Big Al Posted August 19, 2015 Report Share Posted August 19, 2015 Guys, Im considering shortening my 20BR from a 26" barrel to something in the 16"-18" range, now before you all shout in horror I believe there is method in what Im doing. I have a 20TAC and a 20BR and they sort of cross over in terms of use, I decided I would keep the TAC and sell the BR, only because the TAC is already at 20" and is generally the rifle I use most due to its shorter barrel length and portability. Unsurprisingly when I listed the BR for sale I didn't get a sniff but I appreciate its quite a specialist caliber. So then the thought occurred that if I shortened the BR it still has the case capacity to give me 20TAC performance at even a 16" barrel length which would make a very portable rifle. Ive worked this on the basis of losing 40fps/inch so it will do 4000fps easily with a 39gr SBK's and at 16" with 3600fps still available would be good enough for me. The question as per the title is would it require new load development, I suspect it would? I dont mind sacrificing the barrel on this and will be happy to accept the rifle will be even less saleable but if it works out then the 20TAC would be sold and I end up with what I wanted, a portable .20cal. I would welcome any thoughts. Link to comment Share on other sites More sharing options...
The Gun Pimp Posted August 19, 2015 Report Share Posted August 19, 2015 Just do it! But, I'd stick at 18 inches. Be prepared to tune your load a little. Link to comment Share on other sites More sharing options...
Big Al Posted August 19, 2015 Author Report Share Posted August 19, 2015 Just do it! But, I'd stick at 18 inches. Be prepared to tune your load a little. Thanks for the encouragement, can I ask why you would stay at 18" over 16"? Link to comment Share on other sites More sharing options...
justin credible Posted August 19, 2015 Report Share Posted August 19, 2015 I will watch this post as I have a 22br with a 26 inch barrel which is great but a bit long for getting in and out of a vehicle. I have a .308 which had a 32inch barrel that I used for ftr and deer shooting, however it was like trying to lug a scaffold pole up into a high seat so I had it cut to 18inches to just use for deer shooting. I assumed like you that cutting 14 inches off would reduce the velocity by 40 fps per inch, however chrono readings indicate otherwise and velocity only reduced by about 20 fps per inch. I did not bother with redoing load development as it is still as accurate with the short barrel as it was before. Link to comment Share on other sites More sharing options...
247sniper Posted August 19, 2015 Report Share Posted August 19, 2015 Yes you will have to tune your load, it may take just a little tuning or might require a whole new load development with different/probably faster burning powder to enable a complete powder burn instead of spiting out half the un-burnt powder out into the mod and out through the muzzle. Link to comment Share on other sites More sharing options...
The Gun Pimp Posted August 19, 2015 Report Share Posted August 19, 2015 Thanks for the encouragement, can I ask why you would stay at 18" over 16"? The BR case holds a fair bit of powder - if the barrel gets too short you could get muzzle-flash. Link to comment Share on other sites More sharing options...
Big Al Posted August 19, 2015 Author Report Share Posted August 19, 2015 The BR case holds a fair bit of powder - if the barrel gets too short you could get muzzle-flash. Can the likes of Quickload be of help here in giving an idea of percentage burn? Do you need a fair bit of unburnt powder to get flash or can it be relatively small percentages? Link to comment Share on other sites More sharing options...
Big Al Posted August 19, 2015 Author Report Share Posted August 19, 2015 I will watch this post as I have a 22br with a 26 inch barrel which is great but a bit long for getting in and out of a vehicle. I have a .308 which had a 32inch barrel that I used for ftr and deer shooting, however it was like trying to lug a scaffold pole up into a high seat so I had it cut to 18inches to just use for deer shooting. I assumed like you that cutting 14 inches off would reduce the velocity by 40 fps per inch, however chrono readings indicate otherwise and velocity only reduced by about 20 fps per inch. I did not bother with redoing load development as it is still as accurate with the short barrel as it was before. Thats really encouraging Justin, thanks. Link to comment Share on other sites More sharing options...
Blaserman Posted August 19, 2015 Report Share Posted August 19, 2015 Hi Big Al, when I shortened my 6.5x47 from 26" to 20", I lost around 20-25fps per inch, I can't find my data, but it's somewhere, then I chopped another 2" from it and lost 40fps per inch, quite a difference. My load, however, stayed excactly the same and produced the same groups with no tweaking whatsoever. The greatest difference I found was muzzle noise using the same mod, it was noticeably louder for obvious reasons. My take on this is that if I had taken the barrel straight down to 18", I would have divided the velocity loss by the amount of inches cut off, as anyone would, but I wouldn't have realised that the greatest loss of fps was in the last two inches I cut off. Another anomaly I found was that my lighter bullet loads, 95g V-Max lost a huge amount of fps, I will try to find my data and update my post, but my 130g load was the one that lost only 20-25fps per inch for the first 6" I cut off. Hope this helps, just get it cut! Best Regards, Mark Link to comment Share on other sites More sharing options...
Blaserman Posted August 19, 2015 Report Share Posted August 19, 2015 Sorry just to add, I did quite a lot of research on load data before I had my barrel chopped, the general consensus was that if your relatively long barrel worked with a certain powder, it would work with the same barrel if it was shortened, there is apparently, and true for me as I found out, no need to look for a faster burning powder as we all probably think we need to. Cheers, Mark Link to comment Share on other sites More sharing options...
Big Al Posted August 19, 2015 Author Report Share Posted August 19, 2015 Thanks Mark, really useful info. I really would like to go the whole hog to 16" as it would be a really handy rifle at that length, especially with a lighter moderator as well. Mmm, now its a deliberation over the final length 16" or 18" - I guess I should try 18" first as you can't add it back on! Unless of course I can get any further info on the likelihood of muzzle flash? Link to comment Share on other sites More sharing options...
Blaserman Posted August 19, 2015 Report Share Posted August 19, 2015 Hi Al, I have shot mine without a mod to log where the bullet lands just in case I'm out shooting and I suffer a problem with my mod, I can't honestly say I'd turned my rifle into a flame thrower, but I can say without a doubt I have turned it into a "cross county bird scarer", my permissions neighbours dream, and I'm not joking! Link to comment Share on other sites More sharing options...
justin credible Posted August 19, 2015 Report Share Posted August 19, 2015 No muzzle flash from the 18 inch .308 either, and that's holding 50% more powder than your BR case. Go on....get the hacksaw out!! Link to comment Share on other sites More sharing options...
baldie Posted August 20, 2015 Report Share Posted August 20, 2015 Think about it logically. The 20 Br has been necked down by two calibers and still retains the same sized case and capacity. Its massively overbored . If you cut it down to 16"-18" you will, without doubt get muzzle flash. You will also castrate its performance. A .223 will give pretty impressive muzzle flash from a 16" tube....I see it regularly on AR,s. I also remember cutting down a .204 from 26" to 22". That cost 400 feet per second. If you are adamant about a 16" gun, you would be far better advised to stick with the 20 practical. Link to comment Share on other sites More sharing options...
Big Al Posted August 20, 2015 Author Report Share Posted August 20, 2015 Think about it logically. The 20 Br has been necked down by two calibers and still retains the same sized case and capacity. Its massively overbored . If you cut it down to 16"-18" you will, without doubt get muzzle flash. You will also castrate its performance. A .223 will give pretty impressive muzzle flash from a 16" tube....I see it regularly on AR,s. I also remember cutting down a .204 from 26" to 22". That cost 400 feet per second. If you are adamant about a 16" gun, you would be far better advised to stick with the 20 practical. Thanks for the input Dave, I would far rather thrash this one out before the hacksaw than after. The two main issues I have are what velocity will I have and will I suffer from muzzle flash? On the velocity issue, I currently have a 20TAC which I believe you originally shortened to 20" - with 24gr of N133 this gives 3675 which seems very respectable from that load and barrel length, I read here of guys who have lower fps from 24" tubes? surely with a 26" barrel that same load wouldn't have topped 4000+. Im not disputing your figures you got on your rifle but I dont understand why you would lose 100fps per inch, thats miles and miles higher than most people seem to lose? As for castrating the BR's performance? yes if the 26" barrel will do 4000 and I end up with 3500-3600 out of the shortened barrel you could look at it that way but you could also look at it differently, could I get 3600 from a 20TAC/Practical with a 16" barrel? probably not. My idea was that only the size of the BR case would allow me to lose velocity by shortening the barrel but still retain good .20cal performance. If you think a 16" barrelled 20 Practical/TAC wont flash with say 24-25gr of powder then maybe I need to run a faster powder in the BR case to keep the overall powder volume down? The 20BR runs well with N133 so I have read and 30gr seems to give 4000 from a longer barrel so maybe 27gr-30gr will get me where I want to be? Also, if a 223 will flash at 16" why do you feel a .20 cal wont when the charge weight and powder speed will be very similar if not identical? I appreciate the time everyone has put into this thread, I dont want to go chopping until I feel confident I wont ruin the rifle. Link to comment Share on other sites More sharing options...
andybrock Posted August 20, 2015 Report Share Posted August 20, 2015 I'd be more concerned if it lost any accuracy rather than a few hundred fps, a 39gn bullet travelling at 3400, 3600, 3800 or 4000 fps will kill what ever it hits! Link to comment Share on other sites More sharing options...
Big Al Posted August 20, 2015 Author Report Share Posted August 20, 2015 I'd be more concerned if it lost any accuracy rather than a few hundred fps, a 39gn bullet travelling at 3400, 3600, 3800 or 4000 fps will kill what ever it hits! Barrels are shortened all the time with no loss in accuracy, its not a big enough concern to stop me compared to the more relevant points of the discussion. Link to comment Share on other sites More sharing options...
baldie Posted August 20, 2015 Report Share Posted August 20, 2015 Firstly, the rifle i shortened was a .204 ruger NOT a 20 tactical. Its well known the ruger is a far less efficient case. These are facts, measured on a chronograph. What other people lose is irrelevant. A 16" .223 will flash, that means a .20 with a smaller bore will flash even more....its a smaller hole and needs a longer barrel to burn it all. My experiences with the above, are just that...experiences, not quick load predictions or other such guesses. Hard facts, learnt by experiments on my own rifles. The 22 " .204 killed foxes just as dead as it did when it was 26". Link to comment Share on other sites More sharing options...
walkabout Posted August 20, 2015 Report Share Posted August 20, 2015 Big Al I cut down my 6.5x47 from 28" to 26" then 22" then 18". No loss of accuracy, no new load development and still as accurate (When I get my act together). Much more managable, a bit noisier but not enough that my regular shooting buddies sent me to another parish and only lost 260fps with RS60. I have got to like short Barreled rifles and have just cut dow my 6 x 47L. Mark Link to comment Share on other sites More sharing options...
Danpd Posted August 20, 2015 Report Share Posted August 20, 2015 Heres the link to a review by Bruce Potts on a .20 PPC I built, It had a 19" barrel and in the review Bruce gives various loads and velocities with different bullets. http://jmsarmsuk.blogspot.co.uk/2014/08/20-ppc-custom-rifle-from-second-hand.html Link to comment Share on other sites More sharing options...
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