My load workup for 17 Hornet Jan 26, 2015 11:31:23 GMT sako75varminter, bangbangman, and 1 more like this
Post by sam17hh on Jan 26, 2015 11:31:23 GMT
I thought I’d give a detailed account of how I’ve got to where I am now regarding loads for the 17 Hornet. It’s a bit of a read but hopefully will be of interest to anyone looking to develop a load for the 17 Hornet (although it seems to be quite an uncommon calibre at the moment).
I have an Anschutz model 1730 which had a previous life as a 22Hornet before being re-barrelled with a 1 in 10” twist 24” Walther match grade S/S heavy varmint barrel by Brock and Norris. I bought it with 25 rounds down the new barrel (cock up as the customer wanted a lightweight barrel for walking around so it ended up being sold). The chamber size seems to be on the large side of SAAMI specs from what I have measured.
So far I've developed two excellent well-sub-MOA loads - one for Hornady 20gr V-Max and one for 25gr V-Max.
For the 20gr load I started with Lil' gun as I noted a few people online sharing success stories with this powder. I could not get anywhere near the 10gr max load with pressure signs showing at 9.4gr, and in fact I settled on 9.1gr at a safe 3630fps (the quoted max velocity for a 10gr load). I found the powder quite inconsistent in terms of velocity spread so after a little more research I tried Accurate A1680.
A1680 is superb in this calibre! Book max for the 20gr V-Max (as per Hornady 9th edition manual) suggests 12.4gr and MV of 3750fps. With my rifle I’m getting 3750fps with a load of 12.55gr. (I worked up to find my max load where pressure signs are showing and ended up at 12.8gr compressed and 3880fps!) I carried out Dan Newberry’s Optimum Charge Weight tests for both powder load and seating depth with my final load being 12.55gr A1680, seated at 1.404” CBTO (factory COAL of 1.710” equates to 1.401” CBTO measurement). These achieve 1/2MOA groups quite consistently with the occasional ¼” 4 shot group at 100yds. Primers used are CCI BR-4 and all cases fireformed, flash hole uniformed/deburred, primer pocket uniformed, neck sized (using a Hornady full length die and shoulder bumped 0.002” and trimmed to 1.340” plus weight sorted to within 0.5gr of each other. Anal I know, but the work pays off! Incidentally I was next to SwampDonkey from this forum on the 100yds point at Bisley when I did this test.
Over the last 2 weeks concluding on the weekend just gone I have done some load testing with 25gr V-Max bullets. Now these are the most surprising loads of all…
I tried to source some H322 powder which showed the most promising load data for high velocity but instead bought some AA2015BR powder (now Lovex S3060 or something) as it is the nearest thing I could find available. I began testing with this purely over the chronograph to find a max load. Due to the large grains I was only able to achieve 3200fps with the 25gr bullets with ZERO pressure signs. That was a completely full case compressed load. I then turned to the A1680 once again and began testing with this from the recommended start load. 10.9gr is the max listed with 3200fps – ish from memory (load data is conflicting depending upon source. At this load it supposedly only develops 36,000psi chamber pressure). This load came and went, but still zero pressure signs so I carried on. Long story short but I finally got up to partly flattened primers and a slightly sticky bolt lift with velocities of 3611fps and 12.1gr A1680!! Quite incredible that I’d gone that far over book max to reach ‘my’ gun’s max. I’m sure the inevitable flaming will arise from this but do understand I carried this out safely by working up in stages, checking each case for pressure signs and each shot over the chrono, with eye and ear protection worn.
I prepped some loads to start OCW testing and seated at the same depth as my 20gr load, so 1.404” CBTO with loads tested from 11.1-11.9gr in 0.2gr increments. Testing at 200yds last weekend I wasn’t hugely impressed with the accuracy with most groups (5 shots) landing in around 2.5 - 3” but one group at 11.9gr managed 4 shots in ¾” with one flyer another ¾” away from that. There was huge spread in where the bullets were impacting too which surprised me, but no obvious node. I decided to repeat the test around the 11.9gr accurate load and go 0.1gr either side of it (a quick test at 110yds at home one still afternoon). 11.8gr and 11.9gr hit the same spot and 12.0gr impacted ¼” high and right of the previous two loads. Next was time for the bullet seating OCW test.
I loaded 4-5 rounds in 0.005” increments from 1.400” to 1.440” which is the max mag length available, with still around 0.090” jump to lands at that length. Test range was 110yds and I used CCI No: 400 SRP. Starting round robin style after warming and dirtying a previously cleaned barrel from shortest to longest it was quickly evident that 1.400/405/410 were scattering badly, but from 1.415 through to 1.425 the bullets hit the same POI, then moved again at 1.430”. I immediately discounted any further shots in this ‘scatter node’ and continued round robin from 1.415 to 1.430, and again this confirmed a node in this area. Further testing refined it to a node between 1.415 and 1.425 with 1.420 producing the best 5 shot group of 0.6” overall with 4 of the shots in a 0.3” group and the flier being a slightly overcharged round sending the bullet out 70fps faster than the other 4! 1.425 produced a 0.63” 5 shot group and 1.415 a 0.8” group. Chrono data for the 1.420” CBTO group was 3542fps/3546fps/3522fps/3611fps(flier)/3541fps. I’m impressed with the group and the velocity data and going forward will be sticking to the 25gr V-Max bullets for their improved ballistics, higher energy and accuracy.