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Thank you to the 20 Practical Gurus and some rookie questions

Yeah Mike, make it easy on yourself!

Lapua brass, temp insensitive powders, hard primer cups, and medium loads. Don't try to make cartridges what they aren't, if you want higher velocity then get a bigger case and even doing that can lead to other problems....

Find the balance, coming from someone who used to resist sensibility.
 
I am odd man out here - I had a tight neck chambered(.230). I've only shot if 30X but its been a laser shooting my fireforming loads of Lapua (turned)/H4198/32gr Sierras. Once I get 100 rounds down range, I'll chrony, looking for something in 3900 range.

Good luck with it.

Gerald
 
geraldgee said:
I am odd man out here - I had a tight neck chambered(.230). I've only shot if 30X but its been a laser shooting my fireforming loads of Lapua (turned)/H4198/32gr Sierras. Once I get 100 rounds down range, I'll chrony, looking for something in 3900 range.

Good luck with it.

Gerald
Click to expand...

Not the odd man out, just shooting the .20 I. :D I had best accuracy in the 32s IIRC, around 3750.
 
I will say this thread has provided lot's of useful info on the 20P and the 20I/20C. Thanks to all. I have pretty much have my questions answered. Perhaps if I had phrased my initial question better (it was clear as mud) I would not have led some to believe I was after 20I/20C stuff.
Lets start again. I have assembled a 20P. 11T, 3 grove Ex-Caliber, 26". Bullet is 39BK at .010 off. Primer BR4. Started with H335 and got leery of temp sensitivity. I have a bunch of H4895 and from Google. Google, Google I decided to use it. Brass was new General Dynamics mil-spec. the plan for doing the brass is clearly spelled out in a daily bulletin article, also has links for you AR guys. I don't do links yet. Easy to find. Anyway, call that the brass "PLAN". Use the PLAN and follow a highly technical procedure to implement the PLAN. The procedure is MIL-T-FP41. (Make It Like the Freakin Plan For once).
Loaded some rounds for pressure check. Not exactly informative. But got a SWAG for max load. Located a node with the Magnetospeed. Loaded up 3 cartridges each at 25.1, 25.3, 25.5, 25.7 & 25.9. Shot targets @ 100yds. Looked at targets and damn near crapped my pants. First group was < 3/4" all the rest you could easily cover with a dime. The 25.5 (~3850ish) group was almost a single hole, Saaweeeet! started putzing around shooting groups to narrow down charge. Settled on 25.5, imagine that! I was just starting to tweak seating depth. Then I realized I had a my first ever PD hunt coming up and 142 pcs of brass was not probably gonna cut it. Picked up some Mil surp 1X prepped stuff. Ended up with 376 pcs of LC15 ready to rock. Load some rounds to check node. the 25.1 load gives ~ 3860ish. So I go hmmm that's interesting. Using a case with slightly larger capacity (~ 1%) I expected to have to go to ~25.6 to get back to old node speed. Hence the question on barrel speed up. I left out that I hadn't shot it over the chrony since about round #25. I'm now at #182. I was concerned because I could picture myself hunting PDs and if the barrel hadn't settled down I was going to maybe get slight POI changes. I can hear my buddy "You used to be able to shoot, what happened" etc, etc. My worry has faded away, per provided info that the barrel should be seasoned.
I am still slightly curious about POI and slight MV changes. I am now going to start shooting groups again, determine final charge weight and seating depth. This is the fun part. One of the tests I will do is make 5 or so charges across the node window. Shoot them into one group and see what it looks like. Any chance I will be able to cover that group with a dime?
I appreciate the info on pressure signs. I still wish the small brass would behave like their bigger brothers.
On that subject I pose a hypothetical. In looking over the chrono data from my last range session, I noticed some odd numbers. Average MV change per .2gr change in charge weight was averaging ~ 35fps or so. Then 3908, 3905,4005,4017, 4012 a step increase of 100fps and then flattens out ~ in the 4012 area. I have a dim memory of reading about when the velocity plateaus you have reached max pressure. Anything to that? No big deal, just curious.
One more thing: KISS Anyway, thanks Mike
 
I kind of doubt there are many guys blasting off thirty rounds then checking their speed with a chrono to see how it may affect their trajectory. You are going to have far more interference with a mile or two in wind change. I'd just find a powder that gives you a wide node and on the longer shots (400+ in my opinion) with that 39 - adjust your fire as needed. If you miss and see that you are in a no-wind condition - simply adjust the clicks as needed to get you on. It is seldom I go on a trip and don't adjust the clicks one way or another to suit the elevation, humidity, air temperature, etc.. Inside 400 I start with my zero dope. Beyond that - I shoot at a small rock or something to show where I'm impacting then note the adjustment needed at that range. You simply can't control all the variables beforehand. That is what, after all, makes the A/R so special - a fast second shot with a quick mental elevation/windage change before conditions change again. Welcome to the site. Lots of good guys and gals here that are very knowledgeable and willing to share.
 
searcher said:
I kind of doubt there are many guys blasting off thirty rounds then checking their speed with a chrono to see how it may affect their trajectory. You are going to have far more interference with a mile or two in wind change. I'd just find a powder that gives you a wide node and on the longer shots (400+ in my opinion) with that 39 - adjust your fire as needed. If you miss and see that you are in a no-wind condition - simply adjust the clicks as needed to get you on. It is seldom I go on a trip and don't adjust the clicks one way or another to suit the elevation, humidity, air temperature, etc.. Inside 400 I start with my zero dope. Beyond that - I shoot at a small rock or something to show where I'm impacting then note the adjustment needed at that range. You simply can't control all the variables beforehand. That is what, after all, makes the A/R so special - a fast second shot with a quick mental elevation/windage change before conditions change again. Welcome to the site. Lots of good guys and gals here that are very knowledgeable and willing to share.
Click to expand...

Hello The difference in round count from chrono session #1 to chrono session #2 was 147 rounds on a new barrel. As I said it doesn't matter now the barrel is seasoned. ie Even if I shoot 300 rounds now on a PD shoot it shouldn't change any. My curiousity was about what appears to be a slight speedup in MV from round 25 to 182. I must have been clear as mud again. Not gonna change anymore, doesn't matter. I have my load, and appears as if it's gonna be very accurate, maybe too fast to be in the comfort zone for for some folks. If it isn't accurate, accuracy trumps speed, I look for as fast as I can lean on it safely & hopefully it's accurate there. If not, reluctantly I move down to the next node till the accuracy is there. If I have to go down further, new powder and or bullet and start over. Don't do ARs. Short reason: 'Nam, M16, dead friends. I will defend your right to have them, don't want one. You really don't want to know my real opinion. I do have a BAR 243 and a Mini 14. The BAR works great on those a$$hole running coyotes if (ok, when) you miss with the bolt. 70BK
 
MikeT49 said:
I will say this thread has provided lot's of useful info on the 20P and the 20I/20C. Thanks to all. I have pretty much have my questions answered. Perhaps if I had phrased my initial question better (it was clear as mud) I would not have led some to believe I was after 20I/20C stuff.
Lets start again. I have assembled a 20P. 11T, 3 grove Ex-Caliber, 26". Bullet is 39BK at .010 off. Primer BR4. Started with H335 and got leery of temp sensitivity. I have a bunch of H4895 and from Google. Google, Google I decided to use it. Brass was new General Dynamics mil-spec. the plan for doing the brass is clearly spelled out in a daily bulletin article, also has links for you AR guys. I don't do links yet. Easy to find. Anyway, call that the brass "PLAN". Use the PLAN and follow a highly technical procedure to implement the PLAN. The procedure is MIL-T-FP41. (Make It Like the Freakin Plan For once).
Loaded some rounds for pressure check. Not exactly informative. But got a SWAG for max load. Located a node with the Magnetospeed. Loaded up 3 cartridges each at 25.1, 25.3, 25.5, 25.7 & 25.9. Shot targets @ 100yds. Looked at targets and damn near crapped my pants. First group was < 3/4" all the rest you could easily cover with a dime. The 25.5 (~3850ish) group was almost a single hole, Saaweeeet! started putzing around shooting groups to narrow down charge. Settled on 25.5, imagine that! I was just starting to tweak seating depth. Then I realized I had a my first ever PD hunt coming up and 142 pcs of brass was not probably gonna cut it. Picked up some Mil surp 1X prepped stuff. Ended up with 376 pcs of LC15 ready to rock. Load some rounds to check node. the 25.1 load gives ~ 3860ish. So I go hmmm that's interesting. Using a case with slightly larger capacity (~ 1%) I expected to have to go to ~25.6 to get back to old node speed. Hence the question on barrel speed up. I left out that I hadn't shot it over the chrony since about round #25. I'm now at #182. I was concerned because I could picture myself hunting PDs and if the barrel hadn't settled down I was going to maybe get slight POI changes. I can hear my buddy "You used to be able to shoot, what happened" etc, etc. My worry has faded away, per provided info that the barrel should be seasoned.
I am still slightly curious about POI and slight MV changes. I am now going to start shooting groups again, determine final charge weight and seating depth. This is the fun part. One of the tests I will do is make 5 or so charges across the node window. Shoot them into one group and see what it looks like. Any chance I will be able to cover that group with a dime?
I appreciate the info on pressure signs. I still wish the small brass would behave like their bigger brothers.
On that subject I pose a hypothetical. In looking over the chrono data from my last range session, I noticed some odd numbers. Average MV change per .2gr change in charge weight was averaging ~ 35fps or so. Then 3908, 3905,4005,4017, 4012 a step increase of 100fps and then flattens out ~ in the 4012 area. I have a dim memory of reading about when the velocity plateaus you have reached max pressure. Anything to that? No big deal, just curious.
One more thing: KISS Anyway, thanks Mike
Click to expand...

either you or me need a Xanax..
 
Nothing wrong with pushing for speed but I do hope that "high node" has a little wiggle room for that rifle when considering the heat of summer when out prairie doggin'. If you are within 3/10 of a grain to "maxing" that load out (in my rifles - that would be with the same barrel length) - and your test loads were in under 65 temp weather - you will probably find that load too hot when in 95 temps with most powders. Sorry about your friends in 'Nam. I was a Marine during 'Nam and lost lots too. If I were you - I'd try not to hold a darn thing against an A/R-15 or M-16 unless your friends had gun accidents or friendly fire was to blame. You might learn to hate the AK-47 instead. Why allow those commie xxxxxxxs to deny you a fine varmint rifle?
 
searcher said:
Nothing wrong with pushing for speed but I do hope that "high node" has a little wiggle room for that rifle when considering the heat of summer when out prairie doggin'. If you are within 3/10 of a grain to "maxing" that load out (in my rifles - that would be with the same barrel length) - and your test loads were in under 65 temp weather - you will probably find that load too hot when in 95 temps with most powders. Sorry about your friends in 'Nam. I was a Marine during 'Nam and lost lots too. If I were you - I'd try not to hold a darn thing against an A/R-15 or M-16 unless your friends had gun accidents or friendly fire was to blame. You might learn to hate the AK-47 instead. Why allow those commie xxxxxxxs to deny you a fine varmint rifle?
Click to expand...

I have been and will be using the low end of the high node ~ 25.1 gr. I switched to H4895 from H335 because of the temp sensitivity issue with H335. My response to the AR suggestion was kind of a knee jerk thing, I hope I didn't offend anybody. I was in the Navy during Nam, or what my Marine friends from back home referred to as Uncle Sam's Canoe Club. AAaarggh! One of the friends I lost went down in 1967. Partly to fault was a jammed M-16 or so we heard. I know I need to let it go, after all the M-16 is the bastard child of the AR. Took the military to figure out how to take a perfectly functioning firearm and get it to fail. Wrong powder, etc. I am slowly coming around to the AR. My bud where I'm headed to visit and shoot some PDs hardly ever uses his bolt guns anymore. Mostly ARs. He has a couple of them with 20P chambering. I suspect I will be shooting them. My opinion of the AK-47 is not printable.
 
Last edited:
I am a .20P fan. I like LC 5.56 brass (new, no swage pp), 40 Vmax, & IMR 8508 or H CFE.223. CCI 41 primers. I use either 25.5 IMR 8208 or 27 H CFE.223. I size necks to .226 OD, Redding F/L bushing die and then skim turn necks to just clean up. My rifle has a 4 l/g barrel, 11 twist. I also use whatever .223 brass I can scrounge up but small base resize it if once fired (used). Brass lasts a long time with minimum neck work hardening, primer pockets stay tight. I have an unopened box of 100 Lapua .223 that has been around since 2013. My velocities are a leisurely 3750. Just a guess but at over 300 the 40 grainers might be going faster than 32's.
 
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