-300 PRC... Sherman Improved!
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<blockquote data-quote="KH_Outdoors" data-source="post: 3082860" data-attributes="member: 123559"><p>Making some progress here!</p><p></p><p>Getting some baselines for safe pressures and a general feel of what the rifle is going to like with the 225 Accubonds. Decided to start with H1000 & H4831sc, then moved on to H4350 & N555.</p><p></p><p>Speeds listed:</p><p></p><p>[ATTACH=full]563177[/ATTACH]</p><p></p><p>Notes: all charge weight ladders shot at 100 yards, same aiming point, 40-50 F, and noting point of impacts looking for charge weights landing close to one another along with general grouping size/shape.</p><p></p><p>H1000 - Definitely on the "slow burn" side of what this cartridge/bullet combo is going to run with. I didn't expect this to be the winner with 225's but just tested to be sure. Pretty large scattered group overall however showed potential with charge weights 81/82/83 & 86/87/88 gr clustering/touching. 84 & up is compressed which I'm not a fan of, less than that is slower than my goal. Zero pressure signs. Moving on to H4831sc.</p><p></p><p>H4831sc - Had high hopes for this powder, it has the most linear increase of speed accross the ladder and seems "just right" for case fill. However, very scattered grouping. Only two charge weights landing close to one another. 82/83 gr showing potential but with everything being so scattered I'm going one more step "faster" burn rate. No pressure signs still.</p><p></p><p>H4350 - I had a hunch this was going to be the standout. Research on the 338-300 PRC variants showed many shooters finding best results with H4350 even up to 250 gr projectiles. I fully expected to be able to hit some pressure signs stepping up to H4350 and I did, just a faint ejector mark starting on the top end. No heavy bolt, click, flat primer, or anything super concerning even up to 3000 fps. I did not want to push it further though with my goal being 2900+. Accuracy wise, hands down best promise of everything tested (see pic below). Charge weights 75/76/77 all clustering, then again 78/79/80 nearly in the same hole clustered. This is exactly what I look for during initial testing. I will go forward with H4350!</p><p></p><p>N555 - This is an interesting powder and I've always wanted to find a use for it. Not completely ruling it out yet but H4350 is the clear choice. The N555 showed some good promise on the low end of 76/77/78/79 all in one hole or within 1/2", so very forgiving around that 2800 fps mark. Good case fill being a bulkier powder than the H series, and known to be one of the most stable powders offered by Vhit. Just on the slower end, above 79 gr it just started scattering, so again H4350 is just the clear choice.</p><p></p><p>This is my preferred method of starting load work on my setups. I'm simply looking for components that are most likely to work well together and meet my goals. Always going with a "coarse to fine" approach, I've found that I can really waste a whole lot of time tinkering and tuning with the wrong combination otherwise. So rather than fine incremental ladders and fine seating depth tests I usually just start bullets approximately .030" off the lands and put charge weight ladders together with full 1 grain incremental changes (in large magnums, .5 in smaller cases). If I need to, or just want to do further testing I'll get into finer tuning of course. In the case of this exact combination, the next step is to go shoot groups at the charge weights of the combinations showing most promise.</p><p></p><p>[ATTACH=full]563182[/ATTACH]</p></blockquote><p></p>
[QUOTE="KH_Outdoors, post: 3082860, member: 123559"] Making some progress here! Getting some baselines for safe pressures and a general feel of what the rifle is going to like with the 225 Accubonds. Decided to start with H1000 & H4831sc, then moved on to H4350 & N555. Speeds listed: [ATTACH type="full" alt="Screenshot_20240411_172527_Sheets.jpg"]563177[/ATTACH] Notes: all charge weight ladders shot at 100 yards, same aiming point, 40-50 F, and noting point of impacts looking for charge weights landing close to one another along with general grouping size/shape. H1000 - Definitely on the "slow burn" side of what this cartridge/bullet combo is going to run with. I didn't expect this to be the winner with 225's but just tested to be sure. Pretty large scattered group overall however showed potential with charge weights 81/82/83 & 86/87/88 gr clustering/touching. 84 & up is compressed which I'm not a fan of, less than that is slower than my goal. Zero pressure signs. Moving on to H4831sc. H4831sc - Had high hopes for this powder, it has the most linear increase of speed accross the ladder and seems "just right" for case fill. However, very scattered grouping. Only two charge weights landing close to one another. 82/83 gr showing potential but with everything being so scattered I'm going one more step "faster" burn rate. No pressure signs still. H4350 - I had a hunch this was going to be the standout. Research on the 338-300 PRC variants showed many shooters finding best results with H4350 even up to 250 gr projectiles. I fully expected to be able to hit some pressure signs stepping up to H4350 and I did, just a faint ejector mark starting on the top end. No heavy bolt, click, flat primer, or anything super concerning even up to 3000 fps. I did not want to push it further though with my goal being 2900+. Accuracy wise, hands down best promise of everything tested (see pic below). Charge weights 75/76/77 all clustering, then again 78/79/80 nearly in the same hole clustered. This is exactly what I look for during initial testing. I will go forward with H4350! N555 - This is an interesting powder and I've always wanted to find a use for it. Not completely ruling it out yet but H4350 is the clear choice. The N555 showed some good promise on the low end of 76/77/78/79 all in one hole or within 1/2", so very forgiving around that 2800 fps mark. Good case fill being a bulkier powder than the H series, and known to be one of the most stable powders offered by Vhit. Just on the slower end, above 79 gr it just started scattering, so again H4350 is just the clear choice. This is my preferred method of starting load work on my setups. I'm simply looking for components that are most likely to work well together and meet my goals. Always going with a "coarse to fine" approach, I've found that I can really waste a whole lot of time tinkering and tuning with the wrong combination otherwise. So rather than fine incremental ladders and fine seating depth tests I usually just start bullets approximately .030" off the lands and put charge weight ladders together with full 1 grain incremental changes (in large magnums, .5 in smaller cases). If I need to, or just want to do further testing I'll get into finer tuning of course. In the case of this exact combination, the next step is to go shoot groups at the charge weights of the combinations showing most promise. [ATTACH type="full" alt="20240411_085940.jpg"]563182[/ATTACH] [/QUOTE]
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