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Author Topic: Chamber reamer dimensions?  (Read 4676 times - 1 votes) 
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Offline Precisionaitworkz

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Chamber reamer dimensions?
« on: September 13, 2017, 12:28:03 PM »
Hello, I have a .25cal barrel coming and will nee to cut the chamber. I do have a Lathe and access to a full machine shop also was a machinist before an injury. So i am looking for dimensions to make my own reamers for .177, .22 and .25 if anyone can help me out that would be awesome
Thanks eveyone
William Donohoe
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Offline rsterne

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Re: Chamber reamer dimensions?
« Reply #1 on: September 13, 2017, 12:57:56 PM »
I assume you want a side view, with dimensions.... Here is a cross-section to start.... Dimension are in "calibers", where 1.000 = the groove dimension of your barrel (chamber size)....



A three flute reamer is shown, but you can also make a single flute reamer by using the dotted lines.... Plunging the end of the mill about 5% of the caliber below the centerline of the reamer is what creates the cutting angle, but you probably already know that.... I'll see what I have for a side view....

Bob

  • Coalmont, BC, Canada
🇺🇦 Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since! 🇺🇦

Airsenal:
1750 CO2 Carbine, .177 Uber-Pumper, .22 Uber-Carbine, .25 Discovery, 2260 PCP 8-shot Carbine, 2260 HPA (37 FPE), 2560 HPA (52 FPE), XS-60c HPA in .30 cal (90 FPE), .22 cal QB79 HPA, Disco Doubles in .22, .25 & .30 cal, "Hayabusa" Custom PCP Project (Mk.I is .22 & .25 cal regulated; Mk.II is .224, .257, 7mm, .308 & .357; Mk.III is .410 shotgun and .458 cal), .257 "Monocoque" Benchrest PCP, .172/6mm Regulated PCP and .224/.257 Unregulated, Three regulated BRods in .25 cal (70 FPE), .30 cal (100 FPE) & .35 cal (145 FPE), .257 Condor (180 FPE).

Offline rsterne

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Re: Chamber reamer dimensions?
« Reply #2 on: September 13, 2017, 12:59:03 PM »
Here is a photo of a finished chamber reamer I made for a .22 cal.... From right to left....

Pilot (just under land diameter)
Undercut
Taper to create Leade (1 deg. per side)
Straight section to create Chamber (starts about halfway along blades)
Step Down to shaft diameter



Same reamer, after use....



You can clearly see the polished area where most of the cutting action takes place.... Forward (right) of that the reamer blades do no touch the lands.... Behind that, the reamer is parallel, of the diameter you wish to make your chamber (I use about 0.001" over groove diameter, to just remove the rifling)....

and for a .257 cal....



Bob
« Last Edit: September 13, 2017, 01:12:47 PM by rsterne »
  • Coalmont, BC, Canada
🇺🇦 Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since! 🇺🇦

Airsenal:
1750 CO2 Carbine, .177 Uber-Pumper, .22 Uber-Carbine, .25 Discovery, 2260 PCP 8-shot Carbine, 2260 HPA (37 FPE), 2560 HPA (52 FPE), XS-60c HPA in .30 cal (90 FPE), .22 cal QB79 HPA, Disco Doubles in .22, .25 & .30 cal, "Hayabusa" Custom PCP Project (Mk.I is .22 & .25 cal regulated; Mk.II is .224, .257, 7mm, .308 & .357; Mk.III is .410 shotgun and .458 cal), .257 "Monocoque" Benchrest PCP, .172/6mm Regulated PCP and .224/.257 Unregulated, Three regulated BRods in .25 cal (70 FPE), .30 cal (100 FPE) & .35 cal (145 FPE), .257 Condor (180 FPE).

Offline Precisionaitworkz

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Re: Chamber reamer dimensions?
« Reply #3 on: September 13, 2017, 01:09:24 PM »
Thanks that helps alot. But i still need groove dimensions for 25 caliber Barrel as I just ordered one and want to have a reamer made before the barrel gets here

William Donohoe
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Offline Finn

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Re: Chamber reamer dimensions?
« Reply #4 on: September 13, 2017, 01:14:00 PM »
Wouldn't the supplier of your barrel know better what those dimensions are? If it is an LW barrel, the dimensions are listed on their website 6,29 mm land and 6,46 mm groove.
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Offline rsterne

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Re: Chamber reamer dimensions?
« Reply #5 on: September 13, 2017, 01:17:17 PM »
I would suggest that is a very bad idea.... There is NO standardization on pellet barrels between manufacturers, you need to measure the groove diameter of your barrel by slugging it, and make the reamer to the appropriate size for YOUR barrel....

If you are intending to use pellets, the chamber and leade is not critical, as the pellet skirt is way oversize, and the head diameter varies widely between makes, and even models of pellets.... You don't need such a shallow leade for pellets, you can literally use 30-45 deg. between the chamber and the rifling.... There is so little pellet area in contact with the rifling, loading is not an issue, like with bullets....

Bob
  • Coalmont, BC, Canada
🇺🇦 Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since! 🇺🇦

Airsenal:
1750 CO2 Carbine, .177 Uber-Pumper, .22 Uber-Carbine, .25 Discovery, 2260 PCP 8-shot Carbine, 2260 HPA (37 FPE), 2560 HPA (52 FPE), XS-60c HPA in .30 cal (90 FPE), .22 cal QB79 HPA, Disco Doubles in .22, .25 & .30 cal, "Hayabusa" Custom PCP Project (Mk.I is .22 & .25 cal regulated; Mk.II is .224, .257, 7mm, .308 & .357; Mk.III is .410 shotgun and .458 cal), .257 "Monocoque" Benchrest PCP, .172/6mm Regulated PCP and .224/.257 Unregulated, Three regulated BRods in .25 cal (70 FPE), .30 cal (100 FPE) & .35 cal (145 FPE), .257 Condor (180 FPE).

Offline rsterne

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Re: Chamber reamer dimensions?
« Reply #6 on: September 13, 2017, 01:29:51 PM »
I uploaded the side view for the 22 cal reamer shown above.... Here it is....



This was made to fit a barrel which had 0.213" lands x 0.217" grooves.... The undercut behind the pilot is made deep enough that the cutting takes place in about the middle of the blades.... in the area marked "Leade" on the drawing.... It ended up at about 0.200" on this reamer.... The front half of the "working part" of the reamer is tapered 1 deg. per side (to the back of where the "Leade" is), and the rear half (for the chamber) is parallel.... The shaft is also undercut to about 0.200"....

Bob
  • Coalmont, BC, Canada
🇺🇦 Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since! 🇺🇦

Airsenal:
1750 CO2 Carbine, .177 Uber-Pumper, .22 Uber-Carbine, .25 Discovery, 2260 PCP 8-shot Carbine, 2260 HPA (37 FPE), 2560 HPA (52 FPE), XS-60c HPA in .30 cal (90 FPE), .22 cal QB79 HPA, Disco Doubles in .22, .25 & .30 cal, "Hayabusa" Custom PCP Project (Mk.I is .22 & .25 cal regulated; Mk.II is .224, .257, 7mm, .308 & .357; Mk.III is .410 shotgun and .458 cal), .257 "Monocoque" Benchrest PCP, .172/6mm Regulated PCP and .224/.257 Unregulated, Three regulated BRods in .25 cal (70 FPE), .30 cal (100 FPE) & .35 cal (145 FPE), .257 Condor (180 FPE).

Offline Precisionaitworkz

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Re: Chamber reamer dimensions?
« Reply #7 on: September 13, 2017, 04:46:18 PM »
Thank you for the info. The barrel is a cheap Crosman one i ordered to modify it to fit a Crosman 2240 and may even put one on my 1322 just for fun lol
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Offline Precisionaitworkz

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Re: Chamber reamer dimensions?
« Reply #8 on: September 13, 2017, 04:48:25 PM »
Also just curious there's no standardized dimensions for air gun barrels how are manufacturers reaming out the chambers? Im pretty sure they wont check each one.
Thanks
William Donohoe
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Offline Precisionaitworkz

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Re: Chamber reamer dimensions?
« Reply #9 on: September 13, 2017, 05:19:09 PM »
I should clarify I am asking about the people that sell conversions using somebody else's Barrel not necessarily big manufacturers
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Offline rsterne

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Re: Chamber reamer dimensions?
« Reply #10 on: September 13, 2017, 09:07:05 PM »
Barrels from any given manufacturer will have "standard" dimensions, and also an allowable tolerance range, for THAT manufacturer.... What I meant by "no standardization" is that Crosman barrels could be different from BSA, from Evanix, from Hatsan, or from Lothar Walther.... All you need to do to satisfy yourself that this is the case is push some pellets through various brands, and examine what they look like.... and also how hard it is to get them started will give you an idea on the large range of tolerances for chambers....

As I said, pellets are VERY forgiving as to barrel tolerances.... but the difference in barrels, not only from one manufacturer, but from one barrel to the next in a give model airgun.... is the reason that one gun loves one pellet, while the same pellet is terrible in another....

Bob
  • Coalmont, BC, Canada
🇺🇦 Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since! 🇺🇦

Airsenal:
1750 CO2 Carbine, .177 Uber-Pumper, .22 Uber-Carbine, .25 Discovery, 2260 PCP 8-shot Carbine, 2260 HPA (37 FPE), 2560 HPA (52 FPE), XS-60c HPA in .30 cal (90 FPE), .22 cal QB79 HPA, Disco Doubles in .22, .25 & .30 cal, "Hayabusa" Custom PCP Project (Mk.I is .22 & .25 cal regulated; Mk.II is .224, .257, 7mm, .308 & .357; Mk.III is .410 shotgun and .458 cal), .257 "Monocoque" Benchrest PCP, .172/6mm Regulated PCP and .224/.257 Unregulated, Three regulated BRods in .25 cal (70 FPE), .30 cal (100 FPE) & .35 cal (145 FPE), .257 Condor (180 FPE).

Offline rrdstarr

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Re: Chamber reamer dimensions?
« Reply #11 on: November 06, 2017, 12:23:30 AM »
Hey Bob, long time no questions from me!  Lol!
What material are you making the creamer from?  O2?

Thanks, Rick
I have a.300 TJ barrel and need to cut the chamber in for an AF talon.
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Offline rsterne

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Re: Chamber reamer dimensions?
« Reply #12 on: November 06, 2017, 12:59:12 AM »
O1 drill rod....

Bob
  • Coalmont, BC, Canada
🇺🇦 Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since! 🇺🇦

Airsenal:
1750 CO2 Carbine, .177 Uber-Pumper, .22 Uber-Carbine, .25 Discovery, 2260 PCP 8-shot Carbine, 2260 HPA (37 FPE), 2560 HPA (52 FPE), XS-60c HPA in .30 cal (90 FPE), .22 cal QB79 HPA, Disco Doubles in .22, .25 & .30 cal, "Hayabusa" Custom PCP Project (Mk.I is .22 & .25 cal regulated; Mk.II is .224, .257, 7mm, .308 & .357; Mk.III is .410 shotgun and .458 cal), .257 "Monocoque" Benchrest PCP, .172/6mm Regulated PCP and .224/.257 Unregulated, Three regulated BRods in .25 cal (70 FPE), .30 cal (100 FPE) & .35 cal (145 FPE), .257 Condor (180 FPE).

Offline kirktink

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Re: Chamber reamer dimensions? It's not that complicated....
« Reply #13 on: December 17, 2017, 02:09:31 AM »
you guys are making this entirely too complicated.. Call Dave Kiff at pacific tool and gauge and get throating reamers in whatever caliber you need.. the are piloted with interchangeable (caliber specific of course) rotating bushing that you can order in sets to match any barrel you will run across. No respectable benchrest gunsmith will use anything other than a piloted bushing type reamer. without a rotating pilot, the rifleing just ahead of your bullet is apt to be galled/rough/ & unacceptable
Barrel specs are only consistent as in you can get barrels with the exact same land and groove dimensions in cut rifled and hammer forged barrels... button rifled barrels have variation as the button (which swages the grooves into the barrel,  wears slowly until the barrel maker decides they are out of tolerance & then they are then replaced.) With air rifle barrels, only a throating reamer is all that is required (as you don't have to ream out a chamber for whatever round you are shooting).

If you wanted to get really serious,, you can send Dave the  bullets you will be using, and he will make the throater to match the exact dimensions of your bullet!!. Most likely, he will have "in stock" excellent fantastic throaters that will accommodate your needs right now. I used his reamers exclusively for more than 20 years of my benchrest (centerfire and rimfire) and custom hunting rifle smithing builds. & now use his throating reamers on my air rifle barrels.. He is a really nice guy to boot.

Kirk
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Offline kirktink

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Re: Chamber reamer dimensions?
« Reply #14 on: December 17, 2017, 03:00:51 AM »
re the standard...Chambers are dictated by Saami standards... (a chamber would be for any particular round,, ie .223 or .308 winchester ect.) Bob mentioned the barrel variation...

The main reason i suggest buying the throater, is that with a bushing set, you can fit your reamer to any barrel.. otherwise as Bob suggested measuring the barrel (by using a cerrosafe cast i assume??) You would have to grind a reamer potentially for every barrel you (chamber/throat).  unless the barrel specs were smaller & you could grind off the old reamer to fit.. if bigger you would have to start anew....

I admire your ability to grind a reamer that actually works... You must be a "tool and die" machinist??.. grinding reamers i don't think is on the average machinist skill set???? I would never have attempted it myself (my gunsmithing skills were self taught with a little tutoring from a tool and die machinist that i bought my 2 lathes & milling machine & surface grinder from I decided to start building my own stuff because of the wait time... ie i would need/want a new barrel on one of my competition rifles and would have to wait 6 months for it.. after i learned how to do the work myself, obviously i didn't have to wait anymore;>) I even started making custom match bullets for the same reason. It was all fun for 20 yrs or so until dad died.. Now i mainly just do personal work.

... . The only time i didn't use one of Dave's products,, was for a wadcutter style bullet/pellet, here i used a mini boring bar to relieve the bore enough for the bullet to have a snug fit & it worked quite well. ..

anyway Bob,, i hope you run across a topic i posted re my 45 "bigbore" I look forward to hearing from you.. time for bed...

Kirk
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Offline Hobbyman2007

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Re: Chamber reamer dimensions?
« Reply #15 on: February 24, 2018, 08:56:46 AM »
Thanks for the tip Kirk . I just placed an order for .25 and .22 air rifle dealers and bushings . The prices are quite reasonable . The nice thing is you don't need a lathe and can use a t handle if just cleaning up an existing mess you've made with a dremel ( not that I would do such a thing )
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Offline Motorhead

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Re: Chamber reamer dimensions?
« Reply #16 on: February 24, 2018, 12:41:18 PM »
I have done quite a few barrels w/o using reamers, but just a slightly modified drill.
By diamond or stone lapping the drills outer most corners into a neutral rake large radius you eliminate spiraling tooling marks on cut surface while also having drill be self centering as it cuts just a few thousandths of material.
Done in a lathe running at slow speed been able to perform perfect leade throats that only required a quick cratex point polish/deburr.

Just earlier this week did an LW .22 barrel using a .221 ( #2 drill ) which just removed rifling enough for pellets head to enter but catch the skirt.
Drilled to the forward edge of transfer port hole, when pellet seated the skirt sets right on the riflings starting edge.  Shot excellent !!

Getto, but it works great if you can use fractional, metric, number or letter size drills that are correct size for leade wanted and get a nice radius on the outer point edges.

Scott
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